Specialist or generalist? The question of which physicians are best suited to treat patients with a single condition or in a particular care setting has been the subject of study and debate for decades.13 Investigators have asked whether cardiologists provide better care for patients with acute myocardial infarction1 or whether intensivists achieve superior outcomes in critical care settings.2 One implication of these studies is that a hospital or health plan armed with this knowledge would be capable of improving outcomes by directing a greater proportion of patients to the superior physician group. In fact, much of the literature reporting on the effect of hospitalists is simply a new variation on this old theme.48 Of course, to realize any potential gains, there must be an adequate number of specialists or the ability to increase the supply quickly. Neither option tends to be especially realistic. Further, these studies have a tendency to create false dilemmas because consultation and comanagement are more common than single‐handed care.

Because studies comparing the outcomes of physician groups are generally not randomized trials, minimizing the threat of selection bias (ie, patient prognosis influencing treatment assignment) is of paramount importance. For example, one can imagine how patients with a particularly poor prognosis in the setting of acute myocardial infarction (perhaps related to age or the presence of multiple comorbidities) might be preferentially directed toward a general medicine service, especially when remunerative cardiac intervention is unlikely. In such instances, comparing simple mortality rates would erroneously lead to the conclusion that patients cared for by cardiologists had better outcomes.

Multivariable modeling techniques like logistic and liner regression and more recently, propensity‐based methods, are the standard approaches used to adjust for differences in patient characteristics stemming from nonrandom assignment. When propensity methods are used, a multivariable model is created to predict the likelihood, or propensity, of a patient receiving treatment. Because it is not necessary to be parsimonious in the development of propensity models, they can include many factors and interaction terms that might be left out of a standard multivariable logistic regression. Then, the outcomes of patients with a similar treatment propensity who did receive the intervention can be compared to the outcomes of those who did not. Some have gone so far as to use the term pseudorandomized trial to describe this approach because it is often capable balancing covariates between the treated and nontreated patients. However, as sophisticated as this form of modeling may be, these techniques at best are only capable of reducing bias related to measured confounders. Residual bias from confounders that go unmeasured remains a threatand is particularly common when relying on administrative data sources.

In this issue of the Journal of Hospital Medicine, Gillum and Johnston9 apply a version of instrumental variable analysis, a technique borrowed from econometrics, to address the issue of unmeasured confounding head‐on. The approach, called group‐treatment analysis, is based on the relatively simple notion that if neurologist care is superior to that provided by generalists, all other things being equal, hospitals that admit a large proportion of their patients to neurologists should have better outcomes than those admitting a smaller proportion. This approach has theoretical advantages over propensity adjustment because it does not attempt to control for differences between treated and untreated patients at the individual hospital level, where, presumably, the problem of selection bias is more potent. Although their standard multivariable models suggested that patients admitted to a neurologist were 40% less likely to die while hospitalized than patients admitted to generalists, Gillum and Johnston found that after adjusting for the institutional rate of neurologist admission, any apparent benefit had disappeared. Similar results were observed in their analyses of length of stay and cost.

In some ways, the findings of this study are more startling for the questions they raise about the presence of residual bias in observational studies using conventional multivariable methods than for the fact that generalist care was found to be as safe as neurologist care and add to a growing body of evidence suggesting that stronger methods are required to deal with residual bias in observational studies.10

Although the results largely speak for themselves and should be reassuring given that most patients with ischemic stroke in the United States are and will continue to be cared for by generalists, a number of important questions remain unanswered. First, the focus of this study was on short‐term outcomes. Because functional status and quality of life probably matter as much or more to stroke patients than in‐hospital mortality and certainly length of stay or cost, we can only hope that it is safe to extrapolate from the authors' mortality findings. Second, this study relied on data from the late 1990s, before the widespread availability of hospitalists. How generalizable the findings would be in today's environment is uncertain. On a more practical level, the authors were unable to assess the impact of formal or informal consultation by a neurologist. If this played a significant role (a reasonable assumption, I think), this would have blurred any distinction between the 2 physician groups. For this reason one cannot draw any conclusions about a more pragmatic questionthe necessity or benefit of neurologist consultation in patients with ischemic stroke.

Looking ahead, researchers hoping to improve the outcomes of patients with acute ischemic stroke should focus on developing novel models of collaboration between hospitalists and neurologists, instead of simply trying to prove that a neurologist should take care of a patient suffering a stroke alone versus a hospitalist without help from a neurologist. We also should recognize that the use of protocols and checklists or leveraging information technology investments may provide clinical decision support that improves care more than just consulting a specialist or having them care for the patient.

Specialist or generalist? The question of which physicians are best suited to treat patients with a single condition or in a particular care setting has been the subject of study and debate for decades.13 Investigators have asked whether cardiologists provide better care for patients with acute myocardial infarction1 or whether intensivists achieve superior outcomes in critical care settings.2 One implication of these studies is that a hospital or health plan armed with this knowledge would be capable of improving outcomes by directing a greater proportion of patients to the superior physician group. In fact, much of the literature reporting on the effect of hospitalists is simply a new variation on this old theme.48 Of course, to realize any potential gains, there must be an adequate number of specialists or the ability to increase the supply quickly. Neither option tends to be especially realistic. Further, these studies have a tendency to create false dilemmas because consultation and comanagement are more common than single‐handed care.

Because studies comparing the outcomes of physician groups are generally not randomized trials, minimizing the threat of selection bias (ie, patient prognosis influencing treatment assignment) is of paramount importance. For example, one can imagine how patients with a particularly poor prognosis in the setting of acute myocardial infarction (perhaps related to age or the presence of multiple comorbidities) might be preferentially directed toward a general medicine service, especially when remunerative cardiac intervention is unlikely. In such instances, comparing simple mortality rates would erroneously lead to the conclusion that patients cared for by cardiologists had better outcomes.

Multivariable modeling techniques like logistic and liner regression and more recently, propensity‐based methods, are the standard approaches used to adjust for differences in patient characteristics stemming from nonrandom assignment. When propensity methods are used, a multivariable model is created to predict the likelihood, or propensity, of a patient receiving treatment. Because it is not necessary to be parsimonious in the development of propensity models, they can include many factors and interaction terms that might be left out of a standard multivariable logistic regression. Then, the outcomes of patients with a similar treatment propensity who did receive the intervention can be compared to the outcomes of those who did not. Some have gone so far as to use the term pseudorandomized trial to describe this approach because it is often capable balancing covariates between the treated and nontreated patients. However, as sophisticated as this form of modeling may be, these techniques at best are only capable of reducing bias related to measured confounders. Residual bias from confounders that go unmeasured remains a threatand is particularly common when relying on administrative data sources.

In this issue of the Journal of Hospital Medicine, Gillum and Johnston9 apply a version of instrumental variable analysis, a technique borrowed from econometrics, to address the issue of unmeasured confounding head‐on. The approach, called group‐treatment analysis, is based on the relatively simple notion that if neurologist care is superior to that provided by generalists, all other things being equal, hospitals that admit a large proportion of their patients to neurologists should have better outcomes than those admitting a smaller proportion. This approach has theoretical advantages over propensity adjustment because it does not attempt to control for differences between treated and untreated patients at the individual hospital level, where, presumably, the problem of selection bias is more potent. Although their standard multivariable models suggested that patients admitted to a neurologist were 40% less likely to die while hospitalized than patients admitted to generalists, Gillum and Johnston found that after adjusting for the institutional rate of neurologist admission, any apparent benefit had disappeared. Similar results were observed in their analyses of length of stay and cost.

In some ways, the findings of this study are more startling for the questions they raise about the presence of residual bias in observational studies using conventional multivariable methods than for the fact that generalist care was found to be as safe as neurologist care and add to a growing body of evidence suggesting that stronger methods are required to deal with residual bias in observational studies.10

Although the results largely speak for themselves and should be reassuring given that most patients with ischemic stroke in the United States are and will continue to be cared for by generalists, a number of important questions remain unanswered. First, the focus of this study was on short‐term outcomes. Because functional status and quality of life probably matter as much or more to stroke patients than in‐hospital mortality and certainly length of stay or cost, we can only hope that it is safe to extrapolate from the authors' mortality findings. Second, this study relied on data from the late 1990s, before the widespread availability of hospitalists. How generalizable the findings would be in today's environment is uncertain. On a more practical level, the authors were unable to assess the impact of formal or informal consultation by a neurologist. If this played a significant role (a reasonable assumption, I think), this would have blurred any distinction between the 2 physician groups. For this reason one cannot draw any conclusions about a more pragmatic questionthe necessity or benefit of neurologist consultation in patients with ischemic stroke.

Looking ahead, researchers hoping to improve the outcomes of patients with acute ischemic stroke should focus on developing novel models of collaboration between hospitalists and neurologists, instead of simply trying to prove that a neurologist should take care of a patient suffering a stroke alone versus a hospitalist without help from a neurologist. We also should recognize that the use of protocols and checklists or leveraging information technology investments may provide clinical decision support that improves care more than just consulting a specialist or having them care for the patient.

Specialist or generalist? The question of which physicians are best suited to treat patients with a single condition or in a particular care setting has been the subject of study and debate for decades.13 Investigators have asked whether cardiologists provide better care for patients with acute myocardial infarction1 or whether intensivists achieve superior outcomes in critical care settings.2 One implication of these studies is that a hospital or health plan armed with this knowledge would be capable of improving outcomes by directing a greater proportion of patients to the superior physician group. In fact, much of the literature reporting on the effect of hospitalists is simply a new variation on this old theme.48 Of course, to realize any potential gains, there must be an adequate number of specialists or the ability to increase the supply quickly. Neither option tends to be especially realistic. Further, these studies have a tendency to create false dilemmas because consultation and comanagement are more common than single‐handed care.

Because studies comparing the outcomes of physician groups are generally not randomized trials, minimizing the threat of selection bias (ie, patient prognosis influencing treatment assignment) is of paramount importance. For example, one can imagine how patients with a particularly poor prognosis in the setting of acute myocardial infarction (perhaps related to age or the presence of multiple comorbidities) might be preferentially directed toward a general medicine service, especially when remunerative cardiac intervention is unlikely. In such instances, comparing simple mortality rates would erroneously lead to the conclusion that patients cared for by cardiologists had better outcomes.

Multivariable modeling techniques like logistic and liner regression and more recently, propensity‐based methods, are the standard approaches used to adjust for differences in patient characteristics stemming from nonrandom assignment. When propensity methods are used, a multivariable model is created to predict the likelihood, or propensity, of a patient receiving treatment. Because it is not necessary to be parsimonious in the development of propensity models, they can include many factors and interaction terms that might be left out of a standard multivariable logistic regression. Then, the outcomes of patients with a similar treatment propensity who did receive the intervention can be compared to the outcomes of those who did not. Some have gone so far as to use the term pseudorandomized trial to describe this approach because it is often capable balancing covariates between the treated and nontreated patients. However, as sophisticated as this form of modeling may be, these techniques at best are only capable of reducing bias related to measured confounders. Residual bias from confounders that go unmeasured remains a threatand is particularly common when relying on administrative data sources.

In this issue of the Journal of Hospital Medicine, Gillum and Johnston9 apply a version of instrumental variable analysis, a technique borrowed from econometrics, to address the issue of unmeasured confounding head‐on. The approach, called group‐treatment analysis, is based on the relatively simple notion that if neurologist care is superior to that provided by generalists, all other things being equal, hospitals that admit a large proportion of their patients to neurologists should have better outcomes than those admitting a smaller proportion. This approach has theoretical advantages over propensity adjustment because it does not attempt to control for differences between treated and untreated patients at the individual hospital level, where, presumably, the problem of selection bias is more potent. Although their standard multivariable models suggested that patients admitted to a neurologist were 40% less likely to die while hospitalized than patients admitted to generalists, Gillum and Johnston found that after adjusting for the institutional rate of neurologist admission, any apparent benefit had disappeared. Similar results were observed in their analyses of length of stay and cost.

In some ways, the findings of this study are more startling for the questions they raise about the presence of residual bias in observational studies using conventional multivariable methods than for the fact that generalist care was found to be as safe as neurologist care and add to a growing body of evidence suggesting that stronger methods are required to deal with residual bias in observational studies.10

Although the results largely speak for themselves and should be reassuring given that most patients with ischemic stroke in the United States are and will continue to be cared for by generalists, a number of important questions remain unanswered. First, the focus of this study was on short‐term outcomes. Because functional status and quality of life probably matter as much or more to stroke patients than in‐hospital mortality and certainly length of stay or cost, we can only hope that it is safe to extrapolate from the authors' mortality findings. Second, this study relied on data from the late 1990s, before the widespread availability of hospitalists. How generalizable the findings would be in today's environment is uncertain. On a more practical level, the authors were unable to assess the impact of formal or informal consultation by a neurologist. If this played a significant role (a reasonable assumption, I think), this would have blurred any distinction between the 2 physician groups. For this reason one cannot draw any conclusions about a more pragmatic questionthe necessity or benefit of neurologist consultation in patients with ischemic stroke.

Looking ahead, researchers hoping to improve the outcomes of patients with acute ischemic stroke should focus on developing novel models of collaboration between hospitalists and neurologists, instead of simply trying to prove that a neurologist should take care of a patient suffering a stroke alone versus a hospitalist without help from a neurologist. We also should recognize that the use of protocols and checklists or leveraging information technology investments may provide clinical decision support that improves care more than just consulting a specialist or having them care for the patient.

A 26‐year‐old woman presented with a 1‐week history of epigastric and left upper quadrant pain associated with nausea and vomiting. She also described 3 weeks of constant substernal chest pain, dyspnea, and decreased exercise tolerance.

Her medical history was significant for a pituitary macroadenoma diagnosed 6 years previously that had been treated with cabergoline. She had a miscarriage 7 years ago but gave birth to a healthy child 5 months prior to admission. She had smoked 2 cigarettes per day for the last 7 years. She denied alcohol or illicit drug use. Her mother had sickle cell trait.

On admission, her heart rate was 112 beats/minute, blood pressure was 110/80 mm Hg, and respiratory rate was 26 per minute. Jugular venous distension was not appreciated. She had decreased breath sounds over the right lung base. The apical impulse was palpated in the left sixth intercostal space 1 cm lateral to the midclavicular line, and a 2/6 holosystolic murmur was auscultated at the left lower sternal border. No other murmurs or S3 or S4 gallop could be appreciated. There were no vascular or immunological phenomena suggestive of infective endocarditis. She had abdominal tenderness in the epigastrium and bilateral upper quadrants. There was no lower extremity edema, and the extremities were well perfused.

Complete blood count, electrolytes, and liver, renal, and coagulation profiles were normal. Her chest x‐ray revealed cardiomegaly and bilateral pleural effusions. EKG showed sinus tachycardia and nonspecific T‐wave changes. To further evaluate her abdominal pain, a CT scan of the abdomen and pelvis (Fig. 1) was ordered. This revealed a 3 by 1.8 cm splenic infarct. Because of her respiratory symptoms and tachycardia, a pulmonary embolism was suspected but was ruled out with a CT angiogram of the chest.

Figure 1

She was diagnosed with new‐onset heart failure and a splenic infarct. However, it was unclear if the 2 problems were linked. Possible etiologies of the splenic infarct included thrombus from hypercoagulable state (given her prior miscarriage, postpartum state), infarct from hemoglobinopathy (given her family history), septic emboli from infective endocarditis, and peripartum cardiomyopathy associated with embolism to the spleen.

Pain control, empiric antibiotics, and intravenous diuretics were started. Twelve hours later, the patient's dyspnea and chest pain resolved. Her blood culture results were negative, and hemoglobin electrophoresis was normal. Results of a hypercoagulable workup for an arterial thrombus that included lupus anticoagulant, anticardiolipin antibodies, and antibodies to 2‐glycoprotein‐I were negative. The echocardiogram (Fig. 2) showed a dilated left ventricle with an ejection fraction (EF) of 10%15%, normal valvular morphology without vegetations, moderate mitral and tricuspid regurgitation, and a 1‐cm left ventricular thrombus and 3 small adjacent thrombi.

Figure 2

Based on the echocardiographic data, recent pregnancy, and absence of other risk factors for heart failure, a diagnosis was made of peripartum cardiomyopathy with left ventricular thrombi and subsequent embolization to the spleen.

Standard heart failure therapy including diuretics, beta‐blockers, and angiotensin‐converting enzyme inhibitors and anticoagulation with warfarin were started. Within 24 hours, the patient was asymptomatic except for minimal abdominal pain. The patient was discharged home in a stable condition the following day. At her outpatient follow‐up 3 months later, she was well compensated and asymptomatic.

DISCUSSION

Using the search terms peripartum cardiomyopathy, cardiomyopathy, thromboembolism, and postpartum period, we performed a MEDLINE search of the English literature from 1950 to 2007. We did not find any reported cases of splenic infarction complicating peripartum cardiomyopathy.

Peripartum cardiomyopathy (PPCM) is a form of dilated cardiomyopathy that occurs as a complication of pregnancy. It can present with heart failure in the last month of pregnancy or within 5 months after delivery.1, 2 The incidence of PPCM is unknown but has been estimated at 1 in 30004000 live births.3

Our patient met the criteria for PPCM as set forth by the National Heart, Lung, and Blood Institute (NHLBI), in conjunction with the Office of Rare Disease of the National Institutes of Health in April 1997.3 To establish a diagnosis of PPCM, 4 criteria have to be met:

• 1

  Development of heart failure in the last month of pregnancy or within 5 months after delivery;

• 2

  Absence of an identifiable cause of heart failure;

• 3

  Absence of recognizable heart disease prior to the last month of pregnancy; and

• 4

  Left ventricular systolic dysfunction demonstrated by echocardiographic variables such as depressed shortening fraction or left ventricular ejection fraction < 45%.

Thromboembolism has been reported with an incidence of 4% to 30% in peripartum cardiomyopathy.4 In our literature review, we found several case reports of thromboembolic phenomena complicating peripartum cardiomyopathy. These included lower extremity arterial thromboembolism with compromised circulation,5 cerebral embolism,6 and acute myocardial infarction secondary to coronary artery embolism.7 This is the first reported case of splenic artery embolization leading to splenic infarct as a complication of peripartum cardiomyopathy.

Because of the high risk of thromboembolism, the NHLBI recommends that anticoagulation be added to the standard heart failure treatment of PPCM patients with an ejection fraction of less than 35%,3 although there are no prospective randomized clinical trial data to support this recommendation. For anticoagulation, heparin is generally used in the antepartum period and warfarin in the postpartum period. It has been recommended that anticoagulation be continued for as long as the cardiomegaly persists.1

In addition to anticoagulation for PPCM patients with an EF < 35%, standard heart failure therapy includes salt restriction, diuretics, and beta‐blockers. Angiotensin‐converting enzyme inhibitors can be teratogenic during pregnancy but can be used after delivery. Hydralazine can be used safely during pregnancy as an alternative to angiotensin‐converting enzyme inhibitors. Patients failing maximal medical management may be candidates for cardiac transplantation.

Recommendations regarding subsequent pregnancies seem related to the return of ventricular size and function. Patients whose heart size does not return to normal should be strongly advised to avoid future pregnancies.2, 3 Patients who recover ventricular function may have deterioration of left ventricular function with future pregnancies.8 They should be counseled about the risk and closely monitored for development of heart failure if they become pregnant again.

A 26‐year‐old woman presented with a 1‐week history of epigastric and left upper quadrant pain associated with nausea and vomiting. She also described 3 weeks of constant substernal chest pain, dyspnea, and decreased exercise tolerance.

Her medical history was significant for a pituitary macroadenoma diagnosed 6 years previously that had been treated with cabergoline. She had a miscarriage 7 years ago but gave birth to a healthy child 5 months prior to admission. She had smoked 2 cigarettes per day for the last 7 years. She denied alcohol or illicit drug use. Her mother had sickle cell trait.

On admission, her heart rate was 112 beats/minute, blood pressure was 110/80 mm Hg, and respiratory rate was 26 per minute. Jugular venous distension was not appreciated. She had decreased breath sounds over the right lung base. The apical impulse was palpated in the left sixth intercostal space 1 cm lateral to the midclavicular line, and a 2/6 holosystolic murmur was auscultated at the left lower sternal border. No other murmurs or S3 or S4 gallop could be appreciated. There were no vascular or immunological phenomena suggestive of infective endocarditis. She had abdominal tenderness in the epigastrium and bilateral upper quadrants. There was no lower extremity edema, and the extremities were well perfused.

Complete blood count, electrolytes, and liver, renal, and coagulation profiles were normal. Her chest x‐ray revealed cardiomegaly and bilateral pleural effusions. EKG showed sinus tachycardia and nonspecific T‐wave changes. To further evaluate her abdominal pain, a CT scan of the abdomen and pelvis (Fig. 1) was ordered. This revealed a 3 by 1.8 cm splenic infarct. Because of her respiratory symptoms and tachycardia, a pulmonary embolism was suspected but was ruled out with a CT angiogram of the chest.

Figure 1

She was diagnosed with new‐onset heart failure and a splenic infarct. However, it was unclear if the 2 problems were linked. Possible etiologies of the splenic infarct included thrombus from hypercoagulable state (given her prior miscarriage, postpartum state), infarct from hemoglobinopathy (given her family history), septic emboli from infective endocarditis, and peripartum cardiomyopathy associated with embolism to the spleen.

Pain control, empiric antibiotics, and intravenous diuretics were started. Twelve hours later, the patient's dyspnea and chest pain resolved. Her blood culture results were negative, and hemoglobin electrophoresis was normal. Results of a hypercoagulable workup for an arterial thrombus that included lupus anticoagulant, anticardiolipin antibodies, and antibodies to 2‐glycoprotein‐I were negative. The echocardiogram (Fig. 2) showed a dilated left ventricle with an ejection fraction (EF) of 10%15%, normal valvular morphology without vegetations, moderate mitral and tricuspid regurgitation, and a 1‐cm left ventricular thrombus and 3 small adjacent thrombi.

Figure 2

Based on the echocardiographic data, recent pregnancy, and absence of other risk factors for heart failure, a diagnosis was made of peripartum cardiomyopathy with left ventricular thrombi and subsequent embolization to the spleen.

Standard heart failure therapy including diuretics, beta‐blockers, and angiotensin‐converting enzyme inhibitors and anticoagulation with warfarin were started. Within 24 hours, the patient was asymptomatic except for minimal abdominal pain. The patient was discharged home in a stable condition the following day. At her outpatient follow‐up 3 months later, she was well compensated and asymptomatic.

DISCUSSION

Using the search terms peripartum cardiomyopathy, cardiomyopathy, thromboembolism, and postpartum period, we performed a MEDLINE search of the English literature from 1950 to 2007. We did not find any reported cases of splenic infarction complicating peripartum cardiomyopathy.

Peripartum cardiomyopathy (PPCM) is a form of dilated cardiomyopathy that occurs as a complication of pregnancy. It can present with heart failure in the last month of pregnancy or within 5 months after delivery.1, 2 The incidence of PPCM is unknown but has been estimated at 1 in 30004000 live births.3

Our patient met the criteria for PPCM as set forth by the National Heart, Lung, and Blood Institute (NHLBI), in conjunction with the Office of Rare Disease of the National Institutes of Health in April 1997.3 To establish a diagnosis of PPCM, 4 criteria have to be met:

• 1

  Development of heart failure in the last month of pregnancy or within 5 months after delivery;

• 2

  Absence of an identifiable cause of heart failure;

• 3

  Absence of recognizable heart disease prior to the last month of pregnancy; and

• 4

  Left ventricular systolic dysfunction demonstrated by echocardiographic variables such as depressed shortening fraction or left ventricular ejection fraction < 45%.

Thromboembolism has been reported with an incidence of 4% to 30% in peripartum cardiomyopathy.4 In our literature review, we found several case reports of thromboembolic phenomena complicating peripartum cardiomyopathy. These included lower extremity arterial thromboembolism with compromised circulation,5 cerebral embolism,6 and acute myocardial infarction secondary to coronary artery embolism.7 This is the first reported case of splenic artery embolization leading to splenic infarct as a complication of peripartum cardiomyopathy.

Because of the high risk of thromboembolism, the NHLBI recommends that anticoagulation be added to the standard heart failure treatment of PPCM patients with an ejection fraction of less than 35%,3 although there are no prospective randomized clinical trial data to support this recommendation. For anticoagulation, heparin is generally used in the antepartum period and warfarin in the postpartum period. It has been recommended that anticoagulation be continued for as long as the cardiomegaly persists.1

In addition to anticoagulation for PPCM patients with an EF < 35%, standard heart failure therapy includes salt restriction, diuretics, and beta‐blockers. Angiotensin‐converting enzyme inhibitors can be teratogenic during pregnancy but can be used after delivery. Hydralazine can be used safely during pregnancy as an alternative to angiotensin‐converting enzyme inhibitors. Patients failing maximal medical management may be candidates for cardiac transplantation.

Recommendations regarding subsequent pregnancies seem related to the return of ventricular size and function. Patients whose heart size does not return to normal should be strongly advised to avoid future pregnancies.2, 3 Patients who recover ventricular function may have deterioration of left ventricular function with future pregnancies.8 They should be counseled about the risk and closely monitored for development of heart failure if they become pregnant again.

A 26‐year‐old woman presented with a 1‐week history of epigastric and left upper quadrant pain associated with nausea and vomiting. She also described 3 weeks of constant substernal chest pain, dyspnea, and decreased exercise tolerance.

Her medical history was significant for a pituitary macroadenoma diagnosed 6 years previously that had been treated with cabergoline. She had a miscarriage 7 years ago but gave birth to a healthy child 5 months prior to admission. She had smoked 2 cigarettes per day for the last 7 years. She denied alcohol or illicit drug use. Her mother had sickle cell trait.

On admission, her heart rate was 112 beats/minute, blood pressure was 110/80 mm Hg, and respiratory rate was 26 per minute. Jugular venous distension was not appreciated. She had decreased breath sounds over the right lung base. The apical impulse was palpated in the left sixth intercostal space 1 cm lateral to the midclavicular line, and a 2/6 holosystolic murmur was auscultated at the left lower sternal border. No other murmurs or S3 or S4 gallop could be appreciated. There were no vascular or immunological phenomena suggestive of infective endocarditis. She had abdominal tenderness in the epigastrium and bilateral upper quadrants. There was no lower extremity edema, and the extremities were well perfused.

Complete blood count, electrolytes, and liver, renal, and coagulation profiles were normal. Her chest x‐ray revealed cardiomegaly and bilateral pleural effusions. EKG showed sinus tachycardia and nonspecific T‐wave changes. To further evaluate her abdominal pain, a CT scan of the abdomen and pelvis (Fig. 1) was ordered. This revealed a 3 by 1.8 cm splenic infarct. Because of her respiratory symptoms and tachycardia, a pulmonary embolism was suspected but was ruled out with a CT angiogram of the chest.

Figure 1

She was diagnosed with new‐onset heart failure and a splenic infarct. However, it was unclear if the 2 problems were linked. Possible etiologies of the splenic infarct included thrombus from hypercoagulable state (given her prior miscarriage, postpartum state), infarct from hemoglobinopathy (given her family history), septic emboli from infective endocarditis, and peripartum cardiomyopathy associated with embolism to the spleen.

Pain control, empiric antibiotics, and intravenous diuretics were started. Twelve hours later, the patient's dyspnea and chest pain resolved. Her blood culture results were negative, and hemoglobin electrophoresis was normal. Results of a hypercoagulable workup for an arterial thrombus that included lupus anticoagulant, anticardiolipin antibodies, and antibodies to 2‐glycoprotein‐I were negative. The echocardiogram (Fig. 2) showed a dilated left ventricle with an ejection fraction (EF) of 10%15%, normal valvular morphology without vegetations, moderate mitral and tricuspid regurgitation, and a 1‐cm left ventricular thrombus and 3 small adjacent thrombi.

Figure 2

Based on the echocardiographic data, recent pregnancy, and absence of other risk factors for heart failure, a diagnosis was made of peripartum cardiomyopathy with left ventricular thrombi and subsequent embolization to the spleen.

Standard heart failure therapy including diuretics, beta‐blockers, and angiotensin‐converting enzyme inhibitors and anticoagulation with warfarin were started. Within 24 hours, the patient was asymptomatic except for minimal abdominal pain. The patient was discharged home in a stable condition the following day. At her outpatient follow‐up 3 months later, she was well compensated and asymptomatic.

DISCUSSION

Using the search terms peripartum cardiomyopathy, cardiomyopathy, thromboembolism, and postpartum period, we performed a MEDLINE search of the English literature from 1950 to 2007. We did not find any reported cases of splenic infarction complicating peripartum cardiomyopathy.

Peripartum cardiomyopathy (PPCM) is a form of dilated cardiomyopathy that occurs as a complication of pregnancy. It can present with heart failure in the last month of pregnancy or within 5 months after delivery.1, 2 The incidence of PPCM is unknown but has been estimated at 1 in 30004000 live births.3

Our patient met the criteria for PPCM as set forth by the National Heart, Lung, and Blood Institute (NHLBI), in conjunction with the Office of Rare Disease of the National Institutes of Health in April 1997.3 To establish a diagnosis of PPCM, 4 criteria have to be met:

• 1

  Development of heart failure in the last month of pregnancy or within 5 months after delivery;

• 2

  Absence of an identifiable cause of heart failure;

• 3

  Absence of recognizable heart disease prior to the last month of pregnancy; and

• 4

  Left ventricular systolic dysfunction demonstrated by echocardiographic variables such as depressed shortening fraction or left ventricular ejection fraction < 45%.

Thromboembolism has been reported with an incidence of 4% to 30% in peripartum cardiomyopathy.4 In our literature review, we found several case reports of thromboembolic phenomena complicating peripartum cardiomyopathy. These included lower extremity arterial thromboembolism with compromised circulation,5 cerebral embolism,6 and acute myocardial infarction secondary to coronary artery embolism.7 This is the first reported case of splenic artery embolization leading to splenic infarct as a complication of peripartum cardiomyopathy.

Because of the high risk of thromboembolism, the NHLBI recommends that anticoagulation be added to the standard heart failure treatment of PPCM patients with an ejection fraction of less than 35%,3 although there are no prospective randomized clinical trial data to support this recommendation. For anticoagulation, heparin is generally used in the antepartum period and warfarin in the postpartum period. It has been recommended that anticoagulation be continued for as long as the cardiomegaly persists.1

In addition to anticoagulation for PPCM patients with an EF < 35%, standard heart failure therapy includes salt restriction, diuretics, and beta‐blockers. Angiotensin‐converting enzyme inhibitors can be teratogenic during pregnancy but can be used after delivery. Hydralazine can be used safely during pregnancy as an alternative to angiotensin‐converting enzyme inhibitors. Patients failing maximal medical management may be candidates for cardiac transplantation.

Recommendations regarding subsequent pregnancies seem related to the return of ventricular size and function. Patients whose heart size does not return to normal should be strongly advised to avoid future pregnancies.2, 3 Patients who recover ventricular function may have deterioration of left ventricular function with future pregnancies.8 They should be counseled about the risk and closely monitored for development of heart failure if they become pregnant again.

Status asthmaticus, although a relatively infrequent cause of admission to the intensive care unit, carries a significant risk of mortality and complications of critical care.1 Asthma prevalence has risen,2 and recent data have suggested an improvement in overall mortality.3 Yet there may remain a subgroup of patients with the most severe asthma in whom this outcome benefit may not be seen. Asthma severity and mortality may be concentrated in certain urban areas, and there may even be disparities within cities. One recent study found a trend toward fewer and less severe presentations of ICU patients with status asthmaticus.4 Our clinical experience in an urban hospital suggested otherwise, and we undertook an examination of status asthmaticus and compared these data with those of our previously published experience at this center.5

MATERIALS AND METHODS

A retrospective review was performed of all patients with status asthmaticus admitted to the medical intensive care unit (MICU) of St. Luke's Hospital during the 5‐year period January 2002 through December 2006. St. Luke's Hospital is a university‐affiliated hospital in New York City. Patients were identified by discharge diagnosis of status asthmaticus through a computerized medical record database. Demographic data, initial presentation data, MICU course, and outcome were collected. Results were compared to our previous study during the 5‐year period 19951999 at this institution.5 Data are presented as means standard deviations.

The means of the groups were compared using the Student t test.

RESULTS

There were 89 MICU admissions for status asthmaticus; the records of 84 patients were available for review. The hospital admission rate for asthma remained stable at 1.6% of admissions during the period 20022006, compared with 1.4% of hospital admissions during the previous study period of 19951999. In the current study, 3% of asthma admissions required MICU care compared with 5% in the prior era.

Between the 2 study periods, there were no changes in MICU admission criteria or new protocols for management of status asthmaticus in the emergency department. The only difference in ICU management of intubated patients is that in the most recent study period there was an emphasis on earlier identification of patients for extubation. A new sedative, propofol, was available for ICU sedation during the current study period.

Two patients were admitted to the MICU 4 times, and 9 patients were admitted twice. Each presentation was counted as a separate admission and was analyzed individually. Seven patients (8%) had sustained a cardiopulmonary arrest prior to MICU admission. All were intubated in the field by emergency medical services. Characteristics of the patients are shown in Table 1. African American and Hispanic patients constituted 96% of the group. Half the patients were current cigarette smokers, and 30% admitted to current use of illicit drug. Fifty‐five percent of patients reported allergies (dust, pollen, pets), and 59% had previously been intubated for asthma.

Status asthmaticus was associated with an upper respiratory tract infection in 54%, illicit drug use in 15%, allergies in 12%, and a recent corticosteroid taper in 8% of exacerbations. Almost all patients had used a short‐acting beta‐2 agonist, and 78% had been prescribed inhaled corticosteroids either alone or in combination. Thirty‐six percent had used oral prednisone. Nonadherence was self‐reported by 45% of patients (Table 2).

Emergency department management for all patients included inhaled beta‐2 agonist therapy administered continuously, intravenous corticosteroid therapy (methylprednisolone 125 mg once), and magnesium sulfate (2 g intravenously).

Noninvasive ventilation was initiated in 10 patients (Table 2).

DISCUSSION

We identified greater severity of status asthmaticus among patients requiring admission to our urban intensive care unit. Despite reports of improvement in outcome3 and reduction in the severity and number of MICU admissions by other investigators4 in New York City, patients with status asthmaticus admitted to the MICU suffered significant mortality and morbidity. During the recent 5‐year period, compared with the period reported in our previous report,5 these patients had greater respiratory acidosis, more frequent need for neuromuscular blockade, longer duration of mechanical ventilation, increased complications, and higher unadjusted mortality.

There remain few large series of status asthmaticus. Episodes of life‐threatening asthma occur more frequently in specific high‐risk areas. We had the benefit of a prior study in our institution in order to compare trends in status asthmaticus. With greater attention to asthma severity, treatment, access to information, and medical care, a change in demographic features may have been expected. Yet we found that noncompliance with medications and smoking and illicit drug usage increased in this recent 5‐year period compared with the prior study period. Minority populations are also at particular risk for severe asthma.6

Noninvasive ventilation has been shown to be effective in acute hypercapnic respiratory failure in patients with chronic obstructive lung disease.7, 8 A small study of asthma found that NIV was associated with a reduction in PaCO₂ during the early hours of use and that mortality and complications were not increased in those who subsequently required intubation.9 However, in another study of 27 patients managed with NIV, 2 of the 5 patients requiring intubation died.10 In the 1 randomized controlled study of NIV in severe asthma, Soroksky et al. found that NIV significantly improved lung function and decreased hospitalization rate compared with the use of conventional therapy alone. The average PaCO₂ and pH of these patients were 33.59 mm Hg and 7.41, respectively.11 Meduri et al. reported a small series of 17 patients with severe asthma treated with NIV, 2 of whom were subsequently intubated. The initial pH and PaCO₂ of these patients averaged 7.25 and 65 mm Hg, respectively.12 In our series, NIV was used in 10 patients, 4 of whom were subsequently intubated. The average time on NIV before intubation was 2 hours, and there were no deaths in this group. Patients who were intubated after NIV had a statistically significant lower pH (7.17) and higher PaCO₂ (76 mm Hg) on admission than those who were successfully managed with NIV, with the pH and PaCO₂ of the latter group 7.32 and 50 mm Hg, respectively.

Improvement in mortality of status asthmaticus over the past decades has been attributed to improved ventilatory strategy using permissive hypercapnia. This approach has been credited with a decrease in barotrauma, hemodynamic instability, and mortality.5, 13 The latter complications were mainly a result of the dynamic hyperinflation found in patients with severe asthma. Decreasing the respiratory rate and tidal volume as well as increasing the inspiratory flow rate will lead to an increase in expiratory time and will subsequently decrease the dynamic hyperinflation. With this approach, hypercapnia may occur. Hypercapnia (PaCO₂ level up to 90 mm Hg) is generally well tolerated when oxygenation is maintained.14 Sedation is crucial to achieving optimal ventilation. Because of its short duration of action and bronchodilator effects,15, 16 propofol was the main sedative used in our MICU. Additional sedatives were required for half our patients. A prolonged sedative effect was noted in several cases, which prompted additional neurologic evaluation. It is conceivable that higher doses of sedatives are required for ventilatory control of young patients with a strong respiratory drive.

The administration of therapeutic paralysis is generally avoided in patients with status asthmaticus treated concurrently with corticosteroids. Myopathy may develop in the setting of neuromuscular blockade and corticosteroid administration and prolong ventilatory failure.17 In our earlier series, only 1 patient received a paralytic agent; in the current series, neuromuscular paralysis was needed in 6 episodes despite maximum sedative infusion. Patients requiring neuromuscular blockade were younger and had a significantly lower pH and higher PaCO₂ than did those not receiving neuromuscular blockade. These patients developed more complications, including prolonged weakness, supporting the general approach of avoiding paralytic use unless absolutely necessary. It is noteworthy that despite this greater degree of respiratory failure and subsequent ICU complications, no patients in this group died.

The median duration of mechanical ventilation was 4.4 days. Complications included ventilator‐associated pneumonia, catheter‐related infection, excessive sedation, and prolonged weakness. These events occurred primarily in patients who received paralytics and patients whose mechanical ventilation was prolonged. The average duration of mechanical ventilation for patients who had ventilator‐associated pneumonia and catheter‐related infection was 22 and 31 days, respectively.

Status asthmaticus in pregnancy deserves special attention, and its course has not been well described in the literature. We report finding that in the current study period there were 5 pregnant patients requiring ICU management for status asthmaticus, all with dramatic degrees of hypercapnia and acidosis during controlled mechanical ventilation; the highest PaCO₂ and lowest pH averaged 101 mm Hg and 7.06, respectively. Management of status asthmaticus in pregnancy is no different than in nonpregnant individuals, but there are concerns about the effects of hypercapnia and acidosis on the fetus.18 In all 4 patients who delivered, the pregnancies resulted in healthy babies. In the 1 patient who suffered a pneumomediastinum during early labor, the decision was made for cesarean delivery because of concerns about potential worsening of the barotrauma and maternal cardiopulmonary condition. This patient did not require intubation prior to or during the cesarean delivery. Collaboration with the obstetrician is essential in the management of these cases.

Despite advances in ventilator management and critical care, there remains a mortality risk in patients with status asthmaticus.17, 19, 20 In our study, 6 patients (7%) died; 3 patients died after suffering pre‐MICU cardiac arrest, and 3 patients died of multiorgan failure. Regular asthma clinic follow‐up, to include counseling about smoking cessation and illicit drugs, is essential. Unfortunately, only 45% of our patients had specialty clinic referral on discharge. Lack of patient understanding of their illness may also complicate their care, as demonstrated by nonadherence to medication and medical appointments. Five of our patients left against medical advice, 4 of them within a day of extubation.

Our study had several limitations. Patients were identified based on admission diagnosis by the attending physician; the coexistence of chronic obstructive pulmonary disease could not always be definitely excluded. However, all patients had a prior diagnosis of asthma and had been treated for asthma. The young age of the patient group is consistent with that reported in the literature.

It is difficult to compare studies of status asthmaticus, given the dynamic nature of the airways disease and individual clinician judgments about intubation and extubation. We believe that longer duration of ventilation reflects more severe asthma, especially in this time when clinicians attempt noninvasive ventilation and daily trials of spontaneous breathing for earlier extubation.

In conclusion, this report describes an increase in the severity of status asthmaticus in patients admitted to an urban MICU. The reason for the increase in severity compared to our previous study is uncertain. Possible factors include: cigarette and substance use, refractoriness to therapy because of environment or smoking, inadequate medical care, poor understanding of illness, and adherence to therapy. As the ICU management is supportive, the best approach is prevention, targeting at‐risk minority populations with education, counseling for smoking and drug cessation, and specialty care. Once status asthmaticus has developed, a careful, limited trial of NIV in selected patients may offer benefits in the management of ventilatory failure and avoidance of ICU complications.

Status asthmaticus, although a relatively infrequent cause of admission to the intensive care unit, carries a significant risk of mortality and complications of critical care.1 Asthma prevalence has risen,2 and recent data have suggested an improvement in overall mortality.3 Yet there may remain a subgroup of patients with the most severe asthma in whom this outcome benefit may not be seen. Asthma severity and mortality may be concentrated in certain urban areas, and there may even be disparities within cities. One recent study found a trend toward fewer and less severe presentations of ICU patients with status asthmaticus.4 Our clinical experience in an urban hospital suggested otherwise, and we undertook an examination of status asthmaticus and compared these data with those of our previously published experience at this center.5

MATERIALS AND METHODS

A retrospective review was performed of all patients with status asthmaticus admitted to the medical intensive care unit (MICU) of St. Luke's Hospital during the 5‐year period January 2002 through December 2006. St. Luke's Hospital is a university‐affiliated hospital in New York City. Patients were identified by discharge diagnosis of status asthmaticus through a computerized medical record database. Demographic data, initial presentation data, MICU course, and outcome were collected. Results were compared to our previous study during the 5‐year period 19951999 at this institution.5 Data are presented as means standard deviations.

The means of the groups were compared using the Student t test.

RESULTS

There were 89 MICU admissions for status asthmaticus; the records of 84 patients were available for review. The hospital admission rate for asthma remained stable at 1.6% of admissions during the period 20022006, compared with 1.4% of hospital admissions during the previous study period of 19951999. In the current study, 3% of asthma admissions required MICU care compared with 5% in the prior era.

Between the 2 study periods, there were no changes in MICU admission criteria or new protocols for management of status asthmaticus in the emergency department. The only difference in ICU management of intubated patients is that in the most recent study period there was an emphasis on earlier identification of patients for extubation. A new sedative, propofol, was available for ICU sedation during the current study period.

Two patients were admitted to the MICU 4 times, and 9 patients were admitted twice. Each presentation was counted as a separate admission and was analyzed individually. Seven patients (8%) had sustained a cardiopulmonary arrest prior to MICU admission. All were intubated in the field by emergency medical services. Characteristics of the patients are shown in Table 1. African American and Hispanic patients constituted 96% of the group. Half the patients were current cigarette smokers, and 30% admitted to current use of illicit drug. Fifty‐five percent of patients reported allergies (dust, pollen, pets), and 59% had previously been intubated for asthma.

Status asthmaticus was associated with an upper respiratory tract infection in 54%, illicit drug use in 15%, allergies in 12%, and a recent corticosteroid taper in 8% of exacerbations. Almost all patients had used a short‐acting beta‐2 agonist, and 78% had been prescribed inhaled corticosteroids either alone or in combination. Thirty‐six percent had used oral prednisone. Nonadherence was self‐reported by 45% of patients (Table 2).

Emergency department management for all patients included inhaled beta‐2 agonist therapy administered continuously, intravenous corticosteroid therapy (methylprednisolone 125 mg once), and magnesium sulfate (2 g intravenously).

Noninvasive ventilation was initiated in 10 patients (Table 2).

DISCUSSION

We identified greater severity of status asthmaticus among patients requiring admission to our urban intensive care unit. Despite reports of improvement in outcome3 and reduction in the severity and number of MICU admissions by other investigators4 in New York City, patients with status asthmaticus admitted to the MICU suffered significant mortality and morbidity. During the recent 5‐year period, compared with the period reported in our previous report,5 these patients had greater respiratory acidosis, more frequent need for neuromuscular blockade, longer duration of mechanical ventilation, increased complications, and higher unadjusted mortality.

There remain few large series of status asthmaticus. Episodes of life‐threatening asthma occur more frequently in specific high‐risk areas. We had the benefit of a prior study in our institution in order to compare trends in status asthmaticus. With greater attention to asthma severity, treatment, access to information, and medical care, a change in demographic features may have been expected. Yet we found that noncompliance with medications and smoking and illicit drug usage increased in this recent 5‐year period compared with the prior study period. Minority populations are also at particular risk for severe asthma.6

Noninvasive ventilation has been shown to be effective in acute hypercapnic respiratory failure in patients with chronic obstructive lung disease.7, 8 A small study of asthma found that NIV was associated with a reduction in PaCO₂ during the early hours of use and that mortality and complications were not increased in those who subsequently required intubation.9 However, in another study of 27 patients managed with NIV, 2 of the 5 patients requiring intubation died.10 In the 1 randomized controlled study of NIV in severe asthma, Soroksky et al. found that NIV significantly improved lung function and decreased hospitalization rate compared with the use of conventional therapy alone. The average PaCO₂ and pH of these patients were 33.59 mm Hg and 7.41, respectively.11 Meduri et al. reported a small series of 17 patients with severe asthma treated with NIV, 2 of whom were subsequently intubated. The initial pH and PaCO₂ of these patients averaged 7.25 and 65 mm Hg, respectively.12 In our series, NIV was used in 10 patients, 4 of whom were subsequently intubated. The average time on NIV before intubation was 2 hours, and there were no deaths in this group. Patients who were intubated after NIV had a statistically significant lower pH (7.17) and higher PaCO₂ (76 mm Hg) on admission than those who were successfully managed with NIV, with the pH and PaCO₂ of the latter group 7.32 and 50 mm Hg, respectively.

Improvement in mortality of status asthmaticus over the past decades has been attributed to improved ventilatory strategy using permissive hypercapnia. This approach has been credited with a decrease in barotrauma, hemodynamic instability, and mortality.5, 13 The latter complications were mainly a result of the dynamic hyperinflation found in patients with severe asthma. Decreasing the respiratory rate and tidal volume as well as increasing the inspiratory flow rate will lead to an increase in expiratory time and will subsequently decrease the dynamic hyperinflation. With this approach, hypercapnia may occur. Hypercapnia (PaCO₂ level up to 90 mm Hg) is generally well tolerated when oxygenation is maintained.14 Sedation is crucial to achieving optimal ventilation. Because of its short duration of action and bronchodilator effects,15, 16 propofol was the main sedative used in our MICU. Additional sedatives were required for half our patients. A prolonged sedative effect was noted in several cases, which prompted additional neurologic evaluation. It is conceivable that higher doses of sedatives are required for ventilatory control of young patients with a strong respiratory drive.

The administration of therapeutic paralysis is generally avoided in patients with status asthmaticus treated concurrently with corticosteroids. Myopathy may develop in the setting of neuromuscular blockade and corticosteroid administration and prolong ventilatory failure.17 In our earlier series, only 1 patient received a paralytic agent; in the current series, neuromuscular paralysis was needed in 6 episodes despite maximum sedative infusion. Patients requiring neuromuscular blockade were younger and had a significantly lower pH and higher PaCO₂ than did those not receiving neuromuscular blockade. These patients developed more complications, including prolonged weakness, supporting the general approach of avoiding paralytic use unless absolutely necessary. It is noteworthy that despite this greater degree of respiratory failure and subsequent ICU complications, no patients in this group died.

The median duration of mechanical ventilation was 4.4 days. Complications included ventilator‐associated pneumonia, catheter‐related infection, excessive sedation, and prolonged weakness. These events occurred primarily in patients who received paralytics and patients whose mechanical ventilation was prolonged. The average duration of mechanical ventilation for patients who had ventilator‐associated pneumonia and catheter‐related infection was 22 and 31 days, respectively.

Status asthmaticus in pregnancy deserves special attention, and its course has not been well described in the literature. We report finding that in the current study period there were 5 pregnant patients requiring ICU management for status asthmaticus, all with dramatic degrees of hypercapnia and acidosis during controlled mechanical ventilation; the highest PaCO₂ and lowest pH averaged 101 mm Hg and 7.06, respectively. Management of status asthmaticus in pregnancy is no different than in nonpregnant individuals, but there are concerns about the effects of hypercapnia and acidosis on the fetus.18 In all 4 patients who delivered, the pregnancies resulted in healthy babies. In the 1 patient who suffered a pneumomediastinum during early labor, the decision was made for cesarean delivery because of concerns about potential worsening of the barotrauma and maternal cardiopulmonary condition. This patient did not require intubation prior to or during the cesarean delivery. Collaboration with the obstetrician is essential in the management of these cases.

Despite advances in ventilator management and critical care, there remains a mortality risk in patients with status asthmaticus.17, 19, 20 In our study, 6 patients (7%) died; 3 patients died after suffering pre‐MICU cardiac arrest, and 3 patients died of multiorgan failure. Regular asthma clinic follow‐up, to include counseling about smoking cessation and illicit drugs, is essential. Unfortunately, only 45% of our patients had specialty clinic referral on discharge. Lack of patient understanding of their illness may also complicate their care, as demonstrated by nonadherence to medication and medical appointments. Five of our patients left against medical advice, 4 of them within a day of extubation.

Our study had several limitations. Patients were identified based on admission diagnosis by the attending physician; the coexistence of chronic obstructive pulmonary disease could not always be definitely excluded. However, all patients had a prior diagnosis of asthma and had been treated for asthma. The young age of the patient group is consistent with that reported in the literature.

It is difficult to compare studies of status asthmaticus, given the dynamic nature of the airways disease and individual clinician judgments about intubation and extubation. We believe that longer duration of ventilation reflects more severe asthma, especially in this time when clinicians attempt noninvasive ventilation and daily trials of spontaneous breathing for earlier extubation.

In conclusion, this report describes an increase in the severity of status asthmaticus in patients admitted to an urban MICU. The reason for the increase in severity compared to our previous study is uncertain. Possible factors include: cigarette and substance use, refractoriness to therapy because of environment or smoking, inadequate medical care, poor understanding of illness, and adherence to therapy. As the ICU management is supportive, the best approach is prevention, targeting at‐risk minority populations with education, counseling for smoking and drug cessation, and specialty care. Once status asthmaticus has developed, a careful, limited trial of NIV in selected patients may offer benefits in the management of ventilatory failure and avoidance of ICU complications.

Status asthmaticus, although a relatively infrequent cause of admission to the intensive care unit, carries a significant risk of mortality and complications of critical care.1 Asthma prevalence has risen,2 and recent data have suggested an improvement in overall mortality.3 Yet there may remain a subgroup of patients with the most severe asthma in whom this outcome benefit may not be seen. Asthma severity and mortality may be concentrated in certain urban areas, and there may even be disparities within cities. One recent study found a trend toward fewer and less severe presentations of ICU patients with status asthmaticus.4 Our clinical experience in an urban hospital suggested otherwise, and we undertook an examination of status asthmaticus and compared these data with those of our previously published experience at this center.5

MATERIALS AND METHODS

A retrospective review was performed of all patients with status asthmaticus admitted to the medical intensive care unit (MICU) of St. Luke's Hospital during the 5‐year period January 2002 through December 2006. St. Luke's Hospital is a university‐affiliated hospital in New York City. Patients were identified by discharge diagnosis of status asthmaticus through a computerized medical record database. Demographic data, initial presentation data, MICU course, and outcome were collected. Results were compared to our previous study during the 5‐year period 19951999 at this institution.5 Data are presented as means standard deviations.

The means of the groups were compared using the Student t test.

RESULTS

There were 89 MICU admissions for status asthmaticus; the records of 84 patients were available for review. The hospital admission rate for asthma remained stable at 1.6% of admissions during the period 20022006, compared with 1.4% of hospital admissions during the previous study period of 19951999. In the current study, 3% of asthma admissions required MICU care compared with 5% in the prior era.

Between the 2 study periods, there were no changes in MICU admission criteria or new protocols for management of status asthmaticus in the emergency department. The only difference in ICU management of intubated patients is that in the most recent study period there was an emphasis on earlier identification of patients for extubation. A new sedative, propofol, was available for ICU sedation during the current study period.

Two patients were admitted to the MICU 4 times, and 9 patients were admitted twice. Each presentation was counted as a separate admission and was analyzed individually. Seven patients (8%) had sustained a cardiopulmonary arrest prior to MICU admission. All were intubated in the field by emergency medical services. Characteristics of the patients are shown in Table 1. African American and Hispanic patients constituted 96% of the group. Half the patients were current cigarette smokers, and 30% admitted to current use of illicit drug. Fifty‐five percent of patients reported allergies (dust, pollen, pets), and 59% had previously been intubated for asthma.

Status asthmaticus was associated with an upper respiratory tract infection in 54%, illicit drug use in 15%, allergies in 12%, and a recent corticosteroid taper in 8% of exacerbations. Almost all patients had used a short‐acting beta‐2 agonist, and 78% had been prescribed inhaled corticosteroids either alone or in combination. Thirty‐six percent had used oral prednisone. Nonadherence was self‐reported by 45% of patients (Table 2).

Emergency department management for all patients included inhaled beta‐2 agonist therapy administered continuously, intravenous corticosteroid therapy (methylprednisolone 125 mg once), and magnesium sulfate (2 g intravenously).

Noninvasive ventilation was initiated in 10 patients (Table 2).

DISCUSSION

We identified greater severity of status asthmaticus among patients requiring admission to our urban intensive care unit. Despite reports of improvement in outcome3 and reduction in the severity and number of MICU admissions by other investigators4 in New York City, patients with status asthmaticus admitted to the MICU suffered significant mortality and morbidity. During the recent 5‐year period, compared with the period reported in our previous report,5 these patients had greater respiratory acidosis, more frequent need for neuromuscular blockade, longer duration of mechanical ventilation, increased complications, and higher unadjusted mortality.

There remain few large series of status asthmaticus. Episodes of life‐threatening asthma occur more frequently in specific high‐risk areas. We had the benefit of a prior study in our institution in order to compare trends in status asthmaticus. With greater attention to asthma severity, treatment, access to information, and medical care, a change in demographic features may have been expected. Yet we found that noncompliance with medications and smoking and illicit drug usage increased in this recent 5‐year period compared with the prior study period. Minority populations are also at particular risk for severe asthma.6

Noninvasive ventilation has been shown to be effective in acute hypercapnic respiratory failure in patients with chronic obstructive lung disease.7, 8 A small study of asthma found that NIV was associated with a reduction in PaCO₂ during the early hours of use and that mortality and complications were not increased in those who subsequently required intubation.9 However, in another study of 27 patients managed with NIV, 2 of the 5 patients requiring intubation died.10 In the 1 randomized controlled study of NIV in severe asthma, Soroksky et al. found that NIV significantly improved lung function and decreased hospitalization rate compared with the use of conventional therapy alone. The average PaCO₂ and pH of these patients were 33.59 mm Hg and 7.41, respectively.11 Meduri et al. reported a small series of 17 patients with severe asthma treated with NIV, 2 of whom were subsequently intubated. The initial pH and PaCO₂ of these patients averaged 7.25 and 65 mm Hg, respectively.12 In our series, NIV was used in 10 patients, 4 of whom were subsequently intubated. The average time on NIV before intubation was 2 hours, and there were no deaths in this group. Patients who were intubated after NIV had a statistically significant lower pH (7.17) and higher PaCO₂ (76 mm Hg) on admission than those who were successfully managed with NIV, with the pH and PaCO₂ of the latter group 7.32 and 50 mm Hg, respectively.

Improvement in mortality of status asthmaticus over the past decades has been attributed to improved ventilatory strategy using permissive hypercapnia. This approach has been credited with a decrease in barotrauma, hemodynamic instability, and mortality.5, 13 The latter complications were mainly a result of the dynamic hyperinflation found in patients with severe asthma. Decreasing the respiratory rate and tidal volume as well as increasing the inspiratory flow rate will lead to an increase in expiratory time and will subsequently decrease the dynamic hyperinflation. With this approach, hypercapnia may occur. Hypercapnia (PaCO₂ level up to 90 mm Hg) is generally well tolerated when oxygenation is maintained.14 Sedation is crucial to achieving optimal ventilation. Because of its short duration of action and bronchodilator effects,15, 16 propofol was the main sedative used in our MICU. Additional sedatives were required for half our patients. A prolonged sedative effect was noted in several cases, which prompted additional neurologic evaluation. It is conceivable that higher doses of sedatives are required for ventilatory control of young patients with a strong respiratory drive.

The administration of therapeutic paralysis is generally avoided in patients with status asthmaticus treated concurrently with corticosteroids. Myopathy may develop in the setting of neuromuscular blockade and corticosteroid administration and prolong ventilatory failure.17 In our earlier series, only 1 patient received a paralytic agent; in the current series, neuromuscular paralysis was needed in 6 episodes despite maximum sedative infusion. Patients requiring neuromuscular blockade were younger and had a significantly lower pH and higher PaCO₂ than did those not receiving neuromuscular blockade. These patients developed more complications, including prolonged weakness, supporting the general approach of avoiding paralytic use unless absolutely necessary. It is noteworthy that despite this greater degree of respiratory failure and subsequent ICU complications, no patients in this group died.

The median duration of mechanical ventilation was 4.4 days. Complications included ventilator‐associated pneumonia, catheter‐related infection, excessive sedation, and prolonged weakness. These events occurred primarily in patients who received paralytics and patients whose mechanical ventilation was prolonged. The average duration of mechanical ventilation for patients who had ventilator‐associated pneumonia and catheter‐related infection was 22 and 31 days, respectively.

Status asthmaticus in pregnancy deserves special attention, and its course has not been well described in the literature. We report finding that in the current study period there were 5 pregnant patients requiring ICU management for status asthmaticus, all with dramatic degrees of hypercapnia and acidosis during controlled mechanical ventilation; the highest PaCO₂ and lowest pH averaged 101 mm Hg and 7.06, respectively. Management of status asthmaticus in pregnancy is no different than in nonpregnant individuals, but there are concerns about the effects of hypercapnia and acidosis on the fetus.18 In all 4 patients who delivered, the pregnancies resulted in healthy babies. In the 1 patient who suffered a pneumomediastinum during early labor, the decision was made for cesarean delivery because of concerns about potential worsening of the barotrauma and maternal cardiopulmonary condition. This patient did not require intubation prior to or during the cesarean delivery. Collaboration with the obstetrician is essential in the management of these cases.

Despite advances in ventilator management and critical care, there remains a mortality risk in patients with status asthmaticus.17, 19, 20 In our study, 6 patients (7%) died; 3 patients died after suffering pre‐MICU cardiac arrest, and 3 patients died of multiorgan failure. Regular asthma clinic follow‐up, to include counseling about smoking cessation and illicit drugs, is essential. Unfortunately, only 45% of our patients had specialty clinic referral on discharge. Lack of patient understanding of their illness may also complicate their care, as demonstrated by nonadherence to medication and medical appointments. Five of our patients left against medical advice, 4 of them within a day of extubation.

Our study had several limitations. Patients were identified based on admission diagnosis by the attending physician; the coexistence of chronic obstructive pulmonary disease could not always be definitely excluded. However, all patients had a prior diagnosis of asthma and had been treated for asthma. The young age of the patient group is consistent with that reported in the literature.

It is difficult to compare studies of status asthmaticus, given the dynamic nature of the airways disease and individual clinician judgments about intubation and extubation. We believe that longer duration of ventilation reflects more severe asthma, especially in this time when clinicians attempt noninvasive ventilation and daily trials of spontaneous breathing for earlier extubation.

In conclusion, this report describes an increase in the severity of status asthmaticus in patients admitted to an urban MICU. The reason for the increase in severity compared to our previous study is uncertain. Possible factors include: cigarette and substance use, refractoriness to therapy because of environment or smoking, inadequate medical care, poor understanding of illness, and adherence to therapy. As the ICU management is supportive, the best approach is prevention, targeting at‐risk minority populations with education, counseling for smoking and drug cessation, and specialty care. Once status asthmaticus has developed, a careful, limited trial of NIV in selected patients may offer benefits in the management of ventilatory failure and avoidance of ICU complications.

Hospital practices are increasingly responsible for ensuring enhanced patient safety, satisfaction, and cost containment. Recently developed models of care have achieved the necessary efficiency to attain these measures, not only in the use of hospitalists managing general medical1, 2 and postoperative orthopedic patients,3, 4 but also in the use of midlevel providers in busy primary care settings.5 In addition, stroke units6 and geriatric evaluation and management units7, 8 worldwide have demonstrated reduced disability and improved survival and importantly have been proven to provide cost‐effective care. Specialized orthopedic surgery (SOS) units may be a means to reproduce the results observed in these other models.

The economic potential of SOS units will become more significant with changing demographics. The percentage of patients greater than 65 years old will increase, from 12.3% in 2002 to 20% by 2030, with a parallel increase in the prevalence of osteoarthritis (OA).9 The World Health Organization has declared 2000‐2010 the Bone and Joint Decade,10, 11 reflecting that OA affects some 43 million people, with more than 60 million projected to be affected by 2020.12, 13 The National Center for Health Statistics reported that more than 280,000 total knee arthroplasties (TKAs) are performed annually in the United States, which marks an increase in frequency in the last decade that is likely to continue.1419

Approximately 75% of all TKAs are reimbursed under Medicare,17 whereas elective TKA continues to be one of the most common surgeries in the Medicare‐age patient population,20 foreshadowing the prominent cost burden of osteoarthritis in the aging population. The concomitant decreasing reimbursement for arthroplasty in general supports an examination of what constitutes efficient, high‐quality, and cost‐effective care21 for TKA. At our institution, patients undergoing TKA are preferentially triaged to an SOS nursing unit for postoperative care. As hospital bed capacity continues to decline, patients may be triaged to open beds at locations that may not be the optimal choice for nursing care. The primary purpose of this study was to determine the impact of SOS units versus nonorthopedic nursing (NON) units on resource utilization for and outcomes of patients undergoing elective knee arthroplasty. We hypothesized that length of stay would be shorter and cost of inpatient care would be lower for patients cared for on SOS units.

MATERIALS AND METHODS

RESULTS

Baseline patient characteristics are represented in Table 2. Five thousand and eighty‐two patients were admitted to an SOS unit, and 452 patients were admitted to a NON unit. The annual number of patients undergoing TKA increased during our study period, as did the number of patients cared for on NON units. There were no differences between groups in the number of local county patients or in the number of patients primarily referred by other providers for elective arthroplasty. Mean length of stay was 4.9 days in both groups. After adjusting for the specified covariates, including age, sex, year of surgery, Charlson comorbidities, ASA class, and type of anesthesia, LOS was 0.234 days shorter in the SOS group (95% confidence interval [CI]: 0.08, 0.39; P = .002). Overall and hospital costs were significantly lower in the SOS group, as outlined with the other costs in Table 3. Room‐and‐board costs were 5.3% lower for SOS patients than for patients on NON units, representing a per‐patient difference of $244 $87 (95% CI: $72, $415; P = .005).

There were 83 patients (1.63%) transferred from SOS units to the ICU, compared with 14 patients (3.1%) transferred from NON units (P = .02), but no differences in the mean number of ICU days or associated costs between groups. A priori, the authors were aware of the small number of postoperative medical events in this population. In examining the combined endpoint of reoperations, readmissions, and mortality, there were no differences observed in our regression analysis between SOS patients and NON unit patients (0.03 events, standard error: 0.1859; odds ratio: 0.976). Table 4 demonstrates a higher percentage of patients discharged with home health on the NON units than on the SOS units (8.41% vs. 4.62%; P < .001).

DISCUSSION

To the best of our knowledge, this is the first study to examine the impact of specialized orthopedic surgery units on resource utilization in elective knee arthroplasty patients. Our findings demonstrate that patients admitted following elective TKA to SOS units will have a reduced length of stay, lower overall and hospital costs, and fewer unexpected transfers to higher levels of care (ICUs). We believe that these findings are a result in part of the specialized expertise allied health care providers develop by taking care of and focusing on a large volume of patients over time with the same group and type of surgeons. This multidisciplinary setting in which care providers are familiar not only with each other but with this specific population of patients creates the environment necessary for adherence to specialized clinical pathways.27

Patient LOS is an important determinant of resource utilization. In a study by Husted et al., the mean length of stay in Danish hospitals following TKA was 8.6 days in 2003.28 An epidemiological study using the Nationwide Inpatient Sample database of patients in the United States showed that from 1998 to 2000, the mean LOS was 4.3 days.18 In our study, the mean LOS was slightly higher (4.9 days), potentially reflecting referral bias. Achieving additional savings and improved outcomes by further reducing LOS in an environment in which care pathways are already in place is often difficult; hence, alternative approaches and strategies are often necessary.29, 30 Our results suggest that in TKA patients, after adjusting for other factors, there is a decrease in the length of stay of 0.234 days among those cared for on SOS units. However, we cannot state that the existence of the clinical pathway alone is responsible for our data differences because certain components of the care pathway for elective TKA patients are used throughout the hospital regardless of type of postoperative nursing unit. We believe that the interdisciplinary specialty care provided to orthopedic patients on SOS units is a critical component of a successfully implemented care pathway and not just a convenience or practice preference. The same surgeons admitting patients to the same nursing unit, with the same nurses, physical therapists and pharmacists providing care to the same type of patient population over time, leverages the collective experience of all care providers. This integrated, multidisciplinary teamwork may optimize timeliness, achieve incremental cost savings, and improve safety (including a decreased number of unanticipated transfers to an ICU setting).

Clinical pathways are known to reduce overall costs, normally by reducing LOS,29, 3133 and our results suggest approximately an incremental 6% cost reduction with the use of improving patient logistics by using SOS units. An economic evaluation study by Healy et al. suggests that focusing on nursing units may be a means of reducing total costs.29 Our cost savings were slightly lower than the reported savings by other practice assessments; however, we excluded operative and anesthesia costs, both significant contributors to overall and hospital costs. By eliminating these variables, our costs were specifically limited to the postoperative course, which is highly dependent on specialized interdisciplinary care.29

Providing specialized care has a significant impact on society. Although there is a per‐patient savings of only $600 when elective TKA patients are cared for on SOS units, this could be the difference between a positive and negative margin in the setting of fixed reimbursement. With a current average of 90 patients annually triaged postoperatively to NON units, there is a potential loss of $54,000 annually at our institution in just this single patient population with the current mechanisms of perioperative hospital flow. Multiply this potential savings to a national level, and the total is significant. With an aging population, the number of arthroplasties and concomitantly the number of hospitalizations in general are likely to increase, suggesting that changes in hospital flow are required to ensure optimal, cost‐effective care in the best setting available for patients. Such care is often related to surgical volume, and our institution observes such volume. Our results indicate that SOS units are one possible means of achieving this objective of fiscal sustainability, but further studies are needed to determine the indirect and hidden costs of sustaining such units in order to observe the actual cost savings.34 It could be argued that for elective TKA patients to have the most optimal outcomes and most efficient care, the surgical procedure should be performed only if beds are available on the nursing units whose staff has the most specific training.

CONCLUSIONS

In conclusion, postoperative patients after elective knee arthroplasty cared for on specialized orthopedic surgery units have shorter length of stays and cost hospitals less than patients admitted to nonspecialized orthopedic nursing units. In an era in which quality indicators and external reviews are forcing practitioners and health care organizations to become increasingly responsible for their own practices, more research is required to better address specific questions pertaining to different processes of care. Our study is meant to increase the attention paid to patient flow and postoperative logistics in the elective TKA population. SOS units, as a unique model of care, may become an additional step toward ensuring quality care and improved resource utilization.

Hospital practices are increasingly responsible for ensuring enhanced patient safety, satisfaction, and cost containment. Recently developed models of care have achieved the necessary efficiency to attain these measures, not only in the use of hospitalists managing general medical1, 2 and postoperative orthopedic patients,3, 4 but also in the use of midlevel providers in busy primary care settings.5 In addition, stroke units6 and geriatric evaluation and management units7, 8 worldwide have demonstrated reduced disability and improved survival and importantly have been proven to provide cost‐effective care. Specialized orthopedic surgery (SOS) units may be a means to reproduce the results observed in these other models.

The economic potential of SOS units will become more significant with changing demographics. The percentage of patients greater than 65 years old will increase, from 12.3% in 2002 to 20% by 2030, with a parallel increase in the prevalence of osteoarthritis (OA).9 The World Health Organization has declared 2000‐2010 the Bone and Joint Decade,10, 11 reflecting that OA affects some 43 million people, with more than 60 million projected to be affected by 2020.12, 13 The National Center for Health Statistics reported that more than 280,000 total knee arthroplasties (TKAs) are performed annually in the United States, which marks an increase in frequency in the last decade that is likely to continue.1419

Approximately 75% of all TKAs are reimbursed under Medicare,17 whereas elective TKA continues to be one of the most common surgeries in the Medicare‐age patient population,20 foreshadowing the prominent cost burden of osteoarthritis in the aging population. The concomitant decreasing reimbursement for arthroplasty in general supports an examination of what constitutes efficient, high‐quality, and cost‐effective care21 for TKA. At our institution, patients undergoing TKA are preferentially triaged to an SOS nursing unit for postoperative care. As hospital bed capacity continues to decline, patients may be triaged to open beds at locations that may not be the optimal choice for nursing care. The primary purpose of this study was to determine the impact of SOS units versus nonorthopedic nursing (NON) units on resource utilization for and outcomes of patients undergoing elective knee arthroplasty. We hypothesized that length of stay would be shorter and cost of inpatient care would be lower for patients cared for on SOS units.

MATERIALS AND METHODS

RESULTS

Baseline patient characteristics are represented in Table 2. Five thousand and eighty‐two patients were admitted to an SOS unit, and 452 patients were admitted to a NON unit. The annual number of patients undergoing TKA increased during our study period, as did the number of patients cared for on NON units. There were no differences between groups in the number of local county patients or in the number of patients primarily referred by other providers for elective arthroplasty. Mean length of stay was 4.9 days in both groups. After adjusting for the specified covariates, including age, sex, year of surgery, Charlson comorbidities, ASA class, and type of anesthesia, LOS was 0.234 days shorter in the SOS group (95% confidence interval [CI]: 0.08, 0.39; P = .002). Overall and hospital costs were significantly lower in the SOS group, as outlined with the other costs in Table 3. Room‐and‐board costs were 5.3% lower for SOS patients than for patients on NON units, representing a per‐patient difference of $244 $87 (95% CI: $72, $415; P = .005).

There were 83 patients (1.63%) transferred from SOS units to the ICU, compared with 14 patients (3.1%) transferred from NON units (P = .02), but no differences in the mean number of ICU days or associated costs between groups. A priori, the authors were aware of the small number of postoperative medical events in this population. In examining the combined endpoint of reoperations, readmissions, and mortality, there were no differences observed in our regression analysis between SOS patients and NON unit patients (0.03 events, standard error: 0.1859; odds ratio: 0.976). Table 4 demonstrates a higher percentage of patients discharged with home health on the NON units than on the SOS units (8.41% vs. 4.62%; P < .001).

DISCUSSION

To the best of our knowledge, this is the first study to examine the impact of specialized orthopedic surgery units on resource utilization in elective knee arthroplasty patients. Our findings demonstrate that patients admitted following elective TKA to SOS units will have a reduced length of stay, lower overall and hospital costs, and fewer unexpected transfers to higher levels of care (ICUs). We believe that these findings are a result in part of the specialized expertise allied health care providers develop by taking care of and focusing on a large volume of patients over time with the same group and type of surgeons. This multidisciplinary setting in which care providers are familiar not only with each other but with this specific population of patients creates the environment necessary for adherence to specialized clinical pathways.27

Patient LOS is an important determinant of resource utilization. In a study by Husted et al., the mean length of stay in Danish hospitals following TKA was 8.6 days in 2003.28 An epidemiological study using the Nationwide Inpatient Sample database of patients in the United States showed that from 1998 to 2000, the mean LOS was 4.3 days.18 In our study, the mean LOS was slightly higher (4.9 days), potentially reflecting referral bias. Achieving additional savings and improved outcomes by further reducing LOS in an environment in which care pathways are already in place is often difficult; hence, alternative approaches and strategies are often necessary.29, 30 Our results suggest that in TKA patients, after adjusting for other factors, there is a decrease in the length of stay of 0.234 days among those cared for on SOS units. However, we cannot state that the existence of the clinical pathway alone is responsible for our data differences because certain components of the care pathway for elective TKA patients are used throughout the hospital regardless of type of postoperative nursing unit. We believe that the interdisciplinary specialty care provided to orthopedic patients on SOS units is a critical component of a successfully implemented care pathway and not just a convenience or practice preference. The same surgeons admitting patients to the same nursing unit, with the same nurses, physical therapists and pharmacists providing care to the same type of patient population over time, leverages the collective experience of all care providers. This integrated, multidisciplinary teamwork may optimize timeliness, achieve incremental cost savings, and improve safety (including a decreased number of unanticipated transfers to an ICU setting).

Clinical pathways are known to reduce overall costs, normally by reducing LOS,29, 3133 and our results suggest approximately an incremental 6% cost reduction with the use of improving patient logistics by using SOS units. An economic evaluation study by Healy et al. suggests that focusing on nursing units may be a means of reducing total costs.29 Our cost savings were slightly lower than the reported savings by other practice assessments; however, we excluded operative and anesthesia costs, both significant contributors to overall and hospital costs. By eliminating these variables, our costs were specifically limited to the postoperative course, which is highly dependent on specialized interdisciplinary care.29

Providing specialized care has a significant impact on society. Although there is a per‐patient savings of only $600 when elective TKA patients are cared for on SOS units, this could be the difference between a positive and negative margin in the setting of fixed reimbursement. With a current average of 90 patients annually triaged postoperatively to NON units, there is a potential loss of $54,000 annually at our institution in just this single patient population with the current mechanisms of perioperative hospital flow. Multiply this potential savings to a national level, and the total is significant. With an aging population, the number of arthroplasties and concomitantly the number of hospitalizations in general are likely to increase, suggesting that changes in hospital flow are required to ensure optimal, cost‐effective care in the best setting available for patients. Such care is often related to surgical volume, and our institution observes such volume. Our results indicate that SOS units are one possible means of achieving this objective of fiscal sustainability, but further studies are needed to determine the indirect and hidden costs of sustaining such units in order to observe the actual cost savings.34 It could be argued that for elective TKA patients to have the most optimal outcomes and most efficient care, the surgical procedure should be performed only if beds are available on the nursing units whose staff has the most specific training.

CONCLUSIONS

In conclusion, postoperative patients after elective knee arthroplasty cared for on specialized orthopedic surgery units have shorter length of stays and cost hospitals less than patients admitted to nonspecialized orthopedic nursing units. In an era in which quality indicators and external reviews are forcing practitioners and health care organizations to become increasingly responsible for their own practices, more research is required to better address specific questions pertaining to different processes of care. Our study is meant to increase the attention paid to patient flow and postoperative logistics in the elective TKA population. SOS units, as a unique model of care, may become an additional step toward ensuring quality care and improved resource utilization.

Hospital practices are increasingly responsible for ensuring enhanced patient safety, satisfaction, and cost containment. Recently developed models of care have achieved the necessary efficiency to attain these measures, not only in the use of hospitalists managing general medical1, 2 and postoperative orthopedic patients,3, 4 but also in the use of midlevel providers in busy primary care settings.5 In addition, stroke units6 and geriatric evaluation and management units7, 8 worldwide have demonstrated reduced disability and improved survival and importantly have been proven to provide cost‐effective care. Specialized orthopedic surgery (SOS) units may be a means to reproduce the results observed in these other models.

The economic potential of SOS units will become more significant with changing demographics. The percentage of patients greater than 65 years old will increase, from 12.3% in 2002 to 20% by 2030, with a parallel increase in the prevalence of osteoarthritis (OA).9 The World Health Organization has declared 2000‐2010 the Bone and Joint Decade,10, 11 reflecting that OA affects some 43 million people, with more than 60 million projected to be affected by 2020.12, 13 The National Center for Health Statistics reported that more than 280,000 total knee arthroplasties (TKAs) are performed annually in the United States, which marks an increase in frequency in the last decade that is likely to continue.1419

Approximately 75% of all TKAs are reimbursed under Medicare,17 whereas elective TKA continues to be one of the most common surgeries in the Medicare‐age patient population,20 foreshadowing the prominent cost burden of osteoarthritis in the aging population. The concomitant decreasing reimbursement for arthroplasty in general supports an examination of what constitutes efficient, high‐quality, and cost‐effective care21 for TKA. At our institution, patients undergoing TKA are preferentially triaged to an SOS nursing unit for postoperative care. As hospital bed capacity continues to decline, patients may be triaged to open beds at locations that may not be the optimal choice for nursing care. The primary purpose of this study was to determine the impact of SOS units versus nonorthopedic nursing (NON) units on resource utilization for and outcomes of patients undergoing elective knee arthroplasty. We hypothesized that length of stay would be shorter and cost of inpatient care would be lower for patients cared for on SOS units.

MATERIALS AND METHODS

RESULTS

Baseline patient characteristics are represented in Table 2. Five thousand and eighty‐two patients were admitted to an SOS unit, and 452 patients were admitted to a NON unit. The annual number of patients undergoing TKA increased during our study period, as did the number of patients cared for on NON units. There were no differences between groups in the number of local county patients or in the number of patients primarily referred by other providers for elective arthroplasty. Mean length of stay was 4.9 days in both groups. After adjusting for the specified covariates, including age, sex, year of surgery, Charlson comorbidities, ASA class, and type of anesthesia, LOS was 0.234 days shorter in the SOS group (95% confidence interval [CI]: 0.08, 0.39; P = .002). Overall and hospital costs were significantly lower in the SOS group, as outlined with the other costs in Table 3. Room‐and‐board costs were 5.3% lower for SOS patients than for patients on NON units, representing a per‐patient difference of $244 $87 (95% CI: $72, $415; P = .005).

There were 83 patients (1.63%) transferred from SOS units to the ICU, compared with 14 patients (3.1%) transferred from NON units (P = .02), but no differences in the mean number of ICU days or associated costs between groups. A priori, the authors were aware of the small number of postoperative medical events in this population. In examining the combined endpoint of reoperations, readmissions, and mortality, there were no differences observed in our regression analysis between SOS patients and NON unit patients (0.03 events, standard error: 0.1859; odds ratio: 0.976). Table 4 demonstrates a higher percentage of patients discharged with home health on the NON units than on the SOS units (8.41% vs. 4.62%; P < .001).

DISCUSSION

To the best of our knowledge, this is the first study to examine the impact of specialized orthopedic surgery units on resource utilization in elective knee arthroplasty patients. Our findings demonstrate that patients admitted following elective TKA to SOS units will have a reduced length of stay, lower overall and hospital costs, and fewer unexpected transfers to higher levels of care (ICUs). We believe that these findings are a result in part of the specialized expertise allied health care providers develop by taking care of and focusing on a large volume of patients over time with the same group and type of surgeons. This multidisciplinary setting in which care providers are familiar not only with each other but with this specific population of patients creates the environment necessary for adherence to specialized clinical pathways.27

Patient LOS is an important determinant of resource utilization. In a study by Husted et al., the mean length of stay in Danish hospitals following TKA was 8.6 days in 2003.28 An epidemiological study using the Nationwide Inpatient Sample database of patients in the United States showed that from 1998 to 2000, the mean LOS was 4.3 days.18 In our study, the mean LOS was slightly higher (4.9 days), potentially reflecting referral bias. Achieving additional savings and improved outcomes by further reducing LOS in an environment in which care pathways are already in place is often difficult; hence, alternative approaches and strategies are often necessary.29, 30 Our results suggest that in TKA patients, after adjusting for other factors, there is a decrease in the length of stay of 0.234 days among those cared for on SOS units. However, we cannot state that the existence of the clinical pathway alone is responsible for our data differences because certain components of the care pathway for elective TKA patients are used throughout the hospital regardless of type of postoperative nursing unit. We believe that the interdisciplinary specialty care provided to orthopedic patients on SOS units is a critical component of a successfully implemented care pathway and not just a convenience or practice preference. The same surgeons admitting patients to the same nursing unit, with the same nurses, physical therapists and pharmacists providing care to the same type of patient population over time, leverages the collective experience of all care providers. This integrated, multidisciplinary teamwork may optimize timeliness, achieve incremental cost savings, and improve safety (including a decreased number of unanticipated transfers to an ICU setting).

Clinical pathways are known to reduce overall costs, normally by reducing LOS,29, 3133 and our results suggest approximately an incremental 6% cost reduction with the use of improving patient logistics by using SOS units. An economic evaluation study by Healy et al. suggests that focusing on nursing units may be a means of reducing total costs.29 Our cost savings were slightly lower than the reported savings by other practice assessments; however, we excluded operative and anesthesia costs, both significant contributors to overall and hospital costs. By eliminating these variables, our costs were specifically limited to the postoperative course, which is highly dependent on specialized interdisciplinary care.29

Providing specialized care has a significant impact on society. Although there is a per‐patient savings of only $600 when elective TKA patients are cared for on SOS units, this could be the difference between a positive and negative margin in the setting of fixed reimbursement. With a current average of 90 patients annually triaged postoperatively to NON units, there is a potential loss of $54,000 annually at our institution in just this single patient population with the current mechanisms of perioperative hospital flow. Multiply this potential savings to a national level, and the total is significant. With an aging population, the number of arthroplasties and concomitantly the number of hospitalizations in general are likely to increase, suggesting that changes in hospital flow are required to ensure optimal, cost‐effective care in the best setting available for patients. Such care is often related to surgical volume, and our institution observes such volume. Our results indicate that SOS units are one possible means of achieving this objective of fiscal sustainability, but further studies are needed to determine the indirect and hidden costs of sustaining such units in order to observe the actual cost savings.34 It could be argued that for elective TKA patients to have the most optimal outcomes and most efficient care, the surgical procedure should be performed only if beds are available on the nursing units whose staff has the most specific training.

CONCLUSIONS

In conclusion, postoperative patients after elective knee arthroplasty cared for on specialized orthopedic surgery units have shorter length of stays and cost hospitals less than patients admitted to nonspecialized orthopedic nursing units. In an era in which quality indicators and external reviews are forcing practitioners and health care organizations to become increasingly responsible for their own practices, more research is required to better address specific questions pertaining to different processes of care. Our study is meant to increase the attention paid to patient flow and postoperative logistics in the elective TKA population. SOS units, as a unique model of care, may become an additional step toward ensuring quality care and improved resource utilization.

Over the past decade, an emerging body of literature established a link between nurses' working conditions and their ability to provide safe care. Nurses who are not at their best are both prone to making errors themselves, and less able to serve as effective safety nets for their patients, intercepting errors made by physicians and others.1 Excessive nurse workloads predict an increased rate of adverse events,2, 3 and, by their own reports, nurses working shifts of >12 hours are at greatly increased risk of making medical errors.4, 5 On the basis of these and related findings, the Institute of Medicine has recommended: a) that efforts be made to assure appropriate nurse workloads and b) that nurses work no more than 12 hours per day and 60 hours per week;6 but these recommendations have not been broadly enforced.7

Two articles in the current issue of the Journal of Hospital Medicine add to our understanding of the relationship between nurse working conditions and safety, and substantiate the need to improve nurses' working conditions. In the first, Surani et al. conducted a pilot study of 20 night nurses working 12‐hour shifts in which well‐validated, objective tools revealed that ICU nurses were suffering from pathologic levels of drowsiness on the job.8 The topic is of importance as recent survey work demonstrated that nurses working >12 hours and resident‐physicians working shifts of 24 of more hours make significantly more medical errors and suffer many more occupational injuries than those working less exhausting schedules.4, 5, 912 Objective data on resident‐physicians has corroborated these findings,13, 14 but objective data measuring sleepiness in nurses has been lacking. Surani et al.'s study helps to fill this need. Further, this study suggests that hospitals should not be complacent about the safety of 12‐hour shifts, which may still be associated with dangerous levels of drowsiness‐induced impairment. Careful management of the number of consecutive night shifts,15 or further reductions in nursing work hours even beyond the 12‐hour limit endorsed by the IOM may be in orderparticularly in high‐risk critical care environmentsthough further research substantiating Surani et al.'s findings and comparing alternative scheduling options would be valuable.

The second study by Conway et al. analyzed data for acute care hospitals in California from 1993 to 2004, and found that following the passage of nurse staffing legislation in 1999 and its implementation in 2004, nurse‐patient staffing ratios increased significantly.16 Safety‐net hospitals, however, with high proportions of vulnerable patient populations, were least likely to achieve mandated ratios. As the authors point out, diverting funds to achieve mandated ratios in under‐funded safety net hospitals could potentially lead to reductions in other essential services, though whether such an eventuality might come to pass has not been adequately assessed to date.

In light of these data, where should we go from here? Public and professional concerns over the impact of fewer nurses on the delivery of care have led to the passage of legislation or adoption of regulations by many states in an attempt to ensure safe care. Examples include elimination of mandatory overtime in the following states: CT, IL, ME, MD, MN, NJ, NH, OR, RI, WA, WV, CA, MO, and TX; implementation of nurse staffing plans with input from staff nurses (WA, IL, OR, RI, TX), and mandates of specific nurse to patient ratios (CA [as discussed by Conway et al.] and FL).17 Proposed legislation regarding nurse staffing and nurse‐to‐patient ratios is currently under consideration in many additional states. Legislation broadly restricting nurse work hours has not been passed by the federal government or individual states, but some hospital systems including the Veteran's Administration now have policies prohibiting shifts of greater than 12 hours and work weeks of greater than 60 hours.18

Unfortunately, several major barriers have made the implementation of safer work hours and workloads challenging, and uncertainty about the effectiveness of implementation efforts remains. A major challenge has been the presence of a serious shortage of nurses, which is expected to peak by 2020.19 A lack of nurses will make both staffing and scheduling initiatives difficult. Over the next 10 to 15 years, policies that fund nursing education or otherwise address this shortfall will consequently be essential.

A second challenge in efforts to implement safer work schedules appears to be an absence of knowledge about the hazards of sleep deprivation, compounded by financial pressures that may lead to unsafe schedules. Some nurses oppose restriction of work hours citing that they know when they are tired, their schedule works for their personal life, and they should be allowed to work as much as they want to earn the salary they want/need. Unfortunately, it has been well‐demonstrated that chronically sleep‐deprived individuals routinely under‐estimate their level of impairment, calling into question the ability of nurses and others working extreme hours to accurately judge their abilities to perform safely.20

Clearly, education on the effects of fatigue on performance is needed, as are widespread efforts to implement safe schedules. Further study of work injuries, medical errors, and their relation to fatigue and specific work schedules is warranted, as well as studies of the impact of fatigue on sick calls and absenteeism. In many tightly staffed hospitals, overtime is used to provide coverage for sick calls, which in turn potentiates further risk of fatigue. As a profession, nurses need to take the fear factor out of saying I'm tired and advocate for adequate breaks, naps, and diet. Nurse leaders often find that offering 12‐hour shifts is required to recruit nurses, and that rotating shiftssometimes in a manner that can lead to significant circadian misalignmenthelps balance the schedule and preference for day shifts. They are also aware that a scheduled 3‐day work week is attractive to many nurses, as it allows those desiring greater income to work additional shifts through an agency at premium pay, though this may lead to further sleep deprivation. It is easy to conceive how these factors can lead to a serious conundrum.

How best to address concerns over nurse staffing remains a subject of ongoing debate. Higher nurse‐to‐patient ratios have been associated in multiple studies and a meta‐analysis with lower rates of complications and mortality.3, 21 Understanding the causal relationship between ratios and outcomes, however, has been complicated by consideration of confounding hospital variables and varying acuity of patient care between centers. The number of patients a nurse can safely care for at any one time is likely a product of the acuity of the patients, the education and experience of the nurse, and the makeup of the team available to care for the patients' needs. How well implementation of mandates regarding nurse‐patient ratios can address this complex need is unclear, and should be a focus of future research.

Leadership is essential in implementing work hour standards and staffing plans to promote a high‐quality nursing environment. Hospitals with poor operating margins, poor leadership, or poor environments of care will be unable to retain nurses to meet care requirements. Magnet hospitals, with nurse leaders who promote RN empowerment, can develop less stressful work environments with lower turnover rates and greater job satisfaction, which positively impacts quality of care. The Magnet Recognition Program, developed by the American Nurses Credentialing Center (ANCC), has recognized less than 300 hospitals in the US as providing nursing excellence (http://www.nursecredentialing.org/magnet/).

State and federal regulation may address initial safety needs, but it cannot in isolation address all of the elements that contribute to high‐quality care. While data are limited, it is possible that in financially constrained hospitals, suboptimal implementation of mandates may potentially lead to misuse of limited resources. Future research should directly assess the net effects of implementing nurse scheduling and staffing policies on mortality, hospital complication rates, and the safety of patient care processes across diverse medical centers and patient care settings. Building upon the research of Surani, Conway, and their colleagues, such research could help promote the further development of optimal care policies and the quality of patient care.

Over the past decade, an emerging body of literature established a link between nurses' working conditions and their ability to provide safe care. Nurses who are not at their best are both prone to making errors themselves, and less able to serve as effective safety nets for their patients, intercepting errors made by physicians and others.1 Excessive nurse workloads predict an increased rate of adverse events,2, 3 and, by their own reports, nurses working shifts of >12 hours are at greatly increased risk of making medical errors.4, 5 On the basis of these and related findings, the Institute of Medicine has recommended: a) that efforts be made to assure appropriate nurse workloads and b) that nurses work no more than 12 hours per day and 60 hours per week;6 but these recommendations have not been broadly enforced.7

Two articles in the current issue of the Journal of Hospital Medicine add to our understanding of the relationship between nurse working conditions and safety, and substantiate the need to improve nurses' working conditions. In the first, Surani et al. conducted a pilot study of 20 night nurses working 12‐hour shifts in which well‐validated, objective tools revealed that ICU nurses were suffering from pathologic levels of drowsiness on the job.8 The topic is of importance as recent survey work demonstrated that nurses working >12 hours and resident‐physicians working shifts of 24 of more hours make significantly more medical errors and suffer many more occupational injuries than those working less exhausting schedules.4, 5, 912 Objective data on resident‐physicians has corroborated these findings,13, 14 but objective data measuring sleepiness in nurses has been lacking. Surani et al.'s study helps to fill this need. Further, this study suggests that hospitals should not be complacent about the safety of 12‐hour shifts, which may still be associated with dangerous levels of drowsiness‐induced impairment. Careful management of the number of consecutive night shifts,15 or further reductions in nursing work hours even beyond the 12‐hour limit endorsed by the IOM may be in orderparticularly in high‐risk critical care environmentsthough further research substantiating Surani et al.'s findings and comparing alternative scheduling options would be valuable.

The second study by Conway et al. analyzed data for acute care hospitals in California from 1993 to 2004, and found that following the passage of nurse staffing legislation in 1999 and its implementation in 2004, nurse‐patient staffing ratios increased significantly.16 Safety‐net hospitals, however, with high proportions of vulnerable patient populations, were least likely to achieve mandated ratios. As the authors point out, diverting funds to achieve mandated ratios in under‐funded safety net hospitals could potentially lead to reductions in other essential services, though whether such an eventuality might come to pass has not been adequately assessed to date.

In light of these data, where should we go from here? Public and professional concerns over the impact of fewer nurses on the delivery of care have led to the passage of legislation or adoption of regulations by many states in an attempt to ensure safe care. Examples include elimination of mandatory overtime in the following states: CT, IL, ME, MD, MN, NJ, NH, OR, RI, WA, WV, CA, MO, and TX; implementation of nurse staffing plans with input from staff nurses (WA, IL, OR, RI, TX), and mandates of specific nurse to patient ratios (CA [as discussed by Conway et al.] and FL).17 Proposed legislation regarding nurse staffing and nurse‐to‐patient ratios is currently under consideration in many additional states. Legislation broadly restricting nurse work hours has not been passed by the federal government or individual states, but some hospital systems including the Veteran's Administration now have policies prohibiting shifts of greater than 12 hours and work weeks of greater than 60 hours.18

Unfortunately, several major barriers have made the implementation of safer work hours and workloads challenging, and uncertainty about the effectiveness of implementation efforts remains. A major challenge has been the presence of a serious shortage of nurses, which is expected to peak by 2020.19 A lack of nurses will make both staffing and scheduling initiatives difficult. Over the next 10 to 15 years, policies that fund nursing education or otherwise address this shortfall will consequently be essential.

A second challenge in efforts to implement safer work schedules appears to be an absence of knowledge about the hazards of sleep deprivation, compounded by financial pressures that may lead to unsafe schedules. Some nurses oppose restriction of work hours citing that they know when they are tired, their schedule works for their personal life, and they should be allowed to work as much as they want to earn the salary they want/need. Unfortunately, it has been well‐demonstrated that chronically sleep‐deprived individuals routinely under‐estimate their level of impairment, calling into question the ability of nurses and others working extreme hours to accurately judge their abilities to perform safely.20

Clearly, education on the effects of fatigue on performance is needed, as are widespread efforts to implement safe schedules. Further study of work injuries, medical errors, and their relation to fatigue and specific work schedules is warranted, as well as studies of the impact of fatigue on sick calls and absenteeism. In many tightly staffed hospitals, overtime is used to provide coverage for sick calls, which in turn potentiates further risk of fatigue. As a profession, nurses need to take the fear factor out of saying I'm tired and advocate for adequate breaks, naps, and diet. Nurse leaders often find that offering 12‐hour shifts is required to recruit nurses, and that rotating shiftssometimes in a manner that can lead to significant circadian misalignmenthelps balance the schedule and preference for day shifts. They are also aware that a scheduled 3‐day work week is attractive to many nurses, as it allows those desiring greater income to work additional shifts through an agency at premium pay, though this may lead to further sleep deprivation. It is easy to conceive how these factors can lead to a serious conundrum.