Jason Filopei, MD

Applications of point‐of‐care ultrasonography (POC‐US) have grown rapidly over the past 20 years. POC‐US training is required by the Accreditation Council for Graduate Medical Education for several graduate medical education training programs, including emergency medicine residency and pulmonary/critical care fellowships.[1] Recent efforts have examined the utility of ultrasound in the education of medical students[2] and the diagnostic and procedural applications performed by residents.[3] One powerful application of POC‐US is the use of lung ultrasound to diagnose causes of respiratory failure at the bedside.[4] Although lung ultrasound has been shown to have superior diagnostic accuracy to chest x‐rays,[5] limited availability of expert physicians and ultrasound equipment have presented barriers to wider application. The advent of lower cost pocket ultrasounds may present a solution given the early reports of similar efficacy to traditional devices in the assessment of left ventricular dysfunction, acute decompensated heart failure,[6] and focused assessment with sonography for trauma.[7] We assessed the feasibility and diagnostic accuracy of residents trained in lung ultrasound with a pocket device for evaluating patients with dyspnea.

MATERIALS AND METHODS

Diagnostic Protocol

Upon admission, residents recorded a clinical diagnosis of dyspnea based on a standard diagnostic evaluation including complete history, physical exam, and all relevant laboratory and imaging studies, including chest x‐ray and computed tomography (CT) scans. A diagnosis of dyspnea after lung ultrasound was then recorded based on the lung ultrasound findings and integrated with all other clinical information available. Standard lung ultrasound patterns and diagnostic correlates are shown in Figure 1. Diagnoses of dyspnea were recorded as one of 7 possibilities; 1) exacerbation of chronic obstructive pulmonary disease or asthma (COPD/asthma), 2) acute pulmonary edema (APE), 3) pneumonia (PNA), 4) pulmonary embolus (PE), 5) pneumothorax (PTX), 6) pleural effusion (PLEFF), and 7) other (OTH), namely anemia, ascites, and dehydration.

Figure 1

RESULTS

Five residents performed lung ultrasound on a convenience sample of 69 newly admitted patients. Patient baseline characteristics are shown in Table 1. Three residents made up the focused training group and examined 21 patients, resulting in 27 clinical diagnoses, 27 ultrasound diagnoses, and 31 final attending diagnoses. Two residents made up the extended training group and examined 48 patients, resulting in 61 clinical diagnoses, 60 ultrasound diagnoses, and 60 final attending diagnoses. Improvements in sensitivity and specificity using lung ultrasound were more pronounced for the extended training group and are shown for each diagnosis in Table 2.

Overall diagnostic accuracy using lung ultrasound improved only for the extended training group (clinical 92% vs ultrasound 97%), whereas the focused training group's accuracy was unchanged (clinical 87% vs ultrasound 88%).

ROC analysis demonstrated a superior diagnostic performance of ultrasound when compared to clinical diagnosis (Table 3).

DISCUSSION

In this prospective, observational study of residents performing lung ultrasound of patients with dyspnea, the diagnostic accuracy incorporating ultrasound increased compared to a standard diagnostic approach relying on history, physical exam, blood tests, and radiography. To our knowledge, this is the first study of residents independently performing lung ultrasound with a pocket ultrasound to diagnose dyspnea. Receiver operating curve analysis shows improvements in diagnostic accuracy for causes such as PNA, pleural effusion and COPD/asthma and demonstrates the feasibility and clinical utility of residents using pocket ultrasounds. The finding that improvements in sensitivity and specificity were larger in the extended training group highlights the need for sufficient training to demonstrate increased utility. Although a 2‐week critical care ultrasound elective may not be possible for all residents, perhaps training of intensity somewhere in between these 2 levels would be most feasible.

Challenges in diagnosing dyspnea have been well described, attributed to a lack of accurate history combined with often insensitive and nonspecific physical exam findings, blood tests, and radiographs.[8, 9] Further, patients often present with multiple contributing causes as was evidenced in this study.[10] Lack of initial, accurate diagnoses often leads to the provision of multiple, incorrect treatment regimens that may increase mortality.[11] The high accuracy of lung ultrasound in defining causes of respiratory failure suggests potential as a low‐cost solution.[12]

This study design differed from prior work in several respects. First, it included patients presenting with dyspnea to a hospital ward rather than acute respiratory failure to an intensive care unit (ICU), suggesting its diagnostic potential in a broader population of patients and settings. Second, the lung ultrasound was integrated with traditional clinical information rather than relied upon alone, a situation mimicking real‐world application of POC‐US. Third, operators were residents with limited amounts of training rather than highly trained experts. Finally, the lung ultrasound exams were performed using a pocket ultrasound with inferior imaging capability than larger, more established ultrasound devices. Despite these constraints, the utility of lung ultrasound was still evident, particularly in the diagnosis or exclusion of pneumonia and PLEFF.

Limitations include reliance on a small cohort of highly motivated residents with an interest in pulmonary and critical care, 2 who are authors of this article, making reproducibility a concern. Although convenience sampling may more closely mimic real world practices of POC‐US, a bias toward less challenging patients is possible and may limit conclusions regarding utility. Over‐reading and feedback were not provided to residents to improve their performance of lung ultrasound exams. Also, because chest CT is considered the gold standard in most studies examining the diagnostic accuracy of lung ultrasound, all residents aware of these data may underestimate the potential impact of integrating lung ultrasound with all clinical findings. Finally, the high cost of pocket ultrasounds is a barrier to general use. Recent studies on the significant cost savings associated with POC‐US make a further analysis of cost‐benefit ratios mandatory before broad use can be recommended.[13]

CONCLUSIONS

Residents participating in lung ultrasound training with a pocket ultrasound device showed improved diagnostic accuracy in their evaluation of patients with dyspnea. Those who received extended training had greater improvements across all causes of dyspnea. Training residents to apply lung ultrasound in non‐ICU settings appears to be feasible. Further study with a larger cohort of internal medicine residents and perhaps training duration that lies in between the focused and extended training groups is warranted.

Applications of point‐of‐care ultrasonography (POC‐US) have grown rapidly over the past 20 years. POC‐US training is required by the Accreditation Council for Graduate Medical Education for several graduate medical education training programs, including emergency medicine residency and pulmonary/critical care fellowships.[1] Recent efforts have examined the utility of ultrasound in the education of medical students[2] and the diagnostic and procedural applications performed by residents.[3] One powerful application of POC‐US is the use of lung ultrasound to diagnose causes of respiratory failure at the bedside.[4] Although lung ultrasound has been shown to have superior diagnostic accuracy to chest x‐rays,[5] limited availability of expert physicians and ultrasound equipment have presented barriers to wider application. The advent of lower cost pocket ultrasounds may present a solution given the early reports of similar efficacy to traditional devices in the assessment of left ventricular dysfunction, acute decompensated heart failure,[6] and focused assessment with sonography for trauma.[7] We assessed the feasibility and diagnostic accuracy of residents trained in lung ultrasound with a pocket device for evaluating patients with dyspnea.

MATERIALS AND METHODS

Diagnostic Protocol

Upon admission, residents recorded a clinical diagnosis of dyspnea based on a standard diagnostic evaluation including complete history, physical exam, and all relevant laboratory and imaging studies, including chest x‐ray and computed tomography (CT) scans. A diagnosis of dyspnea after lung ultrasound was then recorded based on the lung ultrasound findings and integrated with all other clinical information available. Standard lung ultrasound patterns and diagnostic correlates are shown in Figure 1. Diagnoses of dyspnea were recorded as one of 7 possibilities; 1) exacerbation of chronic obstructive pulmonary disease or asthma (COPD/asthma), 2) acute pulmonary edema (APE), 3) pneumonia (PNA), 4) pulmonary embolus (PE), 5) pneumothorax (PTX), 6) pleural effusion (PLEFF), and 7) other (OTH), namely anemia, ascites, and dehydration.

Figure 1

RESULTS

Five residents performed lung ultrasound on a convenience sample of 69 newly admitted patients. Patient baseline characteristics are shown in Table 1. Three residents made up the focused training group and examined 21 patients, resulting in 27 clinical diagnoses, 27 ultrasound diagnoses, and 31 final attending diagnoses. Two residents made up the extended training group and examined 48 patients, resulting in 61 clinical diagnoses, 60 ultrasound diagnoses, and 60 final attending diagnoses. Improvements in sensitivity and specificity using lung ultrasound were more pronounced for the extended training group and are shown for each diagnosis in Table 2.

Overall diagnostic accuracy using lung ultrasound improved only for the extended training group (clinical 92% vs ultrasound 97%), whereas the focused training group's accuracy was unchanged (clinical 87% vs ultrasound 88%).

ROC analysis demonstrated a superior diagnostic performance of ultrasound when compared to clinical diagnosis (Table 3).

DISCUSSION

In this prospective, observational study of residents performing lung ultrasound of patients with dyspnea, the diagnostic accuracy incorporating ultrasound increased compared to a standard diagnostic approach relying on history, physical exam, blood tests, and radiography. To our knowledge, this is the first study of residents independently performing lung ultrasound with a pocket ultrasound to diagnose dyspnea. Receiver operating curve analysis shows improvements in diagnostic accuracy for causes such as PNA, pleural effusion and COPD/asthma and demonstrates the feasibility and clinical utility of residents using pocket ultrasounds. The finding that improvements in sensitivity and specificity were larger in the extended training group highlights the need for sufficient training to demonstrate increased utility. Although a 2‐week critical care ultrasound elective may not be possible for all residents, perhaps training of intensity somewhere in between these 2 levels would be most feasible.

Challenges in diagnosing dyspnea have been well described, attributed to a lack of accurate history combined with often insensitive and nonspecific physical exam findings, blood tests, and radiographs.[8, 9] Further, patients often present with multiple contributing causes as was evidenced in this study.[10] Lack of initial, accurate diagnoses often leads to the provision of multiple, incorrect treatment regimens that may increase mortality.[11] The high accuracy of lung ultrasound in defining causes of respiratory failure suggests potential as a low‐cost solution.[12]

This study design differed from prior work in several respects. First, it included patients presenting with dyspnea to a hospital ward rather than acute respiratory failure to an intensive care unit (ICU), suggesting its diagnostic potential in a broader population of patients and settings. Second, the lung ultrasound was integrated with traditional clinical information rather than relied upon alone, a situation mimicking real‐world application of POC‐US. Third, operators were residents with limited amounts of training rather than highly trained experts. Finally, the lung ultrasound exams were performed using a pocket ultrasound with inferior imaging capability than larger, more established ultrasound devices. Despite these constraints, the utility of lung ultrasound was still evident, particularly in the diagnosis or exclusion of pneumonia and PLEFF.

Limitations include reliance on a small cohort of highly motivated residents with an interest in pulmonary and critical care, 2 who are authors of this article, making reproducibility a concern. Although convenience sampling may more closely mimic real world practices of POC‐US, a bias toward less challenging patients is possible and may limit conclusions regarding utility. Over‐reading and feedback were not provided to residents to improve their performance of lung ultrasound exams. Also, because chest CT is considered the gold standard in most studies examining the diagnostic accuracy of lung ultrasound, all residents aware of these data may underestimate the potential impact of integrating lung ultrasound with all clinical findings. Finally, the high cost of pocket ultrasounds is a barrier to general use. Recent studies on the significant cost savings associated with POC‐US make a further analysis of cost‐benefit ratios mandatory before broad use can be recommended.[13]

CONCLUSIONS

Residents participating in lung ultrasound training with a pocket ultrasound device showed improved diagnostic accuracy in their evaluation of patients with dyspnea. Those who received extended training had greater improvements across all causes of dyspnea. Training residents to apply lung ultrasound in non‐ICU settings appears to be feasible. Further study with a larger cohort of internal medicine residents and perhaps training duration that lies in between the focused and extended training groups is warranted.

Applications of point‐of‐care ultrasonography (POC‐US) have grown rapidly over the past 20 years. POC‐US training is required by the Accreditation Council for Graduate Medical Education for several graduate medical education training programs, including emergency medicine residency and pulmonary/critical care fellowships.[1] Recent efforts have examined the utility of ultrasound in the education of medical students[2] and the diagnostic and procedural applications performed by residents.[3] One powerful application of POC‐US is the use of lung ultrasound to diagnose causes of respiratory failure at the bedside.[4] Although lung ultrasound has been shown to have superior diagnostic accuracy to chest x‐rays,[5] limited availability of expert physicians and ultrasound equipment have presented barriers to wider application. The advent of lower cost pocket ultrasounds may present a solution given the early reports of similar efficacy to traditional devices in the assessment of left ventricular dysfunction, acute decompensated heart failure,[6] and focused assessment with sonography for trauma.[7] We assessed the feasibility and diagnostic accuracy of residents trained in lung ultrasound with a pocket device for evaluating patients with dyspnea.

MATERIALS AND METHODS

Diagnostic Protocol

Upon admission, residents recorded a clinical diagnosis of dyspnea based on a standard diagnostic evaluation including complete history, physical exam, and all relevant laboratory and imaging studies, including chest x‐ray and computed tomography (CT) scans. A diagnosis of dyspnea after lung ultrasound was then recorded based on the lung ultrasound findings and integrated with all other clinical information available. Standard lung ultrasound patterns and diagnostic correlates are shown in Figure 1. Diagnoses of dyspnea were recorded as one of 7 possibilities; 1) exacerbation of chronic obstructive pulmonary disease or asthma (COPD/asthma), 2) acute pulmonary edema (APE), 3) pneumonia (PNA), 4) pulmonary embolus (PE), 5) pneumothorax (PTX), 6) pleural effusion (PLEFF), and 7) other (OTH), namely anemia, ascites, and dehydration.

Figure 1

RESULTS

Five residents performed lung ultrasound on a convenience sample of 69 newly admitted patients. Patient baseline characteristics are shown in Table 1. Three residents made up the focused training group and examined 21 patients, resulting in 27 clinical diagnoses, 27 ultrasound diagnoses, and 31 final attending diagnoses. Two residents made up the extended training group and examined 48 patients, resulting in 61 clinical diagnoses, 60 ultrasound diagnoses, and 60 final attending diagnoses. Improvements in sensitivity and specificity using lung ultrasound were more pronounced for the extended training group and are shown for each diagnosis in Table 2.

Overall diagnostic accuracy using lung ultrasound improved only for the extended training group (clinical 92% vs ultrasound 97%), whereas the focused training group's accuracy was unchanged (clinical 87% vs ultrasound 88%).

ROC analysis demonstrated a superior diagnostic performance of ultrasound when compared to clinical diagnosis (Table 3).

DISCUSSION

In this prospective, observational study of residents performing lung ultrasound of patients with dyspnea, the diagnostic accuracy incorporating ultrasound increased compared to a standard diagnostic approach relying on history, physical exam, blood tests, and radiography. To our knowledge, this is the first study of residents independently performing lung ultrasound with a pocket ultrasound to diagnose dyspnea. Receiver operating curve analysis shows improvements in diagnostic accuracy for causes such as PNA, pleural effusion and COPD/asthma and demonstrates the feasibility and clinical utility of residents using pocket ultrasounds. The finding that improvements in sensitivity and specificity were larger in the extended training group highlights the need for sufficient training to demonstrate increased utility. Although a 2‐week critical care ultrasound elective may not be possible for all residents, perhaps training of intensity somewhere in between these 2 levels would be most feasible.

Challenges in diagnosing dyspnea have been well described, attributed to a lack of accurate history combined with often insensitive and nonspecific physical exam findings, blood tests, and radiographs.[8, 9] Further, patients often present with multiple contributing causes as was evidenced in this study.[10] Lack of initial, accurate diagnoses often leads to the provision of multiple, incorrect treatment regimens that may increase mortality.[11] The high accuracy of lung ultrasound in defining causes of respiratory failure suggests potential as a low‐cost solution.[12]

This study design differed from prior work in several respects. First, it included patients presenting with dyspnea to a hospital ward rather than acute respiratory failure to an intensive care unit (ICU), suggesting its diagnostic potential in a broader population of patients and settings. Second, the lung ultrasound was integrated with traditional clinical information rather than relied upon alone, a situation mimicking real‐world application of POC‐US. Third, operators were residents with limited amounts of training rather than highly trained experts. Finally, the lung ultrasound exams were performed using a pocket ultrasound with inferior imaging capability than larger, more established ultrasound devices. Despite these constraints, the utility of lung ultrasound was still evident, particularly in the diagnosis or exclusion of pneumonia and PLEFF.

Limitations include reliance on a small cohort of highly motivated residents with an interest in pulmonary and critical care, 2 who are authors of this article, making reproducibility a concern. Although convenience sampling may more closely mimic real world practices of POC‐US, a bias toward less challenging patients is possible and may limit conclusions regarding utility. Over‐reading and feedback were not provided to residents to improve their performance of lung ultrasound exams. Also, because chest CT is considered the gold standard in most studies examining the diagnostic accuracy of lung ultrasound, all residents aware of these data may underestimate the potential impact of integrating lung ultrasound with all clinical findings. Finally, the high cost of pocket ultrasounds is a barrier to general use. Recent studies on the significant cost savings associated with POC‐US make a further analysis of cost‐benefit ratios mandatory before broad use can be recommended.[13]

CONCLUSIONS

Residents participating in lung ultrasound training with a pocket ultrasound device showed improved diagnostic accuracy in their evaluation of patients with dyspnea. Those who received extended training had greater improvements across all causes of dyspnea. Training residents to apply lung ultrasound in non‐ICU settings appears to be feasible. Further study with a larger cohort of internal medicine residents and perhaps training duration that lies in between the focused and extended training groups is warranted.