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CASE Medication management
Mr. L, age 58, presents to the outpatient psychiatric clinic seeking treatment for attention-deficit/hyperactivity disorder (ADHD), which was first diagnosed 11 years ago. Since discontinuing his ADHD medication, lisdexamfetamine 60 mg/d, 8 months ago, he has not been completing tasks and has been distracted in his job as a limousine driver. Mr. L says that when he was taking the medication, “I could focus and prioritize.” He reports that he has trouble retaining information and is easily distracted. He says he generally is organized with appointments and keeping track of things but is messy, forgetful, tardy, and impatient. Procrastination is an ongoing problem. He denies misplacing things or being impulsive. Mr. L reports that as a child he was frequently reprimanded for talking in class. He states, “I get in trouble even now for talking too much.”
Mr. L is cooperative and polite, maintains good eye contact, and is alert. No psychomotor abnormalities are noted. His speech is spontaneous and coherent, with normal rate, rhythm, and volume. He reports that his mood is “all right,” and denies suicidal or homicidal ideation. His insight is full, judgment is intact, and thought is linear and logical. Mr. L sleeps 5 hours at night and takes a nap during the day, but his energy varies.
His psychiatric history is negative for suicide attempts or hospitalizations. Mr. L denies a history of major depressive episodes, manic symptoms, hallucinations, or delusions. Anxiety history is negative for excessive worrying, obsessions and compulsions, and panic attacks. Mr. L has no family history of mental illness or substance abuse, and he denies any personal history of drug use. He stopped using tobacco 14 years ago. Mr. L says he drinks 3 caffeinated drinks a day and 2 glasses of wine once a week. Previous medications included
A review of systems is negative. Vital signs are unremarkable. A recent electrocardiogram (EKG) showed normal sinus rhythm. Thyroid-stimulating hormone, comprehensive metabolic panel (CMP), lipids, iron, vitamin B12, folate, complete blood count (CBC), hemoglobin A1c, and urine analysis are normal, except for mildly elevated low-density lipoprotein. Testing for hepatitis C is negative.
The previous diagnosis of ADHD is confirmed, and Mr. L is started on
[polldaddy:9928295]
The author’s observations
Anxiety, irritability, agitation, and palpitations can all be symptoms of stimulant medications.1,2 There are numerous other iatrogenic causes, including steroid-based asthma treatments, thyroid medications, antidepressants in bipolar patients, and caffeine-based migraine treatments. Mr. L’s theory that his 15-lb weight loss was the result of his methylphenidate ER dose being too high was a reasonable one. Often, medication doses need to be adjusted with weight changes. His decrease in energy during the day could be explained by the methylphenidate ER controlling his hyperactive symptoms, which include high energy. At night, when the medication wears off, his hyperactivity symptoms could be returning, which would account for the increase in energy when he gets home from work. Although longer-acting stimulants tend to have a more benign adverse effects profile, they can cause insomnia if they are still in the patient’s system at bedtime. Shorter-acting stimulants wear off quickly but can be advantageous for patients who want to target concentration during certain times of day, such as for school and homework.
TREATMENT A surprising cause
The next month, Mr. L presents to the emergency room complaining of jitteriness, headache, and tingling in his fingers, and is evaluated for suspected carbon monoxide (CO) poisoning. Three months earlier, he had noted the odor of exhaust fumes in the limousine he drives 7 days a week. He took it to the mechanic twice for evaluation, but no cause was found. Despite his concerns, he continued to drive the car until an older client, in frail health, suddenly became short of breath and developed chest pain shortly after entering his vehicle, on a day when the odor was particularly bad. Before that, a family of passengers had complained of headaches upon entering his vehicle. The third time he brought his car to be checked, the mechanic identified an exhaust system leak.
[polldaddy:9928298]
The author’s observations
Work-up for suspected CO poisoning includes ABG, COHb level, CBC, basic metabolic panel, EKG, cardiac enzymes, and chest radiography, as well as other laboratory tests as deemed appropriate. Treatment includes oxygen by mask for low-level poisoning.
High levels of poisoning may require hyperbaric oxygen, which should be considered for patients who are unconscious or have an abnormal score on the Carbon Monoxide Neuropsychological Screening Battery, COHb of >40%, signs of cardiac ischemia or arrhythmia, history of ischemic heart disease with COHb level >20%, recurrent symptoms for up to 3 weeks, or symptoms that have not resolved with normobaric oxygen after 4 to 6 hours.9 Any pregnant woman with CO poisoning should receive hyperbaric therapy.10
OUTCOME Lasting improvement
Mr. L presents for follow-up in the psychiatric clinic 3 weeks after his emergency room visit. After his limousine was repaired, his symptoms resolved. He no longer experiences fatigue during the day with higher energy at night, palpitations, jitteriness, headache, or tingling. His concentration has improved, so he opts to stick with the 18-mg dose of methylphenidate ER rather than increase it to the initial dose. He places a CO detector in his vehicle, which proves to be a good decision when it gives him a warning that the exhaust leak had not been properly repaired.
[polldaddy:9928299]
The author’s observations
Although the correct cause of Mr. L’s symptoms was found incidentally, this case is an important reminder to always consider medical causes in the differential diagnosis. We are taught in medical school to look first for horses (more likely causes), not zebras (less likely causes), but sometimes zebras do occur. Be mindful that medical causes should be considered not only for symptoms of primary illnesses, but also for symptoms thought to be caused by adverse effects of medications. The differential diagnosis for Mr. L’s symptoms (palpitations, agitation, anxiety, irritability, weight loss, fatigue, nausea, and headache) included metabolic and endocrine abnormalities (thyroid disease, pheochromocytoma, hypoglycemia); psychiatric conditions (panic, bipolar disorder, depression); substance abuse (caffeine, cocaine, amphetamines); immune disorders; cardiac disorders; malignancy; toxic exposure; infectious sources; and nutritional deficiencies. CO poisoning can cause many of these symptoms (Table 2).1,2,8
Intentional CO poisoning should be considered in an obtunded or unconscious patient with depression. Patients may consider CO poisoning a more peaceful way to complete suicide than shooting, cutting, or hanging. As for unintentional poisoning, clinical suspicion can be increased by time of year, occupation, locale, and smoking status. Winter months increase risk because of the high use of heating devices, cars warming up in the garage, closed fireplace flues, and vehicle tailpipes blocked by snow. As in Mr. L’s case, occupation also may increase suspicion; drivers, mechanics, tollbooth operators, parking attendants, miners, and firefighters are all at increased risk for CO poisoning. Regarding locale, polluted urban environments as well as cold climates requiring heating sources cause higher risks for CO exposure. Rarely, excessive smoking can result in CO poisoning. The author once had a patient with schizophrenia who was admitted to the hospital with delirium. It was determined that he had CO poisoning from his 5-pack-a-day smoking habit.
Psychiatric patients often have the frustrating experience of their physical symptoms being attributed to psychiatric causes, which results in major medical issues being overlooked. We psychiatrists can fall into the same trap of overlooking medical illnesses, as indicated in this case, where Mr. L’s CO poisoning initially was attributed to adverse effects of his psychiatric medication.
1. Drugs.com. Amphetamine side effects. https://www.drugs.com/sfx/amphetamine-side-effects.html. Accessed December 7, 2017.
2. Golmirzaei J, Mahboobi H, Yazdanparast M, et al. Psychopharmacology of attention-deficit hyperactivity disorder: effects and side effects. Curr Pharm Des. 2016;22(5):590-594.
3. Bleecker ML. Carbon monoxide intoxication. Handb Clin Neurol. 2015;131(3):191-203.
4. Carter D. Carbon monoxide: the forgotten killer. http://scot.nhs.uk/sehd/cmo/CMO(1998)19.pdf. Published September 7, 1998. Accessed January 10, 2018.
5. Stewart RD, Baretta ED, Platte LR, et al. Carboxyhemoglobin levels in American blood donors. JAMA. 1974;229(9):1187-1195.
6. AA1Car. Troubleshoot odors & smells inside your car. http://www.aa1car.com/library/troubleshoot_odors.htm. Accessed December 7, 2017.
7. Rodkey FL, O’Neal JD, Collison HA, et al. Relative affinity of hemoglobin S and hemoglobin A for carbon monoxide and oxygen. Clin Chem. 1974;20(1):83-84.
8. Kirkpatrick JN. Occult carbon monoxide poisoning. West J Med. 1987;146(1):52-56.
9. Ernst A, Zibrak JD. Carbon monoxide poisoning. N Engl J Med. 1998;339(22):1603-1608.
10. Guzman JA. Carbon monoxide poisoning. Critical Care Clin. 2012;28(4):537-548.
CASE Medication management
Mr. L, age 58, presents to the outpatient psychiatric clinic seeking treatment for attention-deficit/hyperactivity disorder (ADHD), which was first diagnosed 11 years ago. Since discontinuing his ADHD medication, lisdexamfetamine 60 mg/d, 8 months ago, he has not been completing tasks and has been distracted in his job as a limousine driver. Mr. L says that when he was taking the medication, “I could focus and prioritize.” He reports that he has trouble retaining information and is easily distracted. He says he generally is organized with appointments and keeping track of things but is messy, forgetful, tardy, and impatient. Procrastination is an ongoing problem. He denies misplacing things or being impulsive. Mr. L reports that as a child he was frequently reprimanded for talking in class. He states, “I get in trouble even now for talking too much.”
Mr. L is cooperative and polite, maintains good eye contact, and is alert. No psychomotor abnormalities are noted. His speech is spontaneous and coherent, with normal rate, rhythm, and volume. He reports that his mood is “all right,” and denies suicidal or homicidal ideation. His insight is full, judgment is intact, and thought is linear and logical. Mr. L sleeps 5 hours at night and takes a nap during the day, but his energy varies.
His psychiatric history is negative for suicide attempts or hospitalizations. Mr. L denies a history of major depressive episodes, manic symptoms, hallucinations, or delusions. Anxiety history is negative for excessive worrying, obsessions and compulsions, and panic attacks. Mr. L has no family history of mental illness or substance abuse, and he denies any personal history of drug use. He stopped using tobacco 14 years ago. Mr. L says he drinks 3 caffeinated drinks a day and 2 glasses of wine once a week. Previous medications included
A review of systems is negative. Vital signs are unremarkable. A recent electrocardiogram (EKG) showed normal sinus rhythm. Thyroid-stimulating hormone, comprehensive metabolic panel (CMP), lipids, iron, vitamin B12, folate, complete blood count (CBC), hemoglobin A1c, and urine analysis are normal, except for mildly elevated low-density lipoprotein. Testing for hepatitis C is negative.
The previous diagnosis of ADHD is confirmed, and Mr. L is started on
[polldaddy:9928295]
The author’s observations
Anxiety, irritability, agitation, and palpitations can all be symptoms of stimulant medications.1,2 There are numerous other iatrogenic causes, including steroid-based asthma treatments, thyroid medications, antidepressants in bipolar patients, and caffeine-based migraine treatments. Mr. L’s theory that his 15-lb weight loss was the result of his methylphenidate ER dose being too high was a reasonable one. Often, medication doses need to be adjusted with weight changes. His decrease in energy during the day could be explained by the methylphenidate ER controlling his hyperactive symptoms, which include high energy. At night, when the medication wears off, his hyperactivity symptoms could be returning, which would account for the increase in energy when he gets home from work. Although longer-acting stimulants tend to have a more benign adverse effects profile, they can cause insomnia if they are still in the patient’s system at bedtime. Shorter-acting stimulants wear off quickly but can be advantageous for patients who want to target concentration during certain times of day, such as for school and homework.
TREATMENT A surprising cause
The next month, Mr. L presents to the emergency room complaining of jitteriness, headache, and tingling in his fingers, and is evaluated for suspected carbon monoxide (CO) poisoning. Three months earlier, he had noted the odor of exhaust fumes in the limousine he drives 7 days a week. He took it to the mechanic twice for evaluation, but no cause was found. Despite his concerns, he continued to drive the car until an older client, in frail health, suddenly became short of breath and developed chest pain shortly after entering his vehicle, on a day when the odor was particularly bad. Before that, a family of passengers had complained of headaches upon entering his vehicle. The third time he brought his car to be checked, the mechanic identified an exhaust system leak.
[polldaddy:9928298]
The author’s observations
Work-up for suspected CO poisoning includes ABG, COHb level, CBC, basic metabolic panel, EKG, cardiac enzymes, and chest radiography, as well as other laboratory tests as deemed appropriate. Treatment includes oxygen by mask for low-level poisoning.
High levels of poisoning may require hyperbaric oxygen, which should be considered for patients who are unconscious or have an abnormal score on the Carbon Monoxide Neuropsychological Screening Battery, COHb of >40%, signs of cardiac ischemia or arrhythmia, history of ischemic heart disease with COHb level >20%, recurrent symptoms for up to 3 weeks, or symptoms that have not resolved with normobaric oxygen after 4 to 6 hours.9 Any pregnant woman with CO poisoning should receive hyperbaric therapy.10
OUTCOME Lasting improvement
Mr. L presents for follow-up in the psychiatric clinic 3 weeks after his emergency room visit. After his limousine was repaired, his symptoms resolved. He no longer experiences fatigue during the day with higher energy at night, palpitations, jitteriness, headache, or tingling. His concentration has improved, so he opts to stick with the 18-mg dose of methylphenidate ER rather than increase it to the initial dose. He places a CO detector in his vehicle, which proves to be a good decision when it gives him a warning that the exhaust leak had not been properly repaired.
[polldaddy:9928299]
The author’s observations
Although the correct cause of Mr. L’s symptoms was found incidentally, this case is an important reminder to always consider medical causes in the differential diagnosis. We are taught in medical school to look first for horses (more likely causes), not zebras (less likely causes), but sometimes zebras do occur. Be mindful that medical causes should be considered not only for symptoms of primary illnesses, but also for symptoms thought to be caused by adverse effects of medications. The differential diagnosis for Mr. L’s symptoms (palpitations, agitation, anxiety, irritability, weight loss, fatigue, nausea, and headache) included metabolic and endocrine abnormalities (thyroid disease, pheochromocytoma, hypoglycemia); psychiatric conditions (panic, bipolar disorder, depression); substance abuse (caffeine, cocaine, amphetamines); immune disorders; cardiac disorders; malignancy; toxic exposure; infectious sources; and nutritional deficiencies. CO poisoning can cause many of these symptoms (Table 2).1,2,8
Intentional CO poisoning should be considered in an obtunded or unconscious patient with depression. Patients may consider CO poisoning a more peaceful way to complete suicide than shooting, cutting, or hanging. As for unintentional poisoning, clinical suspicion can be increased by time of year, occupation, locale, and smoking status. Winter months increase risk because of the high use of heating devices, cars warming up in the garage, closed fireplace flues, and vehicle tailpipes blocked by snow. As in Mr. L’s case, occupation also may increase suspicion; drivers, mechanics, tollbooth operators, parking attendants, miners, and firefighters are all at increased risk for CO poisoning. Regarding locale, polluted urban environments as well as cold climates requiring heating sources cause higher risks for CO exposure. Rarely, excessive smoking can result in CO poisoning. The author once had a patient with schizophrenia who was admitted to the hospital with delirium. It was determined that he had CO poisoning from his 5-pack-a-day smoking habit.
Psychiatric patients often have the frustrating experience of their physical symptoms being attributed to psychiatric causes, which results in major medical issues being overlooked. We psychiatrists can fall into the same trap of overlooking medical illnesses, as indicated in this case, where Mr. L’s CO poisoning initially was attributed to adverse effects of his psychiatric medication.
CASE Medication management
Mr. L, age 58, presents to the outpatient psychiatric clinic seeking treatment for attention-deficit/hyperactivity disorder (ADHD), which was first diagnosed 11 years ago. Since discontinuing his ADHD medication, lisdexamfetamine 60 mg/d, 8 months ago, he has not been completing tasks and has been distracted in his job as a limousine driver. Mr. L says that when he was taking the medication, “I could focus and prioritize.” He reports that he has trouble retaining information and is easily distracted. He says he generally is organized with appointments and keeping track of things but is messy, forgetful, tardy, and impatient. Procrastination is an ongoing problem. He denies misplacing things or being impulsive. Mr. L reports that as a child he was frequently reprimanded for talking in class. He states, “I get in trouble even now for talking too much.”
Mr. L is cooperative and polite, maintains good eye contact, and is alert. No psychomotor abnormalities are noted. His speech is spontaneous and coherent, with normal rate, rhythm, and volume. He reports that his mood is “all right,” and denies suicidal or homicidal ideation. His insight is full, judgment is intact, and thought is linear and logical. Mr. L sleeps 5 hours at night and takes a nap during the day, but his energy varies.
His psychiatric history is negative for suicide attempts or hospitalizations. Mr. L denies a history of major depressive episodes, manic symptoms, hallucinations, or delusions. Anxiety history is negative for excessive worrying, obsessions and compulsions, and panic attacks. Mr. L has no family history of mental illness or substance abuse, and he denies any personal history of drug use. He stopped using tobacco 14 years ago. Mr. L says he drinks 3 caffeinated drinks a day and 2 glasses of wine once a week. Previous medications included
A review of systems is negative. Vital signs are unremarkable. A recent electrocardiogram (EKG) showed normal sinus rhythm. Thyroid-stimulating hormone, comprehensive metabolic panel (CMP), lipids, iron, vitamin B12, folate, complete blood count (CBC), hemoglobin A1c, and urine analysis are normal, except for mildly elevated low-density lipoprotein. Testing for hepatitis C is negative.
The previous diagnosis of ADHD is confirmed, and Mr. L is started on
[polldaddy:9928295]
The author’s observations
Anxiety, irritability, agitation, and palpitations can all be symptoms of stimulant medications.1,2 There are numerous other iatrogenic causes, including steroid-based asthma treatments, thyroid medications, antidepressants in bipolar patients, and caffeine-based migraine treatments. Mr. L’s theory that his 15-lb weight loss was the result of his methylphenidate ER dose being too high was a reasonable one. Often, medication doses need to be adjusted with weight changes. His decrease in energy during the day could be explained by the methylphenidate ER controlling his hyperactive symptoms, which include high energy. At night, when the medication wears off, his hyperactivity symptoms could be returning, which would account for the increase in energy when he gets home from work. Although longer-acting stimulants tend to have a more benign adverse effects profile, they can cause insomnia if they are still in the patient’s system at bedtime. Shorter-acting stimulants wear off quickly but can be advantageous for patients who want to target concentration during certain times of day, such as for school and homework.
TREATMENT A surprising cause
The next month, Mr. L presents to the emergency room complaining of jitteriness, headache, and tingling in his fingers, and is evaluated for suspected carbon monoxide (CO) poisoning. Three months earlier, he had noted the odor of exhaust fumes in the limousine he drives 7 days a week. He took it to the mechanic twice for evaluation, but no cause was found. Despite his concerns, he continued to drive the car until an older client, in frail health, suddenly became short of breath and developed chest pain shortly after entering his vehicle, on a day when the odor was particularly bad. Before that, a family of passengers had complained of headaches upon entering his vehicle. The third time he brought his car to be checked, the mechanic identified an exhaust system leak.
[polldaddy:9928298]
The author’s observations
Work-up for suspected CO poisoning includes ABG, COHb level, CBC, basic metabolic panel, EKG, cardiac enzymes, and chest radiography, as well as other laboratory tests as deemed appropriate. Treatment includes oxygen by mask for low-level poisoning.
High levels of poisoning may require hyperbaric oxygen, which should be considered for patients who are unconscious or have an abnormal score on the Carbon Monoxide Neuropsychological Screening Battery, COHb of >40%, signs of cardiac ischemia or arrhythmia, history of ischemic heart disease with COHb level >20%, recurrent symptoms for up to 3 weeks, or symptoms that have not resolved with normobaric oxygen after 4 to 6 hours.9 Any pregnant woman with CO poisoning should receive hyperbaric therapy.10
OUTCOME Lasting improvement
Mr. L presents for follow-up in the psychiatric clinic 3 weeks after his emergency room visit. After his limousine was repaired, his symptoms resolved. He no longer experiences fatigue during the day with higher energy at night, palpitations, jitteriness, headache, or tingling. His concentration has improved, so he opts to stick with the 18-mg dose of methylphenidate ER rather than increase it to the initial dose. He places a CO detector in his vehicle, which proves to be a good decision when it gives him a warning that the exhaust leak had not been properly repaired.
[polldaddy:9928299]
The author’s observations
Although the correct cause of Mr. L’s symptoms was found incidentally, this case is an important reminder to always consider medical causes in the differential diagnosis. We are taught in medical school to look first for horses (more likely causes), not zebras (less likely causes), but sometimes zebras do occur. Be mindful that medical causes should be considered not only for symptoms of primary illnesses, but also for symptoms thought to be caused by adverse effects of medications. The differential diagnosis for Mr. L’s symptoms (palpitations, agitation, anxiety, irritability, weight loss, fatigue, nausea, and headache) included metabolic and endocrine abnormalities (thyroid disease, pheochromocytoma, hypoglycemia); psychiatric conditions (panic, bipolar disorder, depression); substance abuse (caffeine, cocaine, amphetamines); immune disorders; cardiac disorders; malignancy; toxic exposure; infectious sources; and nutritional deficiencies. CO poisoning can cause many of these symptoms (Table 2).1,2,8
Intentional CO poisoning should be considered in an obtunded or unconscious patient with depression. Patients may consider CO poisoning a more peaceful way to complete suicide than shooting, cutting, or hanging. As for unintentional poisoning, clinical suspicion can be increased by time of year, occupation, locale, and smoking status. Winter months increase risk because of the high use of heating devices, cars warming up in the garage, closed fireplace flues, and vehicle tailpipes blocked by snow. As in Mr. L’s case, occupation also may increase suspicion; drivers, mechanics, tollbooth operators, parking attendants, miners, and firefighters are all at increased risk for CO poisoning. Regarding locale, polluted urban environments as well as cold climates requiring heating sources cause higher risks for CO exposure. Rarely, excessive smoking can result in CO poisoning. The author once had a patient with schizophrenia who was admitted to the hospital with delirium. It was determined that he had CO poisoning from his 5-pack-a-day smoking habit.
Psychiatric patients often have the frustrating experience of their physical symptoms being attributed to psychiatric causes, which results in major medical issues being overlooked. We psychiatrists can fall into the same trap of overlooking medical illnesses, as indicated in this case, where Mr. L’s CO poisoning initially was attributed to adverse effects of his psychiatric medication.
1. Drugs.com. Amphetamine side effects. https://www.drugs.com/sfx/amphetamine-side-effects.html. Accessed December 7, 2017.
2. Golmirzaei J, Mahboobi H, Yazdanparast M, et al. Psychopharmacology of attention-deficit hyperactivity disorder: effects and side effects. Curr Pharm Des. 2016;22(5):590-594.
3. Bleecker ML. Carbon monoxide intoxication. Handb Clin Neurol. 2015;131(3):191-203.
4. Carter D. Carbon monoxide: the forgotten killer. http://scot.nhs.uk/sehd/cmo/CMO(1998)19.pdf. Published September 7, 1998. Accessed January 10, 2018.
5. Stewart RD, Baretta ED, Platte LR, et al. Carboxyhemoglobin levels in American blood donors. JAMA. 1974;229(9):1187-1195.
6. AA1Car. Troubleshoot odors & smells inside your car. http://www.aa1car.com/library/troubleshoot_odors.htm. Accessed December 7, 2017.
7. Rodkey FL, O’Neal JD, Collison HA, et al. Relative affinity of hemoglobin S and hemoglobin A for carbon monoxide and oxygen. Clin Chem. 1974;20(1):83-84.
8. Kirkpatrick JN. Occult carbon monoxide poisoning. West J Med. 1987;146(1):52-56.
9. Ernst A, Zibrak JD. Carbon monoxide poisoning. N Engl J Med. 1998;339(22):1603-1608.
10. Guzman JA. Carbon monoxide poisoning. Critical Care Clin. 2012;28(4):537-548.
1. Drugs.com. Amphetamine side effects. https://www.drugs.com/sfx/amphetamine-side-effects.html. Accessed December 7, 2017.
2. Golmirzaei J, Mahboobi H, Yazdanparast M, et al. Psychopharmacology of attention-deficit hyperactivity disorder: effects and side effects. Curr Pharm Des. 2016;22(5):590-594.
3. Bleecker ML. Carbon monoxide intoxication. Handb Clin Neurol. 2015;131(3):191-203.
4. Carter D. Carbon monoxide: the forgotten killer. http://scot.nhs.uk/sehd/cmo/CMO(1998)19.pdf. Published September 7, 1998. Accessed January 10, 2018.
5. Stewart RD, Baretta ED, Platte LR, et al. Carboxyhemoglobin levels in American blood donors. JAMA. 1974;229(9):1187-1195.
6. AA1Car. Troubleshoot odors & smells inside your car. http://www.aa1car.com/library/troubleshoot_odors.htm. Accessed December 7, 2017.
7. Rodkey FL, O’Neal JD, Collison HA, et al. Relative affinity of hemoglobin S and hemoglobin A for carbon monoxide and oxygen. Clin Chem. 1974;20(1):83-84.
8. Kirkpatrick JN. Occult carbon monoxide poisoning. West J Med. 1987;146(1):52-56.
9. Ernst A, Zibrak JD. Carbon monoxide poisoning. N Engl J Med. 1998;339(22):1603-1608.
10. Guzman JA. Carbon monoxide poisoning. Critical Care Clin. 2012;28(4):537-548.
