MKSAP quiz on intensive care

The following cases and commentary, which focus on the ICU, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP 18).

Case 1: Altered mental status

A 65-year-old man is evaluated in the ICU for a 24-hour history of altered mental status with a fluctuating level of consciousness. He was admitted to the hospital 5 days ago for urosepsis and acute kidney injury and developed acute respiratory distress syndrome on hospital day 3. The patient is currently intubated, mechanically ventilated, and receiving continuous hemodialysis. Medications are cefepime, norepinephrine, and fentanyl.

On physical examination, temperature is 38.4 °C (101.1 °F), blood pressure is 105/71 mm Hg, pulse rate is 108/min, and respiration rate is 12/min; Fio2 is 0.9. The patient opens his eyes to voice but does not fixate on the examiner or follow commands. Pupils are reactive, and gag and corneal reflexes are present. All limbs move intermittently but not on command. The patient withdraws from painful stimuli in all four limbs. Intermittent twitching of the shoulders and eyelids is noted.

Results of laboratory studies show a serum creatinine level of 5.4 mg/dL (477 µmol/L). Glucose, calcium, and electrolyte levels are within normal limits.

A 20-minute electroencephalogram shows generalized slow activity, a nonspecific finding compatible with encephalopathy, but no evidence of seizure activity.

A head CT scan is normal.

Which of the following is the most appropriate next step in management?

A. Continuous (24-hour) electroencephalography
B. Intravenous fosphenytoin
C. Intravenous lorazepam
D. No treatment

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Case 2: Urosepsis and abdominal pain

A 68-year-old man is evaluated in the ICU for cramping abdominal pain in the left lower quadrant, which began approximately 3 hours before the evaluation. Twenty minutes before the evaluation, he had a loose stool with hematochezia. The patient has been in the ICU for 24 hours, after being admitted with fever and hypotension secondary to urosepsis. He was treated with intravenous fluids, vasopressors, and piperacillin-tazobactam. His medical history includes hypertension, benign prostatic hypertrophy, and hyperlipidemia. His daily medications are chlorthalidone, atorvastatin, and low-dose aspirin.

On physical examination, the patient is alert. Temperature is 38.7 °C (101.7 °F), blood pressure is 106/60 mm Hg, pulse rate is 90/min, respiration rate is 18/min, and oxygen saturation is 96% breathing ambient air. There is tenderness to palpation over the left side of the abdomen without guarding. The remainder of the examination is unremarkable.

MKSAP 18 image  American College of Physicians
MKSAP 18 image © American College of Physicians

Colonoscopy findings are shown.

Which of the following is the most likely diagnosis?

A. Acute mesenteric ischemia
B. Diverticular bleeding
C. Enterohemorrhagic Escherichia coli
D. Ischemic colitis

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Case 3: Subarachnoid hemorrhage

A 61-year-old woman is admitted to the ICU 1 hour after having a subarachnoid hemorrhage (SAH). An emergent CT scan of the head showed an SAH, and a cerebral angiogram revealed a 6-mm rupture of the anterior communicating artery. The patient has hypertension treated with amlodipine.

On physical examination, vital signs are stable, and oxygen saturation is 96% with the patient breathing ambient air. She is somnolent. Nuchal rigidity is present. Subhyaloid hemorrhages are seen on funduscopic examination. No motor or sensory deficits are present.

Administration of which of the following medications is the most appropriate treatment?

A. Dexamethasone
B. Magnesium sulfate
C. Nimodipine
D. Nitroglycerin
E. Verapamil

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Case 4: Arrhythmia

A 51-year-old woman is evaluated in the ICU after being admitted 2 days ago for severe community-acquired pneumonia. A chest radiograph demonstrated right lower lobe consolidation, and she was started on moxifloxacin. Today, she developed an arrhythmia that terminated after 20 seconds. An electrocardiogram (ECG) obtained at the time of admission was normal. Medical history is significant for hypertension, hyperlipidemia, and depression. Other medications are venlafaxine, carvedilol, and simvastatin.

On physical examination, temperature is 38.4 °C (101.1 °F), blood pressure is 140/90 mm Hg, pulse rate is 61/min, and respiration rate is 18/min. Diminished breath sounds are located in the right lower posterior thorax. The remainder of the examination is unremarkable.

MKSAP 18 image  American College of Physicians
MKSAP 18 image © American College of Physicians

An ECG at the time of the arrhythmic event is shown. An ECG after the episode reveals a corrected QT interval of 550 ms.

Which of the following medications should be discontinued on the basis of this patient's ECG findings?

A. Carvedilol
B. Moxifloxacin
C. Simvastatin
D. Venlafaxine

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Case 5: Pregnant patient

A 25-year-old woman is evaluated in the hospital for right-upper-quadrant abdominal pain, jaundice, and nausea of 10 days' duration. She is in her 35th week of pregnancy. Her only medication is a prenatal vitamin.

On physical examination, the patient is drowsy. Temperature is normal. Blood pressure is 95/60 mm Hg, pulse rate is 108/min, and respiration rate is 22/min. Jaundice is apparent. Abdominal examination shows tenderness to palpation in the right upper quadrant. The uterus is of appropriate size for gestation.

Laboratory studies show hematocrit 34%, leukocyte count 6000/μL (6 × 109/L), platelet count 155,000/μL (155 × 109/L), INR 2.2, alanine aminotransferase 115 U/L, aspartate aminotransferase 130 U/L, total bilirubin 6.2 mg/dL (106.0 µmol/L), and glucose 55 mg/dL (3.1 µmol/L).

On abdominal ultrasonography, the liver is hyperechoic. Hepatic vasculature is patent, and there is no bile-duct dilation.

She is transferred to an ICU setting, and intravenous fluids with glucose are administered.

Which of the following is the most appropriate next step in management?

A. Endoscopic retrograde cholangiopancreatography
B. Immediate delivery of the fetus
C. Lactulose
D. Ursodeoxycholic acid

View correct answer for Case 5

Answers and commentary

Case 1

Correct answer: A. Continuous (24-hour) electroencephalography.

The patient should undergo continuous (24-hour) electroencephalography (EEG). He has fluctuating mental status of unknown origin in the setting of a critical illness, sepsis, and multiorgan dysfunction. These findings raise suspicion of nonconvulsive status epilepticus (NCSE), which is intermittent electrical seizure activity without clinically evident seizure activity. A 20-minute EEG usually is inadequately sensitive to capture seizures, particularly if they are occurring intermittently. NCSE also is increasingly diagnosed in critically ill comatose or stuporous patients with acute neurologic or medical conditions who have not had a convulsive seizure. Similar to NCSE following convulsive status epilepticus (CSE), NCSE in critically ill populations also is associated with increased morbidity and mortality and requires prompt attention and intervention. The diagnostic test of choice is continuous (24-hour) EEG monitoring. Most critically ill patients with nonconvulsive seizures have their first detectable seizure with EEG monitoring within 24 hours of initiating the recording, but an additional 12% have detectable seizures with 48 hours of continuous monitoring. Cefepime has been known to cause encephalopathy, coma, and status epilepticus in patients with or without epilepsy, especially those with acute kidney injury, and its use should raise the clinician's suspicion of NCSE.

Empiric treatment with fosphenytoin or lorazepam is generally not recommended until the diagnosis of NCSE or intermittent nonconvulsive seizures is confirmed by EEG. This approach differs from the treatment of generalized convulsive status epilepticus, which is diagnosed clinically and, optimally, treated without delay.

Providing no treatment is inadequate as the next step in management for this patient with altered mental status, a fluctuating level of consciousness, and other abnormalities on neurologic and laboratory testing. The diagnosis of NCSE first must be established (or excluded).

Key Point

  • Nonconvulsive status epilepticus should be suspected in patients with critical illness who develop altered mental status; the diagnosis is confirmed with continuous (24-hour) electroencephalography.

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Case 2

Correct answer: D. Ischemic colitis.

Ischemic colitis is the most likely diagnosis in this patient. The patient initially presented in septic shock from a urinary tract infection. He was hypotensive and required intravenous fluids and vasopressor support, which are risk factors for ischemic colitis in elderly patients. Ischemic colitis is a low-flow state of the colon occurring most frequently in the left colon. Conditions that can alter circulation include hypotension, dehydration, strenuous physical activity, medications and illicit drugs, thrombophilia, aortic or cardiac bypass, vasculitis, or an obstructing colon lesion. Diarrhea with rectal bleeding is common. Colonoscopy may show sharply demarcated pale mucosa with petechial bleeding, as it does in this patient. Left colon inflammatory changes may be detected by colonoscopy or abdominal CT. Treatment is supportive care with normalization of blood pressure.

Acute mesenteric ischemia (AMI) is an uncommon vascular emergency. Embolism to the mesenteric arteries causes 50% of cases of AMI. Most emboli are from cardiac sources. Patients typically present in the seventh decade of life and often have associated cardiovascular comorbidities. The classic presentation of early AMI is central abdominal pain out of proportion to the physical examination findings. This patient's gradual onset of left-sided, moderate-intensity abdominal pain is not typical of AMI.

Diverticula represent herniation of mucosa or submucosa through the muscular layers of the colon, typically at the entry site of vasa recta (small arteries), which are a source for bleeding. Diverticular bleeding is usually painless with passage of large-volume red- to maroon-colored blood per rectum. It occurs spontaneously without associated infection or other illness, making it unlikely in this patient.

The most common initial symptoms of enterohemorrhagic Escherichia coli are bloody diarrhea and abdominal tenderness, without fever. The timing of this patient's development of gastrointestinal symptoms, 1 day after presentation with hypotension secondary to urosepsis, makes the diagnosis of ischemic colitis more likely.

Key Point

  • Ischemic colitis is a low-flow state of the colon occurring most frequently in the left colon and characterized by moderate, left-sided, cramping abdominal pain followed by bloody diarrhea.

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Case 3

Correct answer: C. Nimodipine.

This patient should receive nimodipine. She has an aneurysmal SAH and is at high risk for neurologic decline from cerebral vasospasm. The risk of vasospasm is greatest 5 to 10 days after SAH onset. Nimodipine is indicated for all nonhypotensive patients with SAH and is associated with improved neurologic outcomes and survival. Because nimodipine may not directly reduce the vasospasm, additional monitoring with repeat neurologic examinations and transcranial Doppler ultrasonography is indicated in a specialized ICU. The presence of vasospasm is suggested by worsening findings on neurologic examination and can be confirmed with CT angiography or catheter angiography, with the latter test having the additional benefit of providing endovascular therapy.

Glucocorticoids, such as dexamethasone, are not routinely indicated for any stroke subtype and are ineffective in reducing intracranial pressure in that setting. One randomized study of 95 patients with aneurysmal SAH treated with 3 days of methylprednisolone showed improved 1-year functional outcomes in patients. However, the preponderance of evidence does not support glucocorticoid treatment for SAH.

Magnesium sulfate therapy has been used to prevent vasospasm following SAH, but randomized trials have not shown improved clinical outcomes. A 2013 systematic review and meta-analysis concluded that while intravenous magnesium reduced delayed cerebral ischemia, there was no improvement in clinical neurologic outcomes.

Nitroglycerin is not an appropriate treatment for this patient. Given the risk of cerebral vasospasm, blood pressure often is allowed to remain elevated in such patients. If her blood pressure were to require treatment, nitroglycerin would be inappropriate because it can increase cerebral venous volume and intracranial pressure, which is a concern in patients with SAH.

Verapamil is a calcium channel blocker, as is nimodipine, but verapamil has not been shown to improve outcomes in patients with SAH or vasospasm.

Key Point

  • Nimodipine is indicated for all nonhypotensive patients with subarachnoid hemorrhage and is associated with improved neurologic outcomes and survival.

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Case 4

Correct answer: B. Moxifloxacin.

Moxifloxacin should be discontinued in this patient who had an episode of nonsustained polymorphic ventricular tachycardia (VT). VT is subdivided into sustained VT and nonsustained VT. VT is sustained when it persists for longer than 30 seconds or requires termination because of hemodynamic collapse. Nonsustained VT has three or more beats but lasts for less than 30 seconds. VT is also categorized by the morphology of the QRS complexes. VT is monomorphic if QRS complexes in the same leads do not vary in contour or polymorphic if the QRS complexes in the same leads vary in contour. In this patient, the electrocardiogram obtained after the episode of VT also demonstrates QT-interval prolongation, which is consistent with the diagnosis of torsades de pointes. Torsades de pointes is a special subset of polymorphic VT; the ventricular rate ranges from 200/min to 300/min and is associated with long QT syndrome, which may be congenital or acquired. The patient's electrocardiogram was normal upon admission, and her corrected QT interval is greater than 550 ms following the arrhythmic event, suggesting an acquired long QT interval. Causes of acquired QT-interval prolongation include medications such as antiarrhythmic agents, antibiotics (macrolides and fluoroquinolones), antipsychotic drugs, and antidepressants; structural heart disease; and electrolyte abnormalities.

Although carvedilol slows the heart rate and can increase the risk for bradycardia-dependent arrhythmias in patients with acquired QT-interval prolongation, discontinuing the offending QT-prolonging agents is the most important intervention in this patient.

Simvastatin is a statin used in the treatment of dyslipidemia. It has no effect on the QT interval and does not need to be discontinued.

Venlafaxine is a serotonin-norepinephrine reuptake inhibitor that is used to treat depression and anxiety disorders. There is a possible risk for QT-interval prolongation with venlafaxine, but there is no evidence that this occurs when the medication is taken as recommended. Therefore, discontinuation of venlafaxine is unnecessary.

Key Point

  • QT-interval prolongation has many causes, including medications such as antiarrhythmic agents, antibiotics (macrolides and fluoroquinolones), antipsychotic drugs, and antidepressants; structural heart disease; and electrolyte abnormalities.

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Case 5

Correct answer: B. Immediate delivery of the fetus.

Immediate delivery of the fetus is the most appropriate next step in management. This patient has findings of acute fatty liver of pregnancy, which is a rare but serious condition occurring most commonly in the third trimester. Women with this condition typically present with a 1- to 2-week history of nausea and vomiting, right-upper-quadrant or epigastric pain, headache, jaundice, anorexia, and/or polyuria and polydipsia (due to associated transient diabetes insipidus). Maternal and neonatal mortality rates are high in this setting. This patient's presentation with coagulopathy, hypoglycemia, and somnolence consistent with hepatic encephalopathy are indications of acute liver failure, which can result from acute fatty liver of pregnancy. Immediate delivery of the fetus is indicated to prevent fetal mortality and to reverse the mother's liver failure and improve her condition. Prompt delivery typically results in improvement of the mother's medical condition within 48 to 72 hours. Acute fatty liver of pregnancy can reoccur in subsequent pregnancies. It is also associated with long-chain 3-hydroxyacyl CoA dehydrogenase deficiency, and affected women and their children should be screened for this deficiency. HELLP (Hemolysis, Elevated Liver enzymes, and Low Platelets) syndrome can also occur in the third trimester of pregnancy. It has similarly life-threatening consequences and also requires emergent delivery of the fetus to resolve the condition. HELLP syndrome can present similarly to acute fatty liver of pregnancy in that manifestations of liver failure are present.

This patient's ultrasound showed no dilation of bile ducts, and no stones were seen in the common bile duct; therefore, endoscopic retrograde cholangiopancreatography is not indicated.

This patient's drowsiness is due to impending liver failure. Lactulose, which is used for treatment of hepatic encephalopathy in patients with chronic liver disease, is not indicated for patients with acute liver failure because it may exacerbate symptoms of ileus, and there is no evidence of benefit in the acute setting. Any symptoms referable to hepatic encephalopathy will resolve with delivery of the fetus, which resolves acute fatty liver of pregnancy.

Intrahepatic cholestasis of pregnancy occurs during the second or third trimester and resolves after delivery. The most common laboratory findings are elevated bilirubin and alkaline phosphatase levels. The condition is believed to result from sex hormone–induced inhibition of bile salt export from hepatocytes. It is treated with ursodeoxycholic acid, which can result in alleviation of symptoms. Although the maternal effects of intrahepatic cholestasis of pregnancy are mild, it can cause fetal distress and premature labor. Because this patient's clinical profile is not compatible with intrahepatic cholestasis of pregnancy, ursodeoxycholic acid therapy is not indicated.

Key Point

  • The fetus should be delivered immediately upon recognition of acute fatty liver of pregnancy.