Questions, Board Review

Board Review Questions: October 2019

PEER (Physician’s Evaluation and Educational Review in Emergency Medicine) is ACEP’s gold standard in self-assessment and educational review. These questions are from PEER, updated continually on its digital platform. Order PEER to prepare!

1. A 64-year-old man presents with gradual onset of swelling in his face, a cough, a headache, shortness of breath, and, that morning, blue lips. When asked, he says that he smokes “not quite two” packs of cigarettes per day. Which test will most likely reveal the diagnosis?
A. Brain MRI with diffusion-weighted imaging
B. Chest CT with contrast
C. Lower-extremity Doppler ultrasonography
D. Lumbar puncture and CSF cell count


2. When managing an acute aortic dissection, which medical therapy should be initiated first?
A. Esmolol
B. Nicardipine
C. Nifedipine
D. Nitroprusside 


3. Which statement regarding Bordetella pertussis infection is correct?
A. Blood cultures are an effective means of identifying patients with active disease
B. Identifying disease in infants is difficult because apnea can be the only symptom
C. Previous infection confers lifelong immunity for subsequent infection or disease
D. Treatment to prevent infectivity is most effective during the paroxysmal phase


4. Which statement about the metabolism of ethanol is correct?
A. Approximately 20 mg/dL is eliminated per hour in nontolerant individuals
B. Cytochrome P450 is responsible for the majority of metabolism
C. Elimination occurs predominantly by renal metabolism
D. It is characterized by zero-order kinetics at lower concentrations


5. Which structure is best evaluated for traumatic injury using noncontrast CT?
A. Pancreas
B. Small bowel
C. Spine
D. Stomach

ANSWERS 

1. The correct answer is B, Chest CT with contrast.
Why is this the correct answer?
Superior vena cava (SVC) syndrome is caused by occlusion of the SVC by a thrombus or mediastinal mass, and it should be easily identified with a CT scan of the chest with contrast. The symptoms usually develop over weeks to months, as a tumor grows and compresses venous return from the head and neck. The tumor is most commonly a non–small-cell cancer of the lung but can also be small-cell lung cancer or lymphoma. The syndrome can develop more quickly in the case of a thrombus, which is the most common nonmalignant cause of the condition. Other nonmalignant causes include restrictive pericarditis, mediastinal fibrosis, and goiter. Patients with SVC syndrome present with gradual onset of periorbital edema and facial swelling that is most prominent in the early morning after spending a night lying flat. This can progress to plethora of the face, edema of the upper extremities and neck, and headaches from cerebral venous backflow. Patients typically have a cough, either from the lack of venous drainage or primarily from irritation of the tumor itself. Some develop dyspnea and hypoxia, leading to cyanosis.

Why are the other choices wrong?

  • An SVC compression from a tumor can cause cerebral sinus congestion and cerebral edema that can be identified using MRI, but CT of the chest to evaluate the vena cava is a more reasonable approach.

  • PE should always be considered for patients with dyspnea and chest discomfort; identifying DVT in the leg is sufficient to make the diagnosis by inference. This patient, however, has a more gradual onset of symptoms, and facial swelling is not a recognized symptom of PE.

  • Lumbar puncture is indicated to rule out meningitis or subarachnoid hemorrhage, but facial swelling and a cough are not usually symptoms of these conditions. Idiopathic intracranial hypertension is diagnosed and relieved with a lumbar puncture, but imaging should be done first to ensure that the patient is not at risk of herniation.

REFERENCES
Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. St. Louis, MO: Elsevier; 2014:129-134.

Tintinalli JE, Stapczynski JS, Ma OJ, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:1500-1504.


2. The correct answer is A, Esmolol.
Why is this the correct answer?
The primary goal in the medical management of an acute aortic dissection is to decrease the blood pressure and heart rate to minimize the aortic shearing force that could worsen the intimal tear and further propagate the dissection. Beta-blockers such as esmolol or labetalol should be given first. They effectively reduce blood pressure and shearing force but additionally prevent the reflex tachycardia that occurs with primary administration of vasodilators. The goal systolic blood pressure is 100 to 120 mm Hg, and the goal heart rate is less than 60 beats/min. Note that the blood pressure goal is independent of the patient’s baseline blood pressure, unlike the approach to most hypertensive emergencies.

Why are the other choices wrong?

  • Nicardipine is a vasodilator. It is part of the treatment for an acute aortic dissection, but it should be added after the beta-blocker. Increased heart rate is a common side effect of vasodilator therapy, so it should not be the first medication given.

  • Nifedipine is a calcium channel blocker and vasodilator. It can be used as part of the treatment for an acute aortic dissection, but it should be added after the beta-blocker. As with nicardipine, it can increase heart rate and should not be the first medication given.

  • Nitroprusside also is a vasodilator and should be administered after a beta-blocker.

REFERENCES
Adams JG, Barton ED, Collings J, et al, eds. Emergency Medicine: Clinical Essentials. 2nd ed. Philadelphia, PA: Saunders; 2013:561-570, 592-601.

Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. St. Louis, MO: Elsevier; 2014:1124-1128.


3. The correct answer is B, Identifying disease in infants is difficult because apnea can be the only symptom.
Why is this the correct answer?
Pertussis is the acute and highly contagious respiratory infection caused by B. pertussis. Infected infants do not typically develop the characteristic “whooping” cough, and they can present with apneic episodes as the sole symptom, without fever. In fact, even among adults, only one-third of patients develop the characteristic cough. Pertussis arises in three distinct, sequential clinical stages: the catarrhal phase, paroxysmal phase, and convalescent phase. The catarrhal, or prodromal, phase begins after an incubation period of approximately 7 to 10 weeks and lasts approximately 1 to 2 weeks. In this early phase, the signs and symptoms include rhinorrhea, a low-grade fever, malaise, conjunctival injection, and in some, apnea. A dry cough usually begins at the end of the catarrhal phase. The paroxysmal phase begins as the fever subsides and the cough increases. Paroxysms of staccato coughing occur 40 to 50 times per day. The patient coughs repeatedly in short exhalations, followed by a single, sudden, forceful inhalation that produces the characteristic “whoop.” This phase lasts 1 to 6 weeks or perhaps longer. Recovery from pertussis is gradual; the convalescent stage lasts 2 to 3 weeks. Coughing subsides, but many patients remain susceptible to other respiratory infections.

Why are the other choices wrong?

  • The B. pertussis organism is a small, aerobic, gram-negative coccobacilli that occurs singly or in pairs. It adheres preferentially to ciliated respiratory epithelial cells. The organism produces several toxins that act locally and systemically. These toxins include pertussis toxin, dermonecrotic toxin, adenylate cyclase toxin, and tracheal cytotoxin. B. pertussis does not invade beyond the submucosal layer in the respiratory tract and is almost never recovered in the bloodstream. 

  • Vaccination and previous infection do not confer lifelong immunity. Patients require five doses of the DTaP vaccine at ages 2, 4, and 6 months, then again between 15 and 18 months and between 4 and 6 years. Then, every 10 years, a booster with Tdap is required to continue immunity. A booster immunization may be required sooner than every 10 years if the patient is exposed to tetanus. Since 1990, the number of B. pertussis cases has increased, particularly in the adolescent population, most likely as a result of waning immunity and a lack of compliance with episodic booster immunization recommendations.

  • Infectivity is greatest during the catarrhal phase (not the paroxysmal phase). The catarrhal phase begins after a 7- to 10-week incubation period and lasts approximately 1 to 2 weeks. During this time, the disease is clinically indistinguishable from other upper respiratory tract infections.

REFERENCES
Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. St. Louis, MO: Elsevier; 2014:1693-1717.

Tintinalli JE, Stapczynski JS, Ma OJ, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:440-445, 741-747.


4. The correct answer is A, Approximately 20 mg/dL is eliminated per hour in nontolerant individuals.
Why is this the correct answer?
In general, unless the patient has developed a tolerance for ethanol, about 20 mg/dL is eliminated per hour. Alcohol dehydrogenase and the specific cytochrome P450 are the enzymes that metabolize most of the ethanol. Both enzymes are inducible, which is why rates of ethanol metabolism are actually higher in chronic drinkers, at an estimated 30 mg/dL per hour. 

Why are the other choices wrong?

  • Hepatic alcohol dehydrogenase is the major enzyme responsible for initial ethanol metabolism. A specific cytochrome P450 also metabolizes ethanol but is a minor pathway.

  • Elimination of ethanol is predominantly by hepatic (not renal) metabolism. Smaller amounts leave the body in sweat and urine.

  • Zero-order kinetics is the term used to characterize the metabolism of a substance at a fixed amount per hour. This rate of metabolism is rare; with regard to ethanol, it occurs in high concentrations when the enzymes become saturated, which is the case with chronic users and alcoholics. More commonly, among persons with low concentrations of ethanol in the blood and those who are nontolerant, metabolism follows first-order kinetics — a fixed percentage of total ethanol is metabolized per hour.

REFERENCES
Tintinalli JE, Stapczynski JS, Ma OJ, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:1244.

Wolfson AB, Hendey GW, Ling LJ, et al, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2014:1332.


5. The correct answer is C, Spine.
Why is this the correct answer?
CT is excellent at identifying bony injuries in trauma patients, especially those with a suspected spinal injury. Trauma scans are typically performed without oral contrast. Any delay in the time to scan is unacceptable, and patients with cervical spine precautions may be at risk for aspiration. Performing a CT without contrast is especially beneficial for elderly patients who may have underlying renal dysfunction and for patients with limited intravenous access who are clinically stable. For these patients, even without contrast, CT can still identify bony trauma and significant solid organ injury. The use of intravenous contrast material can help reveal vascular injury and more subtle solid organ trauma as well as identify active extravasation of contrast; it does not inhibit identification of bony injury.

Why are the other choices wrong?

  • CT is excellent at identifying injuries to solid organs, with the exception of the pancreas. It is often unable to reveal pancreatic injuries resulting from trauma.

  • Although CT is, again, excellent at identifying injuries to bone and solid organs, it is not as sensitive for mesenteric or hollow viscus injuries resulting from trauma to the small bowel area.

  • Retroperitoneal injuries and hemoperitoneum or retroperitoneal hematoma can be identified using CT. However, CT is not as sensitive when it comes to injuries to the stomach. If there is a high degree of suspicion of injury to any of these three organs, the patient should undergo further workup and management, such as the addition of oral or rectal contrast material, serial abdominal examinations, or an exploratory laparotomy if the patient has peritoneal signs or is ill.

REFERENCES
Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. St. Louis, MO: Elsevier; 2014:465-467.

Wolfson AB, Hendey GW, Ling LJ, et al, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2014:221.

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