Questions

Board Review Questions: February 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 38-year-old man with diabetes presents complaining of recurrent fever for 1 week, measured as 102°F at home. He has no other symptoms. Physical examination reveals a fever of 38.6°C (101.5°F), a grade 2/6 systolic murmur, and linear streaks under several fingernails. Which of the following tests is most likely to diagnose his condition?
A. Blood cultures
B. Chest x-ray
C. Influenza PCR assay
D. Lyme serology

2. What is the most likely underlying etiology of cardiac arrest from polymorphic ventricular tachycardia?
A. Brugada syndrome
B. Electrolyte abnormality
C. Myocardial ischemia
D. Re-entrant mechanism through scarred myocardium

3. A 27-year-old woman presents with intermittent, sharp, right-sided chest pain of 3 days’ duration that is worse with deep inspiration. She says the pain occasionally occurs when she is not active; it is sharp for about 1 minute then dull and is reproducible with palpation along the right sternal border. She is otherwise healthy; lungs are clear with equal breath sounds. Which of the following concomitant conditions, if present, would lessen concern that this presentation represents a life-threatening problem?
A. Pregnancy
B. Rheumatoid arthritis
C. Systemic lupus erythematosus
D. Type II diabetes mellitus

4. A 35-year-old man presents comatose. Vital signs include BP 124/68, P 74, R 26, T 35.6°C (96.1°F). Glucose level is normal. Blood gas analysis reveals pH 7.23, Po2 96, and Pco2 23. Toxicity from which of these agents is most consistent with this presentation?
A. Ethylene glycol
B. Isopropanol
C. Phenobarbital
D. Salicylate

5. A 27-year-old man presents by ambulance after a high-speed head-on collision in which he was an unrestrained driver. On arrival, he has decreased breath sounds on the left side and is in severe respiratory distress. A chest x-ray reveals abdominal contents in the thoracic cavity. Which of the following statements about this patient’s injury is correct?
A. Blunt trauma typically produces smaller tears than penetrating trauma
B. It occurs most commonly on the right side of the body
C. Mortality rate is higher when the injury is due to penetrating trauma
D. Symptoms are related to the degree of herniation of abdominal contents 

1. The correct answer is A, Blood cultures.
Why is this the correct answer?
This patient likely has endocarditis, and the two most definitive tests for this disease are blood cultures (from at least two different venipuncture sites) and echocardiography. These are the two major Duke criteria and, if results of both tests are positive, indicate a definitive diagnosis of infective endocarditis. The minor Duke criteria are a predisposing factor (such as intravenous drug use), fever above 38°C (100.4°F), evidence of septic emboli (such as Janeway lesions, Osler nodes, or, as in this case, splinter hemorrhages), and a single positive blood culture. With two positive blood cultures, the patient has one major criterion and at least two minor criteria, providing good evidence for endocarditis. An echocardiogram, preferably transesophageal, would be an appropriate next step: It is more sensitive (>90%) for valve disease than is a transthoracic echocardiogram (only about 60%).

Why are the other choices wrong?

  • A chest xray might reveal evidence of septic emboli with scattered infiltrates in the lungs, but it is unlikely to be diagnostic in a case of infective endocarditis.
  • Influenza is an important consideration when evaluating a patient with a fever and no clear localizing signs. This patient had a more protracted course and is less symptomatic than most patients with influenza.
  • Lyme disease is an important consideration when evaluating a patient with a chronic fever and no clear localizing signs. Most patients with Lyme disease are more symptomatic, especially with muscle aches, joint pain, and a possible target-lesion rash.

REFERENCES
Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. St. Louis, MO: Elsevier; 2014:1106-1112.

Tintinalli JE, Stapczynski JS, Ma OJ, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:1057-1061.

2. The correct answer is C, Myocardial ischemia.
Why is this the correct answer?
The most common cause of polymorphic ventricular tachycardia (VT) is myocardial ischemia, in contrast to monomorphic VT, which can also be seen in the setting of myocardial ischemia but is most often secondary to a re-entrant mechanism through scarred myocardium (chronic forms of ischemic heart disease). In the acute phase of an MI, polymorphic VT and ventricular fibrillation are more common than monomorphic VT. Although re-entry might still be a factor in the etiology of polymorphic VT during acute ischemia, abnormal automaticity is a more likely mechanism. Patients presenting with polymorphic VT should be considered candidates for urgent revascularization therapy due to the high incidence of ischemia. Both monomorphic and polymorphic VT involve an ectopic pacemaker originating within or below the bundle of His. In monomorphic VT, the QRS complexes in one lead have the same morphology. In polymorphic VT, the QRS complexes have different morphologies in one lead.

Why are the other choices wrong?

  • An inherited reduction in cardiac sodium activity is seen in Brugada syndrome. This syndrome can lead to a polymorphic VT. However, myocardial ischemia is the most common underlying cause of polymorphic VT.
  • Electrolyte abnormalities can exacerbate the tendency toward ventricular ectopy, thus leading to polymorphic VT. However, the most common underlying cause of polymorphic VT is acute myocardial ischemia. It is still prudent to correct any electrolyte abnormalities that might be present.
  • A re-entrant mechanism through scarred myocardium is the most frequent etiology underlying monomorphic VT and is commonly seen in the chronic phase after an MI. The likelihood of ventricular arrhythmia in a patient with coronary artery disease is directly related to the extent of myocardial damage and scarring.

REFERENCES
Crawford MH. CURRENT Diagnosis & Treatment: Cardiology. 3rd ed. Philadelphia, PA: Elsevier; 2010:847-859.

Roberts-Thomson KC, Lau DH, Sanders P. The diagnosis and management of ventricular arrhythmias. Nat Rev Cardiol. 2011;8(6):311-321.

3. The correct answer is D, Type II diabetes mellitus.
Why is this the correct answer?
Diabetes mellitus (DM) can significantly increase a patient’s risk for coronary artery disease, but it is a long-term effect. The young, healthy woman in this case is more likely to have costochondritis; she has typical reproducible pain, suggesting a source within the chest wall. Costochondritis is not uncommon in young, healthy patients but should always be a diagnosis of exclusion, taking into account other symptoms and concomitant diseases that can cause chest pain. It is an inflammatory condition of the costochondral junction that can be intermittently sharp followed by dull pain and is reproducible to palpation. Tietze syndrome, as costochondritis is also known, can be worse with inspiration and can be difficult to distinguish from pleurisy, inflammation of the parietal pleura, which is generally not reproducible to palpation. Appropriate management of costochondritis includes pain control with anti-inflammatory medications to treat chest wall pain. Again, with no other associated diseases, other causes for chest pain, such as cardiac disease, pneumothorax, thoracic aortic dissection, and pneumonia, as well as PE, are unlikely given her age and history. Zoster is another consideration if the patient has a rash.

Why are the other choices wrong?

  • Pregnancy would increase this patient’s risk for PE significantly, and symptoms can include the type of sharp pain she reports as ongoing for 3 days. Pain worsening with deep inspiration is a characteristic often noted with PE. It is a leading cause of death in pregnant patients, and classic symptoms are often hard to distinguish from typical findings in pregnancy, including dyspnea.
  • Rheumatoid arthritis (RA) is another chronic inflammatory autoimmune disease that is associated with increased risk of diseases presenting with chest pain that can cause severe illness or death. These include pericarditis and recurrent venous thrombosis that can lead to PE. The risk of coronary artery disease associated with RA is not as high as that for SLE, but it is still increased, similar to that of type II diabetes. Rheumatoid arthritis can affect any joint, including the costochondral junction, but it is more commonly seen as symmetric disease in the extremity joints and cervical spine.
  • Patients with systemic lupus erythematosus (SLE) classically have inflammatory symptoms, including of the chest wall, which makes costochondritis a feasible diagnosis for this patient. But what is of more concern is that patients with SLE have a significantly increased risk of coronary artery disease, including young women (20 to 40 years) with findings of fewer traditional cardiac risk factors. Great care should be taken to rule out the possibility of coronary artery disease before diagnosing costochondritis in a patient with SLE.

REFERENCES
Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. St. Louis, MO: Elsevier; 2014:1157-1169, 1527-1542.

Tintinalli JE, Stapczynski JS, Ma OJ, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:1445-1457, 1911-1921.

4. The correct answer is A, Ethylene glycol.
Why is this the correct answer?
Toxicity from ethylene glycol best explains the combination of coma, mild hypothermia, tachypnea, and blood gas that demonstrates a metabolic acidosis with normal respiratory compensation. In an acute metabolic acidosis with normal respiratory compensation, as would be expected in ethylene glycol (and methanol) poisoning, the second two numbers of the pH roughly equate to the Pco2. Ethylene glycol, typically found in antifreeze, is intoxicating itself and is metabolized, initially by alcohol dehydrogenase, to various toxic metabolites. The result is a progressive anion gap metabolic acidosis. Ethylene glycol, isopropanol, and phenobarbital as sedative-hypnotic agents can cause hypothermia.

Why are the other choices wrong?

  • Isopropanol (isopropyl alcohol), typically referred to as rubbing alcohol, is converted by alcohol dehydrogenase to acetone, a ketone (not a ketoacid). Isopropanol ingestion can cause coma, but the presentation includes a ketosis, not acidosis.
  • Phenobarbital can cause coma, but in such a scenario, a respiratory acidosis is expected.
  • The blood gas analysis in this case demonstrates a metabolic acidosis with normal respiratory compensation, an acid-base scenario that is not typical with salicylate poisoning. Salicylate poisoning in adults characteristically manifests with either a primary respiratory alkalosis or a combination of a mixed acid-base picture (respiratory alkalosis and metabolic acidosis). Hypothermia also is atypical of salicylate poisoning due to the uncoupling of oxidative phosphorylation.

REFERENCES
Hoffman RS, Howland MA, Lewin NA, et al, eds. Goldfrank’s Toxicologic Emergencies. 10th ed. New York, NY: McGraw-Hill; 2015:249-253, 516-527, 1346-1357.

Wolfson AB, Hendey GW, Ling LJ, et al, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2014:1339-1342, 1346.

5. The correct answer is D, Symptoms are related to the degree of herniation of abdominal contents.
Why is this the correct answer?
This patient has a diaphragmatic rupture with herniation of the abdominal contents into the thoracic cavity, thus leading to severe respiratory distress and decreased breath sounds. The degree of his respiratory distress is related to both the size of the diaphragmatic tear as well as the amount of abdominal viscera that is herniated into the hemithorax. Large injuries can be identified on chest xray, but smaller injuries are harder to detect when they do not involve herniation of visceral contents into the thoracic cavity. A CT scan can help identify these injuries when they are not visible on chest xray, but smaller injuries can be missed on CT scan as well and can be notoriously difficult to identify. Patients occasionally present months to years later with symptoms from a previously undiagnosed injury. Patients with smaller tears typically have fewer symptoms. These injuries occur most commonly with blunt trauma due to violent compression of the abdominal cavity and the pressure gradient between the thoracic and abdominal cavities. It is important to proceed cautiously if considering chest tube placement in these patients to avoid iatrogenic visceral injury.

Why are the other choices wrong?

  • Blunt trauma typically causes larger tears in the diaphragm than penetrating trauma due to the forces involved in the injury. Blunt trauma can cause tears as large as 5 to 15 cm typically, and at the posterolateral portion of the diaphragm, due to the inherent weakness of the diaphragm in this area.
  • Diaphragmatic tears were previously thought to be much more common on the left side of the body because the right hemidiaphragm is relatively protected by the liver. Right-sided injuries do occur, but typically these injuries cause more hemodynamic compromise due to the greater force required to cause injury, and because the mortality rate is higher in the field with right-sided injuries. In addition, right-sided injuries can be underdiagnosed due to the protective effect of the liver. It is now thought that left-sided and right-sided injuries occur at about the same frequency.
  • The mortality rate for diaphragmatic rupture is higher with blunt trauma than penetrating trauma because penetrating trauma typically causes smaller defects, and larger forces are required to tear the diaphragm with blunt trauma. Blunt traumatic diaphragm rupture can cause immediate or delayed herniation of abdominal contents into the thoracic cavity that results in complications such as tension gastrothorax, visceral ischemia, or perforated viscus.

REFERENCES
Broder J. Diagnostic Imaging for the Emergency Physician. Philadelphia, PA: Saunders; 2011:323. 

Tintinalli JE, Stapczynski JS, Ma OJ, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2012:1762.

Wolfson AB, Hendey GW, Ling LJ, et al, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2014:209-211.

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