SPEX Exam Emergency Medicine 4

Question 1

A 58-year-old male presents with sudden onset chest pain radiating to the back. BP is 180/60 mmHg in the right arm and 140/90 mmHg in the left arm. CXR shows a widened mediastinum. CT angiography reveals a Type A aortic dissection. Which of the following is the MOST appropriate immediate pharmacologic intervention before surgical consultation?

Accepted Answer

Administer IV labetalol to reduce heart rate to 60 bpm and systolic BP to 100–120 mmHg

Answer

Type A aortic dissection requires immediate surgical repair, but pharmacologic bridging targets heart rate first (to <60 bpm) and then systolic BP (100–120 mmHg) using a beta-blocker like labetalol or esmolol. Reducing dP/dt (rate of pressure rise) is the key principle. Nitroprusside alone is contraindicated as monotherapy because reflex tachycardia worsens shear stress. Heparin is contraindicated. Fluid boluses could worsen aortic wall stress.

Question 2

A 34-year-old woman presents in status epilepticus. She received lorazepam 4 mg IV twice without effect. Fosphenytoin 20 PE/kg IV is now being infused. After 20 minutes she continues seizing. Which agent is MOST appropriate as the next step?

Accepted Answer

IV phenobarbital 20 mg/kg

Answer

This patient is in refractory status epilepticus — defined as seizures persisting after two adequate doses of a benzodiazepine and a second-line agent (fosphenytoin). Per established protocols (including Neurocritical Care Society guidelines), phenobarbital 20 mg/kg IV is the third-line agent of choice in this scenario. Although levetiracetam and valproate are options for second-line therapy, once fosphenytoin has failed, phenobarbital is the appropriate escalation. Repeating benzodiazepines at this point provides minimal benefit.

Question 3

A 72-year-old dialysis-dependent patient presents with peaked T-waves and a widened QRS (160 ms) on ECG. Potassium level returns at 7.8 mEq/L. Which of the following interventions has the FASTEST onset for cardiac membrane stabilization?

Accepted Answer

IV calcium gluconate 1–2 g over 5–10 minutes

Answer

IV calcium (gluconate or chloride) acts within 1–3 minutes to stabilize cardiac membrane potential by raising the threshold potential, thereby reducing excitability — it does NOT lower serum potassium. This is the critical distinction: calcium is the fastest-acting intervention for cardiac protection in severe hyperkalemia with ECG changes. Insulin/glucose and albuterol shift potassium intracellularly (onset 15–30 min). Sodium bicarbonate has a slower and less reliable effect on potassium in dialysis patients who cannot excrete bicarbonate.

Question 4

A 45-year-old man presents after accidental ingestion of an organophosphate pesticide. He is bradycardic, diaphoretic, has bronchospasm, miosis, and urinary incontinence. After adequate atropinization, which additional agent should be administered to address the underlying mechanism of toxicity?

Accepted Answer

Pralidoxime (2-PAM) IV to reactivate acetylcholinesterase before it is permanently inactivated

Answer

Organophosphates irreversibly inhibit acetylcholinesterase by phosphorylating the active site. Pralidoxime (2-PAM) regenerates the enzyme if given before 'aging' — permanent covalent maturation of the phosphorylated enzyme — which occurs within hours to days depending on the specific compound. Atropine blocks muscarinic effects but does not restore enzyme function. Physostigmine is a cholinesterase inhibitor — administering it would worsen the toxidrome. Flumazenil and N-acetylcysteine have no role here.

Question 5

A 28-year-old woman at 32 weeks gestation presents with a BP of 165/115 mmHg, severe headache, and 3+ proteinuria. She develops a generalized tonic-clonic seizure. What is the drug of choice for BOTH seizure prophylaxis/treatment and blood pressure control in this clinical scenario?

Accepted Answer

IV magnesium sulfate for seizure prophylaxis/treatment, combined with IV labetalol or hydralazine for hypertension

Answer

This patient has eclampsia (preeclampsia with severe features plus seizure). Magnesium sulfate is the drug of choice for eclamptic seizure treatment and recurrence prevention — it is superior to phenytoin or benzodiazepines for this indication. Antihypertensive therapy (targeting BP <160/110 mmHg) is given concurrently with IV labetalol or hydralazine, or oral nifedipine. Phenytoin is no longer recommended for eclamptic seizures. The key insight is that magnesium sulfate is an anticonvulsant specific to eclampsia — its mechanism involves N-methyl-D-aspartate receptor antagonism and vasodilation, not general CNS depression.

SPEX Exam Practice Test

SPEX Exam Practice Test

SPEX Exam Emergency Medicine 4