DHA Medical Knowledge 2

Question 1

A 45-year-old male presents with crushing chest pain radiating to the left arm, diaphoresis, and nausea lasting 30 minutes. His ECG shows ST-elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?

Accepted Answer

Right coronary artery

Answer

ST-elevation in leads II, III, and aVF indicates an inferior myocardial infarction. The right coronary artery (RCA) supplies the inferior wall of the left ventricle in approximately 85% of individuals (right-dominant circulation). The LAD supplies the anterior wall, and the circumflex supplies the lateral wall.

Question 2

A 6-year-old child presents with a barking cough, inspiratory stridor, and low-grade fever. Neck X-ray shows a 'steeple sign.' What is the most appropriate initial management?

Accepted Answer

Dexamethasone with or without nebulized epinephrine

Answer

The clinical picture describes croup (laryngotracheobronchitis), most commonly caused by parainfluenza virus. The steeple sign on X-ray confirms subglottic narrowing. Corticosteroids (dexamethasone) are the mainstay of treatment; nebulized epinephrine is added for moderate-to-severe cases. Antibiotics are not indicated for viral croup.

Question 3

Which of the following best describes the mechanism of action of metformin in type 2 diabetes mellitus?

Accepted Answer

Inhibits hepatic glucose production via activation of AMPK

Answer

Metformin primarily works by activating AMP-activated protein kinase (AMPK) in the liver, which suppresses hepatic gluconeogenesis and glycogenolysis, reducing fasting blood glucose. It also improves peripheral insulin sensitivity. It does not stimulate insulin secretion and does not cause hypoglycemia as monotherapy.

Question 4

A 28-year-old woman at 36 weeks gestation presents with sudden-onset severe headache, visual disturbances, and a blood pressure of 165/110 mmHg. Urinalysis shows 3+ proteinuria. What is the definitive treatment for this condition?

Accepted Answer

IV magnesium sulfate and delivery of the fetus

Answer

This patient has severe preeclampsia with severe features. The definitive treatment is delivery of the fetus and placenta, as preeclampsia is a placenta-mediated condition that only resolves after delivery. IV magnesium sulfate is administered to prevent progression to eclampsia (seizures). Antihypertensives control BP but do not treat the underlying condition.

Question 5

A patient with chronic kidney disease (GFR 20 mL/min) develops hyperkalemia (K+ = 6.2 mEq/L) with peaked T-waves on ECG. What is the FIRST priority intervention?

Accepted Answer

IV calcium gluconate

Answer

When hyperkalemia causes ECG changes (peaked T-waves, widened QRS), the immediate priority is cardiac membrane stabilization with IV calcium gluconate. It does not lower potassium but antagonizes the cardiac effects of hyperkalemia within minutes. Subsequent measures (insulin/glucose, bicarbonate, kayexalate, dialysis) then address potassium redistribution and removal.

DHA - Dubai Health Authority Practice Test

DHA - Dubai Health Authority Practice Test

DHA Medical Knowledge 2