NAC OSCE Emergency Medicine 2 — Questions and Answers
Question 1: A 30-year-old male presents to a Canadian ED after a syncopal episode during exercise. ECG shows a short PR interval and a delta wave. What is the diagnosis and the MOST critical concern?
- Wolff-Parkinson-White syndrome — risk of rapid conduction during AF causing ventricular fibrillation and sudden cardiac death (Correct answer)
- First-degree AV block — benign, no treatment needed
- Brugada syndrome — risk of VF in sleep
- Long QT syndrome — risk of torsades de pointes
Correct answer: Wolff-Parkinson-White syndrome — risk of rapid conduction during AF causing ventricular fibrillation and sudden cardiac death
WPW syndrome (short PR, delta wave) carries risk of rapid antegrade conduction via the accessory pathway during AF, potentially causing VF and sudden death; electrophysiology referral for ablation is indicated.
Question 2: A 70-year-old patient with COPD presents in acute hypercapnic respiratory failure (pH 7.28, pCO₂ 78 mmHg, SpO₂ 84%). According to Canadian Thoracic Society guidelines, what is the FIRST-line ventilatory support?
- Non-invasive positive pressure ventilation (NIV/BiPAP) (Correct answer)
- High-flow nasal oxygen at 60 L/min
- Immediate intubation and mechanical ventilation
- Controlled low-flow oxygen at 2 L/min only
Correct answer: Non-invasive positive pressure ventilation (NIV/BiPAP)
CTS guidelines recommend NIV (BiPAP) as first-line for acute hypercapnic respiratory failure in COPD exacerbation; it reduces intubation rates and mortality compared to conventional oxygen therapy.
Question 3: A 22-year-old female presents with right lower quadrant pain, nausea, and a positive urine hCG. Her last period was 7 weeks ago. Transvaginal ultrasound shows no intrauterine gestational sac and free fluid in the pelvis. What is the MOST critical diagnosis to exclude?
- Ruptured ectopic pregnancy — surgical emergency requiring immediate OB/GYN involvement (Correct answer)
- Appendicitis with peritonitis
- Ovarian torsion
- Spontaneous complete miscarriage
Correct answer: Ruptured ectopic pregnancy — surgical emergency requiring immediate OB/GYN involvement
A positive hCG with no intrauterine sac and free pelvic fluid strongly suggests ruptured ectopic pregnancy, which can cause haemorrhagic shock and death; immediate surgical consultation is mandatory.
Question 4: According to ACLS guidelines used in Canadian hospitals, what is the recommended energy for the first defibrillation shock for ventricular fibrillation with a biphasic defibrillator?
- 120-200 J (biphasic) as recommended by the manufacturer, or 200 J if unknown (Correct answer)
- 360 J monophasic equivalent for all shocks
- 50-100 J as a starting dose
- 400 J for better termination of VF
Correct answer: 120-200 J (biphasic) as recommended by the manufacturer, or 200 J if unknown
AHA/Canadian Resuscitation guidelines recommend 120-200 J for biphasic defibrillators (manufacturer-specific) for initial VF shock, with 200 J if the effective dose is unknown; subsequent shocks use equal or higher energy.
Question 5: A 60-year-old male with known liver cirrhosis presents vomiting large volumes of bright red blood. He is haemodynamically unstable. What is the MOST important immediate pharmacological intervention while awaiting endoscopy?
- IV octreotide (somatostatin analogue) to reduce portal pressure, plus IV PPI (Correct answer)
- IV vasopressin as the only vasoactive agent
- Oral propranolol to reduce portal hypertension acutely
- IV furosemide to reduce ascites and portal pressure
Correct answer: IV octreotide (somatostatin analogue) to reduce portal pressure, plus IV PPI
In variceal bleeding, octreotide (or terlipressin) reduces splanchnic blood flow and portal pressure; it should be given immediately alongside PPI, antibiotics (ceftriaxone), and blood products while arranging urgent endoscopy.
Question 6: A 40-year-old male presents with a severe asthma exacerbation (PEFR <25% predicted, SpO₂ 88%, unable to speak in sentences) not responding to repeated salbutamol nebulisation. What is the NEXT most appropriate escalation?
- IV magnesium sulphate 2 g over 20 minutes, IV corticosteroids, and prepare for possible intubation or heliox (Correct answer)
- Increase salbutamol frequency to every 5 minutes indefinitely
- Oral prednisolone alone and discharge
- Aminophylline IV as first additional agent
Correct answer: IV magnesium sulphate 2 g over 20 minutes, IV corticosteroids, and prepare for possible intubation or heliox
For near-fatal or life-threatening asthma unresponsive to bronchodilators, Canadian and GINA guidelines recommend IV magnesium sulphate (2 g over 20 minutes), systemic corticosteroids, and preparation for intubation if deteriorating.
NAC OSCE Emergency Medicine 2
A 30-year-old male presents to a Canadian ED after a syncopal episode during exercise.
ECG shows a short PR interval and a delta wave.
What is the diagnosis and the MOST critical concern?