NAC OSCE Emergency Medicine — Questions and Answers
Question 1: A 45-year-old male presents to a Canadian ED with crushing substernal chest pain radiating to the left arm, diaphoresis, and an ECG showing 2 mm ST elevation in leads II, III, and aVF. What is the MOST time-critical intervention target?
- Door-to-balloon time <90 minutes for primary PCI, or fibrinolysis within 30 minutes if PCI is unavailable (Correct answer)
- Troponin result before any intervention
- Echocardiogram to confirm wall motion abnormality first
- Cardiology consultation before any treatment
Correct answer: Door-to-balloon time <90 minutes for primary PCI, or fibrinolysis within 30 minutes if PCI is unavailable
Canadian Cardiovascular Society STEMI guidelines mandate door-to-balloon time <90 minutes for primary PCI; if PCI cannot be achieved within 120 minutes, fibrinolysis should be given within 30 minutes of ED arrival.
Question 2: A 28-year-old woman is brought to the ED after ingesting an unknown quantity of acetaminophen 4 hours ago. Which investigation is MOST critical to guide treatment?
- Serum acetaminophen level at 4 hours post-ingestion plotted on the Rumack-Matthew nomogram (Correct answer)
- Liver function tests alone
- Urine toxicology screen
- Serum acetaminophen level immediately on arrival
Correct answer: Serum acetaminophen level at 4 hours post-ingestion plotted on the Rumack-Matthew nomogram
The Rumack-Matthew nomogram uses the serum acetaminophen level at 4 hours post-ingestion to determine whether N-acetylcysteine (NAC) is indicated; earlier or later levels are not reliably predictive.
Question 3: According to Canadian Triage and Acuity Scale (CTAS), which level is assigned to a patient presenting with severe respiratory distress, SpO₂ 88%, and inability to complete sentences?
- CTAS 1 — Resuscitation (immediate life threat) (Correct answer)
- CTAS 2 — Emergent (15-minute assessment target)
- CTAS 3 — Urgent (30-minute target)
- CTAS 4 — Less urgent (60-minute target)
Correct answer: CTAS 1 — Resuscitation (immediate life threat)
CTAS 1 (Resuscitation) applies to conditions with immediate threat to life such as severe respiratory failure; the patient requires immediate physician assessment and intervention.
Question 4: A 55-year-old male presents in anaphylactic shock after a bee sting. What is the FIRST-line treatment according to Canadian Emergency Medicine guidelines?
- IM epinephrine 0.3-0.5 mg (1:1000) into the anterolateral thigh (Correct answer)
- IV antihistamine (diphenhydramine) as first priority
- IV corticosteroids as the mainstay of treatment
- Inhaled salbutamol as first-line bronchodilator
Correct answer: IM epinephrine 0.3-0.5 mg (1:1000) into the anterolateral thigh
IM epinephrine into the anterolateral thigh is the first-line treatment for anaphylaxis per Canadian guidelines; antihistamines and corticosteroids are adjuncts that do not replace epinephrine.
Question 5: A 65-year-old woman presents with sudden onset of the worst headache of her life. CT head is negative. What is the next MOST critical investigation?
- Lumbar puncture for xanthochromia and red blood cell count (or CT angiography if available) (Correct answer)
- MRI brain with contrast
- Neurology consult and observation only
- EEG to rule out seizure activity
Correct answer: Lumbar puncture for xanthochromia and red blood cell count (or CT angiography if available)
A thunderclap headache with normal CT requires LP to detect xanthochromia (present 2-12 hours to 2 weeks post-SAH) or elevated RBCs, as CT misses 2% of SAH; CT angiography may be used in some Canadian centres as an alternative.
Question 6: A 3-year-old child is brought to the ED with 48 hours of profuse watery diarrhoea and vomiting. She is listless, has sunken eyes, no tears, and dry mucous membranes. Using the WHO/CPS dehydration scale, what is her dehydration status and MOST appropriate initial management?
- Severe dehydration (>10% body weight) — IV rehydration with 20 mL/kg NS bolus, reassess and repeat as needed (Correct answer)
- Moderate dehydration — oral rehydration solution only
- Mild dehydration — encourage breastfeeding and monitor at home
- Severe dehydration — immediate blood transfusion
Correct answer: Severe dehydration (>10% body weight) — IV rehydration with 20 mL/kg NS bolus, reassess and repeat as needed
Listlessness, sunken eyes, no tears, and dry mucous membranes indicate severe dehydration (>10%); CPS guidelines recommend immediate IV fluid resuscitation with 20 mL/kg isotonic saline boluses, reassessing after each.
NAC OSCE Emergency Medicine
A 45-year-old male presents to a Canadian ED with crushing substernal chest pain radiating to the left arm, diaphoresis, and an ECG showing 2 mm ST elevation in leads II, III, and aVF.
What is the MOST time-critical intervention target?