NAC OSCE Shortness of Breath: COPD Exacerbation
A 67-year-old male smoker presents with 3 days of worsening dyspnea and purulent sputum. Complete station walkthrough — candidate instructions, respiratory history, COPD differential, GOLD-aligned Canadian management, oxygen targets, and smoking cessation counselling.
Station Overview
Station type: History-taking and management. This station tests your ability to distinguish an acute COPD exacerbation from other causes of acute dyspnea in an older adult, and to apply Canadian COPD management guidelines — particularly the critically important oxygen target of 88–92% SpO₂ (not higher) in a patient with chronic hypercapnia.
Competencies assessed: History taking, physical examination (description), diagnosis, investigations, management, communication (smoking cessation counselling).
Key focus: Many IMGs default to high-flow oxygen in any breathless patient. In COPD, this can cause hypercapnic respiratory failure. Knowing the 88–92% SpO₂ target is a high-value mark that distinguishes candidates who know Canadian respirology guidelines from those applying general acute medicine principles.
Candidate Instructions
Setting: Family medicine clinic with access to emergency resources
Mr. Harold Chen, 67 years old, has come to your clinic with a 3-day history of worsening shortness of breath. He is a known COPD patient (last spirometry: FEV₁ 52% predicted) who smokes one pack per day. His oxygen saturation on room air today is 88%. He is using his salbutamol inhaler more frequently than usual.
Your tasks:
1. Take a focused history from Mr. Chen.
2. Perform a relevant physical examination (describe what you would do).
3. Outline your investigations and management plan, including any counselling.
Clinical Approach
Opening
"Mr. Chen, I'm Dr. [Name]. I can see you're having a hard time catching your breath — let's get you comfortable and I'll ask you a few questions so I can understand what's going on and help you. Is that okay?"
Focused history — respiratory
- Dyspnea: Baseline exercise tolerance vs. current — can he walk across a room? Worse than his usual COPD?
- Cough: Baseline chronic productive cough vs. change in character or volume
- Sputum: Colour change to yellow or green (purulent sputum = bacterial infection, key trigger for antibiotic use)
- Fever/chills: Suggests infectious exacerbation (viral or bacterial)
- Inhaler use: How frequently is he using salbutamol? (increase = exacerbation marker)
- Previous exacerbations: How many in the past year? Hospitalizations? ICU admissions? Previous intubations?
- Current inhalers: What is he on — LAMA (tiotropium), LABA/ICS combination (salmeterol/fluticasone), or triple therapy?
- Compliance and technique: Using inhalers correctly?
- Sick contacts, recent travel
- Palpitations, ankle swelling (cor pulmonale, right heart failure in severe COPD)
Focused physical examination (describe to examiner)
- General appearance: respiratory distress, use of accessory muscles, pursed-lip breathing, cyanosis
- Vital signs: respiratory rate (tachypnea), heart rate, BP, temperature, SpO₂
- Chest: hyperinflation (barrel chest), reduced air entry bilaterally, prolonged expiratory phase, expiratory wheeze, coarse crackles (if pneumonia present)
- Signs of right heart failure: JVD, peripheral oedema
- Conscious level: agitation or drowsiness may indicate CO₂ retention
When stating your oxygen management: "I would titrate supplemental oxygen to maintain SpO₂ between 88% and 92% — not higher. In patients with chronic COPD and hypercapnia, high-flow oxygen can blunt the hypoxic respiratory drive and worsen CO₂ retention, potentially leading to type 2 respiratory failure." This single statement earns marks in multiple competency domains.
Differential Diagnosis
| Diagnosis | Supporting features | Distinguishing point |
|---|---|---|
| Acute COPD exacerbation | Known COPD, increased dyspnea, purulent sputum, increased bronchodilator use, smoker | Most likely — diagnose and treat |
| Community-acquired pneumonia | Fever, productive cough, focal consolidation on CXR, elevated WBC | Can coexist with COPD exacerbation; CXR and temperature help distinguish |
| Acute decompensated heart failure | Orthopnea, PND, bilateral crackles, peripheral oedema, elevated BNP | Can coexist with COPD (mixed picture); BNP and CXR central |
| Pulmonary embolism | Pleuritic chest pain, haemoptysis, risk factors (immobility, malignancy) | COPD patients at increased PE risk; Wells score + D-dimer if suspected |
| Pneumothorax | Sudden onset, decreased breath sounds unilaterally, resonant percussion | Can be a COPD complication (emphysematous bullae rupture); CXR diagnostic |
Management — GOLD Guidelines / Canadian Standards
Immediate in-clinic management
- Oxygen: Titrate to SpO₂ 88–92% via controlled-flow nasal prongs or Venturi mask — do NOT give high-flow oxygen
- Short-acting bronchodilators: Salbutamol 2.5 mg nebulised q20 min × 3 doses, then reassess; add ipratropium 0.5 mg nebulised
- Systemic corticosteroids: Prednisone 40 mg PO daily × 5 days — reduces exacerbation severity and duration (GOLD 2024 recommendation)
- Antibiotics — indicated if 2 of 3 Anthonisen criteria met: (1) increased dyspnea, (2) increased sputum volume, (3) purulent sputum change. First-line: amoxicillin-clavulanate, doxycycline, or azithromycin for 5 days (adjust for local resistance patterns)
Investigations to order
- Chest X-ray (portable or PA/lateral — rule out pneumonia, pneumothorax, CHF)
- ABG (if SpO₂ <92% on supplemental O₂, or concern for CO₂ retention)
- CBC, electrolytes, creatinine, glucose
- Sputum Gram stain and culture if purulent and antibiotics being started
- ECG (rule out cor pulmonale, arrhythmia)
- BNP (if heart failure cannot be excluded clinically)
Disposition
- Admit if: SpO₂ <88% despite treatment, CO₂ retention on ABG, failure to respond to initial bronchodilators, altered consciousness, or significant comorbidity
- Discharge with follow-up if responds well: prescribe prednisone course, antibiotics, optimise inhaler therapy, ensure written action plan
- Referral for pulmonary rehabilitation on follow-up — improves outcomes and reduces re-exacerbation rate
Counselling — Smoking Cessation
Smoking cessation is the single most effective intervention in COPD — it slows FEV₁ decline and reduces exacerbation frequency. Every encounter with a smoking COPD patient requires a brief intervention using the 5 A's (Ask, Advise, Assess, Assist, Arrange). On the NAC OSCE, this is a mandatory component of the management plan for any station involving a current smoker.
"Mr. Chen, I want to talk about one thing that would make the biggest difference in your breathing — and that's the smoking. I know that's not easy to hear, and it may not be easy to do. But stopping smoking is the single most effective thing we can do to slow the damage to your lungs and prevent these episodes from getting worse."
"Have you ever tried to quit before? Are you open to talking about it today?"
Assist: Offer pharmacotherapy — varenicline (Champix) is first-line in Canada and most effective; nicotine replacement therapy (patch + short-acting) is a good alternative. Refer to the Canadian Lung Association stop-smoking resources or a cessation program.
Additional counselling points to cover:
- Vaccines: annual influenza vaccine, pneumococcal vaccine (PCV20 or PPSV23 per current NACI schedule)
- Inhaler technique review — up to 80% of COPD patients use inhalers incorrectly
- Written COPD action plan — when to increase bronchodilators, when to start the "rescue pack" (prednisone + antibiotics), when to go to hospital
- Follow-up in 1–2 weeks after acute exacerbation
In the smoking cessation portion, avoid lecturing. Use motivational interviewing: "What do you know about how smoking affects your breathing?" — then build on the patient's own understanding. Acknowledge ambivalence: "It sounds like part of you wants to try, but you're worried about whether you can do it. That's completely understandable." IMGs who lecture patients about quitting smoking without exploring readiness lose communication marks.
This is a practice case based on a station from NAC OSCE: A Comprehensive Review (2nd Edition). The full book version includes a detailed patient history, physical examination findings, an expanded differential diagnosis, step-by-step management aligned to Canadian guidelines, and a complete counselling script — across all 92 stations.