Mastering Acute Shortness of Breath Guidelines for PLAB 2 OSCE

Mastering Acute Shortness of Breath Guidelines for PLAB 2 OSCE Success

Shortness of breath (SOB), or dyspnoea, is one of the most common and high-stakes presentations in the Emergency Department. For PLAB 2 candidates, an Acute SOB station tests not only your clinical knowledge but, crucially, your ability to rapidly prioritize, manage critical situations (ABCDE), and communicate effectively under pressure.

This guide breaks down the essential UK-based guidelines for approaching acute SOB in the PLAB 2 OSCE, ensuring you hit all the critical domains: safety, diagnosis, and management.

1. The Immediate Priority: The ABCDE Approach

Every acute presentation in PLAB 2 must start with the Airway, Breathing, Circulation, Disability, and Exposure framework. This structured approach ensures patient safety is maintained before seeking a definitive diagnosis.

A. Airway

• Check: Is the airway patent? Look for noisy breathing (stridor, gurgling).

• Action: If obstructed, immediately call for senior help and prepare for airway maneuvers or adjuncts.

B. Breathing

• Assess: Respiratory rate, oxygen saturation, use of accessory muscles, signs of cyanosis, and chest expansion.

• Action:

  • Oxygen: Administer high-flow oxygen (15L/min via non-rebreather mask) immediately if the patient is critically unwell (e.g., sats <94% or signs of shock), unless they are known to be at risk of hypercapnic respiratory failure (e.g., severe COPD – start with controlled O2 aiming for 88-92%).

  • Listen: Auscultate the chest for unequal breath sounds, wheeze, or crackles.

  • Request: Immediate Arterial Blood Gas (ABG) analysis.

C. Circulation

• Assess: Heart rate, blood pressure, capillary refill time, and presence of peripheral oedema or JVP.

• Action: Establish two large-bore intravenous (IV) cannulae and send routine bloods (FBC, U&E, LFT, Troponin, BNP, D-dimer, cross-match if clinically indicated).

• Monitor: Place the patient on continuous cardiac monitoring (ECG).

D. Disability

• Assess: Conscious level (AVPU or GCS), pupil response, and blood glucose (crucial as hypoglycaemia or DKA can alter mental status and breathing pattern).

E. Exposure

• Assess: Look for rashes, trauma, evidence of DVT, or track marks. Maintain patient dignity and keep them warm.

2. Targeted History and Examination

Once the patient is stabilized, your history and focused examination must rapidly narrow down the broad differential diagnosis.

PLAB 2 Tip: In the OSCE, always verbalize that you would perform a full top-to-toe examination, but for the purpose of the exam, focus on the respiratory and cardiovascular systems.

3. Key Diagnostic Investigations

These tests are essential and must be requested promptly after initial stabilization:

1. Arterial Blood Gas (ABG): Essential for assessing severity (Type 1 or Type 2 respiratory failure) and monitoring response to treatment.

2. Chest X-ray (CXR): To look for consolidation (Pneumonia), pleural effusion, pulmonary oedema, pneumothorax, or cardiomegaly.

3. ECG: Essential to rule out cardiac causes (e.g., Myocardial Infarction, Atrial Fibrillation) or signs of pulmonary strain (e.g., S1Q3T3 pattern in PE).

4. D-dimer: Useful if PE is suspected and the patient is low-to-intermediate risk (use the WELLS score to stratify risk – vital for PLAB 2).

4. Guideline-Based Management Snapshots

Mastering the initial management steps for the most common critical causes will secure high marks.

A. Acute Severe Asthma (BTS/SIGN Guidelines)

If the patient presents with severe asthma (PEFR 33-50% predicted, respiratory rate >25/min, heart rate >110/min, inability to complete sentences):

1. Oxygen: High flow (aiming for 94-98% saturation).

2. Salbutamol: High-dose nebulized Salbutamol (5mg) immediately.

3. Ipratropium Bromide: Nebulized Ipratropium (500 micrograms) should be added to the Salbutamol for severe or life-threatening attacks.

4. Corticosteroids: Oral Prednisolone (40-50mg daily) or IV Hydrocortisone (100mg) if unable to take oral medication. This must be given immediately.

5. Magnesium Sulphate: IV Magnesium Sulphate (1.2–2g) should be considered for patients with acute severe asthma not responding to initial bronchodilator therapy.

B. Acute Pulmonary Oedema (Caused by Heart Failure)

This requires rapid reduction of fluid overload and afterload:

1. Positioning & Oxygen: Sit the patient up and give high-flow oxygen, aiming for sats >94%.

2. Nitrates: IV or sublingual Glyceryl Trinitrate (GTN) – Caution: Monitor BP to prevent hypotension.

3. Diuretics: IV Furosemide (40-80mg initial dose).

4. Morphine: May be given cautiously to reduce anxiety and preload, but is less favoured in modern guidelines unless severe pain/distress is present.

5. CPAP/NIV: Continuous Positive Airway Pressure (CPAP) or Non-Invasive Ventilation (NIV) should be considered early if respiratory failure is worsening.

C. Suspected Pulmonary Embolism (PE)

Immediate management hinges on the patient's hemodynamic stability:

1. Stabilization: ABCDE approach.

2. Anticoagulation: If haemodynamically stable and PE is high suspicion (or intermediate risk with positive D-dimer/imaging delay), initiate parenteral anticoagulation (e.g., Low Molecular Weight Heparin – LMWH) immediately while awaiting definitive imaging (CTPA).

3. Thrombolysis: Reserved for massive PE causing hemodynamic instability (shock or persistent hypotension). This is a critical care decision; ensure you involve seniors immediately.

5. Final Key Step: Senior Escalation and Safety Netting

In every acute PLAB 2 scenario, knowing when to call for senior help is vital. Acute SOB always warrants immediate senior review (Registrar/Consultant).

Safety Netting: Before concluding, always advise the patient on warning signs and ensure appropriate follow-up. For example, instruct them to return immediately if their breathing worsens, they become dizzy, or they develop chest pain.

Mastering the systematic, guideline-driven approach to acute SOB ensures you demonstrate clinical competence and, most importantly, patient safety—the cornerstones of the PLAB 2 examination.