Acute Respiratory Failure, ARDS and Mechanical Ventilation — WACS Viva & Clinical Scenarios (ICU & HDU)

Exam-style acute respiratory failure, ards and mechanical ventilation viva scenarios with examiner probes and model answers for ANAESTHESIA candidates.

Scenarios covered

• SCENARIO 1: A 38-year-old male is admitted to the ICU 48 hours post-laparotomy for severe acute necrotising pancreatitis. He is intubated and mechanically ventilated on VCV mode: tidal volume 480 mL (PBW 65 kg), respiratory rate 20 breaths/min, PEEP 10 cmH₂O, FiO₂ 0.80. His arterial blood gas reveals pH 7.24, PaCO₂ 48 mmHg, PaO₂ 62 mmHg (PaO₂/FiO₂ 77.5 mmHg), and plateau pressure is measured at 36 cmH₂O with a peak inspiratory pressure of 44 cmH₂O. Formulate a comprehensive ventilatory and therapeutic rescue strategy for this severe ARDS case.
• SCENARIO 2: A 24-year-old female with a history of brittle asthma is brought to the ICU in extremis. She is exhausted, cyanotic, unable to speak, with heart rate 146 beats/min, blood pressure 150/95 mmHg, pulsus paradoxus, SpO₂ 82% on high-flow oxygen mask, and bilateral silent chest on auscultation. Arterial blood gas shows pH 7.10, PaCO₂ 68 mmHg, PaO₂ 54 mmHg, and HCO₃⁻ 21 mmol/L. Detail your immediate anaesthetic approach to emergency intubation, mechanical ventilation, and pharmacological reversal of bronchospasm.
• SCENARIO 3: A 68-year-old known COPD patient is admitted with acute type 2 respiratory failure secondary to community-acquired pneumonia. On non-invasive ventilation (BiPAP: IPAP 16 cmH₂O, EPAP 6 cmH₂O, FiO₂ 0.40), his repeat arterial blood gas after 2 hours shows worsening hypercapnia (pH 7.18, PaCO₂ 82 mmHg, PaO₂ 58 mmHg), and he is becoming progressively somnolent and agitated. Outline your indications for invasive mechanical ventilation, intubation strategy, and initial ventilator programming.
• SCENARIO 4: A 52-year-old male who has been mechanically ventilated for 14 days following severe chest trauma and pulmonary contusion has failed three consecutive spontaneous breathing trials due to tachypnoea, diaphoresis, and haemodynamic instability. Describe your systematic diagnostic evaluation for weaning failure and your management plan, including the role and technique of bedside tracheostomy.