Anaesthesia Machine Safety, Circle Systems, Vaporizers, and Capnography/Gas Delivery Crises — WACS Viva & Clinical Scenarios (General Anaesthesia)

Exam-style anaesthesia machine safety, circle systems, vaporizers, and capnography/gas delivery crises viva scenarios with examiner probes and model answers…

Scenarios covered

• SCENARIO 1: During an elective major pelvic surgery under general anaesthesia with mechanical ventilation using a circle system, the anaesthetic workstation oxygen supply alarm sounds, and the pipeline pressure gauge drops to zero. Detail your immediate, unhesitant actions to ensure uninterrupted patient oxygenation.
• SCENARIO 2: You are conducting general anaesthesia with a circle absorber system for a 45-year-old male. Thirty minutes into the procedure, you observe that the baseline of the capnography waveform does not return to zero (elevated baseline at 12 mmHg), and the end-tidal CO₂ rises progressively to 58 mmHg despite increasing minute ventilation. How do you analyze and resolve this problem?
• SCENARIO 3: You are assigned to an operating room with an older, unfamiliar continuous-flow anaesthetic machine. Walk the examiners through your systematic pre-use machine check (high-pressure, intermediate-pressure, and low-pressure leak checks) before inducing your first patient.
• SCENARIO 4: While maintaining anaesthesia with isoflurane and nitrous oxide/oxygen mixture (inspired oxygen fraction 0.40), the multi-gas monitor suddenly alarms for low FiO₂ (reading 0.18), while the oxygen flowmeter rotameter shows 1.5 L/min. The patient's SpO₂ falls from 99% to 88%. What is the crisis, and what is your emergency management protocol?