Inhalational Anaesthetics, Carrier Gases, and Volatile Toxicity — WACS Viva & Clinical Scenarios (Pharmacology and Applied Pharmacology)

Exam-style inhalational anaesthetics, carrier gases, and volatile toxicity viva scenarios with examiner probes and model answers for ANAESTHESIA candidates.

Scenarios covered

• SCENARIO 1: A 4-year-old child presents with post-tonsillectomy bleeding requiring urgent re-exploration. The child is terrified and uncooperative. Describe your pharmacodynamic considerations and technique for an inhalational induction using sevoflurane versus halothane in an actively bleeding child.
• SCENARIO 2: A 32-year-old female who had two previous gynaecological surgeries under halothane anaesthesia within the last 6 months presents for interval cholecystectomy. Discuss the pharmacology of halothane metabolism, risk of hepatic necrosis, and the physiological rationale for choosing an alternative volatile or intravenous agent.
• SCENARIO 3: During an elective open reduction and internal fixation of a femur fracture under general anaesthesia with isoflurane, the patient suddenly develops an unexplained rise in end-tidal carbon dioxide from 38 mmHg to 82 mmHg, sinus tachycardia of 148 beats per minute, and generalized muscle rigidity. Detail your immediate diagnostic and pharmacological management steps.
• SCENARIO 4: A 50-year-old male with severe chronic obstructive pulmonary disease and bullous emphysema is undergoing emergency repair of an incarcerated inguinal hernia. Justify your decision to avoid Nitrous Oxide based on its physicochemical and pharmacokinetic properties.