Paper I — 2022 May (Supplementary) (2010 Scheme) — Q6
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Paper I
2022 May (Supplementary) (2010 Scheme) · 40 marks · 120 min
Question
Halothane
Q63 marksShort Notes
Answer
Halothane is a potent halogenated volatile general anesthetic, now largely superseded by newer agents because of two specific, high-yield liabilities.
Properties: high potency (low MAC), non-irritant and pleasant-smelling (was once favoured for inhalational induction, especially in children), bronchodilator action.
Adverse effects
Halothane hepatitis — rare but severe, immune-mediated hepatic necrosis; a reactive trifluoroacetyl metabolite forms a hapten with liver proteins, triggering an immune response; risk increases with repeated exposure
Myocardial sensitization to catecholamines — significant risk of arrhythmia if adrenaline is administered concurrently
Malignant hyperthermia (rare, in genetically susceptible individuals — a general risk of volatile anesthetics, not unique to halothane)
Myocardial depression and hypotension
Postoperative shivering
Clinical relevance: these two liabilities (hepatotoxicity, arrhythmogenic catecholamine sensitization) are why halothane has been replaced by isoflurane, sevoflurane, and desflurane in modern practice.
