SN4 SHORT NOTE 5M

Describe Halothane Hepatitis in detail.

General Surgery · Final Professional

Definition

Halothane hepatitis is a rare but potentially fatal, immune-mediated hepatic necrosis occurring after exposure to halothane. A milder, common, transient rise in liver enzymes also occurs, but the feared entity is the severe fulminant hepatitis.

Mechanism & Risk Factors

It is thought to result from an immune (hypersensitivity) reaction to oxidative metabolites of halothane (trifluoroacetyl compounds) that bind liver proteins and become antigenic. Risk factors: repeated exposure to halothane over a short interval, middle-aged obese women, and a previous unexplained reaction to halothane. It typically presents with fever and jaundice several days after anaesthesia with markedly raised transaminases.

DANGER / REMEMBER

Do not re-expose a patient to halothane within a short interval, or at all after a previous unexplained postoperative jaundice/pyrexia following halothane — repeat exposure greatly increases the risk of fatal hepatitis. Use an alternative agent.

Diagnosis & Prevention

The diagnosis of halothane hepatitis is essentially one of exclusion, made when severe hepatitis follows halothane exposure with no other cause found, and it is supported by the typical picture of fever and jaundice appearing several days postoperatively, often after a repeat exposure. Prevention rests entirely on avoiding the circumstances that provoke it — not repeating halothane within a short interval, never giving it again after an unexplained reaction, and, in modern practice, simply using the newer agents, which lack this association — so the condition is now largely of historical and examination interest.

CLINICAL PEARL

The safe rule is absolute: after any unexplained jaundice or fever following halothane, the drug is never given again, and in any case it is not repeated within a short interval — a precaution now made easy by the availability of the newer, non-hepatotoxic agents.

DANGER / REMEMBER

Because the reaction is immune and idiosyncratic rather than dose-related, even a small repeat exposure can be dangerous, which is why the history of a previous reaction is sought and acted upon absolutely.

Repeat exposure within 3 months is the main risk factor.

KEY POINT

Key points TO remember

Rare, potentially fatal immune-mediated hepatic necrosis after halothane.
Immune reaction to oxidative (trifluoroacetyl) metabolites binding liver proteins.
Risk: repeated exposure over a short interval, obese middle-aged women, previous reaction.
Fever + jaundice days after anaesthesia; never re-expose — use another agent.

EXAM TIP

Sources: Morgan & Mikhail’s Clinical Anesthesiology; Miller’s Anesthesia; Ajay Yadav’s Short Textbook of Anaesthesia.

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