SN3 SHORT NOTE 5M

Describe Postoperative Shivering in detail.

General Surgery · Final Professional

Definition & Causes

Postoperative shivering is involuntary muscular activity after anaesthesia. It is most often a thermoregulatory response to perioperative hypothermia (heat lost through anaesthetic-induced vasodilatation and a cold theatre), but it can also be non-thermoregulatory (related to certain anaesthetic agents, pain).

Consequences & Management

Shivering is uncomfortable and — importantly — markedly increases oxygen consumption and cardiac work, which can be harmful in patients with limited cardiorespiratory reserve. Management: active warming (forced-air blanket, warmed fluids), supplemental oxygen, and drug treatment if needed — pethidine (meperidine) is classically effective, and other agents may be used. Prevention is by maintaining normothermia intra-operatively.

CLINICAL PEARL

Postoperative shivering is usually due to hypothermia and matters because it raises oxygen demand and cardiac work. Prevent with normothermia; treat with warming, oxygen and — classically — pethidine.

Significance in the Cardiac Patient

The clinical importance of postoperative shivering lies chiefly in its metabolic cost: the vigorous involuntary muscle activity can increase oxygen consumption several-fold, and this surge in demand, together with the associated rise in cardiac output and catecholamines, can precipitate myocardial ischaemia in a patient with limited coronary reserve. For this reason shivering is not dismissed as a trivial nuisance but actively prevented by maintaining normothermia and treated promptly when it occurs, with warming, supplemental oxygen to meet the increased demand, and drug treatment such as pethidine, which is particularly effective at suppressing the shivering response.

CLINICAL PEARL

Treat postoperative shivering as more than discomfort: it can double or triple oxygen consumption and stress the heart, so prevent it with normothermia and treat it with warming, oxygen and — classically — pethidine, which suppresses the shivering reflex.

In Brief

In short, warm the patient and, where reserve is limited, remember that the shivering itself is a cardiac stressor worth suppressing.

Raises oxygen demand sharply — hazardous in cardiac disease.

KEY POINT

Key points TO remember

Postoperative shivering: usually thermoregulatory (hypothermia); sometimes drug-related/pain.
Raises oxygen consumption & cardiac work — risky in limited reserve.
Manage: active warming, supplemental oxygen, pethidine (classically) if needed.
Prevent by maintaining normothermia intra-operatively.

EXAM TIP

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

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