Malignant hyperthermia may not manifest until the recovery room or later. Which statement is true regarding the timing of MH onset?

Malignant hyperthermia may not manifest until the recovery room or later. Which statement is true regarding the timing of MH onset?

• A. It always presents intraoperatively
• B. It may present only in recovery room or later
• C. It cannot occur after anesthesia
• D. It only occurs with halothane exposure

Answer: (B)

Malignant hyperthermia can have a variable onset, not limited to the time under anesthesia. It may begin during the operation or be delayed and first become evident in the recovery room or even later. This happens because the underlying problem is a genetic susceptibility that causes an exaggerated calcium release in skeletal muscle in response to triggering agents, leading to a hypermetabolic state that can continue to unfold after the anesthetic drugs have been stopped. Triggers include volatile inhaled anesthetics (such as sevoflurane, isoflurane, desflurane) and depolarizing muscle relaxants like succinylcholine, so the reaction is not restricted to halothane or to the intraoperative period. Hence, the true statement is that malignant hyperthermia may present only in the recovery room or later.

Malignant hyperthermia can have a variable onset, not limited to the time under anesthesia. It may begin during the operation or be delayed and first become evident in the recovery room or even later. This happens because the underlying problem is a genetic susceptibility that causes an exaggerated calcium release in skeletal muscle in response to triggering agents, leading to a hypermetabolic state that can continue to unfold after the anesthetic drugs have been stopped. Triggers include volatile inhaled anesthetics (such as sevoflurane, isoflurane, desflurane) and depolarizing muscle relaxants like succinylcholine, so the reaction is not restricted to halothane or to the intraoperative period. Hence, the true statement is that malignant hyperthermia may present only in the recovery room or later.