Hypothermia after accidental intrathecal administration of high-dose morphine

Although it is common to administer intrathecal morphine for relief of pain associated with cesarean section, persistent hypothermia is a little-known adverse effect of subarachnoid morphine administration. We report a case of persistent hypothermia after subarachnoid anesthesia during an elective cesarean delivery. The mother received subarachnoid anesthesia with 11 mg of hyperbaric bupivacaine along with an accidentally high dose of 1 mg of morphine. Shortly after delivery, her temperature was 36.1°C, decreasing at 2 hours after anesthesia induction to 34.0°C, in spite of active warming. At the time, the patient was heavily perspiring, and reported feeling hot and nauseous. Since the symptoms were suspected to be due to subarachnoid morphine, 0.2 mg naloxone was administered intravenously over a 10-minute period. Immediately after commencing naloxone administration, the patient felt cold and began shivering, her body temperature returned to 35.5°C after about 1 hour and did not decrease again, following which a stable course was observed. Delayed and persistent hypothermia attributed to accidental high-dose intrathecal morphine administration was reversed with naloxone administration.