Chapter 58: Hypothermia After Neuraxial Morphine

BACKGROUND

Intrathecal morphine can produce hypothermia after cesarean delivery, likely due to a central effect on opioid receptor for thermoregulation. The incidence is about 6% to 7% in elective cesarean cases and may be dose dependent.¹ In a randomized double-blind controlled study, all parturients received spinal anesthesia containing 150 µg morphine or normal saline in addition to 10 to 12 mg bupivacaine for cesarean delivery. In both groups, a significant decrease in core temperature was noted. The patients in morphine group had lower temperature and longer duration of temperature decrease.² Prompt management of morphine-induced hypothermia can improve patient’s comfort. After lorazepam administration, immediate cessation of symptoms and an increase to normothermia temperature within 90 minutes were often observed.¹ Untreated hypothermia may last up to 6 hours.

DIAGNOSIS

• Core temperature <35.8°C (<96.4°F).

• Paradoxical symptoms: diaphoresis, subjectively feeling of being hot.

• Can be sedated or feel dizzy.

• Hypothermia is usually identified after cesarean delivery while in the recovery room.

TREATMENT

Treatment for Hypothermia After Neuraxial Morphine¹

• Conservative treatment: In mild cases, warm blankets, heating lamps, and Bair hugger forced hot air warmer; however, patients often feel uncomfortable with heat.

• Medication: For moderate and severe hypothermia, lorazepam 0.5 mg, intravenously, may be repeated once.

• Naloxone 40 to 80 µg can also be effective in some patients.

REFERENCES