Causes of postoperative shivering: Shivering may occur because of hypothermia or the aftereffects of general anesthetic agents. It is also common in postpartum patients. Shivering is the body’s attempt to increase heat production and raise body temperature and may be associated with intense vasoconstriction. Shivering may also be a nonspecific neurologic sign that is sometimes exhibited during emergence from anesthesia. It is most common after long surgeries and with the use of greater concentrations of volatile agent.
Deleterious effects of shivering: Occasionally, shivering can induce hyperthermia (38°–39°C) and metabolic acidosis. Shivering can also be seen after spinal and epidural anesthesia because these techniques lower the shivering threshold and vasoconstrictive response to hypothermia. Shivering increases oxygen consumption by as much as five times, decreases arterial oxygen saturation, and is associated with an increased risk of myocardial ischemia. Shivering can be treated with intravenous meperidine (12.5–25 mg) in adults; however, it is best to try to prevent it by maintaining normothermia intraoperatively and perioperatively. Unintentional hypothermia increases with extremes of age, abdominal surgery, surgeries of long duration, and cold ambient operating room temperature.
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