The implications of hypothermia for early tracheal extubation following cardiac surgery

Thermoregulation is impaired during anesthesia for cardiac surgery. Redistribution of body heat and heat loss to the environment result in mild hypothermia before cardiopulmonary bypass. Maintenance of normothermia, rather than hypothermia, may facilitate early tracheal extubation. Hypothermia alters the distribution and decreases the metabolism of most drugs, including anesthetic drugs and muscle relaxants, thus prolonging recovery. Postoperative shivering increases metabolic rate and potentially leads to myocardial ischemia; prevention is therefore critical to the success of early tracheal extubation after cardiac surgery. Coagulopathies, increased incidence of surgical wound infection, and perioperative cardiac morbidity are other potential risk factors identified in noncardiac patients. Hypothermia, however, does have potential benefits to the patient, including protection from cerebral ischemia and hypoxemia. Mild core hypothermia (approximately 34 degrees C) may represent the optimal balance between risks and benefits for fast-track patients.