What are the physiologic consequences of hypothermia?
The physiologic consequences of hypothermia are sum-marized in Table 83.1.
Electrocardiogram (ECG) changes occur as well and include sinus bradycardia, widened PR interval, widened QRS, and prolonged QT. The Osborn wave is characteristic for hypothermia. This wave is a deflection at the J point (the junction between the QRS complex and the ST seg-ment) in the same direction as that of the QRS complex, with a height proportional to the degree of hypothermia.
Deleterious clinical consequences have been documented:
· Impaired coagulation has been shown to lead to higher transfusion requirements in patients undergoing total hip replacement.
· The incidence of wound infection is increased because of a direct impairment of the immune function and a decrease in oxygen delivery to the tissues.
· The incidence of postoperative myocardial infarction and ventricular dysrhythmias is increased.
· Duration of hospitalization was increased in patients who developed hypothermia during surgery and anesthesia.
The current recommendation is to maintain the tem-perature at or above 36°C in order to avoid these adverse outcomes. Hypothermic patients, especially those with coronary artery disease, might benefit from maintaining anesthesia into the postoperative period until they have been rewarmed, rather than being awakened at the conclu-sion of surgery.