We hear so much about the science and the economics of patient warming, yet not nearly enough about keeping the person outstretched before us comfortable. One of the most common complaints that patients express in the immediate post-op period is that of being cold, which is in part due to our overindulgence in comfort-oriented selfishness.

While the OR's cool atmosphere often is pleasing to the anesthesiologists, surgeons and nursing teams, our patients lie there exposed and shivering, helpless to fight off normal physical heat-transfer mechanisms.

In addition to using patient-warming devices, OR staffs would do well to show patients some compassion. Rather than turning the thermostat down, raise the room temperature during the induction of anesthesia, especially in pediatric cases. Then lower the temperature if necessary during surgery and raise it again during the emergence from anesthesia when the surgery finishes. Pay no attention to your personal comfort and focus on the patient's. This would be a good way to experience the selfless state - that state of truth where the mind voids itself of all selfishness and concentrates on good as opposed to evil.

Alteration of normal body temperature is an underestimated, often-neglected and iatrogenic threat to the anesthetized patient. The greatest threat of temperature variation is the development of hypothermia based on two mechanisms: anesthetic-induced vasodilation and exposure to the cold environment of the operating room. The former is inevitable. We can avoid and control the latter.

Of the four heat-transfer mechanisms - radiation, convection, conduction and evaporation - radiation and convection most significantly contribute to patient heat loss. This means that air-conditioning is the shivering patient's greatest enemy. While there are some benefits to hypothermia (protection against ischemia/hypoxia with

1' to 3' C reduction of temperature and decreased release of excitatory amino acids), there are many more known morbidities, including

• increased incidence of cardiac events, such as angina, myocardial infarction, ventricular tachycardia and cardiac arrest;
• post-anesthetic shivering leading to increased oxygen consumption;
• hypertension and/or tachycardia;
• coagulopathy; platelet and cascade enzymes dysfunction;
• depressed immune function by impairing the production of antibodies;
• increased wound infections and delayed wound healing due to decrease of subcutaneous oxygen tension from the sudden vasoconstriction as the effects of anesthesia wear off;
• delayed post-op recovery due to decreased metabolism of the intravenous drugs and increased tissue solubility of volatile anesthetics with resultant prolongation of anesthetic effect;
• decreased minimal alveolar concentration of anesthetic; and
• patient thermal discomfort, which is often one of the worst complaints.