Heated Humidification System Breathing Circuit for Maintenance of Body Temperature in Pediatric Patients

Temperature management is an important aspect of perioperative care that falls under the purview of the anesthesiologist. Temperature is recognized as one of four primary vital signs and significant deviations from normal values may result in patient harm. General anesthesia disrupts the body's temperature homeostasis by inhibiting temperature regulation mechanisms such as vasoconstriction/-dilation, shivering and behavioral interventions (donning clothes or leaving an area with excessive heat, for example). Anesthetized patient have a tendency to become hypothermic, especially during long surgical procedures. This results from both the redistribution of cooler peripheral temperatures into the core (due to vasodilation) as well as actual temperature loss to a cold operating room environment (which is maintained at a lower temperature for the comfort of fully gowned surgeons and nurses). In addition, large surgical incisions predispose the patient to hypothermia through evaporation and convection. Hypothermia is a recognized risk factor that predisposes the patient to an increased metabolic rate, increased oxygen demand, coagulopathies, impaired wound healing, impaired immune function and increased risk of infection. Therefore, maintenance of normal body temperature is an important goal of every general anesthetic - and is a well-accepted quality metric associated with patient care. Because of the greater surface area to volume relationship, children are thought to be a greater risk of intraoperative hypothermia. The most widely used method of maintaining body temperature during surgery (and a routine at this institution) is by using a forced-air warming blanket (Bair Hugger warming blanket, 3M). Despite its widespread use, the forced-air warming blanket has its limitations. For example, during certain surgical procedures, the location of the surgical field precludes placement of the warming blanket. In addition, the warming blanket often cannot be placed immediately after the induction of anesthesia (when complex patient positioning is required) - leaving the patient exposed to hypothermic conditions for short (10-15min) or long (30-60min) periods of time. There is hence a need for alternative warming systems that could be implemented immediately following anesthetic induction. Westmed, Inc. has developed an alternative system that utilizes a heated, humidified breathing circuit to regulate a patient's body temperature in the intraoperative setting. This system is active from the moment the trachea is intubated following anesthetic induction, i.e. there are no delays in instituting thermal management.