A THERMOELECTRIC-BASED FORCED-AIR DELIVERY SYSTEM TO INDUCE CONTROLLED CHANGES IN BODY TEMPERATURE

Recent research findings in neuroanesthesia and critical care medicine have motivated the development of a forced-air cooling system that can effectively provide controlled, mild hypothermia in an anesthetized patient. The primary benefit of mild hypothermia is to decrease both tissue metabolic rate and oxygen consumption during impairment of tissue blood supply (Sessler 1990). Mild hypothennia (33-36°C) can confer significant protection to the central nervous system during cardiac and carotid surgeries, ischemic or hypoxic insults, neurosurgery, and to the spinal cord during thoracic aortic surgery (Berntman et al. 1981). Preliminary studies have also demonstrated that providing convective cooling to a patient's cutaneous layer proves an effective therapy for heat stress (Iaizzo et ale 1994). A device for inducing controlled, mild hypothennia, designated Polar Bair™, has been developed to produce cool convective air which is diffused over a patient by a standard Bair Hugger ® blanket. Thermoelectric technology is utilized to cool the air. This technology offers several inherent advantages compared with conventional cooling systems such as reliability, quiet operation, and precision temperature control. Furthermore, a thennoelectric cooler can become a heater by merely reversing voltage polarity. One- and three-dimensional mathematical models were developed to quantify the perfonnance characteristics of a three-stage cooling unit. System optimization studies were conducted both numerically and experimentally to assess machine capabilities