The utility of tracheal temperature monitoring.

Tracheal temperature--the temperature of the tracheal wall--is believed to reflect the core temperature. The trachea reacts quickly to temperature changes because it is surrounded by various large arteries and veins. Using the blood temperature from the cardiopulmonary bypass (CPB) and the jugular vein temperature as standards for core temperature, we evaluated the utility of monitoring the tracheal temperature during cardiac surgery. The tracheal temperature was measured by a thermistor which was attached to the anterior inner surface of the cuff of a tracheal tube. The tracheal temperature had correlation coefficients more than 0.99 with both blood temperature from the CPB (r = 0.993, P < 0.001) and jugular vein temperature (r = 0.993, P < 0.001) during CPB. Because the blood from the CPB draining into the ascending aorta and the jugular vein temperature might reflect the hypothalamic temperature directly, the tracheal temperature, which correlates with both of these quite closely, may reflect the core value directly. The monitoring of the tracheal temperature is not only valuable in monitoring the core value, but is also convenient during general anesthesia.