Urinary bladder and rectal temperature monitoring during clinical hypothermia

Three methods of temperature monitoring were studied in 55 adult hypothermic postcardiac surgery patients using the pulmonary artery, rectum, and urinary bladder as measurement sites. Pulmonary artery temperature served as the standard for core body temperature. Measurements in the rectum were recorded with a disposable plastic temperature probe and in the urinary bladder with a thermistor-tipped Foley catheter. Patients were studied within one hour of admission to the cardiac surgical intensive care unit and on an hourly basis until they reached normothermia (37 degrees C). Although mean temperatures did not vary greatly for any group, there was a significant difference between measures over time. Correlations of pulmonary artery and urinary bladder temperatures ranged from .78 to .94, pulmonary artery and rectal temperature from .49 to .82, and urinary bladder and rectal temperature from .46 to .85. The results of this study indicate that the urinary bladder is a reliable indicator of core temperature during rewarming following cardiac surgery.