Canine hyperthermia with cerebral protection.
Extreme whole-body hyperthermia was achieved without lasting side effects in canines by elevating body core temperature to 42 degrees C, using a warm water bath. Cold water irrigation of the nasal alar fold permitted an additional core temperature elevation of 0.5-1.0 degrees C above brain temperature for periods up to 1.5 h. The brain-core temperature differential was maintained by a physiological arteriovenous heat exchanger located at the base of the brain. The maximum tolerable core temperature for the 21 nonirrigated dogs was 42 degrees C for 60-90 min, whereas that for the 28 irrigated dogs was 42.5-43 degrees C for similar time intervals. A mathematical model of the total heat transfer system described the observed dynamic temperature responses. It was the solution of a differential equation which fit the normalized experimental data points and predicted reasonable values for known and unknown experimental parameters.
D000818:Animals; D001833:Body Temperature Regulation; D001921:Brain / Q000503:physiopathology*; D004285:Dogs; D005260:Female; D005334:Fever / Q000503:physiopathology*; D006339:Heart Rate; D008297:Male; D008722:Methods; D008954:Models, Biological; D011482:Protective Devices; D012119:Respiration; D013997:Time Factors