APPROPRIATE THERMAL MANIPULATIONS ELIMINATE TREMORS IN RATS RECOVERING FROM HALOTHANE ANESTHESIA

Tremors are common in mammals emerging from anesthesia. To determine w hether appropriate thermal manipulations immediately before emergence from anesthesia are sufficient to eliminate these tremors, electroence phalographic (EEG) and electromyographic (EMG) activities, hypothalami c temperature (T-hy), and O-2 consumption were monitored in 12 rats re covering from halothane anesthesia under three thermal regimes. EEG an d EMG activities were recorded throughout anesthesia and served as fee dback signals for controlling anesthetic depth. During anesthesia, T-h y was either 1) allowed to fall to 32-34 degrees C, 2) maintained at 3 7-39 degrees C, or 3) allowed to fall to 32-34 degrees C and then rais ed to 37-39 degrees C. When hypothermic on emergence from anesthesia, all of the animals exhibited postanesthetic tremors that persisted unt il T-hy values returned to normothermia. None of the animals expressed postanesthetic tremors when normothermic on emergence from anesthesia . In addition, the time between emergence from anesthesia (as determin ed by EEG/EMG parameters) and the initiation of coordinated motor acti vities was significantly decreased in the normothermic animals.