Effect of hypothermia on recovery from general anaesthesia in the dog.
OBJECTIVE
To discern the effects of anaesthesia protocols and decreasing core body temperature on time to recovery from general anaesthesia.


METHODS
Healthy adult dogs undergoing desexing surgery were enrolled. More excitable dogs were premedicated with intramuscular acepromazine and morphine; calmer dogs were not premedicated. Anaesthesia was induced using halothane, isoflurane or sevoflurane delivered by mask, or by intravenous propofol, and maintained in standard fashion using one of the three inhalant agents. Thermostat controlled heat mats were used during surgical preparation and surgery. Oesophageal temperature was recorded throughout surgery. The time from cessation of anaesthetic administration until the dog successfully raised itself to sternal recumbency was considered the time of recovery.


RESULTS
Sixty-nine dogs completed the study, 42 males anaesthetised for 60.4 +/- 20.5 min, and 27 females anaesthetised for 85.4 +/- 33.2 min. Oesophageal temperature at the end of surgery was 36.8 +/- 0.80 degrees C. Oesophageal temperature had a significant effect on recovery time, with lower temperatures contributing to slower recoveries. Premedication significantly lengthened recovery times. The choice of induction or maintenance anaesthetic agent had no effect on recovery time.


CONCLUSIONS
Hypothermia is a common complication of general anaesthesia and surgery. Amongst other deleterious effects, it is associated with slower recovery from anaesthesia, likely due to a number of different mechanisms.
Pottie
R G
RG
University Veterinary Centre, University of Sydney, Camden NSW 2570, Australia. robertpottie@hotmail.com
Dart
C M
CM
Perkins
N R
NR
Hodgson
D R
DR
D000762:Anesthesia Recovery Period; D000768:Anesthesia, General / Q000009:adverse effects / Q000662:veterinary*; D000769:Anesthesia, Inhalation / Q000009:adverse effects / Q000662:veterinary; D000771:Anesthesia, Intravenous / Q000009:adverse effects / Q000662:veterinary; D000818:Animals; D002369:Castration / Q000662:veterinary*; D004285:Dogs / Q000601:surgery*; D005260:Female; D006221:Halothane; D007035:Hypothermia / Q000139:chemically induced / Q000662:veterinary*; D007530:Isoflurane; D008297:Male; D008738:Methyl Ethers; D015742:Propofol; D000077149:Sevoflurane; D013997:Time Factors
D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane; D006221:Halothane; D015742:Propofol