Intraoperative mild hypothermia does not increase the plasma concentration of stress hormones during neurosurgery.
OBJECTIVE
To determine how mild hypothermia (34 degrees C) affects the hemodynamic and the stress hormonal responses intraoperatively and during extubation in patients undergoing cerebral aneurysm surgery.


METHODS
After induction, anesthesia was maintained with 1.2% isoflurane and 50% nitrous oxide. For the normothermia and the hypothermia groups, the body temperature was maintained at 36.9 +/- 0.3 degrees C and 34.2 +/- 0.2 degrees C respectively up to the recovery room. Hemodynamic changes were recorded continuously. Stress hormones comprising epinephrine, norepinephrine, ADH, ACTH, and cortisol were measured at the awake control, intraoperative, and extubation periods.


RESULTS
Vital signs of the intraoperative and postextubation time periods were not significantly different between the normothermia and hypothermia groups except for a statistically lower pulse rate intraoperatively in the hypothermia group (P <0.05). In the control awake state, all five hormonal concentrations were similar between the two groups. Intraoperatively, all of the hormonal levels tended to be lower in the hypothermia group compared to the normothermia group, but only the epinephrine level decreased sufficiently to reach statistical significance (P <0.05). During extubation, all stress hormone concentrations, except norepinephrine, were lower in the hypothermia group (epinephrine: P <0.05; ADH: P <0.05; ACTH: P <0.05; cortisol: P <0.05).


CONCLUSIONS
Our data suggest that intraoperative mild hypothermia neither significantly affects the blood pressure response nor increases the concentrations of stress hormones intraoperatively. Furthermore, mild hypothermia significantly decreased the plasma concentrations of stress hormones during the extubation period.
Chi
O Z
OZ
Department of Anesthesia University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School New Brunswick, New Jersey, USA. chi@umdnj.edu
Choi
Y K
YK
Lee
D I
DI
Kim
Y S
YS
Lee
I
I
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000328:Adult; D000368:Aged; D004837:Epinephrine / Q000097:blood*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007036:Hypothermia, Induced; D002532:Intracranial Aneurysm / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood*; D014667:Vasopressins / Q000097:blood*
D014667:Vasopressins; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine