Cardiopulmonary bypass, rewarming, and central nervous system dysfunction.
BACKGROUND
During cardiopulmonary bypass a nasopharyngeal temperature greater than 38 degrees C at the end of rewarming may indicate cerebral hyperthermia. This could exacerbate an ischemic brain injury incurred during cardiopulmonary bypass.


METHODS
In a cohort of 150 aortocoronary bypass patients neuropsychologic test scores of 66 patients whose rewarming temperature exceeded 38 degrees C were compared with those who did not. There were no differences between groups with respect to demographic and intraoperative variables.


RESULTS
A trend was seen for hyperthermic patients to do worse on all neuropsychologic tests in the early postoperative period but not at 3-month follow-up. By analysis of covariance hyperthermic patients did worse on the visual reproduction subtest of the Weschler memory scale at 3 months (p = 0.02), but this difference was not found by linear regression (p = 0.10).


CONCLUSIONS
We were unable to demonstrate any significant deterioration in patients rewarmed to greater than 38 degrees C in the early postoperative period. The poorer performance in the visual reproduction subtest of the Wechsler memory scale at 3 months in the group rewarmed to more than 38 degrees C is interesting but far from conclusive. Caution with rewarming is still advised pending more in-depth study of this issue.
Buss
M I
MI
Department of Anaesthesia, Sunnybrook Health Science Centre, University of Toronto, Ontario, Canada.
McLean
R F
RF
Wong
B I
BI
Fremes
S E
SE
Naylor
C D
CD
Harrington
E M
EM
Snow
W G
WG
Gawel
M
M
D001831:Body Temperature; D002315:Cardiopulmonary Bypass / Q000379:methods*; D003072:Cognition Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011184:Postoperative Period; D017694:Rewarming; D014888:Wechsler Scales