Reduced cerebral oxygen saturation during thoracic surgery predicts early postoperative cognitive dysfunction.
BACKGROUND
The objective of this prospective study is to determine cognitive dysfunction after thoracic surgery.


METHODS
Seventy-six patients undergoing thoracic surgery with single-lung ventilation (SLV) of an expected duration of >45 min were enrolled. Monitoring consisted of standard clinical parameters and absolute oximetry (S(ct)O(2)). The Mini-Mental State Exam (MMSE) test was used to assess cognitive function before operation and at 3 and 24 h after operation. Data were analysed using Spearman correlation test; risks for cognitive dysfunction were expressed as odds ratios. P<0.05 and data are presented as median (interquartile range).


RESULTS
One patient was excluded from the study. S(ct)O(2) during SLV decreased to critical values of <65%, 60%, and 55% in 40 (53%), 15 (20%), and 5 patients (7%), respectively. Twenty-two patients (29%) had a decrease of MMSE>2 points 3 h after surgery, eight patients (10%) had a decrease of MMSE>2 points 24 h after surgery. Postoperative cognitive dysfunction correlated at r(2)=0.272, 0.285, 0.297 with patient exposure times to S(ct)O(2)<65% (P=0.018), <60% (P=0.013), <55% (P=0.010), respectively. The odds ratios of developing early cognitive dysfunction ranged from 2.03 (95% CI: 0.74-5.59) for a short (<5 min) exposure to S(ct)O(2)<65% to a maximum of 9.56 (95% CI: 1.75-52.13) when S(ct)O(2) was <60% for more than 30 min.


CONCLUSIONS
Early cognitive dysfunction after thoracic surgery with SLV is positively related to intraoperative decline of S(ct)O(2).
Department of Anaesthesiology, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Canada.
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Tang
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Kazan
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Taddei
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Zaouter
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Cyr
T M
TM
Hemmerling
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000378:metabolism; D002560:Cerebrovascular Circulation; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010092:Oximetry; D010100:Oxygen / Q000378:metabolism; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012121:Respiration, Artificial; D012307:Risk Factors; D016037:Single-Blind Method; D019616:Thoracic Surgical Procedures
D010100:Oxygen