Effects of temperature strategy during cardiopulmonary bypass on cerebral oxygen balance.
BACKGROUND
Cerebral injury is the most serious complication of cardiopulmonary perfusion (CPB). With the advent of warm heart surgery, the effect of temperature strategy during perfusion and its effect on cerebral oxygen balance needs further study.


METHODS
Three groups of patients (n=8, each) undergoing coronary artery bypass graft (CABG) surgery were studied. Group H, M and N underwent CPB at 28 degrees C, 32 degrees C and normothermia (>36 degrees C), respectively. The extracorporeal circuit was primed with Hartmann's solution 2.5 l and flow of 1.8 l min(-1) m(-2) at 28 degrees C, and 2.4 1 min-1 m(-2) at 32 degrees C and normothermia. All patients had a 4F oximetry catheter (Opticath, Oximetrix, Abbott Laboratories) inserted in the right jugular bulb for continuous measurement of jugular venous oxygen saturation (sjvO2). Data was collected at six specific times: T1- within 5 min before initiation of CPB, T2 - within the first minute after CPB, T3 - during stable temperature on CPB (28 degrees C, 32 degrees C, >36 degrees C), T4 - during rewarming at 34 degrees C in groups H and M, 15 min before coming off CPB in group N, T5 - 15 min after CPB, T6 - skin closure. At each time mean arterial pressure (MAP) and sjvO2 were recorded. Arterial blood and jugular venous blood were sampled for measurement of arterial oxygen saturation (saO2) and jugular venous lactate (sjv(lactate)), respectively.


RESULTS
SjvO2 values decreased at times T2, T3 and T4 when compared to baseline (p<0.05) but there were no significant group differences at any time. Cerebral arteriovenous oxygen saturation (a-jvO2) differences mirrored sjvO2 changes. Sjv(lactate) values increased from baseline following CPB but fell consistently with time - there were no significant group differences at each time point. SjvO2 and a-jvO2 values were not significantly correlated with sjv(lactate).


CONCLUSIONS
During pump flows employed in this study, cerebral oxygen balance and perfusion appear unaffected by temperature.
Ip-Yam
P C
PC
Department of Anaesthesia, Royal Liverpool University Hospital, UK.
Thomas
S D
SD
Jackson
M
M
Rashid
A
A
Behl
S
S
D000368:Aged; D001833:Body Temperature Regulation / Q000502:physiology*; D001921:Brain / Q000098:blood supply*; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D002534:Hypoxia, Brain / Q000503:physiopathology; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology*; D011183:Postoperative Complications / Q000503:physiopathology; D012307:Risk Factors
D019344:Lactic Acid; D010100:Oxygen