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Effects of temperature strategy during cardiopulmonary bypass on cerebral oxygen balance
P C Ip-Yam1, S D Thomas, M Jackson
1Department of Anaesthesia, Royal Liverpool University Hospital, UK.
Insights
This study found that different cardiopulmonary perfusion (CPB) temperatures did not significantly affect cerebral oxygen balance during coronary artery bypass graft (CABG) surgery. Cerebral oxygen saturation and lactate levels remained comparable across all temperature groups.
Area of Science:
- Cardiovascular Surgery
- Neuroanesthesia
- Critical Care Medicine
Background:
- Cerebral injury is a significant complication associated with cardiopulmonary perfusion (CPB).
- The impact of varying temperature strategies during CPB on cerebral oxygen balance requires further investigation, especially with advancements in warm heart surgery.
Purpose of the Study:
- To investigate the effect of different cardiopulmonary perfusion temperatures on cerebral oxygen balance during coronary artery bypass graft (CABG) surgery.
Main Methods:
- Three groups of 8 patients each underwent CABG surgery with CPB at 28°C (hypothermia), 32°C (moderate hypothermia), or >36°C (normothermia).
- Jugular venous oxygen saturation (sjvO2) was continuously monitored using an oximetry catheter.
- Mean arterial pressure (MAP), arterial oxygen saturation (saO2), and jugular venous lactate (sjv(lactate)) were measured at six time points.
Main Results:
- SjvO2 values decreased post-CPB compared to baseline, but no significant differences were observed between the temperature groups.
- Cerebral arteriovenous oxygen saturation (a-jvO2) differences mirrored the sjvO2 changes.
- Jugular venous lactate levels increased post-CPB but normalized over time, with no significant group differences.
Conclusions:
- The temperature strategy during cardiopulmonary perfusion (CPB) did not significantly impact cerebral oxygen balance or perfusion in patients undergoing CABG surgery at the pump flow rates used in this study.
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).
Conclusion:
During pump flows employed in this study, cerebral oxygen balance and perfusion appear unaffected by temperature.