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Erschienen in:
01.08.2003 | Original
Effect of cardiopulmonary bypass on lactate metabolism
Erschienen in: Intensive Care Medicine | Ausgabe 8/2003
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Objective
We have investigated the role of cardiopulmonary bypass on lactate metabolism in patients undergoing uncomplicated surgery for elective coronary artery bypass grafting (CABG).
Design
Prospective non-randomized observational study.
Settings
National Cardiovascular Center.
Patients
Three independent groups were studied: preoperative (n=20), postoperative with bypass (CPB, n=20) and postoperative without bypass (NO-CPB, n=20).
Interventions
Lactate metabolism was investigated with the use of an exogenous lactate challenge test (2.5 mmol Na-lactate/kg body weight in 15 min). Blood lactate was sequentially determined after the end of infusion. Lactate clearance and endogenous production were estimated from the area under the curve, and a bi-exponential fitting permitted modeling the lactate-decay into two compartments.
Measurements and main results
Lactate metabolism parameters (basal lactate, clearance, endogenous production and half-lives [HL] I and II) were not different between the NO-CPB and preoperative groups. In the CPB group, as compared to the other two groups, basal lactate and endogenous production were not significantly affected while lactate clearance (CPB: 6.02±0.97 versus preoperative: 9.41±0.93 and NO-CPB: 9.6±0.8 ml/kg per min) and HL-I (CPB: 10.6±1.4 versus preoperative: 17.2±2.3 and NO-CPB: 18.8±2.5 min) were decreased (p<0.001) and HL-II was increased (CPB: 171±41versus preoperative: 73±12 and NO-CPB: 48±2.9 min, p<0.01).
Conclusion
While surgery and anesthesia per se do not seem to alter lactate metabolism, CPB significantly decreased lactate clearance, this effect being possibly related to a mild liver dysfunction even in uncomplicated elective surgery.