| BackgroundThere may be latent low cardiac output in the early post-operation period of cardiac surgery under cardiopulmonary bypass(CPB). Discovery of the relevant tissue mal-perfusion and cell-hypoxia at the early date, and early intervention might improve prognosis tangibly. In the early post-operation period, the status of system oxygen delivery and oxygen consumption displays flow-dependent oxygen consumption. As the peculiar outcome of glycolysis, the degree of increase in blood lactate levels is proportional to the severity of tissue oxygen debt and low degree tissue perfusion. According to the research, Lactic acid concentrations in blood is a sensitive and reliable indicator reacting to tissue hypoxia.ObjectiveThe purpose of this subject was to research the change of concentration of lactic acid in blood in the early postoperation period of cardiac operation under cardiopulmonary byPass(CPB). We hope to master its change rule in an even better fashion by discuss its mechanism, in order to guide clinical work.Methods60 cases patients with heart surgery under CPB were as the CPB group while 12 cases patients were as control group with Patent Ductus Arteriosus (PDA) by ligation under general anesthesia during the same period. Then take the blood specimen of research object for blood gas analysis in the perioperative at fixed time points. We carefully selected 15 consecutive patients accepting Mitral Valve Replacement (MVR)and during the CPB recorded its duration, the lowest perfusion pressure, the lowest hemoglobin concentration(Hb), the lowest temperature, duration of aortic cross-clamp.ResultsLactic acid concentration of Patients in CPB groups in the perioperative increased, while the largest increment appeared at four to eight hours after the surgery. Then gradually regular decline presented. The concentration of Lactic acid of Patients in CPB recovered to normal levels within 24 hours while they were significantly higher than those in the control groupduring different time points. For group of congenital heart disease and acquired heart attack, their Lactic acid concentration in perioperative had the same change trend, but change range have a difference. For 15 cases of patients with MVR, lactic acid concentration significantly increased during CPB. The change of lactic acid concentration was positively correlated with the duration of CPB and duration of aortic cross-clamp in bivariate analysis method.58 cases of patients of CPB group had good prognosis and their postoperative blood lactate concentrations presented regular variations which returned to normal levels within 24 hours.2 patients had bad prognosis. One of them had a evident lactic acid concentration as soon as he back to Intensive Care Unit(ICU) which rose to 15mmol/L within 4 hours. The other's continuly went up after 24 hours.Conclusions1 Blood lactic acid concentration of change in post-operation has general rules,which goes to the highest point four to eight hours then gradually decreases with stable condition and returns to normal levels within 24 hours.2 The increases of Blood lactic acid concentration back to ICU only shows the extent of the oxygen debt incurred during CPB,which Can't be used to predict patients' outcome.3 Patients with general rules of Lactic acid concentration changes in postoperative recovery smoothly. It indicates bad prognosis which needs quick reason-finding and targeted measures if Lactic acid concentration constantly rises after 24 hours or goes up obviously at some time. |
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