Blood lactate levels during cardiopulmonary bypass for valvular heart surgery.

Cardiopulmonary bypass (CPB) is widely used to maintain systemic perfusion and oxygenation during open-heart surgery. Tissue hypoperfusion with resultant lactic acidosis during CPB, may occur during hypothermia, extreme haemodilution, low flow CPB, and excessive neurohormonal activation. There has been no documentation of the correlation between blood lactate level elevations in the perioperative period, and its relation to preoperative New York Heart Association (NYHA) classification and the use of ionotropic support during weaning from CPB, duration of postoperative ventilatory support and perioperative mortality.