Significance of the initial arterial lactate level and transpulmonary arteriovenous lactate difference after open-heart surgery

Purpose. This study was conducted to determine the clinical significance of the initial lactate level and its transpulmonary difference after open-heart surgery in adult patients. Methods. The initial postoperative lactate levels were obtained from both radial and pulmonary arteries (La, Lv) in 65 consecutive patients undergoing coronary (n = 46), valve (n = 8), and aortic (n = 11) surgery. We analyzed the relationships between the perioperative factors and La and transpulmonary arteriovenous lactate difference (%La-v = 100(La - Lv)/Lv). Results. La and %La-v were not correlated with the preoperative factors of age, pulmonary function, or emergency surgery. La significantly correlated with the cardiopulmonary bypass time, initial arterial pH, initial PaO₂/FiO₂, SvO₂, O₂ consumption, O₂ extraction rate, and the peak value of creatine phosphokinase. The %La-v significantly correlated with the aortic cross-clamp time, the lowest rectal temperature, the duration of intubation, and PaO₂/FiO₂ after extubation. Conclusion. La may be an indicator of the invasiveness of the surgery, while %La-v may be a predictor of postoperative pulmonary function. Both La and %La-v, as an initial value in the intensive care unit, may play an important role in planning the postoperative management of patients undergoing open-heart surgery.