Factors affecting on serum lactate after cardiac surgery.

BACKGROUND: The relation between elevated blood lactate level and mortality and morbidity rates after coronary bypass surgery is a proven subject. One of the factors that seems to affect directly the blood lactate level is the storage duration of packed red blood cells.

OBJECTIVES: This study aimed to evaluate the effect of storage duration of transfused blood on serum lactate during cardiac surgery and up to 24 hours after that in the ICU.

PATIENTS AND METHODS: In a cross-sectional study, 228 patients referred to three hospitals of Mashhad University of Medical Sciences for open cardiac surgery, was enrolled using systematic random sampling method. Immediately after accessing arterial line, the first sample of arterial blood gas (ABG) was obtained. For evaluation of lactate levels, the next samples were obtained at the end of surgery and after 24 hours of staying ICU.

RESULTS: Among 5 factors which affected lactate level during surgery, diabetes and higher ejection fraction (EF) reduced changes of the lactate level. On the other hand, the number of infused blood units, duration of on-pump time, and the mean storage duration of blood units were associated with elevated serum lactate during surgery. A significant relationship was found between blood storage duration and serum lactate levels 24 hours after surgery.

CONCLUSIONS: Comparing the serum lactate level before operation and 24 hours after the operation showed that the number of received blood units had a significant effect on serum lactate. We found no significant effect for blood storage duration; however, the number of given blood units was more significant.