Effects of fluid therapy with ringer's vs. ringer lactate solution on acid-base balance and serum electrolytes in patients undergoing coronary artery bypass graft surgery.

Introduction: Preventing acid-base and electrolyte disturbance is crucial in coronary artery bypass graft (CABG) surgery, since any of these conditions can affect outcome. The type of crystalloid solution used during and after the surgery can affect these disturbances.

Methods: In this study, 90 patients who candidates for CABG surgery were randomly allocated to either ringer's lactate (RL) or ringer's group. In order to provide essential blood volume before and after the start of CPB fluid administration with either ringer's or RL solution was started during operation and continued for 18 hours after the patient was transferred to ICU. ABG, serum electrolytes and Lactate level were measured before and at the end of CPB, upon arrival to the ICU, and 6, 12 and 18 hours after ICU admission and compared between the two groups.

Results: Blood PH level was significantly different between the two groups upon arrival to ICU, 6 and 18 hours after ICU admission (P<0.05) which was clinically closer to the normal range in the RL group. Serum bicarbonate level showed a significantly difference between the two groups (P<0.05). There were no significantly differences between the two groups in terms of lactate level, serum electrolytes, blood loss, intake and output of fluids and blood products transfusion.

Conclusion: In this study, ringer's lactate solution creates a more favorable acid-base balance without a significant increase in blood lactate level which is attributed to the buffering effect of existing lactate, and can be used as an appropriate alternative to ringer's solution during and after CABG.