Background & Aims: Metabolic acidosis can be harmful and can complicate cardiopulmonary bypass (CPB) during coronary artery bypass graft surgery. We hypothesized that the pump prime can cause this disturbance. We compared effects of Ringer solution with Ringer Lactate, two types of priming fluid in producing metabolic acidosis in patients undergoing coronary artery bypass graft (CABG) ...

Materials & Methods: In a prospective, double-blind, randomized clinical trial 50 patients undergoing CABG were evaluated at Seiedalshohada hospital of Urmia-Iran. Sampling of arterial blood was performed at three time intervals: Before CPB (t₁), 5 minutes after initiation of CPB(t₂), and at rewarming period (t₃). Measurement of pH, HCO₃, PaCO₂, Lactate and Cl at each collection point were performed and the results were analyzed.

Results: The decrease in pH was seen in both groups and was significant between two groups in the second interval (Ringer: 7.38±0.05 vs. Ringer Lactate: 7.41±0.05, p=0.02). Also in this interval, Lactate had significant difference (Ringer: 2.44±0.9 mmol/L vs. Ringer Lactate: 3.2±0.4 mmol/L, p=0.02) and serum level of chloride was higher in Ringer group (Ringer: 116.6±3.08 mEq/L vs. Ringer Lactate: 113.4±3.9 mEq/L, p: 0.0002)

Conclusion: Our findings showed that Ringer Lactate solution in comparison with Ringer had fewer effects on acid-base changes during cardiopulmonary bypass in patients under coronary artery bypass graft.