Changing the priming solution from Ringer's to Hartmann's solution is associated with less metabolic acidosis during cardiopulmonary bypass

Abstract

Background and objective: Previously, it was noted that changing the solutions used for priming and intravascular volume replacement from Hartmann's to Ringer's resulted in a more profound metabolic acidosis developing during cardiopulmonary bypass (CPB). The aim of this study was to examine the effects of changing the solutions back to Hartmann's on metabolic acidosis that develops during CPB in patients undergoing heart surgery.

Methods: Two groups of patients were studied sequentially: the first received Ringer's (n = 63) and the second Hartmann's solution (n = 66). Arterial blood samples were taken before induction of anaesthesia and towards the end of CPB. Samples were analysed in a blood gas analyser.

Results: Hydrogen ion concentration increased from 38 (4) to 41 (7)mmol/L in the Ringer's group, but decreased from 38 (5) to 36 (6) mmol L(-1) in the Hartmann's group. Changes in PaCO2 (0.77, p < 0.001) and volume of fluid administered (r= 0.23, p <0.01) were significant univariate correlates of change in hydrogen ion concentration, but haemoglobin concentration was not (r < 0.01, p = 0.97). Analysis of variance for repeated measures found significant between subject effects on the change in hydrogen ion concentration during CPB caused by the choice of intravascular solution used (p < 0.001) and PaCO2 (p = 0.001), but not as a result of the volume of solution administered (p > 0.10).

Conclusions: Changing the solutions used for priming and intravascular volume replacement from Ringer's to Hartmann's was associated with a reduction in metabolic acidosis that developed during CPB.