In this study, we examined the effects of magnesium supplementation in the cardiopulmonary bypass (CPB) prime solution on pediatric patients' magnesium levels and potassium loss with open heart surgery. Forty pediatric patients undergoing heart surgery were randomly assigned either magnesium sulfate (magnesium group, n = 20; 0.25 mmol/kg) or saline (placebo group; n = 20) supplementation to the prime solution. Ionized magnesium (IMg) and urinary magnesium and potassium were measured at defined time points during and after CPB. In the magnesium group, IMg concentration was larger during CPB but not after CPB. IMg decreased in the early stages of CPB in the placebo group and decreased to an even smaller level 24 h after CPB. Urinary magnesium levels in the magnesium group were larger than those in the placebo group during and after CPB, and urinary potassium concentrations reached significantly smaller levels 24 h after CPB (44.2 +/- 2.9 versus 60.9 +/- 2.6 mmol/L; P < 0.01). We conclude that the addition of magnesium into prime solution maintains normal IMg levels and prevents potassium flux during the perioperative period.
Implications: In our study, we demonstrate that a magnesium prime solution can prevent hypomagnesemia during and after cardiopulmonary bypass (CPB) and decrease the urinary potassium loss after CPB in pediatric patients undergoing open heart surgery.