Perioperative haemodynamic effects of an intravenous infusion of calcium chloride in children following cardiac surgery

Twelve children received an infusion of 10% calcium chloride 0.1 ml/kg to a maximum dose of 5 ml, infused over 5 min, following open heart surgery. Blood ionized calcium, systemic arterial pH, cardiac index, mean systemic arterial blood pressure and systemic vascular resistance index were measured at baseline and repeated 20 and 40 min following completion of the infusion. There was considerable overlap, with no significant differences in the response to the calcium chloride infusion between children with ionized hypocalcaemia (< 1.1 mmol/l) and those with ionized normocalcaemia when its effect on percentage change in either the haemodynamic or biochemical measurements was assessed (p > 0.2 for all measurements; Mann-Whitney). For this reason they were treated as a single group. Significant changes from baseline were noted in mean systemic arterial pressure (p < 0.02), cardiac index (p < 0.01) and systemic vascular resistance index (p < 0.01) after completion of the calcium chloride infusion when analysed using Friedman's two-way analysis of variance. A significant increase in mean systemic arterial blood pressure occurs after an infusion of 10% calcium chloride as a direct result of an increase in the systemic vascular resistance index with a concomitant decrease in cardiac index.