Comparison of two maintenance electrolyte solutions in children in the postoperative appendectomy period: a randomized, controlled trial.

OBJECTIVE: To compare two electrolyte maintenance solutions in the postoperative period in children undergoing appendectomy, in relation to the occurrence of hyponatremia and water retention.

METHODS: A randomized clinical study involving 50 pediatric patients undergoing appendectomy, who were randomized to receive 2,000mL/m(2)/day of isotonic (Na 150 mEq/L or 0.9% NaCl) or hypotonic (Na 30 mEq/L NaCl or 0.18%) solution. Electrolytes, glucose, urea, and creatinine were measured at baseline, 24h, and 48h after surgery. Volume infused, diuresis, weight, and water balance were analyzed.

RESULTS: Twenty-four patients had initial hyponatremia; in this group, 13 received hypotonic solution. Seventeen patients remained hyponatremic 48h after surgery, of whom ten had received hypotonic solution. In both groups, sodium levels increased at 24h (137.4±2.2 and 137.0±2.7mmol/L), with no significant difference between them (p=0.593). Sodium levels 48h after surgery were 136.6±2.7 and 136.2±2.3mmol/L in isotonic and hypotonic groups, respectively, with no significant difference. The infused volume and urine output did not differ between groups during the study. The water balance was higher in the period before surgery in patients who received hypotonic solution (p=0.021).

CONCLUSIONS: In the post-appendectomy period, the use of hypotonic solution (30 mEq/L, 0.18%) did not increase the risk of hyponatremia when compared to isotonic saline. The use of isotonic solution (150 mEq/L, 0.9%) did not favor hypernatremia in these patients. Children who received hypotonic solution showed higher cumulative fluid balance in the preoperative period.