Postoperative Hydration in Children Using Intermittent Boluses of Balanced Salt Solution: Results of a Randomized Control Trial.

BACKGROUND: Postoperative maintenance fluids are traditionally provided via hypotonic dextrose containing fluids administered intravenously by continuous infusion. We hypothesized that scheduled weight-based boluses of balanced salt solution would be more physiologic, reduce fluid volumes, and improve patient comfort.

METHODS: As part of an IRB-approved randomized controlled trial (Boluses of Ringer's in Surgical Kids, BRiSK), we randomized patients aged 1-21 years undergoing elective abdominal or thoracic surgery to post-operatively receive weight-based D5 0.45NS+20mEq/L KCl at a continuous rate or intermittent boluses of Lactated Ringer's solution until oral liquid toleration. Patients with nephropathy, diabetes, or receiving parenteral nutrition were excluded. We analyzed electrolytes, urine output, fluid volume, and adverse events.

RESULTS: We enrolled and randomized 60 patients: 29 to continuous fluids and 31 to bolus fluids. One patient from the bolus group dropped out. No patients crossed over due to difficulties with application of the bolus protocol. There were no baseline differences between groups with a mean age of 12.6 ± 1.4yr and weight of 50.9 ± 7.2 kg. There were no serious adverse events or electrolyte disturbances in either group. Patients in the bolus group received significantly less total fluid than those in the continuous group (0.43 mL/kg/h vs 1.1 mL/kg/h, p < 0.001) with no difference in urine output [1.4 ± 0.2 mL/kg/h vs 1.6 ± 0.3 mL/kg/h, p = 0.211]. There were two episodes of mild hypoglycemia in the bolus group compared to seven episodes of mild hyperglycemia in the continuous group.

CONCLUSIONS: Administration of post-operative intravenous fluids as boluses of balanced salt solution is feasible, safe, and results in significantly less fluid administered compared to a traditional continuous protocol.

LEVEL OF EVIDENCE: II.