The efficacy of hypotonic and near-isotonic saline for parenteral fluid therapy given at low maintenance rate in preventing significant change in plasma sodium in post-operative pediatric patients: protocol for a prospective randomized non-blinded study

Our prospective randomized non-blinded study will be conducted in healthy children and adolescents aged 1 to 14 years who have been operated for acute appendicitis. Patients will be randomized either to intravenous hypotonic (0.23% or 0.40% sodium chloride in glucose, respectively) or near-isotonic (0.81% sodium chloride in glucose) solution given at approximately three-fourths of the average maintenance rate. The main outcome of interest from this study is to evaluate 24 h post-operatively whether differences in p-Na+ between treatment groups are large enough to be of clinical relevance. In addition, water and electrolyte balance as well as regulatory hormones will be measured.This study will provide valuable information on the efficacy of hypotonic and near-isotonic fluid therapy in preventing a significant decrease in p-Na+. Finally, by means of careful electrolyte and water balance and by measuring regulatory hormones our results will also contribute to a better understanding of the physiopathology of post-operative changes in p-Na+ in a population at risk for hyponatremia.The protocol for this study is registered with the current controlled trials registry; registry number: ISRCTN43896775.Hyponatremia, as defined by plasma sodium concentration (p-Na+) < 136 mmol/L, is the most common electrolyte abnormality in post-operative pediatric patients receiving parenteral maintenance fluid therapy [1]. Patients with hospital-acquired hyponatremia are exposed to major neurological complications if p-Na+ declines to ~ 120 mmol/L in < 48 h [2].Post-operative hyponatremia has been attributed to either an excess of delivered water or a net sodium deficit [1,3-5]. A series of pediatric investigations support the notion that a hospital acquired decrease in p-Na+ in ill children receiving parenteral fluid therapy is the result of administering an excess of water relative to sodium, i.e., hypotonic saline solutions [6,7]. However, there is no definitive pediatric data to suppor