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Open Access Study protocol

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

Urban Fläring1, Per-Arne Lönnqvist1, Björn Frenckner2, Jan F Svensson2, Ingimar Ingolfsson2, Lena Wallensteen3, Shayarina Stigzelius1, Jan Kowalski3 and Rafael T Krmar3*

Author Affiliations

1 Department of Pediatric Anesthesia and Intensive Care, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Solna, S-171 76 Stockholm, Sweden

2 Department of Pediatric Surgery, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Solna, S-171 76 Stockholm, Sweden

3 Karolinska Institutet, Department for Clinical Science, Intervention and Technology, Division of Pediatrics, Karolinska University Hospital, Huddinge, S-141 86 Stockholm, Sweden

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BMC Pediatrics 2011, 11:61  doi:10.1186/1471-2431-11-61

Published: 5 July 2011



Hyponatremia is the most frequent electrolyte abnormality observed in post-operative pediatric patients receiving intravenous maintenance fluid therapy. If plasma sodium concentration (p-Na+) declines to levels below 125 mmol/L in < 48 h, transient or permanent brain damage may occur. There is an intense debate as to whether the administered volume (full rate vs. restricted rate of infusion) and the composition of solutions used for parenteral maintenance fluid therapy (hypotonic vs. isotonic solutions) contribute to the development of hyponatremia. So far, there is no definitive pediatric data to support a particular choice of parenteral fluid for maintenance therapy in post-surgical patients.


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.

Trial registration

The protocol for this study is registered with the current controlled trials registry; registry number: ISRCTN43896775.