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Original research
Hypotonic and isotonic intravenous maintenance fluids in hospitalised paediatric patients: a randomised controlled trial
  1. Silvio Fabio Torres1,2,
  2. Thomas Iolster1,
  3. Eduardo Julio Schnitzler1,
  4. Alejandro Javier Siaba Serrate1,
  5. Nicolás A Sticco1,
  6. Manuel Rocca Rivarola1
  1. 1 Department of Pediatrics, Hospital Universitario Austral, Pilar, Argentina
  2. 2 IRB, Universidad Austral, Pilar, Argentina
  1. Correspondence to Dr Silvio Fabio Torres; silviot68{at}


Objective To compare the changes in serum sodium and acid/base status in patients receiving hypotonic and isotonic solutions.

Design A randomised, controlled and double-blind clinical trial.

Setting Department of Paediatrics in a tertiary general hospital (Hospital Universitario Austral) in Buenos Aires, Argentina.

Patients Children between 29 days and 15 years of age who were hospitalised in the paediatric intensive care unit and general hospital between 12 January 2010 and 30 November 2016, and who required exclusively parenteral maintenance solutions for at least 24 hours.

Interventions A hypotonic solution with 77 mEq/L sodium chloride (0.45% in 5% dextrose) and isotonic solution with 150 mEq/L (0.9% in 5% dextrose) were infused for 48 hours and were labelled.

Main outcome measure The main outcome was to evaluate the incidence of hyponatraemia between patients treated with parenteral hydration with hypotonic or isotonic fluids. The secondary outcome was to estimate the incidence of metabolic acidosis induced by each of the solutions.

Results The 299 patients in the present study were randomised to groups that received the hypotonic solution (n=154) or isotonic solution (n=145). The mean serum sodium concentration measurements at 12 hours were 136.3±3.9 mEq/L and 140.1±2.3 mEq/L in the hypotonic and isotonic groups, respectively, with a hyponatraemia incidence of 8.27% (n=12) and 18.8% (n=29) (p<0.001). At 24 hours, 12.4% (n=18) of the isotonic group had developed hyponatraemia compared with 46.1% (n=71) of the hypotonic group (p<0.001). The mean serum sodium concentration measurements were 134.4±5.6 and 139.3±3.1, respectively. No patient developed hypernatraemia (serum sodium concentrations >150 mEq/L) or other adverse outcomes. The relative risk in the hypotonic group was 3.7 (95% CI 2.3 to 5.9), almost four times the risk of developing hyponatraemia than those who received isotonic fluids. There were also no significant differences between the groups with regard to the development of metabolic acidosis. Hypotonic solution, age <12 months and postoperative abdominal surgery were risk factors associated with hyponatraemia.

Conclusions The incidence of iatrogenic hyponatraemia was greater with the administration of hypotonic fluids compared with that of isotonic fluids. There were no significant differences in the incidence of metabolic acidosis between the groups.

  • intensive care
  • metabolic
  • general paediatrics

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  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Ethics approval The study was approved by the Institutional Evaluation Committee (IEC) of the Austral University Hospital (HUA). The parents and/or guardians of the children authorised their participation in the study after having read and understood the informed consent prepared under the rules of the IEC.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available in a public, open access repository.

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