title: Hypotonic versus isotonic maintenance fluids after surgery for children: a randomized controlled trial.
abstract: OBJECTIVE
  The objective of this randomized controlled trial was to evaluate the risk of hyponatremia following administration of a isotonic (0.9% saline) compared to a hypotonic (0.45% saline) parenteral maintenance solution (PMS) for 48 hours to postoperative pediatric patients.
  
  
  METHODS
  Surgical patients 6 months to 16 years of age with an expected postoperative stay of >24 hours were eligible. Patients with an uncorrected baseline plasma sodium level abnormality, hemodynamic instability, chronic diuretic use, previous enrollment, and those for whom either hypotonic PMS or isotonic PMS was considered contraindicated or necessary, were excluded. A fully blinded randomized controlled trial was performed. The primary outcome was acute hyponatremia. Secondary outcomes included severe hyponatremia, hypernatremia, adverse events attributable to acute plasma sodium level changes, and antidiuretic hormone levels.
  
  
  RESULTS
  A total of 258 patients were enrolled and assigned randomly to receive hypotonic PMS (N = 130) or isotonic PMS (N = 128). Baseline characteristics were similar for the 2 groups. Hypotonic PMS significantly increased the risk of hyponatremia, compared with isotonic PMS (40.8% vs 22.7%; relative risk: 1.82 [95% confidence interval: 1.21-2.74]; P = .004). Admission to the pediatric critical care unit was not an independent risk factor for the development of hyponatremia. Isotonic PMS did not increase the risk of hypernatremia (relative risk: 1.30 [95% confidence interval: 0.30-5.59]; P = .722). Antidiuretic hormone levels and adverse events were not significantly different between the groups.
  
  
  CONCLUSIONS
  Isotonic PMS is significantly safer than hypotonic PMS in protecting against acute postoperative hyponatremia in children.
authors: Department of Pediatrics, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada. choongk@mcmaster.ca
authors: Karen
authors: K
authors: Choong
authors: Steve
authors: S
authors: Arora
authors: Ji
authors: J
authors: Cheng
authors: Forough
authors: F
authors: Farrokhyar
authors: Desigen
authors: D
authors: Reddy
authors: Lehana
authors: L
authors: Thabane
authors: J Mark
authors: JM
authors: Walton
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D007010:Hyponatremia / Q000517:prevention & control*; D007038:Hypotonic Solutions / Q000008:administration & dosage / Q000009:adverse effects*; D007262:Infusions, Intravenous; D008297:Male; D011182:Postoperative Care / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control; D012016:Reference Values; D018570:Risk Assessment; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage*; D013514:Surgical Procedures, Operative / Q000009:adverse effects / Q000379:methods; D016896:Treatment Outcome; D014883:Water-Electrolyte Imbalance / Q000517:prevention & control
chemical_list: D007038:Hypotonic Solutions; D012462:Saline Solution, Hypertonic