title: Hypotonic solution decreases serum sodium in infants with moderate bronchiolitis.
abstract: OBJECTIVE
  To investigate the influence of hypotonic parenteral hydration on serum and urinary sodium and osmolality in infants with moderate bronchiolitis.
  
  
  METHODS
  We studied 36 infants (mean age 3.7 ± 2.3 months), with a diagnosis of moderate bronchiolitis admitted to a paediatric emergency unit in São Paulo, Brazil. Patients received a standard parenteral hypotonic solution, according to Holliday and Segar, during the first 24 h, due to respiratory distress. The disease was monitored by a respiratory severity score (RDAI-Respiratory Distress Assessment Instrument), respiratory rate and oxygen saturation. Serum and urinary sodium and osmolality were monitored at admission, 24 and 48 h after admission.
  
  
  RESULTS
  All respiratory parameters improved during hospitalisation. Serum sodium and osmolality dropped after 24 h (136.8 ± 2.8 and 135.8 ± 2.6 mEq/L, p = 0.031; 283.4 ± 4.1 and 281.6 ± 3.9 mOsm/kg, p = 0.004 respectively) as well as urinary osmolality (486.8 ± 243.4 mOsm/kg and 355.7 ± 205.0 mOsm/kg, p < 0.001) when compared to admission.
  
  
  CONCLUSIONS
  This study reinforces the occurrence of hyponatraemia in bronchiolitis even in patients with moderate disease and highlights the risk of serum sodium drop caused by hypotonic parenteral hydration.
authors.affiliation: Emergency Department, Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Regina M
authors.initials: RM
authors.lastname: Rodrigues
authors.forename: Benita G S
authors.initials: BG
authors.lastname: Schvartsman
authors.forename: Sylvia C L
authors.initials: SC
authors.lastname: Farhat
authors.forename: Cláudio
authors.initials: C
authors.lastname: Schvartsman
mesh_terms: D001938:Brazil / Q000453:epidemiology; D001988:Bronchiolitis / Q000097:blood / Q000150:complications* / Q000652:urine; D015331:Cohort Studies; D018450:Disease Progression; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D007038:Hypotonic Solutions / Q000627:therapeutic use*; D015994:Incidence; D007231:Infant, Newborn; D007262:Infusions, Intravenous; D008297:Male; D011446:Prospective Studies
chemical_list: D007038:Hypotonic Solutions
keywords: Hyponatraemia; Hypotonic solution; Moderate bronchiolitis; Paediatric