title: Decreased free water clearance is associated with worse respiratory outcomes in premature infants.
abstract: OBJECTIVE
  The goal was to elucidate predictors of decreased free water clearance (DFWC) in very low birth weight (VLBW) infants. We hypothesized that DFWC and fluid retention are linked to the severity of pulmonary problems and prolonged respiratory support, especially to nCPAP treatment.
  
  
  METHODS
  The investigation was carried out at Tampere University Hospital between 2001 and 2006. The study population comprised 74 VLBW infants born at 29.21 (24.57-34.14) weeks of gestation. Median birth weight was 1175 (575-1490) grams. We measured plasma and urine osmolality and 24-hour urine volume to calculate free water clearance (FWC) for each infant. If FWC was less than 30 ml/kg/day the infant was classified as having DFWC.
  
  
  RESULTS
  There were 38 (51.4%) infants with DFWC in the study population. The median duration of the observed DFT period was 14 (4-44) days. The gestational age at birth was lower for DFWC infants compared to infants with normal FWC (NFWC), 28.29 (24.57-32.86) vs. 30.00 (25.57-34.14) weeks (p = 0.001). DFWC infants also needed longer ventilator treatment, 2 (0-23) vs. 0.50 (0-23) days (p = 0.046), nCPAP treatment 30 (0-100) vs. 3 (0-41) days (p<0.0001) and longer oxygen supplementation 47 (0-163) vs. 22 (0-74) days (p = 0.011) than NFWC infants. All values presented here are medians with ranges.
  
  
  CONCLUSIONS
  DFWC appears to be frequently connected with exacerbation and prolongation of pulmonary problems in VLBW infants. Cautious fluid administration seems to be indicated in VLBW infants with prolonged respiratory problems and DFWC.
authors.affiliation: Paediatric Research Centre, University of Tampere and Tampere University Hospital, Tampere, Finland. tuomo.vuohelainen@fimnet.fi
authors.forename: Tuomo
authors.initials: T
authors.lastname: Vuohelainen
authors.forename: Riitta
authors.initials: R
authors.lastname: Ojala
authors.forename: Anita
authors.initials: A
authors.lastname: Virtanen
authors.forename: Päivi
authors.initials: P
authors.lastname: Korhonen
authors.forename: Tiina
authors.initials: T
authors.lastname: Luukkaala
authors.forename: Päivi
authors.initials: P
authors.lastname: Holm
authors.forename: Outi
authors.initials: O
authors.lastname: Tammela
mesh_terms: D001127:Arginine Vasopressin / Q000378:metabolism; D001834:Body Water / Q000378:metabolism*; D045422:Continuous Positive Airway Pressure; D005260:Female; D006801:Humans; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008168:Lung / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D011247:Pregnancy; D047928:Premature Birth / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D011379:Prognosis; D014882:Water-Electrolyte Balance
chemical_list: D001127:Arginine Vasopressin