Insensible Water Loss in Extremely Preterm Infants nursed in Incubators with 70% and 90% Relative Humidity.

Abstract Objective: To determine the insensible water losses (IWL) in preterm infants nursed in incubators with 70% or 90% relative humidity (RH). Study design: This was a single center retrospective study of extremely preterm infants between 23- and 28-weeks gestational ages nursed in 70% and 90% RH. IWL was calculated using a formula that utilized infants’ fluid intake, urine output and body weight changes. IWL between the two groups were compared using independent t-test. Multivariate linear regression was used to assess the effects of humidity on IWL after adjusting for confounding variables. Results: IWL was higher in infants nursed in 70% RH when compared with those nursed in 90% RH (47.7 ±30.3 vs. 28.8 ±39.6, p=002). Multivariate linear regression analysis showed that RH has an independent effect on the insensible water loss. Conclusion: Extremely preterm infants nursed in incubator with 70% RH have higher IWL than infants nursed in 90% RH.