Failing to meet relative humidity targets for incubated neonates causes higher heat loss and metabolic costs in the first week of life

International audienceAim: Frequent nursing procedures can modify a newborn infant's thermal environment when their incubator is opened. This study evaluated the impact of relative humidity (RH) on preterm infants in closed incubators and calculated their heat loss and additional metabolic cost. Methods: We studied 45 preterm infants born before 32 + 0 weeks, nursed at the neonatal intensive care unit at Amiens University Hospital, France from January 2009 to November 2011. Their body, skin and air temperatures and the incubator's RH were continuously recorded from day 1 to 8 of life, and the differences between the measured and target RH were calculated. Body heat loss (BHL) was also calculated. Results: On day one, the measured RH (68.7 +/- 1.0%) was significantly lower than the target RH (75%, p < 0.05), but this difference, together with BHL (p < 0.001) and evaporative heat loss (p < 0.001), fell significantly over time (p < 0.05). The additional metabolic cost correlated with the difference between measured and target RH (p < 0.001). Conclusion: RH from day 1 to 8 was below the recommended target value for preterm infants and resulted in high evaporative and greater total BHL and additional metabolic cost. The findings pose numerous challenges, including nursing care and incubator design

Warming the premature infant in the delivery room: Quantification of the risk of hyperthermia

International audienceAim: The efficacy and safety of three polyethylene bags commonly used to prevent hypothermia in premature infants was assessed. Methods: To simulate transfer from the delivery room to a secondary care unit, a thermally stable, bonneted mannequin (skin temperature: 34.4 degrees C) was placed in a climate chamber under different conditions: with a radiant warmer, with various polyethylene bags (open on one side, closed by a draw-string at the neck, or a ``life support pouch'' with several access points) or without a bag. Results: With the radiant warmer turned on, the mean reduction in heat loss from the nude mannequin was 50.8 +/- 1.7% (p <0.0001, vs. warmer off). The mean reduction in heat loss (vs. no bag) was 55.0 +/- 0.9% for the drawstring bag, 49.0 +/- 2.2% for the standard bag (p= 0.0001), and 48.1 +/- 0.7% for the life support pouch (p = 0.006). When a radiant warmer + polyethylene bag were used, heat stress (body temperature: 38 degrees C) and severe hyperthermia (40 degrees C) occurred after 11 and 34 min, respectively. Conclusion: Caution must be taken when using a radiant warmer and polyethylene bag with a prematute infant. Heat stress can occur in only 11 min. Continuous body temperature monitoring is therefore required. (C) 2018 Published by Elsevier Ltd on behalf of IPEM