Pediatric Pulmonology 38:50–54 (2004) Inspired Gas Temperature in Ventilated Neonates

The warming and humidification of inspired gases for ventilated neonates are routine. There are no data on the temperature of the gasat the airway opening in ventilated neonates. Is the inspired gas temperature at the airway opening, as expected and set on the humidifier, around 378C?We aimed to measure temperature at the airway opening and compare this with the circuit temperature. This was an observational study in a neonatal intensive care unit. Twenty-five mechanically ventilated infants were studied. All had humidifiers with chamber temperature set at 368C and the circuit temperature set at 378C. Two temperature probeswere inserted and rested at the circuit-exit andat theairwayopening, and temperaturesweremeasured for 2min ineach infant. At this time, the circuit temperature was also noted. The mean (SD) temperature at the airway opening in infants nursed in incubators was 34.9 (1.2)8C, compared with radiant warmers where the mean (SD) was 33.1 (0.5)8C. The mean (SD) difference in temperature from the circuit temperature probe to the airway opening was greater under radiant warmers, with a mean (SD) drop of 3.9 (0.6)8Ccomparedwith amean (SD) drop of 2.0 (1.3)8C in the incubators. In conclusion, the temperature at the circuit temperature probe does not reflect the temperature at the airway opening. Inspired gas temperatures are lower than the expected 378Cwith the normal circuits and usual humidifier settings. Pediatr Pulmonol. 2004; 38:50–54. 2004 Wiley-Liss, Inc.