Impact of warmed inhaled gas from the mechanical ventilator on esophageal temperature during therapeutic whole body hypothermia

Abstract

During therapeutic whole body cooling (WBC), the core temperature is usually monitored with an esophageal probe. Most infants receive mechanical ventilation while being cooled. As the temperature in the esophagus responds rapidly to changes in the ambient temperature, inhalation of warmed gas from ventilator may lead to overestimation of ventilated patients' actual temperature, causing automated cooling devices to overcool patients well below the desired set temperature targets. To determine if the esophageal temperature recordings during therapeutic WBC differ between ventilated and non-ventilated infants. Twenty-two consecutively cooled infants had simultaneous esophageal and rectal temperatures recorded every 4 h during 72 h of WBC. Other clinical monitoring and treatment during hypothermia were provided under an established protocol. Fourteen infants received mechanical ventilation throughout the duration of cooling. The remaining eight infants were initially ventilated but were extubated later and were not on ventilator between 32 and 72 h of WBC. The esophageal temperatures across every 4 h time points during the 32-72 h interval of WBC did not differ between the ventilated and non-ventilated infants. The magnitude (median, interquartile range) of the difference between esophageal and rectal temperatures was also similar between the two groups. Warmed inhaled gas does not interfere with the esophageal temperature during WBC.