Effect of high flow transnasal dry air on core body temperature in intubated human subjects

Purpose: Early initiation of hypothermia is recommended in the setting of cardiac arrest. Current hypothermia methods are invasive and expensive and not applicable in ambulatory settings. We investigated the evaporative cooling effect of high flow transnasal dry air on core esophageal temperature in human volunteers. Methods & results: A total of 32 subjects (mean age 53.2 +/- 9.3 yrs., mean weight 90 +/- 17 kg) presenting for elective electrophysiological procedures were enrolled for the study. Half of the subjects were men. Following general anesthesia induction, high flow (30 LPM) medical grade ambient dry air with a relative humidity +/- 20% was administered through a nasal mask for 60 min. Core temperature was monitored at the distal esophagus. Half of the subjects (16/32) were subject to high flow air and the remainder served as controls. Over a 1-h period, mean esophageal temperature decreased from 36.1 +/- 0.3 degrees C to 35.5 +/- 0.1 degrees C in the test subjects (p < 0.05). No significant change in temperature was observed in the control subjects (36.3 +/- 0.3 degrees C to 36.2 +/- 0.2 degrees C, p = NS). No adverse events occurred. Conclusion: Transnasal high flow dry air through the nasopharynx reduces core body temperature. This mechanism can be harnessed to induce hypothermia in patients where clinically indicated without any deleteriouseffects in a short time exposure.