Purpose of the stud
y: Early out-of-hospital induction of mild hypothermia after cardiac arrest needs an easy to use and accurate core temperature monitoring, which might be achievable with tracheal temperature measurement. The aim of the study was to evaluate which tracheal temperature site (Ttra) reflects best pulmonary artery temperature (Tpa) during the induction of mild hypothermia.
Methods:
Eight pigs (29 –38 kg) were anesthetized and intubated with a specially designed endotracheal tube with three temperature probes: Ttra1 was attached to the wall of the tube, 1 cm proximal to the cuff-balloon, without contact to the mucosa; Ttra2 and Ttra3 were placed on the cuff-balloon with tight contact to the mucosa, whereas Ttra3 was covered by a plastic tube to protect the mucosa. Core temperature was measured with a pulmonary artery catheter (Tpa). Pigs were cooled with a new surface cooling device (Emcoolspad®, Vienna, Austria). Data are presented as mean (±SD), and mean differences (95% CI).
Results:
Emcoolspad® decreased Tpa from 38.5°C to 33°C in 31±10 min, which translates into a cooling rate of 11.9±3.8°C/h. Overall mean differences of tracheal temperatures to pulmonary artery temperature (Tpa) are shown in table 1
. Ttra 1 showed the least difference to Tpa, followed by Ttra 2 and Ttra 3. There was a significant difference in temperature differences (Ttra-Tpa) related to temperature measurement site on the tracheal tube (p<0.007).
Conclusions:
The temperature probe proximal of the cuff (Ttra 1) reflects best pulmonary artery temperature. It seems to be an accurate surrogate for core temperature during the induction of mild hypothermia. The industry is asked to provide a tracheal tube with a temperature sensor for simple temperature monitoring during fast cooling to facilitate the implementation of mild hypothermia after cardiac arrest in the out-of-hospital setting.
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