Tracheal temperature for monitoring body temperature during mild hypothermia in pigs.
OBJECTIVE
Out-of-hospital induction of mild therapeutic hypothermia after cardiac arrest needs easy to use and accurate body temperature monitoring. The aim of the study was to evaluate the best temperature probe position on a specially designed tracheal tube, as compared to pulmonary artery temperature (Tpa) during cooling to mild hypothermia in pigs.


METHODS
Eight swine (29-38 kg) were anesthetized and intubated with an endotracheal tube with three temperature probes: T1 was attached to the wall of the tube, 1cm proximal to the cuff-balloon, without contact to the mucosa; T2 and T3 were placed on the cuff-balloon with tight contact to the mucosa, T3 was covered by a small plastic tube to protect the mucosa against mechanical alterations. Body temperature was measured with a pulmonary artery catheter. Pigs were cooled from Tpa 38.5 to 33.0 degrees C with fast surface and slow endovascular cooling in a crossover design. To assess hysteresis, areas under the curve (AUC) were compared. Data are presented as mean and 95% confidence intervals.


RESULTS
Temperatures were not different either during fast surface (T1-Tpa: 0.1[-0.3 to 0.5] degrees C, T2-Tpa: 0.2[0.0 to 0.4] degrees C, T3-Tpa: 0.4[0.1 to 0.7] degrees C) or slow endovascular (T1-Tpa: -0.3[-0.5 to 0.2] degrees C, T2-Tpa: -0.1[-0.3 to 0.0] degrees C, T3-Tpa: -0.1[-0.5 to 0.3] degrees C) cooling. There was no difference in hysteresis related to the location of the temperature probes. Faster surface cooling correlated with a larger but not significantly different hysteresis between the probes.


CONCLUSIONS
Tracheal temperature is an accurate surrogate for body temperature during fast and slow cooling to mild hypothermia in pigs and regardless of the location of the temperature probe on the tube.
Krizanac
Danica
D
Department of Emergency Medicine, Medical University of Vienna, Austria.
Haugk
Moritz
M
Sterz
Fritz
F
Weihs
Wolfgang
W
Holzer
Michael
M
Bayegan
Keywan
K
Janata
Andreas
A
Losert
Udo M
UM
Herkner
Harald
H
Behringer
Wilhelm
W
D000818:Animals; D019540:Area Under Curve; D001831:Body Temperature; D016001:Confidence Intervals; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D007036:Hypothermia, Induced; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D016014:Linear Models; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D011651:Pulmonary Artery; D018709:Statistics, Nonparametric; D013552:Swine; D014132:Trachea