Therapeutic hypothermia with a novel surface cooling device improves neurologic outcome after prolonged cardiac arrest in swine.
OBJECTIVE
Devices for rapid induction of mild hypothermia after cardiac arrest are needed. We hypothesized that the Life Recovery Systems' ThermoSuit System provides effective core cooling by pumping ice water over the skin surface and improves neurologic outcome after prolonged cardiac arrest.


METHODS
Prospective experimental study.


METHODS
University research laboratory.


METHODS
Large White breed pigs (29 to 35 kg).


METHODS
Swine were anesthetized and mechanically ventilated. Ten minutes of untreated ventricular fibrillation, 3 mins of basic life support, and 5 mins of advanced cardiac life support, including two 0.4 IU/kg doses of vasopressin, were followed by up to three countershocks. After restoration of spontaneous circulation, swine were randomized to two groups (normothermic control, hypothermia). The hypothermia group was cooled from a pulmonary artery temperature of 38.5 +/- 0.5 degrees C to 33.0 degrees C and kept for 14 hrs. At day 9 of the experiment, overall performance categories scores (1, normal; 2, slightly disabled; 3, severely disabled; 4, comatose; 5, dead, brain dead) and neurologic deficit scores (0%, normal; 100%, brain dead) were assessed. Data are presented as median and interquartile range; group comparison was done with a Mann-Whitney U test.


RESULTS
In total, 16 of 22 animals were randomized. Time to target temperature in the hypothermia group (n = 8) was 9.0 (5.3-11.9) mins (cooling rate 0.4 [0.3-0.8] degrees C/min), and all animals achieved an overall performance categories score of 1. In the control group, one swine achieved an overall performance categories score of 1, three achieved a score of 2, and four achieved a score of 3 (p = .002). Neurologic deficit score was 0% (0%-4%) in the hypothermia group and 39% (19%-55%) in the control group (p = .001). No harmful side effects could be observed.


CONCLUSIONS
The Life Recovery Systems' ThermoSuit System rapidly and safely induced mild therapeutic hypothermia. Hypothermia improved neurologic outcome in swine after cardiac arrest as compared with normothermia. Further studies are warranted to compare the device with established cooling methods.
Janata
Andreas
A
Department of Emergency Medicine, Medical University of Vienna, Austria.
Weihs
Wolfgang
W
Bayegan
Keywan
K
Schratter
Alexandra
A
Holzer
Michael
M
Behringer
Wilhelm
W
Schock
Robert B
RB
Losert
Udo M
UM
Springler
Gregor
G
Schmidt
Peter
P
Sterz
Fritz
F
D000818:Animals; D003080:Cold Temperature; D004867:Equipment Design; D006323:Heart Arrest / Q000150:complications*; D007036:Hypothermia, Induced / Q000295:instrumentation*; D009422:Nervous System Diseases / Q000209:etiology / Q000517:prevention & control*; D013552:Swine; D013997:Time Factors