Rapid non-invasive external cooling to induce mild therapeutic hypothermia in adult human-sized swine.
OBJECTIVE
Mild therapeutic hypothermia is a promising new therapy for patients resuscitated from cardiac arrest. Early and fast induction of hypothermia seems to be crucial for best results. The aim of the study was to investigate the feasibility and safety of a new surface cooling method using cold metal plates.


METHODS
Twelve adult human-sized swine (79+/-9 kg) were cooled from 38 to 33 degrees C brain temperature. The skin surface was covered with -20 degrees C metal plates (M), as compared to ice packs, alcohol rubs, and fans used in a control group (C). Each method was tested during spontaneous circulation and, after re-warming, during cardiac arrest. Temperatures were recorded continuously. Data are given as mean+/-standard deviation or as median (interquartile range), if not normally distributed. Comparisons between the treatment groups were performed with the independent samples t-test, or the Mann-Whitney rank-sum test.


RESULTS
During spontaneous circulation, cooling rates were 9.3+/-1.4 degrees C/h (M), and 6.1+/-1.4 degrees C/h (C) (p=0.003); no skin lesions were observed. During cardiac arrest, cooling rates were 4.1 degrees C/h (1.8-4.8) (M), and 3.7 degrees C/h (3.1-5.3) (C) (p=0.9); no skin lesions were observed.


CONCLUSIONS
Cooling with cold metal plates was an effective method for rapid induction of mild therapeutic hypothermia in adult human-sized swine during spontaneous circulation, without any signs of skin damage. This new surface-cooling device, independent of energy supply during use, should be further investigated.
Bayegan
Keywan
K
Department of Emergency Medicine, Medical University of Vienna, Allgemeines Krankenhaus der Stadt Wien, Währinger Gürtel 18-20, 1090 Vienna, Austria.
Janata
Andreas
A
Frossard
Martin
M
Holzer
Michael
M
Sterz
Fritz
F
Losert
Udo M
UM
Laggner
Anton N
AN
Behringer
Wilhelm
W
D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000503:physiopathology; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004195:Disease Models, Animal; D005260:Female; D006323:Heart Arrest / Q000503:physiopathology / Q000628:therapy*; D007036:Hypothermia, Induced / Q000379:methods*; D013552:Swine; D013997:Time Factors; D016896:Treatment Outcome