Long-term mild hypothermia with extracorporeal lung and heart assist improves survival from prolonged cardiac arrest in dogs.
OBJECTIVE
although normothermic extracorporeal lung and heart assist (ECLHA) improves cardiac outcomes, patients can not benefit from hypothermia-mediated brain protection. The present study evaluated the effects of long-term ECLHA with mild to moderate hypothermia (33 degrees C) in a canine model of prolonged cardiac arrest.


METHODS
15 dogs were assigned to either the hypothermic (seven dogs, 33 degrees C) or normothermic group (eight dogs, 37.5 degrees C). All dogs were induced to normothermic ventricular fibrillation (VF) for 15 min, followed by 24 h of ECLHA and 72 h of intensive care. The hypothermia group maintained core (pulmonary artery) temperature at 33 degrees C for 20 h starting from resuscitation, then were rewarmed by 28 h. Outcome evaluations included: (1) mortality; (2) catecholamine dose; (3) time to extubation; (4) necrotic myocardial mass (g); and (5) neurological deficits score (NDS).


RESULTS
in the normothermic group five dogs died of cardiogenic shock and one dog succumbed to poor oxygenation. The two surviving dogs remained comatose (NDS 60.5 +/- 4.9%) with necrotic myocardial mass of 14.5 +/- 3.5 g. In the hypothermic group, one dog died from pulmonary dysfunction, the other six dogs survived. The surviving dogs showed brain damage (29.8 +/- 2.5%), but there was evidence of some brain-protective effect. The mass of necrotic myocardium was 4.2 +/- 1.3 g in the hypothermic group or 3.4 times smaller than in the normothermic group. The survival rate was significantly higher in the hypothermic than in the normothermic group (P < 0.05). The catecholamine requirement was also lower in the hypothermic than in the normothermic dogs (P < 0.05).


CONCLUSIONS
Long-term mild to moderate hypothermia with ECLHA induced immediately after cardiac arrest improved survival as well as cerebral and cardiac outcomes.
Ao
H
H
Department of Anesthesiology, Kumamoto University School of Medicine, Japan. aohushan@kaiju.medic.kumamoto-u.ac.jp
Tanimoto
H
H
Yoshitake
A
A
Moon
J K
JK
Terasaki
H
H
D000704:Analysis of Variance; D000818:Animals; D002315:Cardiopulmonary Bypass / Q000379:methods*; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D004285:Dogs; D015199:Extracorporeal Membrane Oxygenation; D006323:Heart Arrest / Q000628:therapy*; D007036:Hypothermia, Induced / Q000379:methods*; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome