Determinants of mortality after hypothermic circulatory arrest in a chronic porcine model.
OBJECTIVE
Beside neurological morbidity, mortality is a relevant end-point of experimental porcine model of hypothermic circulatory arrest (HCA) and this study was conducted to identify the determinants for postoperative death.


METHODS
One hundred and thirty-five pigs underwent a 75-min period of HCA at 20 degrees C to evaluate the efficacy of different methods of cerebral protection.


RESULTS
Survival rate at 7-day follow-up was 52%. Lower oxygen extraction, oxygen consumption/kg, and venous lactate at the end of cooling and higher oxygen delivery rates were significantly associated with better outcome. Logistic regression showed that the oxygen consumption/kg at the end of cooling was the only predictor of mortality (P=0.046). Animals with an oxygen consumption/kg rate less than 1.43 ml/min per kg at the end of cooling had a mortality rate of 28%, whereas it was 50% among animals with an oxygen consumption/kg rate higher or equal to 1.43 ml/min per kg (P=0.020). The latter had even an increased 1-day mortality rate (40% vs. 26%) (P not significant). The mortality rate after anesthesia induction with ketamine plus 100% of oxygen was 38%, 45% after anesthesia induction with ketamine plus 35% oxygen, and 53% after anesthesia with medetomidine plus 35% oxygen (P not significant).


CONCLUSIONS
Parameters of oxyhemodynamics should be monitored especially from the induction of anesthesia to the end of cooling before a 75-min period of HCA. The use of medetomidine and/or 35% of oxygen at induction of anesthesia should be avoided in favor of ketamine plus 100% of oxygen.
Juvonen
T
T
Department of Cardio-thoracic and Vascular Surgery, Oulu University Hospital, University of Oulu, 90221 Oulu, Finland. tatu.juvonen@oulu.fi
Biancari
F
F
Rimpiläinen
J
J
Anttila
V
V
Pokela
M
M
Vainionpää
V
V
Romsi
P
P
Kiviluoma
K
K
D000768:Anesthesia, General; D000818:Animals; D002423:Cause of Death; D004195:Disease Models, Animal; D005260:Female; D006324:Heart Arrest, Induced / Q000401:mortality*; D006439:Hemodynamics / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D016019:Survival Analysis; D013552:Swine