Effects of epinephrine in a pig model of hypothermic cardiac arrest and closed-chest cardiopulmonary resuscitation combined with active rewarming.
OBJECTIVE
The aim of the current study was to assess the effects of epinephrine in a pig model of hypothermic cardiac arrest followed by closed-chest cardiopulmonary resuscitation combined with active rewarming, simulating the clinical management of an arrested hypothermic patient in a hospital without cardiopulmonary bypass facilities.


METHODS
Prospective, randomized animal study.


METHODS
University research laboratory.


METHODS
Twelve 12- to 16-week-old domestic pigs.


METHODS
Pigs were surface cooled to a body core temperature of 28 degrees C. After 4 min of untreated cardiac arrest, manual closed-chest CPR and thoracic lavage with 40 degrees C warmed fluid were started. After 3 min of external chest compression animals were randomly assigned to receive epinephrine (45, 45 and 200 microg/kg) or saline placebo in 5-min intervals.


RESULTS
Coronary perfusion pressure was about 15 mmHg in placebo group pigs. Coronary perfusion pressure was significantly higher after epinephrine, but restoration of spontaneous circulation was not more frequent (one of six epinephrine versus three of six saline placebo pigs, P=0.34). After 45 microg/kg epinephrine the arterial PO(2) was significantly lower when compared to the saline placebo. The third 200 microg/kg epinephrine dose resulted in a significantly enhanced mixed venous hypercarbic acidosis.


CONCLUSIONS
After a short 4-min period of hypothermic cardiac arrest, epinephrine may not be necessary to maintain coronary perfusion pressure around the threshold usually correlating with successful defibrillation, even during prolonged closed-chest CPR combined with active rewarming. The enhanced mixed venous hypercarbic acidosis in epinephrine-treated animals may support the argument against repeated or high dose epinephrine administration during hypothermic CPR.
Kornberger
E
E
Department of Anesthesiology and Critical Care Medicine, Leopold-Franzens-University, Anichstrasse 35, A-6020 Innsbruck, Austria. roselies.kornberger@uibk.ac.at
Lindner
K H
KH
Mayr
V D
VD
Schwarz
B
B
Rackwitz
K S
KS
Wenzel
V
V
Krismer
A C
AC
Mair
P
P
D000704:Analysis of Variance; D000818:Animals; D001784:Blood Gas Analysis; D001831:Body Temperature; D016887:Cardiopulmonary Resuscitation; D003326:Coronary Circulation / Q000187:drug effects*; D004195:Disease Models, Animal; D004837:Epinephrine / Q000627:therapeutic use*; D006323:Heart Arrest / Q000188:drug therapy*; D007035:Hypothermia / Q000628:therapy*; D019344:Lactic Acid / Q000097:blood; D017694:Rewarming; D013552:Swine / Q000502:physiology*
D019344:Lactic Acid; D004837:Epinephrine