Failure of epinephrine to improve the balance between myocardial oxygen supply and demand during closed-chest resuscitation in dogs.

Although large doses of epinephrine increase coronary perfusion pressure and flow during cardiopulmonary resuscitation, epinephrine also increases myocardial oxygen consumption during ventricular fibrillation. To test the hypothesis that epinephrine improves the balance between myocardial oxygen supply and demand during cardiopulmonary resuscitation, myocardial adenosine 5'-triphosphate (ATP) and lactate concentrations were measured before and immediately after 10 minutes of cardiopulmonary resuscitation in 10 control dogs and 10 dogs given intravenous epinephrine (1-mg bolus followed by 0.2 mg/min). Left ventricular myocardial blood flow during cardiopulmonary resuscitation was measured with radioactive microspheres and was significantly higher in the epinephrine group (48 +/- 11 vs. 21 +/- 4 ml/min/100 g, p less than 0.05). However, myocardial lactate concentration increased significantly (p less than 0.01) after cardiopulmonary resuscitation in both groups and tended to increase more in epinephrine-treated animals. Myocardial ATP concentration decreased significantly (p less than 0.05) and by comparable amounts in the two groups. These findings suggest that large doses of epinephrine may fail to improve the balance between myocardial oxygen supply and demand during cardiopulmonary resuscitation, even when they result in a substantial increase in coronary blood flow.