Myocardial oxygen delivery/consumption during cardiopulmonary resuscitation: a comparison of epinephrine and phenylephrine.

Our study compared the effect of high-dose epinephrine with the pure alpha-agonist phenylephrine on regional myocardial blood flow (MBF), myocardial oxygen delivery (MDO2), myocardial oxygen consumption (MVO2), and defibrillation rates during CPR. Fifteen swine weighing more than 15 kg were instrumented for measurement of regional MBF using radiolabeled tracer microspheres. Measurements of regional MBF, MDO2, and MVO2 were made during normal sinus rhythm. Ventricular fibrillation was induced and persisted for ten minutes. CPR was begun using a pneumatic compression device. Regional MBF, MDO2, and MVO2 were measured during CPR. Following three minutes of CPR, animals (N = 15) were allocated to one of three groups (n = 5): Group 1, epinephrine 0.2 mg/kg; Group 2, phenylephrine 0.1 mg/kg; or Group 3, phenylephrine 1.0 mg/kg. Measurements of regional MBF, MDO2, and MVO2 were repeated after drug administration. Extraction ratios, defined as MVO2/MDO2, were calculated during normal sinus rhythm, CPR, and after drug administration. Defibrillation was attempted 3 1/2 minutes after drug administration. There was no significant difference in MBF, MDO2, MVO2, and extraction ratio during normal sinus rhythm and CPR for any of the groups. Total MBF following drug administration was 67.2 +/- 49.4 mL/min/100 g for the group receiving epinephrine 0.2 mg/kg; 7.0 +/- 7.1 mL/min/100 g for the group receiving phenylephrine 0.1 mg/kg; and 36.7 +/- 21.1 mL/min/100 g for the group receiving phenylephrine 1.0 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)