EFFECTS OF EPINEPHRINE AND VASOPRESSIN ON MEDIAN FIBRILLATION FREQUENCY AND DEFIBRILLATION SUCCESS IN A PORCINE MODEL OF CARDIOPULMONARY-RESUSCITATION

Objective: This study was designed to assess whether median frequency of ventricular fibrillation (VF) correlates with myocardial blood flow and defibrillation success during cardiopulmonary resuscitation (CPR) after epinephrine or vasopressin administration. Methods and results: After 4 min of VF and 3 min of CPR, 14 pigs received 0.045 mg/kg epin ephrine or 0.4 U/kg vasopressin. Using radio-labeled microspheres, med ian myocardial blood flow during CPR before, and 90 s and 5 min after drug administration (DA) was 15.5 (12.6, 23.1; 25th percentile, 75th p ercentile), 26.4 (18.5, 29.1), 16.9 (14.9, 19.1) ml min(-1) 100 g(-1), respectively, in the epinephrine, and 16.9 (15.4, 18.9), 48.1 (36.9, 68.9) (P < 0.05 vs. before DA), 52.3 (38.5, 65.0) ml min(-1) 100 g(-1) , respectively, in the vasopressin group. Using spectral analysis of V F, median frequency of VF was 11.0 (10.7, 11.8), 11.3 (9.6, 13.1), 10. 2, (8.8, 11.4) Hz, respectively, in the epinephrine, and 10.1 (10.0, 1 0.5), 11.7 (11.1, 14.2) (P < 0.05 vs. before DA), 13.2 (11.5, 13.9) Hz , respectively, in the vasopressin group at the same points in time. M edian frequency correlates significantly with myocardial blood flow in the epinephrine (n = 21; r(s) = 0.772; P < 0.001) and in the vasopres sin group (n = 21; r(s), = 0.905; P < 0.001). Median fibrillation freq uency before the first defibrillation was 13.0 (12.2, 13.2) Hz in resu scitated (n = 8) and 9.2 (8.3, 10.2) Hz (n = 6) in non-resuscitated an imals (P < 0.01). Conclusions: We conclude that median frequency of VF reflects myocardial blood flow and the chance of successful defibrill ation during closed-chest CPR after vasopressor treatment in a porcine model of VF.