Combination pharmacotherapy with delayed countershock vs standard advanced cardiac life support after prolonged ventricular fibrillation.
OBJECTIVE
To test the hypothesis that combination pharmacotherapy with delayed countershock would produce higher rates of return of spontaneous circulation (ROSC) and one-hour survival when compared with standard Advanced Cardiac Life Support (ACLS) therapy.


METHODS
A prospective, block-randomized, blinded, laboratory experiment was conducted in an established swine model of prolonged ventricular fibrillation (VF). Fifty-six female domestic swine were anesthetized, instrumented, and shocked into VF with a bipolar pacing catheter. The VF was untreated for 8 minutes, then basic CPR was done mechanically for 1 minute. At 9 minutes of VF, the animals were randomized to treatment with one of seven therapies: group 1, combination pharmacotherapy with epinephrine (0.20 mg/kg), lidocaine (1.0 mg/kg), bretylium (5.0 mg/kg), propranolol (1.0 mg), and U-74389G (3.0 mg/kg); group 2, epinephrine (0.20 mg/kg); group 3, lidocaine (1.0 mg/kg) and bretylium (5.0 mg/kg); group 4, propranolol (1.0 mg); group 5, U-74389G (3.0 mg/kg); group 6, normal saline solution (volume equal to that for group 1); and group 7, standard ACLS (first countershock at 9 minutes of VF). Initial countershocks for groups 1-6 were given after 11 minutes of VF. Data were analyzed with two-tailed Fisher's exact test, with alpha set at 0.05.


RESULTS
Return of spontaneous circulation occurred in group 1 = 8/8 (100%); group 2 = 7/8 (88%); group 3 = 3/8 (38%); group 4 = 3/8 (38%); group 5 = 5/8 (63%); group 6 = 4/8 (50%); and group 7 = 3/8 (38%). One-hour survival occurred in group 1 = 8/8 (100%); group 2 = 5/8 (63%); group 3 = 2/8 (25%); group 4 = 2/8 (25%); group 5 = 3/8 (38%); group 6 = 2/8 (25%); and group 7 = 1/8 (13%).


CONCLUSIONS
Combination pharmacotherapy with delayed countershock (group 1) produced significantly higher rates of ROSC (p = 0.03) and one-hour survival (p = 0.001) when compared with standard ACLS in this porcine model of prolonged VF.
Menegazzi
J J
JJ
Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pennsylvania, USA. menegazz+@pitt.edu
Seaberg
D C
DC
Yealy
D M
DM
Davis
E A
EA
MacLeod
B A
BA
D000704:Analysis of Variance; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D000975:Antioxidants / Q000737:chemistry / Q000627:therapeutic use; D001949:Bretylium Compounds / Q000627:therapeutic use; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D003131:Combined Modality Therapy; D004359:Drug Therapy, Combination; D004554:Electric Countershock; D004837:Epinephrine / Q000627:therapeutic use; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D008012:Lidocaine / Q000627:therapeutic use; D011281:Pregnatrienes / Q000737:chemistry / Q000627:therapeutic use; D011433:Propranolol / Q000627:therapeutic use; D011897:Random Allocation; D016019:Survival Analysis; D013552:Swine; D013566:Sympathomimetics / Q000627:therapeutic use; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000628:therapy*
D000889:Anti-Arrhythmia Agents; D000975:Antioxidants; D001949:Bretylium Compounds; D011281:Pregnatrienes; D013566:Sympathomimetics; C074965:U 74389F; D008012:Lidocaine; D011433:Propranolol; C045166:bretylium; D004837:Epinephrine