Author Block:

Yun-Te Chang, The Institute of Critical Care Medicine, Rancho Mirage, CA; Wanchun Tang, The Institute of Critical Care Medicine, Rancho Mirage/Keck School of Medicine USC, Los Angeles, CA; Jinglan Wang, The Institute of Critical Care Medicine, Rancho Mirage, CA; James E Brewer, Gary Freeman, Zoll Medical Corporation, Chelmsford, MA; Shijie Sun, The Institute of Critical Care Medicine, Rancho Mirage/Keck School of Medicine USC, Los Angeles, CA; Lei Huang, The Institute of Critical Care Medicine, Rancho Mirage, CA; Max Harry Weil, The Institute of Critical Care Medicine, Rancho Mirage/Keck School of Medicine USC, Los Angeles, CA

Disclosure Block:

 Y. Chang, None; W. Tang, None; J. Wang, None; J.E. Brewer, full time, Modest,A. Employment; G. Freeman, full time, Modest,A. Employment; S. Sun, None; L. Huang, None; M.H. Weil, None.

Abstract Body:

INTRODUCTION: We compared biphasic truncated exponential (BTE) waveform shocks with rectilinear biphasic (RLB) waveform shocks to determine both the success of the defibrillation attempt and post-resuscitation myocardial function. METHODS: Ventricular fibrillation (VF) was induced by occluding the left anterior descending coronary artery with a balloon catheter in 16 domestic pigs. Cardiopulmonary resuscitation (CPR), including chest compression and mechanical ventilation, was begun after 7 min of untreated cardiac arrest and continued for 5 min. Animals were then randomized to receive up to 3 RLB or the BTE shocks. In accord with the recommendation of the manufacturers, RLB shocks were delivered at progressive energy levels of 120, 150, and 200 J and BTE waveform shocks with energy levels of 200, 300, and 360 J. Failing to restore spontaneous circulation (ROSC), the sequence was repeated after 1 min of CPR. The number of shocks required for ROSC, the rapidity with which ROSC was achieved, and the severity of post-resuscitation myocardial dysfunction assessed with transesophageal echocardiography at one hour after ROSC (Model 21363A, Hewlett-Packard Co., Medical Products Group, Andover, MA) were compared. RESULTS: All animals were successfully resuscitated. With RLB waveforms at lower delivered energies, a smaller number of shocks was required than with BTE shocks at higher energy prior to ROSC (1.1±0.4 vs 2.6±1.4, p<0.005). Accordingly, ROSC was achieved more rapidly (2.0±2.9 vs 49.7±50.9 sec, p<0.005). Post-resuscitation ejection fraction was better preserved after RLB shocks (51% vs 43%, p<0.005). CONCLUSION: RLB waveform shocks with delivery of less energies restored spontaneous circulation earlier and with fewer shocks when compared with BTE waveform. This was associated with significantly better post-resuscitation myocardial function.