Abstract 212: Can Return of Spontaneous Circulation Be Achieved Faster in a Resuscitation Algorithm that Directs the Duration of Postshock Chest Compressions According to the Preshock Value of the Amplitude-Spectral Area? A Study of Ventricular Fibrillation Cardiac Arrest in Normal Swine
Background: It has been previously demonstrated in a swine model of cardiac arrest due to ventricular fibrillation (VF) that a return of spontaneous circulation (ROSC) following a shock is predicted by the amplitude spectral area (AMSA), a quantitative measure of the VF waveform. These prior studies were a retrospective analysis of the VF waveform prior to shocks. We hypothesize that AMSA can be utilized in a prospective fashion as part of a resuscitation algorithm to direct the duration of post-shock chest compressions (CC). Specifically, we have tested whether such an AMSA-directed algorithm will shorten the time needed to achieve ROSC in normal swine.
Methods: VF was induced electrically in normal swine and untreated for 10 minutes. Resuscitation was commenced with 1 minute of CC, resumption of mechanical ventilation, followed by the first shock and administration of epinephrine. Subsequently, animals were randomized to a traditional or waveform guided group. In the traditional group, all shocks were followed by 2 minutes of post-shock CC. In the waveform guided group, AMSA was measured prior to each shock and if AMSA>20 mV-Hz then post shock CC duration was shortened to 1 minute. ROSC was defined as a systolic aortic pressure greater than 50 mm Hg and pulse pressure > 20 mm Hg lasting at least one minute. Time to ROSC was compared with a Kruskal-Wallis rank test. AMSA was compared between groups using regression analysis with random effects to account for multiple shocks within the same animal.
Results: A total of N=8 animals were assigned to the traditional group with 22 shocks delivered, and N=8 animals to the waveform guided group with 21 shocks delivered. Time to ROSC (from induction of VF) was 14.5 ±1.2 minutes in the traditional group and 13.5± 1.2 minutes in the waveform guided group, (P=0.2). There was a trend for higher AMSA values in the waveform guided group: 48 ± 15 versus 39 ± 16 mV-Hz (P=0.1).
Conclusions: A resuscitation algorithm that tailors the duration of post-shock chest compressions to the value of AMSA is feasible. In this study of normal swine we found small, but non-significant, reductions in the times to achieve ROSC and higher values of AMSA in swine treated with a waveform guided approach.
- © 2012 by American Heart Association, Inc.