Abstract 271: Continuous Amplitude Spectral Area May Reflect Adequacy of Myocardial Perfusion Before Attempting Defibrillation
Background: Previous studies have shown that analysis of the VF amplitude-spectral area (AMSA) contains information predictive of electrical shock success. However, the underlying factors that determine AMSA remain elusive. We developed an open-chest swine model of VF in which we modeled “average CPR” followed by “highly effective CPR” using extracorporeal circulation (ECC) and assessed AMSA in relation to adequacy of coronary perfusion.
Methods: VF was electrically induced and left untreated for 8 min in 8 pigs after which ECC was started and maintained for 10 min adjusting the flow to generate a coronary perfusion pressure (CPP) of 10 mmHg (low-flow ECC). After delivery of an initial shock, the ECC flow was increased and titrated to secure a mean aortic pressure of 40 mmHg (high-flow ECC) delivering additional electrical shocks at 60 s intervals. Blood flow through the left anterior descending (LAD) artery was reported relative to baseline (LAD rel). AMSA was measured continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s, and was averaged every min for this report (Figure).
Results: AMSA increased during the initial 5 min of low-flow ECC, but subsequently decreased (Figure). The initial shock uniformly failed to terminate VF prompting increases in ECC to high-flow, which then resulted in the return of spontaneous circulation in each instance after 3 to 5 shocks. During the high-flow ECC, AMSA initially increased but then gradually decreased for reasons that are not clear. Before attempting defibrillation, AMSA was positively correlated with LAD rel (r=0.73, p=0.04).
Conclusion: The study provides intriguing data showing changes in AMSA that are time dependent and likely influenced by myocardial perfusion and the effects of electrical shocks on the myocardium. The present study also suggests that the level of AMSA prior to attempting defibrillation may be influenced by the efficacy with which the CPR intervention generates coronary blood flow.
Author Disclosures: R.J. Gazmuri: Research Grant; Significant; VA Merit Review Grant entitled Myocardial Effects of Erythropoietin during Resuscitation from Cardiac Arrest. Other Research Support; Significant; Unrestricted Funds to Support Educational and Research Activities, from ZOLL Medical Corporation. C.L. Kaufman: Other; Significant; Employment with ZOLL Medical Corporation. H.K. Whitehouse: None. A. Baetiong: None. J. Radhakrishnan: None.
- © 2014 by American Heart Association, Inc.