Abstract 2647: Predictors of Resuscitation in a Swine Model of VF Cardiac Arrest: Superiority of Amplitude Spectral Area (AMSA) to Predict a Return of Spontaneous Circulation When Resuscitation Efforts Are Prolonged
Introduction: We have demonstrated that a return of spontaneous circulation (ROSC) within 3 minutes of the initiation of resuscitation in swine is independently predicted by VF duration (2 or 8 minutes) and acute myocardial infarction (AMI) but not independently by VF waveform characteristics. We hypothesized that ROSC requiring prolonged resuscitation efforts with more than one shock is independently predicted by VF duration, AMI, end tidal CO2 (ET-CO2) and VF waveform.
Methods: After 2 or 8 minutes of untreated VF, VF waveform and ETCO2 data prior to defibrillation were evaluated in swine with or without AMI induced by a plug in the left anterior descending artery. Resuscitation was commenced with a defibrillation shock, followed by chest compressions (CC), epinephrine, ventilation, and repeat cycles of shock and CC every two minutes. ROSC was defined as a systolic aortic pressure >50mm Hg and pulse pressure >20mmHg lasting at least one minute. VF waveform was analyzed for amplitude spectral area (AMSA) and slope. Predictors of ROSC within 2 minutes of the last shock were evaluated by multivariate logistic regression with random effects for multiple shocks within the same animal.
Results: Ten animals had VF untreated for 2 minutes, 4 animals with AMI and 6 without AMI. Fifteen animals had VF untreated for 8 minutes, 10 with AMI and 5 without AMI. A total of 54 shocks were analyzed. Multivariate independent predictors of ROSC included AMSA (P=0.002), slope (P=0.001), and untreated VF duration (P=0.03), but not acute MI or ET-CO2. In particular, for animals that did not achieve ROSC with the first shock/CC cycle, only AMSA predicted ROSC (highest compared to lowest tertile OR= 36, P=0.007) with slope of borderline significance (OR=12.5, P=0.07).
Conclusions: If ROSC is not achieved within the first 2 minutes of shock and chest compressions, then AMSA is the sole predictor of achieving ROSC, regardless of short or prolonged duration of VF or presence of AMI, or ET-CO2. This has implications for the ideal means to customize chest compressions prior to further shocks when ROSC is not promptly obtained.
This research has received full or partial funding support from the American Heart Association, Pacific/Mountain Affiliate (Alaska, Arizona, Colorado, Hawaii, Idaho, Montana, Oregon, Washington & Wyoming).