Predictors of resuscitation outcome in a swine model of VF cardiac arrest: A comparison of VF duration, presence of acute myocardial infarction and VF waveform

Abstract

Introduction Factors that affect resuscitation to a perfusing rhythm (ROSC) following ventricular fibrillation (VF) include untreated VF duration, acute myocardial infarction (AMI), and possibly factors reflected in the VF waveform. We hypothesized that resuscitation of VF to ROSC within 3 min is predicted by the VF waveform, independent of untreated VF duration or presence of acute MI. Methods AMI was induced by the occlusion of the left anterior descending coronary artery. VF was induced in normal (N = 30) and AMI swine (N = 30). Animals were resuscitated after untreated VF of brief (2 min) or prolonged (8 min) duration. VF waveform was analyzed before the first shock to compute the amplitude-spectral area (AMSA) and slope. Results Unadjusted predictors of ROSC within 3 min included untreated VF duration (8 min vs 2 min; OR 0.11, 95%CI 0.02–0.54), AMI (AMI vs normal; OR 0.11, 95%CI 0.02–0.54), AMSA (highest to lowest tertile; OR 15.5, 95%CI 1.7–140), and slope (highest to lowest tertile; OR 12.7, 95%CI 1.4–114). On multivariate regression, untreated VF duration (P = 0.011) and AMI (P = 0.003) predicted ROSC within 3 min. Among secondary outcome variables, favorable neurological status at 24 h was only predicted by VF duration (OR 0.22, 95% CI 0.05–0.92). Conclusions In this swine model of VF, untreated VF duration and AMI were independent predictors of ROSC following VF cardiac arrest. AMSA and slope predicted ROSC when VF duration or the presence of AMI were unknown. Importantly, the initial treatment of choice for short duration VF is defibrillation regardless of VF waveform.

Characteristics of ventricular fibrillation in relation to cardiac aetiology and shock success: A waveform analysis study in ICD-patients

“…This relation is (partly) driven by arrest duration, as was shown in a study in animals that reported that an independent association between VF characteristics and shock success could only be demonstrated if VF duration was not included in the multivariate model 6 . As VF duration is often unknown, VF characteristics may be used as indicators of time delay and myocardial metabolic state, and, as such, as predictors of shock success.…”

“…Whereas coarse VF is often seen in the early course of VF and is associated with successful defibrillation, the VF waveform becomes fine as the duration of VF increases and successful defibrillation becomes less likely 5,6 . With delivery of chest compressions shock success may be improved, and the coarseness of the VF waveform seems to increase concurrently 7,8 .…”

Combining Amplitude Spectrum Area with Previous Shock Information Using Neural Networks Improves Prediction Performance of Defibrillation Outcome for Subsequent Shocks in Out-Of-Hospital Cardiac Arrest Patients

“…However, factors that influencing VF characteristics might affect the probability of defibrillation success and therefore the performance of predictability of these features. In animal studies, Indik et al[ 24 , 25 ]observed that VF waveform characteristics were altered substantially in animals with myocardial infarction and heart failure compared to structurally normal controls. Olasveengen et al[ 26 ] confirmed that acute myocardial infarction (AMI) patients have depressed AMSA compared to patients without AMI in 101 OHCA victims.…”

RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 5: Monitoring

“…CPR generates significant ECG artifacts that complicate VF waveform analysis. Techniques (all LOE 6) including amplitude spectrum area transformation (AMSA) and scaling exponents have been applied to summarize the ECG waveform. Due to the complexity of these methods, their clinical utility has been restricted to more sophisticated AED's.…”