Abstract 143: Amplitude Spectrum Area-Based Defibrillation Decision During Prehospital Cardiopulmonary Resuscitation in Lombardia, Italy
Aim. We evaluated the capability of “Amplitude Spectrum Area” (AMSA) to predict defibrillation (DF) outcome in of out-of-hospital cardiac arrest (OHCA), in northern Italy. We hypothesized that threshold values of AMSA could be identified such to be used as a guide for CPR intervention.
Methods. ECG data from AEDs of different manufactures were obtained from 8419 OHCAs occurring in 7 cities in Lombardia, Italy, in 2008/2009. Among these, VF/VT OHCAs with DFs were selected (n=984). A 2 sec ECG window ending at 0.5 sec before DF was analyzed and AMSA calculated, after fast Fourier transformation. DF was defined as successful in the presence of spontaneous rhythm ≥ 40 bpm starting within 60 secs from the DF. Threshold values of AMSA able to discriminate DF outcome were individuated and sensitivity, specificity, accuracy, positive and negative predictive values (PPV, NPV) were calculated. The area under the receiver operating characteristic (ROC) curve was measured.
Results. 1969 quality DF events, including 818 first attempts and 1151 subsequent ones, from 818 OHCAs were included. DF success rate was of 27%, 28%, and 26% for all, first, and subsequent DFs, respectively. AMSA was significantly greater prior to successful DFs, compared to that preceding unsuccessful ones (13.8 vs 6.9 mV-Hz, and 13.9 vs 6.8 mV-Hz, and 13.7 vs 7 mV-Hz, for all, first, and subsequent DFs respectively, p<0.0001). Intersection of sensitivity, specificity and accuracy curves identified a threshold value of AMSA of 9.5 mV-Hz, able to predict DF outcome with a balanced sensitivity, specificity and accuracy of 80%, for all, first, and subsequent DFs. Moreover, intersection of PPV and accuracy curves identified a threshold value of AMSA of 15 mV-Hz able to predict a successful DF with a PPV and accuracy of 80%, for all, first, and subsequent DF attempts. AMSA values greater than 27 mV-Hz predicted successful DF with a PPV of 100%. AMSA below 8 mV-Hz predicted DF failure with a NPV > 95%, for all, first, and subsequent DFs. Further decreases in AMSA ≤ 4 mV-Hz achieved a NPV of 100%. Area under ROC curves was 0.872, 0.869, and 0.875 for all, first, and subsequent DFs, respectively.
Conclusions. In this population, one of the largest studied to now, an AMSA algorithm was capable to predict DF outcome with high accuracy.
- © 2012 by American Heart Association, Inc.