Abstract 10131: Optimizing Timing of Defibrillation Guided by ECG Amplitude Spectrum Analysis Improves the Outcomes of CPR in a Rat Model of Prolonged Ventricular Fibrillation
When VF is prolonged, defibrillation (DF) immediately causes myocardial injury and reduces the success of CPR. AHA guidelines recommend performing 2 minutes of CPR prior to DF. However, since there is currently no objective feedback mechanism to indicate when the heart is ready to be resuscitated, and specifically, when spontaneous circulation would be restored with DF, this recommendation may not be optimal. We investigated whether the optimal timing of DF could be guided by amplitude spectrum analysis (AMSA). Our hypothesis was that DF guided by AMSA would reduce the interruptions of CPR and the numbers of DF, and improve the outcomes of CPR. VF was induced in 30 SD rats. CPR was initiated after 8 minutes of untreated VF. Animals were randomized into 3 groups, 1) AMSA guided: precordial compression was provided continuously and DF was not attempted until the threshold of AMSA reached 10 mV•Hz. 2) Guideline based with 10 sec delay: a single DF is delivered 10 seconds after each 2 minutes of CPR. 3) Guideline based with shock ready: the procedure was the same as group 2 except without 10 seconds delay. A pre-programmed defibrillator was utilized for monitoring AMSA value. Regardless of groups, ROSC was significantly greater when the first DF was delivered after 5 minutes of CPR compared to that of less than 5 minutes of CPR (23/30 vs 4/30, p<0.001), Significantly reduced CPR interruption times (2.0±3 vs 26±11 and 8.4±3 sec, p<0.001) and the number of DF (1.7±1.3 vs 3.1±0.9 and 3.5±1.0 p<0.001) were observed in the AMSA guided group compared with the other two groups, this was associated with significantly better post-resuscitation myocardial function and longer durations of survival. These findings provide evidence that after prolonged VF, the heart may not ready to be resuscitated with 2 minutes of CPR. The continuously and Longer duration of CPR would increases the successful rate of DF. The optimal timing of DF could be guided by AMSA, and therefore improves the outcomes of CPR.
- © 2011 by American Heart Association, Inc.