Abstract 162: During a Cardiopulmonary Resuscitation Cycle it is Necessary to Re-verify a Shockable Rhythm Prior to Defibrillation Attempts
Background: AHA Guidelines recommend two minutes of CPR post-shock followed by ECG analysis and defibrillation if the patient still has shockable rhythm. This requires a pre-shock chest compression pause, which probably reduces the likelihood of return of spontaneous circulation (ROSC) post-shock. This immediate pre-shock pause could be avoided if rhythm analysis occurred earlier in the cycle. In the Circulation Improving Resuscitation Care (CIRC) study ECG was analyzed both one minute post-shock and immediately prior to defibrillation This database therefore enabled studying whether a second pre-shock ECG analysis was warranted. If not, CPR could continue uninterrupted in the pre-shock phase.
Methods: The randomized controlled CIRC trial included patients with out-of-hospital cardiac arrest (OHCA) of presumed cardiac etiology. Defibrillator data was used to categorize ECG rhythms as shockable or non-shockable one minute post-shock and immediately before next possible shock, and to record chest compressions and ventilations from transthoracic impedance (TTI) analysis. Episodes without rhythm analysiis due to compression artefacts or with lack of ECG or transthoracic impedanceTTI data were excluded from the analysis. ROSC was documented based on end-tidal CO2-measures, TTI and patient record.
Results: Of 4,231 patients with OHCA, 1657 (39%) received one shock or more and 1603 of these had analysable data. These patients received 4820 analysable shocks. Of these, 1513 (31%) had a shockable rhythm one minute post-shock, wich was also present immediately before the next possible shock in 1500 (99,1%) instances. Among the 13 shocks where the shockable rhythm one minute post-shock converted to a non-shockable rhythm prior to next possible shock, three instances were identified as ROSC.
Conclusion: This study suggests that it is necessary to reverify VF/VT prior to a defibrillation attempt if determined earlier in the same CPR cycle. Further studies are needed to document the effect of providing shocks to rhythms that are not indicated for shocks. organized rhythms.
- © 2013 by American Heart Association, Inc.