Abstract 11: Is the Outcome from Witnessed VF Cardiac Arrest Improved by Providing More CPR? Results from DEFI2005, a Randomized Controlled Trial of two AED Protocols
Several before/after studies have found that the Guidelines 2005 CPR protocol improved cardiac arrest outcomes compared with historical cohorts treated with Guidelines 2000. These results support the rationale that fewer pauses and more CPR may improve survival. However, the recently reported DEFI2005 randomized controlled comparison of these protocols found no difference in outcome, analyzed on an intention-to-treat basis. To further investigate this outcome, we performed a sub-analysis on all patients with a witnessed arrest of cardiac etiology, presenting in VF, and treated without protocol deviations.
Method: From 09/2005 to 03/2007, 200 biphasic LIFEPAK® 500 AEDs used by firefighters, were randomized bi-monthly by fire station (clinicaltrials.gov NCT00139542). The 100 CONTROL AEDs conformed to Guidelines 2000. The 100 STUDY AEDs added pre-shock CPR, removed stacked shocks and post-shock pulse checks. In both groups, firefighters received weekly CPR training. Cases with protocol deviations such as wrong AED configuration or non-adherence to AED prompts causing inappropriate shocks were excluded. AED ECG and impedance signals were reviewed to quantify CPR.
Results: A total of 164 CONTROL and 168 STUDY patients met our sub-analysis criteria. The STUDY group had significantly more hands-on time, and shorter pauses in chest compressions (CC) around the shock (table⇓). Rates of ROSC (p=0.18) and hospital admission (p=0.27) were numerically though not significantly lower with STUDY than CONTROL protocol.
Conclusion: The results of this prospective randomized trial contradict the findings of before/after studies comparing the two protocols. This contradiction is not explained by protocol deviations, presenting rhythms, or arrest etiologies in the present study. Further study is required to resolve these discrepant findings, and understand their implications for optimizing cardiac arrest resuscitation protocols.