Background Survival from out-of-hospital cardiac arrest (OHCA) is associated with the quality of cardio-pulmonary-resuscitation (CPR). The European Resuscitation Council (ERC) and American Heart Association (AHA) define high quality CPR as compression depth of 5–6 centimeters, compression rate of 100–120 compressions/minute, full recoil (>400 milliseconds) after each compression and a hands-on time (compression fraction) of at least 60% (ERC) or 80% (AHA). The aim of this study was to investigate if unguided CPR performed by Copenhagen Emergency Medical Services (EMS) met these recommendations.

Method From October throughout December 2018, OHCA data were collected from ambulances within the Capital Region of Denmark using Zoll X-series defibrillator (without CPR feedback dashboard or metronome). Only cases where EMS performed CPR were included. Data was uploaded to a central database and extracted to EXCEL for descriptive statistics and preliminary results.

Results EMS CPR was performed in 330 cases of which 252 were available for analysis. Mean (SD) compression depth was 5.6±1.7 centimeters, compression rate was 110±9.8 compressions/minute, release velocity was 410±125.1 milliseconds, compression quality (correct compression depth + correct compression rate) was 13.8% and compression fraction was 69.7%.

Conclusion The quality of EMS-delivered CPR, unguided by feedback or metronome, was within recommendations for compression depth, compression rate and release velocity. CPR fraction was between ERC and AHA guidelines. Compression quality, which is not included in ERC/AHA recommendations, did not reach the manufactures recommended >60%. Further work is ongoing to evaluate the effect of adding real-time feedback to guide EMS CPR.