Factors associated with quality of bystander CPR: the presence of multiple rescuers and bystander-initiated CPR without instruction.

Aims: To identify the factors associated with good-quality bystander cardiopulmonary resuscitation (BCPR).

Methods: Data were prospectively collected from 553 out-of-hospital cardiac arrests (OHCAs) managed with BCPR in the absence of emergency medical technicians (EMT) during 2012. The quality of BCPR was evaluated by EMTs at the scene and was assessed according to the standard recommendations for chest compressions, including proper hand positions, rates and depths.

Results: Good-quality BCPR was more frequently confirmed in OHCAs that occurred in the central/urban region (56.3% [251/446] vs. 39.3% [42/107], p=0.0015), had multiple rescuers (31.8% [142/446] vs. 11.2% [12/107], p<0.0001) and received bystander-initiated BCPR (22.0% [98/446] vs. 5.6% [6/107], p<0.0001). Good-quality BCPR was less frequently performed by family members (46.9% [209/446] vs. 67.3% [72/107], p=0.0001), elderly bystanders (13.5% [60/446] vs. 28.0% [30/107], p=0.0005) and in at-home OHCAs (51.1% [228/446] vs. 72.9% [78/107], p<0.0001). BCPR duration was significantly longer in the good-quality group (median, 8 vs. 6min, p=0.0015). Multiple logistic regression analysis indicated that multiple rescuers (odds ratio=2.8, 95% CI 1.5-5.6), bystander-initiated BCPR (2.7, 1.1-7.3), non-elderly bystanders (1.9, 1.1-3.2), occurrence in the central region (2.1, 1.3-3.3) and duration of BCPR (1.1, 1.0-1.1) were associated with good-quality BCPR. Moreover, good-quality BCPR was initiated earlier after recognition/witness of cardiac arrest compared with poor-quality BCPR (3 vs. 4min, p=0.0052). The rate of neurologically favourable survival at one year was 2.7 and 0% in the good-quality and poor-quality groups, respectively (p=0.1357).

Conclusions: The presence of multiple rescuers and bystander-initiated CPR are predominantly associated with good-quality BCPR.