Does the Type of Mechanical Chest Compressor Affect Resuscitation Outcome of out of Hospital Cardiac Arrest Patients? A Propensity-Score Based Comparison of Three Devices

Background Mechanical cardiopulmonary resuscitation (CPR) devices are currently recommended when high-quality CPR could not be provided and only if used by trained rescuers. Guidelines are against their routinely use since clinical trials results are controversial, and solid evidence of improved survival are missing. Moreover, many studies compared these devices to very high-quality manual CPR, hardly replicable in a pre-hospital emergency setting. Nowadays, different machines are available but literature is poor in direct comparison studies. Purpose To assess whether the type of mechanical chest compressor could affect the probability of return of spontaneous circulation (ROSC) and of 30-days mortality after an out-of-hospital cardiac arrest (OHCA) as compared to manual standard CPR. Methods Data were prospectively collected from our Utstein-based cardiac arrest registry. We considered all OHCAs from January 1, 2015 to December 31, 2022 from 7 provinces covered by the same regional emergency system (population covered 4.2mln. inhabitants) but equipped with three different types of mechanical compressor: Autopulse®; LUCAS® and Easy Pulse®. Patients treated with mechanical CPR and manual CPR were randomly matched via a multivariable logistic regression propensity score considering age, gender, witnessed OHCA, presence of bystander CPR, first rhythm recorded, EMS arrival time and lay defibrillation before EMS arrival. Logistic regression and COX regression models were performed and adjusted for resuscitation duration to investigate the association between the type of CPR and the probability of ROSC and of 30-day mortality. Results Among 13,203 OHCAs with attempted CPR, 10,497 (79.5%) received manual CPR and in 2,405 (18.2%) mechanical CPR [Easy Pulse® in 1,102(45.8%), Autopulse® in 776 (32.3%) and LUCAS® in 521 (21.7%)]. ROSC before hospital admission was obtained in 1,712 patients (13.0%) and 762 (5.8%) were alive after 30 days. After propensity score matching two homogeneous groups of 1,946 patients each (manual and mechanical CRP) were identified. The rate of ROSC and of 30-day survival were lower in the mechanical CPR group (ROSC: 14.7% vs 24.1%; p<0.001; 30-day survival 6% vs 14%; p<0.001). The three devices showed an independent association with the probability of ROSC as compared to manual CPR [Autopulse®: OR 1.76, 95% CI (1.36-2.28) p<0.001; LUCAS®:OR 1.55, 95% CI (1.13-2.13), p=0.006 and Easy Pulse®:OR 0.49; 95% CI (0.37-0.65), p<0.001] (Figure 1A). Only Autopulse® was independently associated with 30-day mortality [AutoPulse HR 0.87, 95%CI (0.79-0.97), p=0.01; LUCAS®: HR 1.00, 95%CI (0.88-1.14), p=0.97) and Easy Pulse®: HR: 1.06, 95%CI (0.97-1.16), p=0.19] (Figure 1B). Conclusions This is the first study comparing the performance of three devices for mechanical chest compressions revealing that they differently affect the probability of ROSC and of 30-day survival.