Mechanical chest compression and extracorporeal life support for out-of-hospital cardiac arrest. A 30-month observational study in the metropolitan area of Milan, Italy

Background: Return of spontaneous circulation (ROSC) is achieved in 25% of out-of-hospital cardiac arrest (OHCA) patients. Mechanical chest compression (mechCPR) may maintain better perfusion during transport, allowing hospital treatments like extracorporeal circulation life support (ECLS). We aim to assess the effectiveness of a pre-hospital protocol introduction. Methods: Observational, retrospective study assessing all OHCA patients aged 12-75, with no-flow time <20 min in a metropolitan area (Milan, Italy, 2013-2016). Primary outcomes: ROSC and Cerebral Performance Category score (CPC) <2 at hospital discharge. Logistic regressions with multiple comparison adjustments balanced with propensity scores calculated with inverse probability of treatment weighting were performed. Results: 1366 OHCA were analysed; 305 received mechCPR, 1061 manual chest compressions (manCPR), and 108 ECLS. ROSC and CPC <2 were associated with low-flow minutes (odds ratio [95% confidence interval] 0.90 [0.88-0.91] and 0.90 [0.87-0.93]), shockable rhythm (2.52 [1.71- 3.72] and 10.68 [5.63-20.28]), defibrillations number (1.15 [1.07-1.23] and 1.15 [1.04-1.26]), and mechCPR (1.86 [1.17-2.96] and 2.06 [1.11- 3.81]). With resuscitation times >13 min, mechCPR achieved more frequently ROSC compared to manCPR. Among ECLS patients, 70% had time exceeding protocol: 8 (7.5%) had CPC <= 2 (half of them with low-flow times between 45 and 90 min), 2 (1.9%) survived with severe neurological disabilities, and 13 brain-dead (12.0%) became organ donors. Conclusions: MechCPR patients achieved ROSC more frequently than manual CPR patients; mechCPR was a crucial factor in an ECLS protocol for refractory OHCA. ECLS offered a chance of survival to patients who would otherwise die.