Eligibility and hypothetical time windows for eCPR in out-of-hospital cardiac arrest patients managed by a nationwide helicopter-emergency medical service: A multicentric, retrospective cohort study

AIM: To determine the proportion of out-of-hospital cardiac arrest (OHCA) patients, who fulfilled eligibility criteria for extracorporeal cardiopulmonary resuscitation (eCPR) on scene and were managed by a national helicopter emergency medical service (HEMS). Additionally, we compared estimated time intervals from collapse until hypothetical eCPR for the scenarios of on scene and in-hospital eCPR.

METHODS: This multicentre, retrospective study included 6687 non-traumatic OHCA patients (01/2010-12/2019). Time intervals from collapse until hypothetical eCPR were calculated using measured, published or estimated data.

RESULTS: ECPR eligibility criteria were fulfilled in 890 [13.3 % (95 %CI, 12.5-14.2 %)] of 6687 patients. In these patients, the estimated time from collapse to hypothetical eCPR was shorter in the on scene than the in-hospital eCPR scenario (42.2 ± 5.2 vs. 82.4 ± 6.1 min, p < 0.001). More patients underwent hypothetical eCPR within 35, 40, 45, 50, 55, 60, 65, 70 and 75 min after collapse in the on scene compared to the in-hospital eCPR scenario (p < 0.001 for all comparisons). The proportions of patients, who fulfilled eCPR eligibility criteria but could not undergo hypothetical eCPR within 60 or 75 min, were lower in the on scene compared to the in-hospital eCPR scenario [60 min: 0.9 % (95 %CI, 0.4-1.8 %) vs. 100 % (95 %CI, 99.6-100 %), p < 0.001; 75 min: 0.1 % (95 %CI, 0-0.6 %) vs. 87.4 % (95 %CI, 85.1-89.5 %), p < 0.001].

CONCLUSION: In Austrian HEMS, one in seven OHCA patients fulfilled eCPR eligibility criteria on scene. Our estimates strongly suggest that initiation of eCPR on scene could significantly shorten low-flow times and increase the proportion of eligible OHCA patients, who receive this potentially life-saving intervention.