Background: Cardiopulmonary resuscitation (CPR) with the use of mechanical devices is recommended during ambulance transport. However, the CPR quality en route and while in transfer to the emergency department (ED) for out-of-hospital cardiac arrests (OHCAs) remains uncertain. We developed a mechanical CPR device outfitted on a reducible stretcher (M-CPR) and compared with standard manual CPR on a standard stretcher (S-CPR) to evaluate CPR quality.
Methods: Adult OHCAs transported by five ambulances in a metropolitan area with a population of 3.5 million (many of whom lived in high-rise buildings) from September to October (before-phase) and November to December (after-phase) in 2015 were collected. The reducible stretcher was developed for use in a small elevator during the transfer from scene to ambulance, and the AutoPulse® (ZOLL Medical, Chelmsford, MA, USA) was used for M-CPR. Chest compression fraction (CCF) was measured by transthoracic impedance data using an X-series® cardiac monitor (ZOLL Medical) during time from attachment to patient to arrival to the ED. A comparison of CCF using a Wilcoxon signed-rank test evaluated the difference between the before- and after-phases.
Results: Of the eligible 49 OHCAs, 31 (21 in the before-phase and 10 in the after-phase) were analyzed, excluding patients for whom CCF was not measured, for whom M-CPR was not used, who had a return of spontaneous circulation in the field before transport, or who collapsed during transport. There were no differences in demographic data. Median total CCF (median, q1-q3) was significantly higher in the after-phase M-CPR group (85.2, 83.4-86.3) than in the before-phase S-CPR group (80.1, 68.0-85.2) (p = 0.03).
Conclusion: Mechanical CPR on the reducible stretcher during the transport of OHCAs to the ED showed a much higher chest compression fraction than standard manual CPR.
Keywords: ambulance transport; cardiopulmonary resuscitation; mechanical compression; stretcher.