Figure 1. Prehospital Flow of Participants in a Study of Intra-arrest Transport, Extracorporeal Cardiopulmonary Resuscitation, and Immediate Invasive Assessment and Treatment in Refractory Out-of-Hospital Cardiac Arrest.

DSMB indicates data and safety monitoring board; ECLS, extracorporeal life support; CPR, cardiopulmonary resuscitation; ICU, intensive care unit; OHCA, out-of-hospital cardiac arrest; ROSC, return of spontaneous circulation.

^aRandomization into standard strategy and invasive strategy groups was based on 4 strata (men ≤45 years, men >45 years, women ≤45 years, women >45 years), with block size of 8.

^bSeven patients were excluded after randomization because consent was refused and information was not available as to how many were randomized to each group for analysis.