Experimental timeline.

After 5 min of untreated ventricular fibrillation, cardiopulmonary resuscitation was initiated using a mechanical chest compression device. The lightning marks indicate the onset of a 10-s pause in chest compression for rhythm analysis and a 150-J electric shock, if indicated. After ROSC, the animals were observed for 60 min in a simulated intensive care setting. Arterial pressure, ETCO₂, MFI, Êpillary number, and PbtO₂ were sampled at pre-arrest baseline, 1-min intervals for 15 min after ROSC, and 30, 45, and 60 min after ROSC. Arterial blood gases were measured at pre-arrest baseline and 3, 15, and 60 min after ROSC. MAP and CPP during cardiopulmonary resuscitation were sampled 2 min after the initiation of cardiopulmonary resuscitation since most of the animals (80%) achieved ROSC 2–4 min after cardiopulmonary resuscitation. ETCO₂, end-tidal carbon dioxide; PbtO₂, brain tissue oxygen tension, MFI, microvascular flow index; Êpillary number, percent of counted number of perfused capillaries relative to that at pre-arrest baseline; PaO₂, partial pressure of oxygen in arterial blood; MAP, mean arterial pressure; CPP, coronary perfusion pressure; ROSC, restoration of spontaneous circulation.