Arterial pressure, end-tidal carbon dioxide, and central venous oxygen saturation in reflecting compression depth

Background We sought to investigate the utility of arterial pressure, end-tidal carbon dioxide (ETCO2), and central venous oxygen saturation (SCVO2) to guide compression depth adjustment. Thus, in a pig model of cardiac arrest, we observed these parameters during cardiopulmonary resuscitation (CPR) with optimal and suboptimal compression depths. Methods Sixteen pigs underwent three experimental sessions after induction of ventricular fibrillation. First, the animals received two 4-min CPR trials with either optimal (20% of the anteroposterior diameter) or suboptimal (70% of the optimal depth) compression depth. Second, the animals received two 5-min CPR trials with optimal compression depth, in which adrenaline (0.02 mg/kg) or saline placebo was administered. Third, the animals randomly received compression with either optimal or suboptimal depth during advanced cardiovascular life support. Results The systolic arterial pressure reflected compression depth most accurately and immediately (area under the curve [AUC], 0.895–0.939 without adrenaline and 0.928–1.000 with adrenaline). Although the response of ETCO2 to the change in compression depth was 0.5 min slower than that of the systolic arterial pressure, the performance of ETCO2 was comparable with that of systolic arterial pressure. SCVO2 did not reflect compression depth. Adrenaline administration remarkably increased systolic arterial pressure, diastolic arterial pressure, and coronary perfusion pressure but did not affect the ETCO2 readings. Conclusion In a pig model of cardiac arrest, systolic arterial pressure reflected compression depth immediately and accurately. The performance of ETCO2 was comparable with that of systolic arterial pressure. SCVO2 did not reflect compression depth.