Effects of incomplete chest wall decompression during cardiopulmonary resuscitation on coronary and cerebral perfusion pressures in a porcine model of cardiac arrest

Abstract: Introduction:: Recent data suggest that generation of negative intrathoracic pressure during the decompression phase of CPR improves hemodynamics, organ perfusion and survival. Hypothesis:: Incomplete chest wall recoil during the decompression phase of standard CPR increases intrathoracic pressure and right atrial pressure, impedes venous return, decreases compression-induced aortic pressures and results in a decrease of mean arterial pressure, coronary and cerebral perfusion pressure. Methods:: Nine pigs in ventricular fibrillation (VF) for 6min, were treated with an automated compression/decompression device with a compression rate of 100min-1, a depth of 25% of the anterior–posterior diameter, and a compression to ventilation ratio of 15:2 with 100% decompression (standard CPR) for 3min. Compression was then reduced to 75% of complete decompression for 1min of CPR and then restored for another 1min of CPR to 100% full decompression. Coronary perfusion pressure (CPP) was calculated as the diastolic (aortic (Ao)–right atrial (RA) pressure). Cerebral perfusion pressure (CerPP) was calculated multiple ways: (1) the positive area (in mmHgs) between aortic pressure and intracranial pressure (ICP) waveforms, (2) the coincident difference in systolic and diastolic aortic and intracranial pressures (mmHg), and (3) CerPP=MAP-ICP. ANOVA was used for statistical analysis and all values were expressed as mean±S.E.M. The power of the study for an alpha level of significance set at 0.05 was >0.90. Results:: With CPR performed with 100%–75%–100% of complete chest wall recoil, respectively, the CPP was 23.3±1.9, 15.1±1.6, 16.6±1.9, p=0.003; CerPP was: (1) area: 313.8±104, 89.2±39, 170.5±42.9, p=0.03, (2) systolic aortic minus intracranial pressure difference: 22.8±3.6, 16.5±4, 23.7±4.5, p=n.s., and diastolic pressure difference: 5.7±3, -2.4±2.4, 3.2±2.5, p=0.04 and (3) mean: 14.3±3, 7±2.9, 12.4±2.9, p=0.03, diastolic aortic pressure was 28.1±2.5, 20.7±1.9, 20.9±2.1, p=0.0125; ICP during decompression was 22.8±1.7, 23±1.5, 19.7±1.7, p=n.s. and mean ICP was 37.1±2.3, 35.5±2.2, 35.2±2.4, p=n.s.; RA diastolic pressure 4.8±1.3, 5.6±1.2, 4.3±1.2 p=0.1; MAP was 52±2.9, 43.3±3, 48.3±2.9, p=0.04; decompression endotracheal pressure, -0.7±0.1, -0.3±0.1, -0.75±0.1, p=0.045. Conclusions:: Incomplete chest wall recoil during the decompression phase of CPR increases endotracheal pressure, impedes venous return and decreases mean arterial pressure, and coronary and cerebral perfusion pressures. [Copyright &y& Elsevier]