Proportional pulmonary pulse pressure: A new index to assess response to veno-arterial extracorporeal membrane oxygenation

Abstract

Background Based on theoretical physiology, the ratio of pulmonary artery pulse pressure to mean pulmonary pressure (PP-MPAP), termed proportional pulmonary pulse pressure, provides a measure of coupling between the right ventricle and the pulmonary circulation. This study tested the hypothesis that lower PP-MPAP ratio was associated with left ventricular (LV) distension in patients with cardiogenic shock who underwent extracorporeal life support (ECLS). Methods This is a retrospective observational single-centre study of 22 patients with cardiogenic shock who underwent ECLS as the primary support modality without and with LV distension and Impella unloading. The relationship between post-support PP-MPAP and 12-hour lactate clearance was also assessed. Results Of the 22 patients: 10 patients underwent additional Impella unloading due to LV distension (Group 1) and 12 patients on ECLS only without LV distension (Group 2). As predicted by the theoretical model, PP-MPAP on ECLS dropped in Group 1 (pre-Impella) from 0.473 ± 0.067 to 0.372 ± 0.087, p < 0.001; but increased in Group 2 patients without LV distension (0.518 ± 0.070 to 0.549 ± 0.072, p = 0.002). Impella support in Group 1 increased PP-MPAP (0.372 ± 0.087 to 0.615 ± 0.094, p < 0.001). On multiple regression analysis, post-support PP-MPAP was significantly associated with 12-hour lactate clearance. Conclusion Changes in PP-MPAP is associated hemodynamic response to ECLS and 12-hour lactate clearance. This simple parameter may guide therapeutic optimization in cardiogenic shock and ECLS.