Hemodynamic Ramp Test in Cardiogenic Shock Supported by Microaxial Flow Pump: Protocol Description, Feasibility, and Hemodynamic Response.

Abstract

Evidence-based protocols for microaxial flow pump (MAFP) weaning remain limited. This study aimed to standardize the ramp test for MAFP and evaluate its feasibility and associated hemodynamic trajectories. In this single-center prospective study, we developed and implemented an Impella ramp test in 54 cardiogenic shock patients who met pretest stability criteria. Forty-six patients (85%) completed the full protocol, while the test was terminated in eight patients according to predefined safety criteria (significant disturbances in arterial pressure or pulmonary artery wedge pressure [PAWP], or sustained arrhythmias), with prompt recovery observed upon returning to the baseline P-level. Under continuous hemodynamic monitoring via a pulmonary artery catheter, the Impella P-level was reduced stepwise from P8 to P2 at 5 minute intervals, while systemic arterial pulse pressure (SAPP), cardiac power output (CPO), and PAWP were recorded. In the overall cohort, SAPP increased by 12.2 mm Hg, CPO decreased by 0.09 W, and PAWP increased by 2.5 mm Hg. Patients supported with Impella 5.5 experienced a greater reduction in flow (-2.8 vs. -1.4 L/minute) and more pronounced hemodynamic changes compared to those with Impella CP. The Impella ramp test is feasible and safe, providing quantitative hemodynamic insights that may inform individualized clinical decision-making and MAFP weaning strategies.