Circulatory response to fluid overload removal by extracorporeal ultrafiltration in refractory congestive heart failure

OBJECTIVES The goal of this study was to investigate the hemodynamic and ci rculatory adjustments to extracorporeal ultrafiltration (UF) in refractory congestive heart failure (rCHF). BACKGROUND In rCHF, UF allows clinical improvement and restores diuretic ef ficacy. However, in the course of a UF session, patients are exposed to rap id variations of body fluid composition so that, as fluid is withdrawn from the intravascular compartment, hypotension or even shock could occur. METHODS In 24 patients with rCHF undergoing UF, we measured, after every li ter of plasma water removed, hemodynamics, blood gas analysis (in both syst emic and pulmonary arteries), plasma volume changes (PV) and plasma refilli ng rate (PRR). The PV and PRR were calculated by considering hematocrit and ultrafiltrate volume. RESULTS In all patients, UF was performed safely, without side effects or h emodynamic instability (ultrafiltrate = 4,880 +/- 896 ml). Mean right atria l, pulmonary artery and wedge pressures progressively reduced during the pr ocedure. Cardiac output increased at the end of the procedure and, to a gre ater extent, 24 h later, in relation to the increase of stroke volume. Hear t rate and systemic vascular resistance did not increase, and other periphe ral biochemical parameters did not worsen during UF. Intravascular volume r emained stable throughout the entire duration of the procedure, indicating that a proportional volume of fluid was refilled from the congested parench yma. CONCLUSIONS In patients with rCHF, subtraction of plasma water by UF is ass ociated with hemodynamic improvement. Fluid refilling from the overhydrated interstitium is the major compensatory mechanism for intravascular fluid r emoval, and hypotension does not occur when plasma refilling rate is adequa te to prevent hypovolemia. (C) 2001 by the American College of Cardiology.