Right Ventricular End-Diastolic Volume as a Predictor of the Hemodynamic Response to a Fluid Challenge

Abstract

Objective: To compare thermodilution right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery occlusion pressure (Ppao) as predictors of the hemodynamic response to a fluid challenge. Design: Prospective cohort study. Setting: Medical ICU of a university-affiliated county hospital and medical-surgical ICU of a community hospital. Patients: Twenty-five critically ill patients who had one or more clinical conditions that suggested the possibility of inadequate preload. Interventions: Thirty-six fluid challenges. Fluid (saline or colloid) was administered rapidly until the Ppao rose by at least 3 mm Hg. When a patient underwent more than one fluid challenge, these were given on separate days and for different clinical indications. Measurements and Results: Responders (n520; >10% increase in stroke volume (SV)) and nonresponders (n516; <10% increase in SV) differed with respect to baseline Ppao (10.063.4 vs 14.263.6 mm Hg; p50.001), but not with respect to baseline RVEDVI (105631 vs 119633 mL/m2; p50.22). There was a moderate correlation between RVEDVI and fluid-induced change in SV (r50.44); the relationship between Ppao and change in SV was stronger (r50.58). A positive response to fluid was observed in 4 of 9 cases in which RVEDVI exceeded 138 mL/m2, a threshold value that has been suggested to reliably predict a poor response to fluid. Conclusion: RVEDVI was not a reliable predictor of the response to fluid. As a predictor of fluid responsiveness, Ppao was superior to RVEDVI. In an individual patient, adequacy of preload is best assessed by an empiric fluid challenge. (CHEST 1998; 113:1048-54)