Supplementary Material for: Cardiac Output Changes during Renal Replacement Therapy: A Scoping Review

Introduction: Renal Replacement Therapy (RRT) is associated with hypotension. However, its impact on cardiac output (CO) is less understood. We aimed to describe current knowledge of CO monitoring and changes during RRT. Methods: We searched Medline, Embase and Cochrane from 01/01/2000 to 31/01/2023 using Covidence for studies of intermittent hemodialysis (IHD) and continuous RRT (CRRT) with at least three CO measurements during treatment. Two independent reviewers screened citations and a third resolved disagreements. The findings did not allow meta-analysis and are presented descriptively. Results: We screened 3285 articles and included 48 (37 during IHD, nine during CRRT, and two during both). Non-invasive devices (electrical conductivity techniques and finger cuff pulse contour) were the most common CO measurement techniques (21 studies). The median baseline cardiac index in IHD studies was 3 L/min/m2 (95% CI, 2.7 to 3.39). Among the 88 patient cohorts studied, a decrease in CO occurred in 63 (72%). In 16 cohorts, the decrease was severe (> 25%). Changes in blood pressure (BP) were not concordant in extent or direction with changes in CO. The decrease in CO correlated weakly with ultrafiltration rate (r = - 0.3, p = 0.05) and strongly with changes in systemic vascular resistance (SVR) (r = - 0.6, p < 0.001). Discussion/Conclusion: There are limited data on CO changes during RRT. However, a decrease in CO appeared common and was marked in one of five patient cohorts. Such decreases often occurred without BP changes and were associated with increased SVR.