Abstract 14688: Relative Blood Volume Change After Single Doses of a Loop Diuretic to Assess Volume Status: A Patient Level Meta-analysis

Abstract

Background: In patients with congestive heart failure administration of an intravenous diuretic results in increased urine production and, depending on the volume status, an immediate change in relative blood volume (RBV). Changes in RBV are already applied clinically to monitor fluid removal and better guide diuresis in patients who undergo peripheral ultrafiltration. Using individual level patient data, we explored whether it is possible to measure changes in RBV after a single intravenous dose of loop diuretic through the measurement of serial hematocrit values. Based on normally occurring variation in volume-stable patients, the smallest change in RBV that would be detectable by routine serial hematocrits ranges from 6.4% to 8.6%. Methods and Results: Electronic databases were queried for articles that contained predefined MeSH terms in order to identify all studies in which patients received intravenous diuretics. The 764 studies that met our entry criteria were systematically reviewed and manually screened. We then conducted a meta-analysis from 14 studies that provided individual, patient-level data from at least 2 time points: just before and within 3 hours of administration of an intravenous loop diuretic. We found that among a total of 240 patients, RBV decreased by 11% (95% CI 10 to 12%) at 2 hours after an intravenous loop diuretic was given (Figure); there was no significant difference in this finding based on whether or not patients had heart failure. Conclusion: We found that anticipated RBV change with single doses of intravenous loop diuretics exceeds the smallest detectable change in RBV that can be obtained by serial hematocrits. This implies that routine hematocrits can be used to track RBV change across serial doses of intravenous loop diuretics, potentially providing a target for a dry interstitium in acute heart failure.