Relative Blood Volume Profiles Hours After Loop Diuretic Administration: A Systematic Review and Meta-analysis.

Background: Plasma refill rates can be estimated by combining measurements of urine output with relative blood volume profiles. Change in plasma refill rates could guide decongestive loop diuretic therapy in acute heart failure. The objective of the study was to assess average relative blood volume profiles generated from 2 or 3 follow-up measurements obtained hours after loop diuretic administration in subjects with vs without baseline congestion.

Methods: A systematic review was conducted of articles written in English, French, Spanish, and German, using MEDLINE (1964 to 2019), Cochrane Reviews (1996 to 2019), and Embase (1974 to 2019). Search terms included the following: diuretics, hemoconcentration, plasma volume, and blood volume. We included studies of adults given a loop diuretic with at least one baseline and one follow-up measurement. A single author extracted subject- or group-level blood volume measurements, aggregated them when needed, and converted them to relative changes.

Results: Across all 16 studies that met the prespecified inclusion criteria, relative blood volume maximally decreased 9.2% (6.6% to 12.0%) and returned to baseline after 3 or more hours. Compared to subjects without congestion, those with congestion experienced smaller decreases in relative blood volume across all follow-up periods ( = 0.001) and returned to baseline within the final follow-up period.

Conclusions: Single doses of loop diuretics produce measurable changes in relative blood volume that follow distinct profiles for subjects with vs without congestion. Measured alongside urine output, these profiles may be used to estimate plasma refill rates-potential patient-specific targets for decongestive therapy across serial diuretic doses.