How Much Does Intravenous Fluid Cause Hematocrit to Drop? Improving Interpretation of Hematocrit Toward Better Post-Hemorrhage Care.

This article focuses on developing an empiric model to predict post-operative hematocrit levels by incorporating patient-specific data such as pre-operative hematocrit, intraoperative fluid intake, estimated blood volume, and estimated blood loss (EBL) among patients undergoing elective knee or hip arthroplasty without substantial post-operative bleeding. Using data from 6,648 cases, the model demonstrated improved predictive accuracy (R² = 0.558) compared to a physician mental model based solely on pre-operative hematocrit (R² = 0.280) and a physiology-based model including blood volume changes (R² = 0.398). The findings suggest that integrating electronic health record (EHR) data enhances the estimation of expected post-operative hematocrit, which may aid in distinguishing ongoing hemorrhage from expected hematocrit changes due to fluid administration. The study acknowledges limitations in generalizability beyond the studied surgical population and highlights the need for further validation in more complex clinical scenarios.