Kidney Week

Abstract: TH-PO222

Postfilter Hematocrit Is a Predictor of Continuous Kidney Replacement Therapy Filter Life

Session Information

• Hemodialysis, Hemodiafiltration, and Frequent Dialysis
  October 24, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 801 Dialysis: Hemodialysis and Frequent Dialysis

Authors

• Radford, Gwyndolyn Maluki, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Gwyndolyn Maluki Radford, MD

• Neyra, Javier A., The University of Alabama at Birmingham, Birmingham, Alabama, United States

Javier A. Neyra, MD, MS, FASN

• Swee, Melissa L., University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Melissa L. Swee, MD, MS, FASN

• Kashani, Kianoush, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Kianoush Kashani, MD, MS, FASN

• Yamada, Masaaki, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Masaaki Yamada, MD

• Sarrazin, Mary Vaughan, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Mary Vaughan Sarrazin, PhD

• Jalal, Diana I., University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Diana I. Jalal, MD

• Griffin, Benjamin R., University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States

Benjamin R. Griffin, MD

Background

Premature filter clotting occurs in up to a quarter of continuous renal replacement therapy (CRRT) filters resulting in blood loss, reduced treatment efficacy, and increased cost. Modifiable factors associated with clotting include access type and location, CRRT modality, and anticoagulation. One additional factor is post-filter hematocrit (Hct), which is a function of pre-filter Hct and filtration fraction (FF). Experts recommend monitoring and minimizing post-filter Hct to reduce clotting risk. However, post-filter Hct is not routinely measured in clinic practice due in part to a paucity of data to support these recommendations. In this study, we hypothesized that there would be an inverse relationship between post-filter Hct and CRRT filter life.

Methods

In this secondary analysis of a previously published study (PMID: 36630406), post-filter Hct was calculated using published formulas utilizing systemic Hct and FF. FF was derived from ultrafiltration rates, rates of pre- and post-filter replacement fluid, and blood flow rate. The primary outcome was filter life (hours). Circuits were excluded if they lasted <2 hours, or if any of the variables used to calculate post-filter Hct were absent. A Generalized Linear Model (GLM) was used to account for multiple filters per patient, and was adjusted for age, race, sex, illness severity, and type of anticoagulation.

Results

A total of 412 filters from 111 patients were included in the analysis. In the final GLM analysis, post-filter Hct was inversely associated with filter life (adjusted estimate = -0.53, 95% CI -0.11 to -0.96, p=0.01). For categorical classification, a post-filter Hct of 29%, the 33rd percentile, was most clinically meaningful. Filters with a post-filter Hct <29% had a median filter life of 34.7 (IQR 18.0-65.6) hours, compared to 24.0 (IQR 13.2-50.9) with post-filter Hct ≥29% (p = 0.04).

Conclusion

In patients receiving CRRT, post-filter Hct was independently associated with decreased filter life and may represent a feasible parameter to monitor during CRRT to maximize filter life. Future prospective studies should determine whether prescription adjustments based on measured post-filter Hct can prolong filter life.