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Abstract: SA-PO022

Estimating Changes in Glomerular Filtration Rate During Dialysis With a Fluorescent Tracer

Session Information

  • Bioengineering
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Bioengineering

  • 300 Bioengineering

Authors

  • Pino, Christopher, Innovative BioTherapies, Ann Arbor, Michigan, United States
  • Chan, Goldia, University of Michigan, Ann Arbor, Michigan, United States
  • Johnston, Kimberly, Innovative BioTherapies, Ann Arbor, Michigan, United States
  • Humes, H. David, Innovative BioTherapies, Ann Arbor, Michigan, United States
Background

Fluorescein-isothiocyanate (FITC)-sinistrin can be used to measure glomerular filtration rate (GFR) as it’s removed from the body exclusively by the kidneys and can be detected transdermally. Currently, there’s a need to rapidly determine estimated GFR (eGFR) in acute kidney injury (AKI) patients during continuous renal replacement therapy (CRRT) to improve clinical decision-making. The viability of measuring changes in eGFR with FITC-sinistrin was tested in a swine model of progressive AKI during CRRT.

Methods

In vitro circuits (IVC) (n=2) were first trialed to mimic conditions that would be tested in vivo. A FITC-sinistrin solution was circulated through a hemofilter to mimic clearance from the kidneys and then through a dialyzer. Ultrafiltrate (UF) was removed from the hemofilter at three progressively decreasing rates to mimic loss of urine production. Dialysis was delivered at a constant rate. Transdermal devices were placed in the circuit to measure FITC-sinistrin. In vivo clearance of FITC-sinistrin was studied by placing anesthetized pigs on CRRT (n=3). Pigs underwent three phases progressing from normal to unilaterally nephrectomized and then bilaterally nephrectomized. FITC-sinistrin was administered prior to each phase and continuously measured transdermally. Dialysis was kept consistent throughout all three phases. Pre- and post-dialyzer blood samples were collected to calculate clearance from measured FITC-sinistrin concentrations in plasma.

Results

FITC-sinistrin clearance was reduced in all experiments, either in vitro, where UF was decreased or with successive nephrectomies in vivo. IVC studies showed agreement between transdermal device-estimated clearance and plasma-measured clearance (r2=0.95). In vivo experiments demonstrated no significant differences between transdermal device-estimated and plasma-measured methods of determining proportional changes in clearance from phase to phase. Clearance of FITC-sinistrin, urea, and creatinine by dialysis were demonstrated to be constant.

Conclusion

For a subject receiving a constant dialysis prescription, clearance of FITC-sinistrin is constant, allowing for changes in eGFR to be attributed to changes in kidney function. Therefore, measurement of FITC-sinistrin clearance is a viable method for estimating changes in GFR during dialysis.

Funding

  • Other NIH Support