Quantifying Glomerular Filtration Rates: Kidney Function Analysis Method and Apparatus
Bruce A. Molitoris,
Daniel J. Meier,
Ruben M. Sandoval,
James S. Strickland.
Acute Kidney Injury (AKI) remains a vexing clinical problem resulting in unacceptably high patient mortality,
development of chronic kidney disease and accelerated progression to end stage kidney disease. Although clinical risks
factors for developing AKI have been identified, there is no reasonable surveillance technique (“biomarker”) to definitively
and rapidly diagnose and determine the extent of severity of AKI in any patient. Since patient outcomes correlate
with the extent of injury, and effective therapy requires early intervention, the ability to rapidly diagnose and stratify patients
by their level of kidney injury is paramount for clinical progress in this field. Therefore, FAST BioMedical is developing
and characterizing an optical measurement technique utilizing a novel minimally invasive Ratiometric Fluorescence
Device (RFD) that can rapidly, accurately, and repetitively quantify kidney function, the measured glomerular filtration
rate (mGFR), independent of serum or urinary measurements. A sub-millimeter optical fiber, that delivers excitation light
and collects fluorescent emissions, is inserted into a peripheral or central venous access via commercial intravenous catheters.
A mixture of two fluorescent dextrans of different sizes and distinct fluorophores, a small freely kidney filterable
“reporter” molecule and large non-filterable plasma volume “marker” molecules, is infused as a bolus, excited sequentially
by light-emitting diodes, and in vivo signals detected and quantified by photomultiplier tubes. The patented quantitative
ratiometric technique, by utilizing two fluorescent reporter molecules, minimizes the inherent limitations of intensity
fluorescence determinations and allows for rapid and accurate determinations of mGFR and plasma volume. Utilization of
plasma fluorescent detection allows for the use of a two compartment model thus markedly minimizing the time needed
for measuring GFR by eliminating extracellular space distribution of the filterable molecule.
Keywords: Acute kidney injury, glomerular filtration rate, kidney biomarker, kidney function, Kidney Function Analysis, GFR Determination, Ratiometric Fluorescence Analysis, Serum Creatinine, exracellular fluid volume, Fluorescence Tissue Imaging, GFR Technique, Plasma Clearance, Fluorescent Detector.
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