Estimating Residual Renal Function via Blood Concentration

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Solution Overview

Problem

Conventional methods for estimating residual renal function in dialysis patients are cumbersome, error-prone, and require urine collection, leading to inaccurate measurements due to factors like urea reabsorption and creatinine secretion.

Innovation Solution

A computer-implemented method that estimates residual renal function using blood concentration values obtained at the start and end of dialysis sessions, along with time points, to calculate an estimation value independent of urine collection, leveraging the standard Kt/V parameter and computation algorithms to derive generation rates and clearance rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional techniques use 24-hour urine collection to estimate GFR, then measurement data can be obtained, but the procedure becomes cumbersome and error-prone due to collection errors and incomplete bladder emptying

Engineering Contradiction:

ImproveGFR measurement accuracyVSAvoidUrine collection procedure

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The invention extracts the measurement process from urine collection to blood sampling. Instead of collecting and analyzing urine over 24 hours, the method measures substance concentrations directly in blood at specific time points, eliminating the cumbersome urine collection procedure while maintaining measurement capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses blood as an intermediary substance to estimate GFR. Rather than directly measuring urine output and concentration, the method uses blood concentration values of substances (like creatinine or urea) at different time points as an intermediary to calculate the generation rate and subsequently estimate GFR

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If residual urea clearance is measured to estimate GFR, then measurement can be performed, but the result underestimates GFR due to urea reabsorption in renal tubules

Engineering Contradiction:

ImproveGFR estimation accuracyVSAvoidUrea reabsorption effect

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful effect of urea reabsorption into a beneficial measurement opportunity. By measuring the generation rate of urea (which accounts for reabsorption) and using it in the GFR estimation formula, the method actually benefits from the reabsorption phenomenon rather than being harmed by it, achieving more accurate GFR estimation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention changes the measurement parameter from direct urine concentration to blood concentration over time. By measuring blood substance concentration at multiple time points and calculating the generation rate, the method transforms the measurement approach to account for tubular reabsorption effects and achieve accurate GFR estimation

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If residual creatinine clearance is measured to estimate GFR, then measurement can be performed, but the result overestimates GFR due to creatinine secretion into renal tubules

Engineering Contradiction:

ImproveGFR estimation accuracyVSAvoidCreatinine secretion effect

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful secretion effect into a beneficial measurement opportunity. By measuring the generation rate of creatinine in blood (which incorporates secretion effects) and using it to estimate GFR, the method benefits from the secretion phenomenon rather than being harmed by it, achieving accurate GFR measurement

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Measurement precision

If mean serum concentration is used to calculate residual clearance, then calculation can be performed, but the procedure requires multiple measurements and increases complexity

Engineering Contradiction:

ImproveClearance calculation accuracyVSAvoidMeasurement procedure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention performs preliminary measurement of blood concentration at the start of dialysis treatment. This preliminary measurement, combined with the known dialysis clearance and treatment time, allows direct calculation of the generation rate without requiring multiple subsequent measurements, simplifying the overall procedure

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20230368908A1Estimating residual renal function

Publication Date: 2023.11.16 GAMBRO LUNDIA AB

AI summary

A computer system is configured to implement a method of estimating residual renal function in a dialysis patient based on data for two consecutive treatment sessions of intermittent dialysis therapy. The computer system obtains first and second blood concentration values (C1, C2) for a substance, e.g. urea, creatinine, at a start and an end of a first treatment session, and a third blood concentration value (C3) at a start of a second treatment session. The computer system also obtains time points (t1, t2, t3) for the start and the end of the first treatment session and the start of the second treatment session. The computer system then estimates the residual renal function as a function of the first, second, and third concentration values (C1, C2, C3), and the time points (t1, t2, t3). The method obviates the need to include data representing collection of urine from the patient.