Zirconium Phosphate Sorbent BUN Estimation via Effluent Ammonia

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Solution Overview

Problem

Current methods for estimating patient blood urea nitrogen (BUN) levels prior to dialysis are expensive, time-consuming, and require manual blood sampling, failing to account for ammonia absorption by zirconium phosphate sorbents and lacking automated measurement capabilities.

Innovation Solution

A method and system that introduce ammonium removal solutions into a zirconium phosphate sorbent module, using an ammonia sensor to determine the total ammonia content in the effluent, which estimates pre-dialysis BUN levels based on the volume-averaged ammonia content, urea reduction ratio, and patient water volumes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual blood sampling is used to measure BUN levels, then measurement accuracy is maintained, but time consumption and operational complexity increase

Engineering Contradiction:
ImproveBUN measurement accuracyVSAvoidtime consumption
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces manual blood sampling and laboratory analysis with an automated sensor-based measurement system. An ammonia sensor continuously monitors the dialysate to estimate BUN levels, eliminating the need for technicians to manually draw blood and perform laboratory tests, thus reducing time consumption while maintaining measurement accuracy through automated detection algorithms

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses ammonia concentration in the dialysate as an intermediary parameter to estimate BUN levels. Instead of directly measuring blood BUN, the system measures ammonia in the dialysate which correlates with patient BUN levels, providing an indirect but accurate measurement method that avoids invasive blood sampling

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If manual blood sampling is used to measure BUN levels, then measurement accuracy is maintained, but operational complexity and cost increase

Engineering Contradiction:
ImproveBUN measurement accuracyVSAvoidoperational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex manual procedures including blood drawing, sample handling, and laboratory analysis with a simple automated sensor system. The ammonia sensor integrated into the dialysis machine automatically monitors dialysate and calculates BUN estimates, eliminating multiple manual steps and reducing operational complexity while maintaining measurement accuracy

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-measurement by automatically monitoring its own dialysate to estimate patient BUN levels. The dialysis machine uses its existing dialysate flow and an added ammonia sensor to continuously estimate BUN without requiring external laboratory services or manual intervention, simplifying the operational process

Inventive Principle:
Principle #25Self-service

3Loss of time

If automated ammonia measurement is implemented, then time consumption is reduced, but measurement precision may be compromised

Engineering Contradiction:
Improvetime consumptionVSAvoidBUN estimation accuracy
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The system continuously monitors ammonia concentration in the dialysate and uses this feedback to dynamically adjust and refine BUN estimates. The ammonia sensor provides real-time data that is processed through calculation algorithms incorporating dialysate flow rate, treatment time, and patient-specific parameters, maintaining measurement precision through continuous feedback and validation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary calibration and validation by comparing automated ammonia-based BUN estimates with traditional blood measurement results during initial use. This preliminary action establishes accuracy baselines and allows the system to maintain measurement precision by validating its automated measurements against gold standard methods

Inventive Principle:
Principle #10Preliminary action

4Productivity

If zirconium phosphate sorbent is used to remove ammonium, then ammonia removal efficiency is improved, but the ability to measure absorbed ammonium is lost

Engineering Contradiction:
Improveammonia removal efficiencyVSAvoidammonium absorption measurement capability
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent uses ammonia concentration in the dialysate as an intermediary measurement that indirectly reflects ammonium absorption by the zirconium phosphate sorbent. By monitoring ammonia levels in the dialysate before and during treatment, the system can estimate how much ammonium has been absorbed by the sorbent without needing to directly measure the sorbent itself, thus preserving measurement capability while maintaining removal efficiency

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables non-invasive, automated estimation of pre-dialysis BUN levels, reducing costs and time, and facilitating the measurement of ammonia displaced from zirconium phosphate during the recharging process, thereby improving dialysis treatment efficiency.

Implementation Method 1

zirconium phosphate is used to remove waste and unwanted solutes including ammonium, potassium, calcium, and magnesium ions from dialysate

Methodology Applied
Scientific EffectIon exchange: Ion Exchange

Implementation Method 2

Urease is used to breakdown urea into carbon dioxide and ammonium in order to facilitate their removal

Methodology Applied
Scientific EffectEnzyme catalysis: Enzyme

Implementation Method 3

determining a total ammonia content in an ammonium removal solution effluent of the zirconium phosphate sorbent module using an ammonia sensor

Methodology Applied
Scientific EffectAmmonia detection:

Data Source

PatentEP3598987B1Patient pre-BUN estimate based on sorbent recharger effluent data
Publication Date: 2021.04.07 MEDTRONIC INC
  • EP3598987B1 patent drawingFigure 1
  • EP3598987B1 patent drawingFigure 2
  • EP3598987B1 patent drawingFigure 3

AI summary

The invention relates to devices, systems, and methods for estimating a patient BUN level prior to a dialysis session based on data received when introducing an ammonium removal solution through a zirconium phosphate sorbent module. The systems and methods can introduce an ammonia removal solution and determine an ammonia content of the ammonium removal solution effluent to estimate the patient pre-dialysis BUN level.