Dialysis Machine Pre-Dialytic Sodium Accuracy via Temporal Evaluation
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Solution Overview
Problem
Current dialysis machines face challenges in accurately determining the predialytic sodium ion concentration in blood plasma due to instability and fluctuations during the initial phase of treatment, leading to imprecise calculations that are not useful for clinical decisions.
Innovation Solution
A dialysis machine with a computing unit that defines temporal evaluation ranges based on stability criteria, using only measured values within these ranges to determine the predialytic property of the blood, and accounting for the flow time between conductivity sensors to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conductivity measurements are taken during the initial phase of dialysis treatment, then pre-dialytic sodium ion concentration can be determined, but the measurements are unstable and inaccurate due to fluctuations in the dialysis system
Solution Approach 1:
The system performs preliminary stabilization measurements during the initial phase of dialysis treatment to establish baseline conductivity values before the system becomes unstable. By capturing measurements during the brief stable period at the very beginning of treatment, the system can extrapolate pre-dialytic sodium concentrations without being affected by later instability
Solution Approach 2:
The computing unit continuously monitors conductivity measurements and automatically identifies temporal evaluation ranges where stability criteria are met. This feedback mechanism allows the system to selectively use only reliable measurements for determining pre-dialytic sodium concentrations, rejecting unstable values that would compromise accuracy
2Productivity
If conductivity measurements are taken simultaneously at fixed positions upstream and downstream of the dialyzer, then clearance can be calculated, but flow time delays cause errors in pre-dialytic concentration determination
Solution Approach 1:
Instead of using fixed simultaneous measurements, the system dynamically adjusts the temporal pairing of upstream and downstream conductivity values based on actual flow conditions. The computing unit identifies matching time points that account for variable flow times through the dialyzer, ensuring accurate correspondence between measurements despite changes in dialysate flow rate
Solution Approach 2:
The system preliminarily determines the flow time characteristic of the dialysate circuit and uses this information to offset time points when pairing upstream and downstream measurements. This preliminary characterization of flow dynamics allows accurate matching of corresponding measurements without requiring complex real-time flow monitoring
3Ease of operation
If blood and dialysate are allowed to equilibrate during the preparation phase, then the system is ready for treatment, but the initial conductivity measurements become unreliable due to mixing artifacts
Solution Approach 1:
The system extracts and excludes the unstable initial measurements from the evaluation period. By identifying and removing measurements taken during the mixing artifact period from the temporal evaluation ranges, the system prevents these unreliable values from affecting the pre-dialytic sodium concentration determination
Solution Approach 2:
The system quickly transitions through the unstable initial phase by establishing a delay period after connection before beginning measurements. This allows the mixing artifacts to subside rapidly, and the system rushes through the transient period to reach the stable evaluation window as quickly as possible
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
This approach enhances the accuracy of predialytic sodium ion concentration determination, reducing errors and providing a reliable input for clinical decisions without additional costs, by excluding unstable treatment phases and considering the flow time delay in conductivity measurements.
Implementation Method 1
at least one sensor for determining a property of the dialysate is arranged in the dialysate circuit
Implementation Method 2
during dialysis treatment, the electrolytes in the blood and those in the dialysate are in equilibrium via contact in the dialyzer
Data Source
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AI summary
The invention relates to a dialysis machine with the capability of determining a pre-dialysis property in the blood of a dialysis patient, which dialysis machine comprises an extracorporeal blood circuit, a dialysate circuit, a dialyzer and a computing unit, wherein at least one sensor for determining a property of the dialysate is arranged in the dialysate circuit. The computing unit is configured in such a way that, during an initial phase of the dialysis treatment, temporal evaluation ranges are established in which all stability criteria from a predetermined group are satisfied, and in such a way that measurement values determined by the at least one sensor are used to determine a pre-dialysis property of the patient's blood only within these temporal evaluation ranges.