Dialyzer Backflush Control for Secondary Membrane Removal
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Solution Overview
Problem
Existing extracorporeal blood treatment devices face inefficiencies due to secondary membrane formation, which leads to reduced flux and altered selectivity of semipermeable membranes, necessitating time-consuming procedures like rinsing and additional equipment, without providing cost-effective solutions.
Innovation Solution
An extracorporeal blood treatment device with a dialyzer and a processor that intermittently switches between operating modes to remove secondary membrane buildup by controlling dialysate flow through the semipermeable membrane, using sensors to detect membrane buildup and adjust pump operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary membrane is removed by rinsing the blood circuit and changing the filter, then membrane fouling is cleared, but treatment time is lost and procedure becomes time-consuming
Solution Approach 1:
The system performs preliminary actions by detecting membrane fouling buildup early through monitoring transmembrane pressure and flux changes, then initiates backflushing before complete fouling occurs. This preventive approach maintains membrane performance without requiring complete treatment interruption for cleaning.
Solution Approach 2:
The backflushing operation is designed to be performed intermittently during treatment rather than requiring complete treatment interruption. The system switches between forward dialysis mode and backflush mode, allowing continuous treatment with periodic membrane cleaning, thus maintaining continuity of useful action.
2Reliability
If additional equipment such as sensors, pumps, and dialysate lines are added to remove secondary membranes, then membrane cleaning capability is improved, but device complexity increases
Solution Approach 1:
The dialysate pump and dialysate distribution system perform multiple functions: they deliver dialysate during normal forward dialysis operation and also perform backflushing by reversing flow direction. This multi-functionality eliminates the need for separate dedicated backflushing equipment, reducing overall device complexity.
Solution Approach 2:
The system uses the existing dialysate flow infrastructure in reverse by switching the dialysate inlet and outlet connections. This inversion of flow direction enables backflushing capability using the same equipment components already present in the system, avoiding additional hardware requirements.
3Productivity
If membrane fouling is allowed to progress, then treatment continues uninterrupted, but flux declines and selectivity changes
Solution Approach 1:
The system continuously monitors treatment parameters including transmembrane pressure, blood flow rate, and dialysate flow rate to detect changes indicating membrane fouling. This feedback mechanism triggers automatic backflushing when fouling thresholds are reached, maintaining membrane efficiency while minimizing treatment interruptions.
Solution Approach 2:
The backflushing operation is performed periodically at predetermined time intervals or when fouling indicators reach specific thresholds. This periodic cleaning maintains consistent membrane performance throughout the treatment, balancing treatment continuity with membrane efficiency.
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
Efficiently removes secondary membrane during treatment, maintaining treatment efficiency by intermittently reversing dialysate flow to dislodge buildup, thus enhancing the performance of existing devices without requiring extensive modifications or additional equipment.
Implementation Method 1
The semipermeable membrane selectively allows matter in the blood to flow across the semipermeable membrane from the blood chamber into the dialysate chamber
Implementation Method 2
In a hemofiltration (HF) treatment, blood flows past the semipermeable membrane and undesirable matter and toxins from the blood are pulled across the semipermeable membrane and carried away by dialysate
Implementation Method 3
Protein adsorption or deposition on the surface or in its pores is caused by proteins that are adsorbed or trapped in the pores of the semipermeable membrane
Implementation Method 4
Concentration polarization is a result of a concentration gradient due to solute accumulation near the semipermeable membrane surface. This solute accumulation is also referred to as a secondary membrane.
Implementation Method 5
a volume of dialysate passes from the dialysate chamber through the semipermeable membrane and into the blood chamber
Data Source
AI summary
An extracorporeal blood treatment device and a method are provided for removing a secondary membrane formed on a semipermeable membrane of a dialyzer during an extracorporeal blood treatment. The extracorporeal blood treatment device operates in a first operating mode in which a dialysate outlet valve is open such that dialysate flows through a dialyzer feed line, through a dialysate chamber, and into and through a dialyzer discharge line. The extracorporeal blood treatment device operates in a second operating mode to remove the secondary membrane from the semipermeable membrane. During the second operating mode, the dialysate outlet valve is closed for a duration of time such that dialysate is prevented from flowing through the dialyzer discharge line. A backflush procedure results wherein a volume of dialysate passes from the dialysate chamber through the semipermeable membrane and into the blood chamber.