Renal Failure Therapy System Electrically Floating Fluid Pathway
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Solution Overview
Problem
Current dialysis machines pose a risk of electrical shock to patients due to inadequate electrical isolation, particularly from external equipment, leading to potential leakage currents and faulty voltage exposure.
Innovation Solution
The implementation of an electrically floating fluid pathway in renal failure therapy systems, which includes a dialyzer, blood circuit, and dialysis fluid circuit, where the only electrical path to ground is through the used dialysis fluid, providing high impedance and thus increased safety against faulty external electrical equipment and stray currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional grounded electrical connections are used in dialysis machines, then electrical components can function normally, but patients are exposed to leakage currents and electrical shock risks from external equipment
Solution Approach 1:
An electrical isolation barrier (isolation transformer or optocoupler) is introduced as an intermediary between the grounded external electrical components and the patient-connected fluid pathways. This mediator transfers electrical signals or power without creating a direct conductive path, thereby blocking leakage currents while maintaining functional connectivity.
Solution Approach 2:
The grounding connection is extracted from the patient-exposed fluid pathways and relocated to isolated electrical components only. The fluid pathways (blood lines, dialysis fluid lines) are electrically decoupled from ground, removing the harmful grounding connection from the patient interface while preserving necessary electrical functions in isolated domains.
2Reliability
If the fluid pathway is electrically isolated to prevent shock, then patient safety improves, but sensitive electrical components like conductivity sensors and flowmeters may experience interference
Solution Approach 1:
The system is segmented into electrically isolated zones: patient-safe isolated fluid pathways and grounded electrical component zones. Conductivity sensors and flowmeters are placed in the grounded zone or use isolated power/signal paths, allowing them to function without direct connection to the patient pathway while maintaining measurement accuracy through controlled electrical environments.
Solution Approach 2:
Isolated power supplies and signal transmission intermediaries (optocouplers, isolation amplifiers) are used to bridge the electrical isolation barrier. These mediators provide stable, interference-free signals to sensitive components while maintaining the electrical isolation that protects the patient, preventing ground loops and electrical noise.
3Adaptability or versatility
If multiple electrical components are connected to the dialysis machine, then treatment functionality is enhanced, but the risk of faulty voltage exposure from external equipment increases
Solution Approach 1:
Each electrical component interface is equipped with isolation barriers (isolation transformers, optocouplers, or isolated DC-DC converters) that act as mediators. These allow multiple components (pumps, sensors, heaters, controllers) to be connected and communicate effectively while each isolation barrier independently blocks faulty voltages and leakage currents from reaching the patient pathway.
Solution Approach 2:
Electrical isolation barriers are implemented as preventive protective measures before any faulty voltage can reach the patient. The isolation architecture is designed upfront to withstand voltage transients, ground potential differences, and electrical noise from external equipment, cushioning the patient pathway from potential harm while enabling full treatment functionality.
Data Source
AI summary
A renal failure therapy system having an electrically floating fluid pathway is disclosed. The example system includes a dialyzer, a blood circuit in fluid communication with the dialyzer, and a dialysis fluid circuit in fluid communication with the dialyzer. The system also includes an electrically floating fluid pathway comprising at least a portion of the blood circuit and at least a portion of the dialysis fluid circuit. The only electrical path to ground is via used dialysis fluid traveling through the renal failure therapy system to earth ground. The disclosed system enables at least one electrical component in the at least a portion of the dialysis fluid circuit of the electrically floating fluid pathway to be electrically bypassed.