Blood Pump No-Flow Period Detection for Dialysis Access Disconnection
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Solution Overview
Problem
Existing systems for detecting needle dislodgment during medical treatments like hemodialysis are inadequate, especially in unsupervised home therapies, as they may require electrical signals and additional contacts, which increase manufacturing complexity and cost, and are not always reliable due to grounding issues.
Innovation Solution
The system measures the no-flow period in blood pumps to detect access disconnection by monitoring the length of time fluid flow stops, using sensors to determine if the no-flow period lengthens, indicating a disconnection, without the need for electrical signals or additional contacts, and can be used with both diaphragm and peristaltic pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical impedance measurement systems are used to detect needle dislodgment, then detection capability is provided, but sensitivity decreases when patient is connected to earth ground and manufacturing complexity increases due to additional contacts
Solution Approach 1:
The patent extracts the detection function from complex electrical impedance measurement systems with multiple contacts and grounding requirements, simplifying it to a basic flow sensor that measures only fluid flow presence. This removes the problematic electrical components while retaining the core detection capability.
Solution Approach 2:
The system uses the existing blood pump and fluid circuit to provide detection functionality. The flow sensor leverages the natural blood flow through the pump to detect dislodgment, eliminating the need for separate power sources, contacts, or grounding systems that would add complexity.
2Reliability
If visual monitoring is used in in-center treatments, then detection of needle dislodgment is possible, but detection is delayed when needle is not in plain view
Solution Approach 1:
The patent introduces a flow sensor as an intermediary detection mechanism that indirectly monitors needle status through blood flow measurement. This mediator provides continuous automated detection without requiring direct visual observation of the needle, eliminating delays caused by obscured views.
3Ease of operation
If home therapies are implemented to improve quality of life, then patient convenience increases, but dislodgment risks increase due to lack of caregiver supervision
Solution Approach 1:
The system enables self-monitoring by the patient through automated flow-based detection. The sensor continuously monitors blood flow and detects dislodgment events without requiring caregiver presence, allowing safe home therapy while maintaining reliability.
Solution Approach 2:
The system provides immediate feedback through alarms when dislodgment is detected. This continuous feedback loop ensures patient safety during unsupervised home therapy by promptly notifying the patient of any access problems.
Data Source
AI summary
A dialysis system includes: a blood filter; a dialysate pump connected to a dialysate portion of the blood filter; a blood pump connected to a blood portion of the blood filter, the blood pump including a diaphragm that is moved in cycles to pump the blood, the cycles having a flow period and a no-flow period; a patient access device in fluid communication with the blood portion of the blood filter, the no-flow period having a first characteristic of a property when the patient access device is lodged in a patient and a second characteristic of the property when the patient access device is dislodged from the patient; and a logic implementer configured to determine that the patient access device has been dislodged from the patient when the second characteristic of the parameter is detected.