Implantable CSF Drainage Valve with Thermal Flowmeter
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Solution Overview
Problem
Conventional implantable drainage devices for cerebro-spinal fluid (CSF) drainage in hydrocephalus treatment face issues with pressure difference measurement stability and obstruction risks, as well as lack of adaptive flow control.
Innovation Solution
An implantable drainage device with a mass flowmeter and a control unit that modifies the operation of a drainage valve based on CSF flow rate measurements, using an on/off, progressive, or passive valve configuration, to ensure reliable and adaptive CSF drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pressure difference measurement is used to control drainage valve operation, then valve opening conditions can be modified, but the narrow passage becomes prone to obstruction and measurement stability deteriorates
Solution Approach 1:
The patent replaces the mechanical pressure difference measurement system with a thermal flowmeter that measures actual CSF flow rate through thermal conduction changes. This substitution eliminates the need for narrow pressure-sensing passages, thereby removing the obstruction risk while maintaining adaptive valve control capability through flow rate-based feedback.
Solution Approach 2:
The patent introduces a thermal flowmeter as an intermediary measurement device that indirectly assesses CSF flow without requiring direct pressure differential measurement through narrow passages. The thermal flowmeter uses heat transfer principles to measure flow rate, serving as a mediator between the CSF and the control system, thus avoiding the reliability issues of direct pressure measurement.
2Extent of automation
If pressure difference sensor is used to measure flow, then valve operation can be controlled, but measurement stability and drift occur over time
Solution Approach 1:
The patent replaces the pressure difference sensor with a thermal flowmeter that measures CSF flow rate through thermal conduction changes. This substitution provides more stable and drift-free measurements over time, as thermal measurements are not subject to the same calibration drift and stability issues as pressure sensors, thereby maintaining automatic control precision.
Solution Approach 2:
The patent changes the measurement parameter from pressure difference to thermal conduction change. By measuring the change in thermal conduction caused by flowing CSF rather than pressure differential, the system achieves more stable long-term measurements without drift, while still enabling automatic valve operation control through flow rate feedback.
3Reliability
If conventional drainage device is used, then CSF drainage is provided, but adaptive adjustment to patient needs and conditions is not achieved
Solution Approach 1:
The patent implements a feedback control system where the thermal flowmeter continuously measures actual CSF flow rate and feeds this information back to the control unit. The control unit then automatically adjusts valve opening conditions based on the measured flow rate, enabling adaptive adjustment to patient needs and conditions while maintaining reliable drainage effectiveness through closed-loop control.
Solution Approach 2:
The patent transforms the static valve operation into a dynamic, adaptive system. The valve opening conditions are no longer fixed but continuously adjusted based on real-time flow rate measurements from the thermal flowmeter. This dynamic adjustment enables the drainage device to adapt to changing patient needs and conditions while maintaining effective drainage.
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
The device effectively and reliably drains CSF, adapting to patient needs and conditions, reducing the risk of obstruction and improving flow rate control, thereby enhancing treatment efficacy for hydrocephalus.
Implementation Method 1
The invention also proposes a flowmeter, in particular a mass flowmeter, which is suitable for evaluating the flow rate of fluid in a shunt valve. The mass flowmeter advantageously uses changes in thermal conduction caused by the flow of fluid
Data Source
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AI summary
The invention relates to an implantable drainage device (10) for draining the cerebro-spinal fluid of a patient, the device comprising: a drainage valve (42) comprising a valve member (65) and a valve seat (63); a control unit (40) suitable for modifying an operating parameter (P0, ?0, F0, t?, tb) of said valve, at least as a function of a measurement (D) of the fluid flow rate through said valve; an actuator (41) controlled by the control unit (40), suitable for modifying the operation of said valve as a function of said operating parameter as modified by the control unit (40); and a mass flowmeter (43) suitable for evaluating said flow rate of fluid through said valve.