Intrathecal Pump Cyclic CSF Aspiration for Catheter Patency
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Solution Overview
Problem
Implantable medical pumps used for intrathecal drug delivery often face occlusion due to tissue encapsulation when the drug reservoir is empty, leading to potential damage if not refilled regularly, as there is no mechanism to maintain continuous fluid flow without medicament or saline.
Innovation Solution
The development of an implantable medical pump capable of aspirating cerebrospinal fluid (CSF) when the drug reservoir is empty, enabling bidirectional fluid flow to maintain continuous infusion and prevent occlusions, with a processor-controlled mechanism that can deliver and aspirate fluid, and include sensors for monitoring biomarkers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the pump operates with a drug reservoir that becomes empty, then the pump can deliver medication for a extended period without refill, but the catheter becomes occluded due to tissue encapsulation and the pump may be damaged from running dry
Solution Approach 1:
The system performs cyclic aspiration of cerebrospinal fluid into the reservoir to maintain continuous fluid flow through the catheter, preventing occlusion even when medication is not being delivered. This continuous action ensures the catheter remains patent throughout the extended period between refills.
Solution Approach 2:
The pump system autonomously aspirates cerebrospinal fluid when the reservoir is empty, eliminating the need for external saline injections or manual intervention to maintain catheter patency. The system serves itself by using the patient's own CSF to prevent occlusion.
2Reliability
If the pump aspirates cerebrospinal fluid into the reservoir, then continuous fluid flow is maintained to prevent occlusion, but the reservoir volume changes and may affect pump operation
Solution Approach 1:
The pump system dynamically adjusts its operation by switching between medication delivery mode and CSF aspiration mode based on reservoir volume and clinical needs. The processor-controlled pump mechanism can vary aspiration rate, duration, and frequency to maintain patency while managing reservoir dynamics.
Solution Approach 2:
The system changes operational parameters by transitioning from unidirectional medication infusion to bidirectional flow with cyclic aspiration. This parameter change enables the pump to maintain catheter patency through controlled fluid movement while managing reservoir dynamics.
3Reliability
If the pump provides continuous infusion to maintain un-occluded fluid pathway, then catheter patency is maintained, but the pump requires saline or other fluid to fill the pump mechanism
Solution Approach 1:
The pump system uses the patient's own cerebrospinal fluid as the flushing medium, eliminating the need for external saline injections. The CSF naturally available in the intrathecal space is aspirated into the reservoir to maintain fluid flow and prevent occlusion.
Solution Approach 2:
Cerebrospinal fluid acts as an intermediary substance that transfers the function of flushing the catheter and maintaining patency. Instead of using external saline, the CSF serves as the medium to maintain continuous fluid flow through the system.
4Ease of operation
If the pump operates bidirectionally to aspirate and deliver fluid, then continuous flow is maintained without saline injections, but the pump mechanism and control system become more complex
Solution Approach 1:
The pump mechanism is designed to perform multiple functions: medication delivery, CSF aspiration, and catheter flushing. This multi-functionality is achieved through a single bidirectional pump mechanism controlled by a processor that can operate in different modes based on clinical needs.
Solution Approach 2:
The system combines the medication delivery function and the catheter flushing function into a single integrated pump system. The same pump mechanism that delivers medication also aspirates CSF to maintain patency, eliminating the need for separate flushing mechanisms or procedures.
Data Source
AI summary
Intrathecal drug delivery pumps can aspirate cerebrospinal fluid (CSF) when the drug reservoir is empty or at other times to maintain a continuous or cyclic fluid flow through the pump and the delivery catheter. This addresses the potential need for continuous infusion to maintain an un-occluded fluid pathway to the intrathecal space by providing an “active port” that aspirates and expels CSF to keep fluid flow going without infusing a drug or requiring saline to fill the pump. If drug refill visits are missed, CSF could be used to keep the pump mechanism functional rather than having it run dry requiring replacement or requiring saline injections to keep the pump mechanism functioning. In addition, by having the pump aspirate CSF into the body of the pump, it would be possible to monitor biomarkers using systems in the fluid pathway and pressure differences for possible issues related to CSF management.