Catheter Needle Deployment Control With Retraction Stop and Clutch
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Solution Overview
Problem
Existing catheter systems face issues with inadvertent deployment of surgical instruments due to catheter shortening during steering, leading to potential tissue damage and difficulty in precise control of instrument extension from the distal end.
Innovation Solution
A catheter design with a retraction stop and biasing element to maintain the relative position of the instrument near the distal end, combined with an advancing mechanism to ensure precise deployment and prevent inadvertent exposure, using a clutch mechanism for controlled advancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If steering cables are pushed or pulled to change catheter direction, then catheter steering capability is improved, but catheter length shortens causing inadvertent needle deployment
Solution Approach 1:
A clutch mechanism serves as an intermediary between the operator and the needle advancement system. The clutch selectively engages to transmit force from the advancing mechanism to the needle, preventing inadvertent deployment while allowing controlled advancement when engaged. This mediator decouples the steering operation from needle position changes.
Solution Approach 2:
The needle is pre-loaded in a retracted position within the catheter inner lumen before steering operations begin. The clutch mechanism is pre-configured in a disengaged state that automatically prevents needle advancement during catheter manipulation, ensuring safety before the operator initiates controlled deployment.
2Ease of manufacture
If needle position is set at proximal end of device, then initial positioning is simplified, but precise control of needle extension at distal end becomes difficult
Solution Approach 1:
The clutch mechanism provides tactile and mechanical feedback to the operator during needle advancement. As the clutch engages and transmits force to the needle, the operator can feel the engagement and control the advancement rate, enabling precise control of needle extension distance at the distal end despite the positioning control being exercised at the proximal end.
3Reliability
If needle is recessed further within catheter inner lumen to prevent inadvertent exposure, then safety during steering is improved, but catheter maneuverability deteriorates
Solution Approach 1:
The safety function is extracted from the needle-catheter geometric relationship and placed into a separate clutch mechanism. Instead of relying on the needle being deeply recessed to prevent accidental deployment, the clutch mechanism independently provides safety by controlling force transmission to the needle, thereby freeing the catheter design from the trade-off between needle recess depth and maneuverability.
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
Prevents inadvertent deployment and allows precise control of surgical instruments, ensuring safe and accurate positioning at the surgical site.
Implementation Method 1
a biasing element coupled to the needle and configured to urge the needle proximally such that the at least one protrusion on the needle abuts against the retraction stop
Implementation Method 2
an advancing mechanism configured to selectively engage the needle and urge the needle distally relative to the catheter
Data Source
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AI summary
Catheters with deployable instruments (e.g., needles) can damage tissue if the instrument unintentionally deploys during use. Described herein are devices and methods for controlling the position of a deployable catheter instrument. In one embodiment, a catheter can include an instrument slidably disposed within an inner lumen of the catheter and coupled to at least one protrusion, as well as a retraction stop coupled to the catheter. The catheter can further include a biasing element coupled to the instrument that can urge the instrument proximally such that the at least one protrusion abuts against the retraction stop, as well as an advancing mechanism to selectively engage the instrument and urge it distally. In some embodiments, the biasing element can be omitted and a deployment stop can be included distal to the retraction stop. These configurations can prevent unintentional instrument deployment and provide greater positioning precision during instrument deployment.