Bipolar Forceps with Non-Conductive Variable Stop Members

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Solution Overview

Problem

Existing electrosurgical instruments are ineffective in consistently sealing tissue due to inadequate control over the gap distance between opposing jaw members, leading to non-uniform or ineffective seals, particularly with larger vessels or thick tissues.

Innovation Solution

A bipolar forceps with a selectively-variable, non-conductive stop member that adjusts the gap distance between electrically conductive sealing surfaces, utilizing sensors to sense tissue impedance and thickness, and a controller to extend or retract the stop member, ensuring optimal sealing by regulating the gap distance between 0.001 inches to 0.008 inches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrosurgical instruments are used to seal tissue, then hemostasis and tissue sealing are achieved, but inconsistent gap distance between jaw members results in non-uniform or ineffective seals

Engineering Contradiction:

Improveseal consistencyVSAvoidgap distance control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent incorporates a stop member that preliminarily sets and limits the gap distance between opposing jaw members before tissue sealing occurs. This pre-established mechanical constraint ensures consistent spacing regardless of tissue thickness variations, directly addressing the gap distance control issue and enabling reliable uniform seals.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If pressure is increased to overcome tissue expansion during heating, then sealing effectiveness improves, but tissue impedance may become too low allowing excessive energy through

Engineering Contradiction:

Improveseal effectivenessVSAvoidenergy transfer control

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs a stop member that mechanically constrains the gap distance between jaw members, thereby controlling the compression force applied to tissue. This parameter control prevents excessive pressure that would lower tissue impedance too much, while still maintaining sufficient pressure for effective sealing. The stop member thus optimizes the balance between sealing effectiveness and energy transfer control.

Inventive Principle:

Principle #35Parameter changes

3Force

If jaw members are allowed to close completely to grasp tissue, then gripping force improves, but electrical short-circuiting may occur preventing energy transfer

Engineering Contradiction:

Improvegripping forceVSAvoidenergy transfer

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The stop member serves as an intermediary element between the opposing jaw members, preventing direct contact between the electrically conductive sealing surfaces. This mechanical intermediary maintains sufficient gripping force to secure tissue while simultaneously preventing electrical short-circuiting, ensuring reliable energy transfer through the tissue during sealing.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If gap distance is increased to prevent short-circuiting, then energy transfer is maintained, but sealing pressure is insufficient creating thick or unreliable seals

Engineering Contradiction:

Improveenergy transferVSAvoidseal thickness control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The stop member establishes an optimal gap distance parameter that simultaneously satisfies two conflicting requirements: it maintains sufficient spacing to prevent electrical short-circuiting and ensure proper energy transfer, while also providing enough compression force to create seals of appropriate thickness. This mechanically enforced parameter achieves the balance between energy transfer reliability and seal quality.

Inventive Principle:

Principle #35Parameter changes

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 solution enables consistent and effective tissue sealing by ensuring precise control over the gap distance, reducing the risk of short-circuiting and improving tissue manipulation, resulting in a reliable and uniform seal across various tissue types.

Implementation Method 1

The electrically conductive sealing surfaces are capable of conducting energy through tissue held therebetween to effect a tissue seal

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a stop member assembly having at least one non-conductive stop member which is selectively adjustable to regulate the gap distance between the opposing electrically conductive sealing surfaces

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentUS7491201B2Tissue sealer with non-conductive variable stop members and method of sealing tissue

Publication Date: 2009.02.17 COVIDIEN AG

AI summary

A bipolar forceps for sealing tissue includes an elongated shaft having opposing jaw members at a distal end thereof, each of the jaw members including an electrically conductive sealing surface. The jaw members are movable relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween. The bipolar forceps is connected to a source of electrical energy such that the jaw members are capable of conducting bipolar energy through tissue held therebetween to effect a seal. The forceps also includes a stop member assembly having at least one non-conductive stop member which is selectively extendible to regulate the distance between the jaw members when tissue is held therebetween.