Surgical Cannula With Pneumatic Expandable Retention
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Solution Overview
Problem
Conventional surgical cannulas tend to back out of the incision during minimally invasive procedures due to the pressurized pneumoperitoneum environment, particularly when instruments are manipulated within them, as they lack effective mechanisms to maintain stability and seal.
Innovation Solution
A surgical cannula assembly featuring an elongated cannula with expandable members and a fluid-transfer assembly that includes proximal and distal flanges, allowing for the transfer of inflation medium between these members to adjust pressure and maintain stability, thereby preventing cannula withdrawal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cannula is used in a pressurized pneumoperitoneum environment, then the cannula can provide access for surgical instruments, but the cannula tends to back out of the incision due to pressure
Solution Approach 1:
The cannula system employs dynamic expandable members that can change volume and pressure in response to the pneumoperitoneum environment. The expandable member inflates under pressure to engage tissue and prevent withdrawal, while deflating for insertion and removal, adapting to different surgical phases.
Solution Approach 2:
The system utilizes pneumatic pressure from the insufflated abdominal cavity to inflate the expandable member through fluid communication. The inflation medium (gas or liquid) transfers pressure to expand the member, creating a mechanical lock against tissue without requiring separate power sources.
2Reliability
If an inflatable balloon is added to the cannula to prevent withdrawal, then cannula stability improves, but device complexity increases
Solution Approach 1:
The expandable member is integrated directly into the cannula structure, with the cannula body serving as both the access conduit and the housing for the expandable retention mechanism. The flange assembly combines sealing, expansion control, and structural support functions in a single integrated component.
Solution Approach 2:
The expandable member serves multiple functions: it provides tissue engagement to prevent withdrawal, creates a sealing interface against the abdominal wall, and can be inflated or deflated as needed during different surgical phases. The flange assembly similarly performs sealing, structural support, and expansion control functions.
3Ease of operation
If the cannula is subjected to pressurized pneumoperitoneum environment, then surgical access is enabled, but the cannula experiences force causing it to back out
Solution Approach 1:
The expanded member creates a counteracting mechanical force against the pneumoperitoneum pressure. When inflated, the expandable member engages the abdominal wall tissue with sufficient friction and mechanical interlocking to balance the outward pressure force, preventing cannula migration.
Solution Approach 2:
The system changes the physical state of the expandable member from compressed (deflated) to expanded (inflated) in response to pressure conditions. This parameter change allows the cannula to adapt to the pressurized environment, transforming the harmful pressure into a useful inflation mechanism that secures the device.
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 cannula assembly effectively resists withdrawal from the tissue site by maintaining a stable pneumoperitoneum and ensuring a secure seal, enhancing the reliability of minimally invasive surgical procedures.
Implementation Method 1
approximation of the proximal and distal flanges may compress the first expandable member therebetween to transfer a portion of the inflation medium from the first expandable member toward the second expandable member
Implementation Method 2
Expansion of the proximal and distal flanges may transfer the portion of the inflation medium from the second expandable member toward the first expandable member
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A surgical cannula assembly includes an elongated cannula member, first and second expandable members mounted to respective proximal and distal portions of the cannula member, and a fluid-transfer assembly. The fluid-transfer assembly includes proximal and distal flanges coupled to the proximal portion of the cannula member. The first expandable member is disposed between the proximal and distal flanges such that movement of one of the proximal or distal flanges along the cannula member adjusts a pressure applied by the proximal and distal flanges on the first expandable member to transfer an inflation medium between the first and second expandable members.