Surgical Cassette Pressure Control for Post-Occlusion Surge Mitigation
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Solution Overview
Problem
Existing ophthalmic surgical systems fail to effectively mitigate post-occlusion surges during cataract surgery, which can cause eye collapse and lens capsule tearing due to sudden changes in intraocular pressure when the aspiration needle becomes blocked.
Innovation Solution
A surgical cassette with an irrigation conduit, aspiration conduit, aspiration pump, reservoir, valve, and pressure sensors, controlled by a computer, that adjusts vacuum pressure in the aspiration conduit to manage fluid flow and maintain stable intraocular pressure by detecting pressure changes and opening/closing channels in the valve to mitigate post-occlusion surges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vacuum pressure is increased to improve tissue aspiration efficiency, then productivity increases, but post-occlusion surge risk increases causing eye collapse and lens capsule tearing
Solution Approach 1:
The system performs preliminary action by detecting pressure changes that indicate an occlusion break before a full post-occlusion surge occurs. The pressure sensor monitors the aspiration line pressure, and when a sudden pressure change is detected, the controller preemptively adjusts the vacuum pressure or opens the bypass valve to prevent the surge that would otherwise collapse the eye or tear the lens capsule.
Solution Approach 2:
The system implements feedback control by continuously monitoring pressure in the aspiration line with a pressure sensor and using this information to dynamically adjust the vacuum pressure or bypass valve position. This closed-loop feedback allows the system to maintain high aspiration efficiency while automatically responding to occlusion events to prevent dangerous pressure surges that could damage ocular structures.
2Quantity of substance
If vacuum pressure is maintained at high levels to ensure continuous fluid flow, then fluid flow consistency improves, but the severity of pressure drops during occlusion breaks increases
Solution Approach 1:
The system applies beforehand cushioning by maintaining a bypass connection between the aspiration line and the vacuum source that can be quickly activated. When an occlusion break is detected through pressure sensor monitoring, the bypass valve opens to provide a compensatory flow path, cushioning the pressure drop that would otherwise occur and preventing harmful surges while maintaining overall fluid flow consistency.
3Reliability
If a bypass valve is added to mitigate post-occlusion surges, then intraocular pressure stability improves, but device complexity increases
Solution Approach 1:
The bypass valve serves as an intermediary element between the aspiration line and the vacuum source, providing a controlled alternative flow path. This intermediary component enables the system to mitigate post-occlusion surges by diverting excess flow during occlusion breaks, improving intraocular pressure stability without requiring fundamental redesign of the entire aspiration system.
4Loss of time
If pressure sensors and automated control are implemented to detect and respond to occlusion breaks, then response time improves, but device complexity and cost increase
Solution Approach 1:
The system uses feedback control with a pressure sensor that continuously monitors aspiration line pressure and feeds this information to a controller. When the sensor detects the characteristic pressure change of an occlusion break, the controller automatically responds by adjusting vacuum pressure or opening the bypass valve, achieving rapid response time through a relatively simple feedback loop that avoids complex control algorithms.
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 system effectively reduces the risk of eye collapse and lens capsule tearing by stabilizing intraocular pressure during occlusion breaks, ensuring consistent fluid flow and pressure management.
Implementation Method 1
The aspiration pump creates a vacuum pressure in the aspiration conduit to draw fluid through the aspiration conduit towards a drain reservoir
Implementation Method 2
Each sensor detects a pressure associated with the surgical site
Implementation Method 3
The computer controls the valve to decrease the vacuum pressure in the aspiration conduit by controlling the valve to provide the one or more channels to allow fluid from the reservoir to the aspiration conduit
Data Source
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AI summary
According to certain embodiments, a surgical cassette for an ophthalmic surgical system comprises an irrigation conduit that is in fluid communication with a handpiece and carries fluid toward a surgical site. An aspiration conduit is in fluid communication with the handpiece and carries fluid away from the surgical site. An aspiration pump creates a vacuum pressure in the aspiration conduit to draw fluid through the aspiration conduit towards a drain reservoir. A reservoir couples with a pressure-vacuum source to manage the reservoir pressure. A valve is in fluid communication with the aspiration conduit and the reservoir, and provides one or more channels between the aspiration conduit and the reservoir. Each sensor detects a pressure associated with the surgical site. A computer controls the valve in response to the pressure detected by the one or more pressure sensors to mitigate a pressure or volume change.