Phacoemulsification Reflux Control via Pedal Release Rate
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Solution Overview
Problem
During phacoemulsification procedures, the existing reflux control systems in phacoemulsification systems do not differentiate between the rate at which the physician releases the pedal, leading to unnecessary excess fluid and potential damage due to uniform application of reflux mode, which can result in increased intraocular pressure.
Innovation Solution
A phacoemulsification system that monitors the rate at which the physician releases the pedal or actuator and adjusts the reflux rate using a proportional-integral-derivative (PID) controller, dynamically adjusting control parameters based on the release rate to determine the severity of inadvertent capture, thereby activating reflux only as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform reflux mode is applied regardless of pedal release rate, then the system responds to all inadvertent captures, but excess fluid accumulates and intraocular pressure increases
Solution Approach 1:
The system dynamically adjusts the reflux flow rate based on the measured pedal release rate. When the pedal is released quickly (indicating severe inadvertent capture), the system applies high reflux flow rate. When released slowly (indicating minor capture), the system applies low or no reflux flow rate, thereby avoiding excess fluid accumulation while still responding to all capture events.
Solution Approach 2:
The system changes the reflux flow rate parameter according to the pedal release rate. The controller measures the release rate and adjusts the reflux parameter accordingly - high flow rate for fast release, low or zero flow rate for slow release. This parameter adaptation resolves the contradiction by making the response proportional to the actual need.
2Reliability
If reflux is activated for all pedal releases, then inadvertent captures are addressed, but unnecessary reflux increases fluid volume in the eye
Solution Approach 1:
The system applies partial reflux action only when necessary. By measuring the pedal release rate, the system determines the appropriate level of reflux - full reflux for severe captures, partial or no reflux for minor captures. This avoids the excessive action of applying full reflux to all situations, thereby preventing unnecessary fluid accumulation while maintaining protective reliability.
3Object-affected harmful factors
If the system monitors and adjusts reflux based on pedal release rate, then fluid management is optimized, but system complexity increases
Solution Approach 1:
The system uses feedback from the pedal release rate measurement to control the reflux flow rate. The controller continuously monitors how quickly the pedal is released and adjusts the reflux pump accordingly. This feedback mechanism optimizes fluid management while keeping the control logic relatively simple - the relationship between release rate and reflux flow can be implemented through straightforward 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
This approach reduces excess fluid and intraocular pressure by tailoring reflux according to the release rate, minimizing unnecessary reflux and maintaining optimal eye conditions during surgery.
Implementation Method 1
a vacuum created by an aspiration pump used to grab suitable material
Implementation Method 2
a proportional-integral-derivative (PID) controller with suitable control parameters. The PID controller may increase the reflux rate for instances of fast release of the pedal
Data Source
AI summary
In one exemplary mode, a phacoemulsification system includes a phacoemulsification probe to be inserted into an eye, an irrigation line to provide irrigation fluid into the eye, an aspiration line to convey aspiration fluid from the eye, an aspiration pump to pump the aspiration fluid from the eye, a pump controller to control a flow direction and rate of the aspiration pump, and an aspiration rate user input device to provide a signal indicative of user actuation of the aspiration rate user input device, wherein the pump controller is configured to receive the signal provided by the aspiration rate user input device, and reverse the flow direction and set the flow rate of the aspiration pump at which to pump the aspiration fluid into the eye, the flow rate in the reverse flow direction being set responsively to an actuation rate at which the aspiration rate user input device is actuated.