Fluid Flow Impedance Control in Surgical Resector Channels
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Solution Overview
Problem
During endoscopic surgery of a distensible organ like the uterus, maintaining optimal fluid flow to prevent organ collapse and avoid fluid intravasation complications is challenging due to imbalances in fluid inflow and outflow, which can lead to visualization issues or serious patient complications.
Innovation Solution
A surgical system with a valve mechanism that maintains consistent fluid flow impedance through the instrument channel, allowing for controlled fluid infusion and suction, ensuring that the fluid pressure within the organ remains between 60 mm Hg and 120 mm Hg, regardless of the presence of a surgical instrument, by using a pump, sensor, and controller to regulate fluid flow and suction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the outflow of fluid from the uterus is greater than the inflow of fluid, then fluid can be removed from the uterus through the endoscope and resector, but the uterus may collapse back to its normal state making visualization difficult
Solution Approach 1:
The system incorporates a pump that actively regulates fluid inflow to the uterus based on real-time conditions, creating a feedback loop that maintains optimal fluid pressure for visualization while coordinating with the outflow through the resector
Solution Approach 2:
The endoscope serves multiple functions: it provides visualization of the uterus interior, a pathway for fluid inflow, and a guide for the resector. The coordinated fluid management system simultaneously maintains visualization quality and enables effective tissue resection through the same instrument channel
2Stress or pressure
If the inflow of fluid is greater than the outflow of fluid such that the pressure created by the fluid is greater than the patient's mean arterial pressure, then fluid pressure can maintain distension of the uterus, but excess fluid can enter the patient's vascular system leading to serious complications or death
Solution Approach 1:
The pump system incorporates feedback control that monitors fluid pressure and flow rates, automatically adjusting inflow parameters to maintain pressure within the safe range (above collapse pressure but below intravasation pressure) based on real-time conditions
Solution Approach 2:
The system dynamically adjusts fluid flow parameters (rate, pressure, volume) through the pump control system to maintain optimal distension pressure while preventing excessive pressure that could cause intravasation, adapting to changing surgical conditions
3Productivity
If a second instrument (resector) is received through the first instrument (endoscope), then tissue resection can be performed in the uterus, but the first instrument channel is partially blocked making fluid flow control more difficult
Solution Approach 1:
The pump system provides active feedback control of fluid inflow, compensating for the partial blockage caused by the resector in the endoscope channel, maintaining consistent fluid delivery and pressure despite the reduced cross-sectional area available for flow
Solution Approach 2:
The fluid management system is dynamically adjustable, allowing the pump to modify flow rates and pressure parameters in real-time based on whether the resector is present in the channel, optimizing performance for both visualization and resection phases
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 maintains a stable fluid pressure and flow impedance, preventing organ collapse and intravasation, while ensuring clear visualization and safe surgical conditions by balancing fluid inflow and outflow.
Implementation Method 1
The pump is programmed to infuse fluid through the first instrument channel to maintain a substantially constant pressure of between about 60 mm Hg and about 120 mm Hg inside a distensible organ
Implementation Method 2
The valve is configured such that impedance of fluid flow through the first instrument channel is substantially the same without the second instrument received in the first instrument channel and with the first instrument channel partially blocked by the second instrument
Implementation Method 3
The second instrument channel is in fluid communication with a source of suction and a regulator is interposed between the second instrument channel and the source of suction to regulate an amount of suction applied through the second instrument channel
Data Source
AI summary
A surgical system includes a first instrument defining a first channel and a second instrument receivable by the first channel. The second instrument defines a second channel. A valve coupled to the first instrument controls fluid flow through the first channel, such that impedance of fluid flow through the first channel is substantially the same without the second instrument received in the first channel and with the first channel partially blocked by the second instrument. In another aspect, a surgical apparatus includes an outer member and an inner member received within the outer member to define a first channel therebetween. The inner member houses an optical lens and defines a second channel for receiving a surgical instrument. The first and second channels are configured such that a pump having an inflow rate of up to about 0.7 L/min connected to the second channel can maintain fluid pressure inside an organ.