Fluid Controller with Mode-Switching PID for Surgical Pressure
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Solution Overview
Problem
Existing fluid control systems in arthroscopic surgical procedures face challenges in maintaining joint pressure and fluid flow, as they often lack direct measurement of joint pressure, leading to inefficiencies and increased surgical fluid usage, and require calibration procedures that can be time-consuming and prone to errors, failing to accommodate varying surgeon preferences between conservative and aggressive operational modes.
Innovation Solution
A fluid controller that infers joint pressure based on outlet pressure and flow rate, using multiple modes of operation with distinct relationships between fluid flow and pressure drop, and adjustable PID parameters to compensate for pressure changes, allowing surgeons to select between aggressive and conservative modes to optimize visibility and fluid usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement of joint pressure is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary calculation approach where joint pressure is not measured directly but inferred through mathematical relationships involving outlet pressure measurements and pressure drop calculations. This mediator (calculation algorithm) bridges the gap between measurable quantities and the desired joint pressure information without requiring direct measurement devices inside the joint.
Solution Approach 2:
The patent replaces potential mechanical pressure measurement devices (transducers, sensors) with a computational approach. Instead of using mechanical systems to directly measure joint pressure, the system uses mathematical models and algorithms to calculate joint pressure from other measurable parameters, thereby reducing device complexity.
2Manufacturing precision
If calibration procedures are performed, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent incorporates calibration procedures as a preliminary action that is performed once during system setup or initialization. The calibration data is stored and reused for subsequent operations, eliminating the need for repeated calibration and thus reducing time loss during actual surgical procedures while maintaining precision.
Solution Approach 2:
The patent creates a computational model (copy) of the pressure-flow relationship that can be reused multiple times without requiring physical recalibration. Once the system characteristics are characterized, this model is copied and applied throughout the procedure, avoiding repeated calibration time while maintaining accuracy.
3Device complexity
If single mode of operation is used, then device complexity is reduced, but adaptability worsens
Solution Approach 1:
The patent implements a dynamic control system that can switch between different operational modes (e.g., conservative and aggressive fluid management strategies). This allows the system to adapt to different surgeon preferences and surgical conditions while maintaining a relatively simple underlying control architecture that can be reconfigured through software or control parameters rather than hardware changes.
Data Source
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AI summary
Fluid management in surgical procedures. At least some of the example embodiments are methods including: pumping surgical fluid through a tube to a surgical site by a fluid controller operating in a first mode, the first mode comprising a first relationship of fluid flow and pressure drop across the tube and cannula, and the first mode comprising a first set of proportional, integral, and differential (PID) parameters; and then pumping surgical fluid through the tube to the surgical site with the fluid controller operating in a second mode, the second mode comprising a second relationship of fluid flow and pressure drop across the tube and cannula, the second relationship different than the first relationship, and the second mode comprising a second set of PID parameters used, the second set of PID parameters different than the first set of PID parameters.