Surgical Stapler Motor Pausing for Tissue Compression
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Solution Overview
Problem
Existing powered surgical staplers face challenges in achieving consistent stapling performance, particularly on thick tissue, due to variations in tissue dynamics and properties.
Innovation Solution
The implementation of a software-driven pausing monitoring process that adjusts the motor speed of a powered surgical stapler. This process monitors the firing speed of the stapler and pauses the motor when a speed error threshold is exceeded, allowing for increased localized tissue compression and improved staple form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor drives the firing assembly at a fixed high speed, then productivity is improved, but manufacturing precision deteriorates due to inconsistent staple form and tissue compression
Solution Approach 1:
The motor speed is changed from a fixed constant to a dynamic variable that adjusts based on real-time feedback. The controller continuously monitors the actual speed and modifies the target speed profile during the firing stroke, transitioning from a static speed profile to a dynamic adaptive profile that responds to tissue characteristics and motor performance variations.
Solution Approach 2:
A closed-loop feedback system is implemented where the actual motor speed is continuously measured and compared against the target speed profile. The controller uses this feedback information to detect speed errors and adjust the target speed accordingly, creating a self-correcting system that maintains optimal firing conditions despite variations in tissue properties or motor performance.
2Loss of time
If the motor speed is increased to complete the firing stroke faster, then loss of time is reduced, but manufacturing precision deteriorates due to insufficient tissue compression
Solution Approach 1:
The firing process is divided into distinct phases with different speed targets. The speed profile includes acceleration phases, steady-state phases, and deceleration phases, with periodic adjustments to target speed based on the firing progression. This periodic modulation of speed allows sufficient time for tissue compression at critical moments while maintaining overall efficiency.
Solution Approach 2:
The target speed parameter is dynamically changed during the firing stroke based on the detected actual speed and tissue response. The controller adjusts the target speed profile to extend or compress specific phases of the firing stroke, optimizing the balance between total firing time and localized compression quality at different positions along the firing path.
3Device complexity
If the motor operates without speed monitoring, then device complexity is reduced, but manufacturing precision deteriorates due to inability to compensate for speed variations
Solution Approach 1:
A feedback mechanism is integrated into the control system where sensors monitor actual motor speed and the controller processes this information to adjust the target speed profile. This feedback loop enables the system to detect and compensate for speed variations caused by tissue dynamics, motor load changes, or mechanical variations, thereby maintaining consistent staple formation without requiring overly complex hardware modifications.
Solution Approach 2:
The control system performs self-adjustment by automatically modifying the target speed profile based on real-time performance data. The controller monitors its own output and autonomously corrects deviations from the desired firing characteristics, eliminating the need for external intervention or overly complex manual adjustment mechanisms while maintaining high manufacturing precision.
Data Source
AI summary
A method of driving a motor in a powered surgical stapler can include a pausing monitoring process that may be effective to improve staple form and/or increase localized compression of tissue. The pausing monitoring process monitors firing speed of a firing bar driving by the motor and pauses the motor when the firing speed passes a speed error threshold. Before pausing the motor, the pausing monitoring process may also require that a pulse width modulated (PWM) electrical signal driving the motor has a duty cycle over a duty cycle threshold while the firing speed is beyond the speed error. The pausing monitoring process may force the firing bar through a predetermined distance immediately after pausing. The pausing monitoring process may be limited in the number of pauses that can be taken during a firing stroke.