Ultrasonic Surgical Instrument Stepped Waveform Impedance Feedback
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Solution Overview
Problem
Current ultrasonic surgical instruments face challenges in effectively sealing blood vessels and providing feedback to users about the completion of tissue cutting, leading to potential damage from excessive heat generation when the cut is complete but the instrument continues to be activated.
Innovation Solution
The ultrasonic surgical instrument employs a step function waveform for the ultrasonic drive signals and a tissue impedance module to monitor and adjust the frequency and current, allowing for precise separation and sealing of tissue layers and providing visual, audible, or tactile feedback to the user when the cut is complete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard ultrasonic energy is applied to cut tissue, then cutting and coagulation are achieved, but heat generation increases exponentially when the cut is complete and the instrument continues to be activated
Solution Approach 1:
The system continuously monitors impedance changes during ultrasonic operation and automatically adjusts power delivery based on real-time feedback. When impedance indicates the cut is complete, the system reduces or stops power delivery to prevent excessive heat generation, while maintaining cutting capability when tissue is present.
Solution Approach 2:
The system dynamically changes the ultrasonic power parameter based on tissue presence detection. When no tissue is detected (cut complete), the power is reduced to a safe level, preventing exponential heat generation. When tissue is detected, power is increased to maintain efficient cutting performance.
2Ease of operation
If the user continues to activate the harmonic instrument after the cut is complete, then the instrument remains operational, but damage occurs to the harmonic instrument and surrounding tissue due to excessive heat
Solution Approach 1:
The impedance monitoring system provides automatic feedback to the control circuit, which adjusts power delivery without requiring user intervention. This feedback mechanism protects the instrument and tissue from damage by automatically reducing power when the cut is complete, while maintaining ease of operation through automated protection.
Solution Approach 2:
The system performs self-protection by automatically detecting when the cut is complete through impedance monitoring and autonomously reducing power delivery. This self-service protection eliminates the need for user awareness or manual intervention to prevent instrument and tissue damage.
3Reliability
If ultrasonic energy is applied to seal blood vessels, then coagulation is achieved, but the inner muscle layer must be separated from the adventitia layer which requires increased clamp force
Solution Approach 1:
The system changes the ultrasonic power parameter in response to tissue separation detection. When the inner muscle layer is separated from the adventitia (detected through impedance changes), the system automatically increases power delivery to enhance coagulation and sealing effectiveness, achieving reliable vessel sealing without requiring excessive clamp force.
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 solution enables efficient and controlled tissue cutting and coagulation with reduced heat generation and damage, improving hemostasis and the overall safety and precision of surgical procedures.
Implementation Method 1
Vibrating at high frequencies (e.g., 55,500 times per second), the ultrasonic blade denatures protein in the tissue
Implementation Method 2
the ultrasonic blade denatures protein in the tissue to form a sticky coagulum
Implementation Method 3
The ultrasonic drive system is configured to resonate at a resonant frequency
Implementation Method 4
a tissue impedance module to monitor and adjust the frequency and current
Data Source
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AI summary
Various embodiments are directed to an apparatus, system, and method for driving an end effector coupled to an ultrasonic transducer in a surgical instrument. The method comprises generating a first ultrasonic drive signal by a generator coupled to an ultrasonic drive system, actuating the ultrasonic transducer with the first ultrasonic drive signal for a first period, generating a second ultrasonic drive signal by the generator, and actuating the ultrasonic transducer with the second ultrasonic drive signal for a second period, subsequent to the first period. The first drive signal is different from the second drive signal over the respective first and second periods. The first and second drive signals define a step function waveform over the first and second periods. The apparatus comprises a generator configured to couple to an ultrasonic instrument. The system comprises a generator coupled to an ultrasonic instrument. The ultrasonic instrument comprises an ultrasonic drive system comprising an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide, and wherein the ultrasonic drive system is configured to resonate at a resonant frequency.