Optical Free Flap Patency Monitoring System
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Solution Overview
Problem
Current methods for monitoring free flap patency after surgery, such as the Cook-Swartz Doppler Probe and System, suffer from high false positive rates, require human interpretation, and are prone to misalignment issues, leading to costly surgical re-explorations and potential flap loss due to difficulty in distinguishing venous flow from background noise.
Innovation Solution
An implantable system with transmit and receive transducers, coupled with circuitry modules for insonifying blood flow, extracting baseband Doppler signals, and generating a binary output based on feature classification, eliminating the need for human interpretation and reducing false positives by processing data in real-time on a microchip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Cook-Swartz Doppler Probe and System is used for monitoring, then blood flow detection capability is provided, but false positive rates increase to 30%
Solution Approach 1:
The patent replaces the mechanical Doppler probe system with an optical detection system that uses light to detect blood flow. The optical sensor detects changes in light absorption or scattering caused by blood flow, eliminating the mechanical contact and audio interpretation requirements of the Doppler system, thereby reducing false positives while maintaining detection capability.
Solution Approach 2:
The patent introduces an optical intermediary (light) to detect blood flow indirectly through absorption or scattering changes, rather than directly detecting acoustic signals from blood flow. This intermediary approach allows for more precise and reliable detection by converting the detection mechanism to a different physical domain with better signal-to-noise characteristics.
2Extent of automation
If the Cook-Swartz Doppler Probe and System is used, then blood flow monitoring is enabled, but human interpretation is required
Solution Approach 1:
The patent replaces the audio-based Doppler system requiring human interpretation with an optical detection system that provides direct visual or electronic signals indicating blood flow presence. The system processes optical signals electronically to generate clear binary outcomes (flow present/absent), eliminating the need for human clinicians to interpret audio signatures.
Solution Approach 2:
The patent enables the monitoring system to automatically detect and report blood flow status without requiring human interpretation. The optical sensor and processing circuitry work together to self-determine patency status, providing automated alerts when flow is lost, thereby making the system self-sufficient in its detection function.
3Reliability
If the Cook-Swartz Doppler Probe and System is used, then venous outflow monitoring is possible, but probe misalignment occurs due to wire tether snagging
Solution Approach 1:
The patent replaces the mechanical wire-tethered Doppler probe with a wireless or integrated optical sensor system. The optical sensor can be positioned closer to the vessel or integrated into the surgical site, eliminating the long wire tether that is prone to snagging and misalignment, thereby ensuring continuous reliable monitoring.
Solution Approach 2:
The patent extracts the problematic wire tether component from the monitoring system, replacing it with a wireless transmission mechanism or direct digital connection. This removal of the mechanical tether eliminates the source of alignment issues and snagging problems while maintaining the core monitoring function.
4Reliability
If the Cook-Swartz Doppler Probe and System is used, then audio output is provided, but costly surgical re-explorations result from false positives
Solution Approach 1:
The patent replaces the audio-based Doppler system with an optical detection system that provides more accurate and reliable blood flow detection. This substitution reduces false positive rates, thereby preventing unnecessary surgical re-explorations and associated costs of $20,000-$30,000 per incident.
Solution Approach 2:
The patent converts the limitation of optical detection in scattering media into a benefit by using the specific optical properties of blood (absorption and scattering characteristics) to detect flow presence. The system leverages these optical interactions to provide reliable detection that reduces false alarms and unnecessary surgeries.
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 provides accurate, automated monitoring of free flap patency with reduced false positive rates, allowing for timely intervention and reducing the need for costly surgical re-explorations by simplifying the interpretation of blood flow data into a binary 'yes' or 'no' status.
Implementation Method 1
extract a baseband Doppler blood flow signal, VBASEBAND, from the scattered signal
Implementation Method 2
receive a scattered signal from the receive transducer, the scattered signal being generated in response to the blood flow volume being insonified
Data Source
AI summary
A system for monitoring free flap patency includes transmit and receive transducers structured to be coupled to a blood vessel, and a plurality of circuitry modules structured to insonify a blood flow volume within the blood vessel and receive a scattered signal from the receive transducer, extract a baseband Doppler blood flow signal, VBASEBAND, from the scattered signal, extract a plurality of features from VBASEBAND, and classify the plurality of features and generate a binary signal based on the classification of the plurality of features, wherein the binary signal will have a first state responsive to the classification of the plurality of features indicating that a flow rate within the blood vessel is less than a predetermined level and a second state responsive to the classification of the plurality of features indicating the flow rate within the blood vessel is greater than or equal to the predetermined level.