Optical Blood Pressure Monitoring via Motion Compensation
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Solution Overview
Problem
Traditional methods for measuring blood pressure are invasive, subjective, and often do not provide timely measurements, leading to patient discomfort and potential injury due to the need for repetitive and frequent occlusive cuff measurements.
Innovation Solution
A non-invasive blood pressure monitoring system using an optical sensor and a motion sensor to derive blood pressure measurements from photoplethysmograph signals, which can be used to trigger occlusive cuff measurements only when necessary, reducing patient discomfort and improving measurement frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional occlusive cuff measurements are used frequently to improve measurement timeliness, then blood pressure monitoring accuracy is improved, but patient discomfort and potential injury increase
Solution Approach 1:
The patent replaces the mechanical occlusive cuff system with an optical sensing system that uses light absorption characteristics of hemoglobin to detect blood pressure changes. The optical sensor continuously monitors blood volume changes in the tissue without applying external pressure, thereby eliminating patient discomfort and potential injury while providing continuous timely measurements
Solution Approach 2:
The patent introduces motion sensors as an intermediary to detect and compensate for motion artifacts in the photoplethysmograph signal. By using the motion signal as a mediator, the system can distinguish between actual blood pressure changes and motion-induced signal variations, maintaining measurement accuracy without requiring frequent occlusive cuff measurements
2Reliability
If repetitive interval measurements are used to trend patient status, then measurement completeness is improved, but patient discomfort and possible patient injury increase
Solution Approach 1:
The patent implements continuous blood pressure monitoring using optical sensors that continuously detect blood volume changes in real-time. This continuous measurement approach provides complete patient status trending information without the need for repetitive discrete measurements, thereby eliminating patient discomfort and potential injury associated with frequent occlusive cuff applications
Solution Approach 2:
The patent replaces the mechanical occlusive cuff measurement system with a non-invasive optical sensing system that uses photoplethysmography to continuously monitor blood pressure. This substitution maintains reliable patient status trending while completely eliminating the harmful effects of repetitive mechanical occlusion on patient comfort and safety
3Ease of operation
If occlusive cuff measurements are reduced in frequency to decrease patient discomfort, then patient comfort is improved, but measurement completeness and timeliness deteriorate
Solution Approach 1:
The patent replaces intermittent mechanical occlusive cuff measurements with continuous non-invasive optical sensing. This substitution maintains measurement timeliness and completeness while significantly improving patient comfort by eliminating the need for repetitive occlusive cuff applications
Solution Approach 2:
The patent implements continuous blood pressure monitoring that provides uninterrupted measurement data, ensuring measurement timeliness and completeness is maintained even as occlusive cuff frequency is reduced to zero, thereby continuously improving patient comfort
4Measurement precision
If motion compensation techniques are applied to improve measurement accuracy during patient motion, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent integrates motion sensing capability into the existing optical measurement system, allowing the same device to perform both photoplethysmograph acquisition and motion detection. This multi-functionality approach improves measurement precision during patient motion while minimizing the increase in device complexity by combining functions in a single integrated sensor unit
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 allows for continuous and non-invasive blood pressure monitoring, reducing patient discomfort and the frequency of occlusive cuff measurements while providing timely and accurate blood pressure readings.
Implementation Method 1
an optical sensor having an emitter configured to emit light on a measurement site of a patient and a detector configured to detect the light after attenuation by the measurement site and to output a photoplethysmograph signal responsive to the attenuated light
Data Source
AI summary
A blood pressure measurement system that non-invasively determines an individual's blood pressure can include a noninvasive blood pressure sensor having an optical sensor and a motion sensor. The optical sensor can provide a photoplethysmograph signal obtained from a patient to a processor. The motion sensor can provide a motion signal to the processor responsive to motion of the patient. In one embodiment, the processor calculates or estimates the blood pressure of the patient based on the photoplethysmograph signal and the motion signal. Advantageously, the system can obtain this blood pressure measurement without an occlusive cuff, thereby reducing patient discomfort. In other implementations, the processor calculates a blood pressure-related parameter from the photoplethysmograph and motion signal. The processor can occasionally trigger an occlusive cuff measurement as this parameter changes, thereby reducing the frequency of occlusive cuff measurements.