Annular Air Bladder Calibration for Accurate Arterial Pressure
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Solution Overview
Problem
Non-invasive arterial pressure sensors using volume clamping techniques face challenges in accurately determining the proper setpoint, leading to inaccurate arterial pressure waveform data.
Innovation Solution
A method and system that continuously vary the air pressure of an annular air bladder to maintain a constant volume, allowing for the determination of mean arterial pressure values and generation of calibration factors based on these values to compensate for variations in air bladder operation, thereby improving the accuracy of arterial pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a volume clamping technique is used to measure arterial pressure, then non-invasive measurement is achieved, but accurate determination of the proper setpoint becomes difficult leading to inaccurate measurements
Solution Approach 1:
The system performs preliminary calibration by acquiring arterial pressure waveforms at multiple known air pressure levels before actual measurement. This preliminary action establishes a calibration factor that compensates for setpoint determination errors, allowing accurate measurements without requiring precise setpoint acquisition during normal operation
Solution Approach 2:
The system changes the air pressure parameter to multiple known levels during calibration, acquiring waveforms at each level. This parameter variation enables the system to determine a calibration factor that accounts for deviations from the proper setpoint, thereby improving measurement accuracy while maintaining non-invasive operation
2Ease of operation
If the air bladder operation varies, then the measurement process becomes simpler, but the arterial pressure waveform data becomes inaccurate
Solution Approach 1:
The system uses feedback from arterial volume waveforms acquired at multiple air pressure levels to determine a calibration factor. This feedback mechanism allows the system to automatically compensate for air bladder operation variations, maintaining measurement accuracy without requiring manual adjustments or complex operational procedures
Solution Approach 2:
The system performs self-calibration by using its own measurement capabilities to determine a calibration factor that compensates for its own operational variations. The calibration process is automatically executed by the system itself, eliminating the need for external calibration equipment or manual intervention while maintaining measurement accuracy
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 method enhances the accuracy of arterial pressure measurements by using a single hemodynamic sensor, without requiring adjustments to the volume clamp setpoint, and significantly improves the alignment with invasive catheter-based measurements.
Implementation Method 1
adjusting an air pressure of an annular air bladder
Implementation Method 2
a photodetector to generate an arterial volume waveform in response to changes in light intensity
Data Source
AI summary
A method of measuring arterial pressure includes receiving a first mean arterial pressure value, adjusting an air pressure of an annular air bladder from a first air pressure to a second air pressure and receiving a plurality of arterial volume signals from the plethysmographic sensor as the air pressure is adjusted from the first air pressure to the second air pressure. The plurality of arterial volume signals is representative of a plurality of arterial volume waveforms and each arterial volume waveform of the plurality of arterial volume waveforms corresponds to an air pressure between the first air pressure and the second air pressure. The method further comprises determining a second mean arterial pressure value based on the plurality of arterial volume waveforms and generating a calibration factor. The calibration factor is based on the second mean arterial pressure value and the first mean arterial pressure value.