Single-Lumen Blood Pressure Cuff Pressure Differential Correction
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Solution Overview
Problem
Single-lumen blood pressure measurement devices face challenges in accurately measuring systolic and diastolic blood pressures due to pressure losses associated with the flow of inflation fluid through a common conduit, which complicates the inflation BP technique and deviates from the accuracy standard of +/- 3 millimeters Hg.
Innovation Solution
A method is developed to correct sensed pressure measurements by determining and accounting for pressure differentials between the pressure sensor and the actual cuff pressure during both inflation and deflation processes, using relationships involving air flow rates and measured pressure differentials to calculate true diastolic and systolic blood pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-lumen device is used to connect the cuff to both the pump and pressure sensor, then the device complexity is reduced, but the measurement precision deteriorates due to pressure losses in the common conduit
Solution Approach 1:
The patent implements a feedback mechanism where the pressure sensor continuously monitors the pressure in the common lumen, and the system uses this feedback information to calculate and compensate for the pressure differential between the sensor and the cuff. This allows the single-lumen device to achieve accurate blood pressure measurements by dynamically adjusting for the pressure losses in the conduit.
Solution Approach 2:
The patent introduces an intermediary calculation step where the pressure differential caused by fluid flow in the common lumen is measured and used as a correction factor. This intermediary measurement allows the system to distinguish between the actual cuff pressure and the pressure sensed at the sensor location, thereby resolving the measurement accuracy issue while maintaining the single-lumen configuration.
2Ease of operation
If the inflation BP technique is used in single-lumen devices, then patient comfort is improved, but the measurement precision deteriorates due to uncorrected pressure losses
Solution Approach 1:
The system uses real-time feedback from the pressure sensor to monitor pressure changes during cuff inflation and deflation. By continuously measuring the pressure differential in the common lumen and using this feedback to correct the blood pressure calculations, the system enables accurate inflation BP measurements that maintain patient comfort while achieving the required measurement precision.
Solution Approach 2:
The patent changes the parameter being measured from the raw sensor pressure to the corrected cuff pressure by accounting for the pressure differential. This parameter transformation allows the system to use the inflation BP technique with accurate results, as the corrected pressure values reflect the true cuff pressure rather than the sensor pressure affected by flow losses.
3Device complexity
If pressure losses in the common conduit are not corrected, then the device complexity remains low, but the measurement precision falls below the accuracy standard of +/- 3 millimeters Hg
Solution Approach 1:
The patent implements a feedback-based correction system where the pressure sensor measures the actual pressure in the common lumen, and this measurement is used to calculate the pressure differential. The system then applies this correction to obtain accurate blood pressure values, achieving compliance with the +/- 3 mmHg accuracy standard while maintaining the simple single-lumen device architecture.
Solution Approach 2:
The patent introduces an intermediary correction mechanism that measures the pressure differential in the common lumen and uses it as a compensation factor. This intermediary step allows the system to maintain low device complexity while achieving high measurement precision by mathematically correcting for the pressure losses rather than adding complex hardware solutions.
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 approach enables accurate measurement of diastolic and systolic blood pressures during cuff inflation and deflation in single-lumen devices, aligning with the established accuracy standards and allowing for the use of the 'inflation BP' technique, thereby improving patient comfort and measurement precision.
Implementation Method 1
A pressure differential exists between the cuff and the pressure sensor due to the pressure losses experienced by the flow of the inflation fluid through the conduit
Data Source
AI summary
The diastolic blood pressure and a systolic blood pressure of a vertebrate are measured using an inflatable pressure cuff disposed about a limb of the vertebrate and connected to an inflation device through a single conduit. A pressure sensor is pneumatically connected to the cuff through the same common conduit. The sensed pressures at the diastolic and systolic points are corrected for a pressure differential associated with the flow of an inflation fluid through the common conduit. The sensed pressures at the diastolic point and the systolic point may be measured during inflation of the cuff or during controlled deflation of the cuff.