NIBP Inflation Pressure Automation Using SpO2 Waveforms
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Solution Overview
Problem
Conventional non-invasive blood pressure (NIBP) monitoring systems often require initial inflation pressures that are either too high, causing patient discomfort and extended measurement times, or too low, necessitating re-inflation, due to reliance on estimated target settings rather than individual patient measurements.
Innovation Solution
A method utilizing a pulse monitor, such as a pulse oximeter, to determine the optimal initial inflation pressure for the blood pressure cuff by analyzing the plethysmographic waveform and its second derivative, allowing the central processor to terminate inflation when acceleration peaks disappear, indicating occlusion of the brachial artery, thus setting the initial inflation pressure based on real-time patient data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the initial inflation pressure is selected well above the systolic blood pressure, then the NIBP system ensures complete artery occlusion and accurate measurement, but the patient experiences discomfort and the measurement time is extended
Solution Approach 1:
The system performs preliminary monitoring of the plethysmographic waveform during the inflation phase to detect when the brachial artery becomes occluded. This preliminary detection allows the system to stop inflation at the appropriate pressure point rather than using a fixed high pressure, thereby ensuring accurate measurement while minimizing patient discomfort
Solution Approach 2:
The system uses real-time feedback from the pulse monitor's plethysmographic waveform to adjust the inflation pressure. By monitoring changes in the waveform (specifically the disappearance of acceleration peaks) during inflation, the system receives feedback about artery occlusion status and automatically terminates inflation when the optimal pressure is reached, resolving the contradiction between ensuring occlusion and minimizing discomfort
2Object-affected harmful factors
If the initial inflation pressure is selected below the systolic blood pressure, then the patient experiences less discomfort, but the blood pressure cuff must re-inflate to obtain an accurate reading
Solution Approach 1:
The system performs preliminary monitoring of the plethysmographic waveform during the inflation phase to detect when the brachial artery becomes occluded. This preliminary detection ensures that the inflation pressure is sufficient for accurate measurement while minimizing the pressure applied, thereby avoiding the need for re-inflation
Solution Approach 2:
The system uses real-time feedback from the pulse monitor to detect artery occlusion during the inflation phase. When the feedback indicates occlusion (disappearance of acceleration peaks), the system automatically terminates inflation at the correct pressure, ensuring both patient comfort and measurement accuracy in a single inflation cycle, thus eliminating time loss
3Ease of operation
If a fixed target inflation pressure setting is used, then the system is simple to operate, but it cannot adapt to individual patient conditions and may require re-inflation
Solution Approach 1:
The system incorporates automatic feedback from the pulse monitor's plethysmographic waveform during inflation. The central processor monitors the waveform changes in real-time and automatically determines when to terminate inflation based on the disappearance of acceleration peaks. This automated feedback mechanism provides patient-specific adaptation while maintaining ease of operation, as no additional user input or complex settings are required
Solution Approach 2:
The system performs self-adjustment by automatically monitoring its own inflation process through the plethysmographic waveform and autonomously determining the optimal termination point. The NIBP monitor serves itself by using the pulse monitor data to control its own inflation/deflation cycle, eliminating the need for manual pressure setting while adapting to each patient's unique blood pressure characteristics
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 ensures the blood pressure cuff is inflated just above the systolic pressure, reducing patient discomfort and measurement time, while providing accurate readings by adapting to individual patient conditions.
Implementation Method 1
a pulse monitor, such as the SpO2 plethysmograph waveform from an SpO2 monitor
Implementation Method 2
The finger probe sensor must be placed upon the finger of the patient on the same arm of the patient that includes the blood pressure cuff
Implementation Method 3
A pressure sensor measures the cuff pressure, including the cuff pressure fluctuations resulting from the heart pumping activity that then causes pressure or volume oscillations in the artery under the cuff
Data Source
AI summary
A method and system for operating a non-invasive blood pressure monitor that utilizes an SpO2 plethysmograph waveform to determine the initial inflation pressure for the NIBP monitor. A pulse sensor is placed on the patient's limb distal to the blood pressure cuff and provides a pulse waveform to the NIBP monitor. The NIBP monitor calculates a second derivative of the pulse waveform, which includes a series of acceleration peaks corresponding to pulse signals within the pulse waveform. When the blood pressure cuff reaches systolic pressure, the acceleration peaks contained within the acceleration waveform are eliminated, thus providing an indication that the cuff pressure has reached systolic pressure for the patient. Use of the SPO2 plethysmograph signal to determine the initial inflation pressure reduces both the over-inflation of the blood pressure cuff and the under-inflation of the blood pressure cuff, which increases the rate at which the blood pressure measurement can be made while increasing patient comfort.