Pulse Rate Determination Using Quality Functions for Noisy Signals
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Solution Overview
Problem
Existing patient monitoring systems face challenges in accurately and reliably determining blood pressure and pulse rate due to interference from patient motion and vibrations, which distort pressure signals and make it difficult to compute pulse periods, especially when pulse amplitudes are low or non-consecutive.
Innovation Solution
A method and apparatus that acquire and analyze pulse data at pressure steps, determining quality values and matching criteria to assess the reliability of pulse measurements, allowing for accurate computation of pulse rate using a minimum number of pulse periods, even in noisy conditions, by employing quality functions such as Peak-Match-Quality, Pulse-Period-Quality, and Envelope-Quality to filter out artifacts and ensure accurate data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional oscillometric methods are used to measure pulse rate, then the measurement process is simple, but the reliability and accuracy deteriorate due to patient motion, vibrations, and artifacts distorting the pressure signal
Solution Approach 1:
The system performs preliminary filtering and quality assessment of pulse signals before final pulse rate calculation. By pre-identifying and removing artifacts through quality functions (Peak-Match-Quality, Pulse-Period-Quality, Envelope-Quality), the system ensures only high-quality pulses are used for measurement, thereby improving reliability without requiring complex post-processing
Solution Approach 2:
The patent introduces quality functions as intermediary evaluation criteria between the raw pressure signal and the final pulse rate calculation. These quality functions act as mediators that assess pulse matching criteria, amplitude ratios, and temporal relationships to filter out distorted signals caused by patient motion and vibrations, allowing accurate pulse rate determination even in noisy conditions
2Measurement precision
If pulse amplitude is low or pulses are non-consecutive, then the measurement can be taken quickly, but the accuracy of pulse period computation deteriorates
Solution Approach 1:
The system continuously monitors pulse quality metrics (amplitude ratios, matching criteria, temporal relationships) and uses this feedback to dynamically adjust the measurement process. When low-quality pulses are detected, the system automatically requests additional pulses or adjusts filtering parameters, ensuring that only sufficiently accurate pulse periods are used for calculation while minimizing unnecessary delays
Solution Approach 2:
The patent changes the parameters used for pulse evaluation based on signal quality. By employing multiple quality functions that assess different aspects (peak matching, envelope characteristics, temporal relationships), the system can adaptively determine which pulses are suitable for measurement, thereby maintaining accuracy even when pulse amplitudes vary or pulses are non-consecutive
3Reliability
If multiple pulses are gathered at each pressure step to ensure accuracy, then the measurement reliability improves, but the time required for blood pressure determination increases
Solution Approach 1:
The system performs partial pulse gathering at each pressure step by using quality functions to identify the minimum number of high-quality pulses needed for reliable measurement. Instead of uniformly collecting a fixed number of pulses regardless of quality, the system collects only sufficient high-quality pulses, thereby maintaining reliability while reducing unnecessary measurement time
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 enhances the reliability and accuracy of pulse rate determination by filtering out noise and ensuring that only high-quality pulse data is used, providing more accurate and consistent blood pressure and pulse rate measurements, even in conditions with low amplitude signals or non-consecutive pulses.
Implementation Method 1
The cuff is inflated to a pressure above the patient's systolic pressure and then reduced over time while a pressure sensor continues to measure the cuff pressure. The sensitivity of the sensor is such that pressure fluctuations within the cuff resulting from the beats of the patient's heart may be detected.
Data Source
AI summary
A method and system for determining pulse rate of a patient are disclosed. The method and system include acquiring measured information for at least one pulse at a pressure step, determining and storing quality values for the at least one pulse at the pressure step, analyzing pulse matching criteria for the pressure step, and determining pulse rate based on the measured information, quality values, and pulse matching criteria.