Self-calibrating systems and methods for blood pressure wave form analysis and diagnostic support
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Publication Number
US-11207034-B2
Publication Date
2021-12-28
Expiration Date
Abstract
Indirect, oscillometric, digital blood pressure monitoring systems and methods enabling self-calibration to obtain absolute blood pressure values using algorithmic analysis of arterial pressure pulses to establish an oscillometric profile and compensate for intervening effects on digital arterial pressure. Proper algorithmic analysis is dependent upon proper positioning and maintained engagement of a digital cuff on the digit of a user and subsequent hydraulic coupling of the cuff to the arteries within the digit.
Core Innovation
The invention relates to an indirect blood pressure monitoring system enabling self-calibration to obtain calibrated, absolute blood pressure values. A digital cuff comprising an air bladder and a securing mechanism is positioned on a digit such that the air bladder is in contact with tissue overlying at least one artery. A receiving module controls operation of the digital cuff and includes pressure controlling means adapted to pump air through an air conduit into the air bladder while sensing pressure changes detected by the air bladder.
After establishing an oscillometric profile as a function of air bladder pressure, the processor maintains the air bladder at a pressure less than the user’s diastolic blood pressure. This circumferentially squeezes the digit to partially unload the at least one artery and creates a hydraulic coupling between the at least one artery and the air bladder. The hydraulically coupled air bladder detects pulse pressure oscillations caused by pulse pressure waves passing through the at least one artery, and at least one pressure sensor senses the pulse pressure oscillations for analysis by the processor.
The processor uses the oscillometric profile to derive a calibrated, absolute blood pressure value against which a relatively continuous blood pressure monitoring mode tracks changes in blood pressure. The analysis extracts parameters affecting digital pulse pressure, considers intervening effects on digital pulse pressure, and includes detecting arterial pulse peaks to derive the oscillometric profile. The profile is tested for irregularities due to digital cuff positioning or scan errors, with rejecting or accepting based on presence or absence of irregularities, followed by preliminary systolic and diastolic threshold determination, categorization into low, normal, or high blood pressure ranges, and calibration adjustments using offsets, spectral content, and slope metrics.
Claims Coverage
The provided partial content includes two independent claims. Each independent claim centers on self-calibration of an indirect oscillometric digital blood pressure monitoring system or device to derive calibrated, absolute blood pressure values.
Self-calibrating indirect digital blood pressure monitoring using a hydraulically coupled finger cuff
A digital cuff on a digit, a receiving module controlling the digital cuff and including pressure controlling means with at least one pressure sensor, and a processor analyzing real-time pressure change data to establish an oscillometric profile and consider intervening effects. After establishing the oscillometric profile, the processor maintains an air bladder pressure less than the user’s diastolic blood pressure to create hydraulic coupling so pulse pressure oscillations are detected by the hydraulically coupled air bladder for analysis. The processor uses the oscillometric profile to derive a calibrated, absolute blood pressure value for tracking changes in a relatively continuous blood pressure monitoring mode.
Self-calibration method using pulse decomposition analysis and profile-based threshold adjustments
A method for obtaining an absolute blood pressure value by positioning a digital cuff on a digit and controlling the digital cuff with a receiving module to take absolute blood pressure readings. After establishing the oscillometric profile, the air bladder is maintained at a pressure less than diastolic blood pressure to create hydraulic coupling, pulse pressure oscillations are sensed and transmitted as pressure oscillation data to a processor, and the processor derives a calibrated, absolute blood pressure value using pulse decomposition analysis. The analysis includes oscillometric pressure scans to detect arterial pulse peaks, testing the oscillometric profile for irregularities and rejecting or accepting it, using preliminary systolic and diastolic threshold values, categorizing low/normal/high ranges, computing offsets using tissue coupling estimation, assessing spectral content at different pressure steps, assessing diastolic and systolic slopes, and calculating final systolic and diastolic thresholds to output a calibrated, absolute blood pressure value and display it.
Across the independent claims, self-calibration is implemented by maintaining a finger cuff air bladder at a pressure less than diastolic to create hydraulic coupling for pulse pressure oscillation sensing, then deriving calibrated absolute blood pressure from an oscillometric profile using profile validation, amplitude-based preliminary thresholds, and calibration adjustments using offsets, spectral content, and slope-based threshold determination.
Stated Advantages
Produces calibrated, absolute blood pressure values.
Enables a relatively continuous blood pressure monitoring mode to track changes in blood pressure against the calibrated absolute blood pressure value.
Calibrated, absolute blood pressure values fall within the guidelines of the ANSI/AAMI/ISO 81060-2:2013 standard.
Documented Applications
Calibration and use of a finger-digit indirect oscillometric blood pressure monitoring system and method to obtain calibrated, absolute blood pressure values, including operation following oscillometric profile establishment for tracking changes in blood pressure in a relatively continuous monitoring mode.
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