Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/021—Measuring pressure in heart or blood vessels
  • A61B5/02108—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics
  • A61B5/02125—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics of pulse wave propagation time
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/021—Measuring pressure in heart or blood vessels
  • A61B5/022—Measuring pressure in heart or blood vessels by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
  • A61B5/0225—Measuring pressure in heart or blood vessels by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
  • A61B5/02438—Detecting, measuring or recording pulse rate or heart rate with portable devices, e.g. worn by the patient
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
  • A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters

Definitions

• the present application relates to systems and methods for monitoring the health status of people, and more specifically to systems and methods for optimizing sensor pressure in continuous or intermittent non-invasive blood pressure (NIBP) measurements using wearable devices.
• NIBP non-invasive blood pressure
• Blood pressure is one of the basic medical parameters used to diagnose human health condition.
• the most accurate methods for BP measurements involve insertion of a catheter into a human artery.
• the BP measurements using a catheter are invasive and costly since they require a medical professional to perform the measurements and, typically, can only be performed in a medical facility environment.
• Less accurate methods for BP measurements include use of an inflatable cuff to pressurize a blood artery.
• cuff-based portable devices for BP measurements that patients can use at home and do not require assistance of a medical professional.
• cuff-based measurements require inflation and deflation of the inflatable cuff. Therefore, such devices are cumbersome to use and not suitable for ongoing BP measurements.
• Some cuff-less devices for BP measurements use an electrical sensor to measure an electrocardiogram (ECG) and optical sensors to measure a photoplethysmogram (PPG).
• ECG electrocardiogram
• PPG photoplethysmogram
• the ECG and PPG can be analyzed to determine pulse transit time (PIT).
• PTT pulse transit time
• the BP can in some cases be determined from the PTT using a pre-defined relationship.
• changes in a cardio-vascular status of a patient require often re-calibration of PTT based blood pressure measurements.
• Cuff -less devices can potentially provide continuous monitoring of the BP while imposing a minimal burden on normal activities when worn on various body parts such as a finger, a wrist, or an ankle.
• Determining the BP based on the PTT alone may not be sufficiently accurate because of other cardiovascular parameters affecting hemodynamics such as vascular resistance, cardiac output, pulse rate (PR), temperature of a finger (if PPG is measured at the finger), and so forth.
• some existing techniques for measuring of BP using the PPG include applying correction factors to account for the vascular resistance and age of patient.
• the correction factors can be determined by an empirical formula.
• Some other techniques attempt to determine compensation factors to compensate for various additional influences (for example, contacting force to sensors, nervous activity and cardiac output of patient, and ambient temperature).
• the compensation factors can be determined using a calibration process.
• the blood artery can be a radial artery at a wrist.
• FIG. 1 is a block diagram showing an example system for performing a blood pressure measurement using a wearable device.
• FIG. 2 is a block diagram showing components of an example device for performing blood pressure measurement.
• FIG. 3 is block diagram illustrating an example device for measuring arterial blood pressure at a wrist.
• FIG. 4 shows an example plot of an ECG and an example plot of a PPG.
• the wearable device 110 can be operable to constantly collect, via sensors 120, sensor data from a patient 130. Based on the sensor data, the wearable device 110 can be operable to provide PPG and ECG. The PPG and ECG can be further used to obtain further medical parameters (for example, pulse rate, pulse transition time, blood pressure, and so forth).
• the system 100 includes a mobile device 140.
• the mobile device 140 can be communicatively coupled to the wearable device 110.
• the mobile device 140 is operable to communicate with the wearable device 110 via a wireless connection such as, for example, Wi-Fi, Bluetooth, Infrared (IR), and the like.
• the mobile device 140 can include a mobile phone, a smart phone, a phablet, a tablet computer, a notebook, and so forth.
• the mobile device 140 can be operable to receive the sensor data and analyze the sensor data to provide ECG and PPG.
• the LEDs 250 are operable to emit light signals.
• the light signals can be of a red wavelength (typically 660 nm) or infrared wavelength (660 nm).
• Each of the LEDs 250 is activated separately and accompanied by a "dark" period where neither of the LEDs 250 is on to obtain ambient light levels.
• a single LED 250 can be used to emit both the infrared and red light signals.
• the lights can be absorbed by human blood (mostly by hemoglobin).
• the oxygenated hemoglobin absorbs more infrared light while deoxygenated hemoglobin absorbs more red light. Oxygenated hemoglobin allows more red light to pass through while deoxygenated hemoglobin allows more infrared light to pass through.
• the isosbestic wavelength includes a near infrared wavelength 810nm (NIR) and a green wavelength 520nm (green).
• NIR near infrared wavelength 810nm
• green green wavelength 520nm
• Mass data storage 730 which can be implemented with a magnetic disk drive, solid state drive, or an optical disk drive, is a non-volatile storage device for storing data and instructions for use by processor units 710. Mass data storage 730 stores the system software for implementing embodiments of the present disclosure for purposes of loading that software into main memory 720.
• Pi nt denotes mean intra-arterial pressure in the blood vessel 320. Determination of the PTT and the BP depend on the accuracy of determination of fluctuation Ad(t) of the blood vessel diameter d(t). The accuracy of determination of fluctuation Ad(t) of the blood vessel diameter d(t) can be contaminated due to either excessive or insufficient amount of the external pressure P ext applied to the blood vessel by the optical sensor(s) 260. Some values of external pressure P ext applied to the blood vessel may result in up to 5% error in PTT and up to 10% in BP.
• FIGs. 9A and 9B shows plots of PPGs 900_k measured at different values P ext k of a pressure of an optical sensor(s) 260, according to some example embodiments.
• FIG. 9A and 9B shows plots of PPGs 900_k measured at different values P ext k of a pressure of an optical sensor(s) 260, according to some example embodiments.
• the method 1000 may commence in block 1002 with recording, by at least one processor, PPG) data using a PPG sensor of a wearable device while the pressure applied by the PPG sensor to a blood artery of the user is gradually increasing.
• the blood artery can be a radial artery of a wrist.
• Determination of the diameter parameter may include modifying the further PPG data by removing, from the further PPG data, an additive contribution resulting from a reflection of a light signal from a surface of a skin covering the blood artery and near-surface tissues underlying the skin and covering the blood artery.
• an additive contribution resulting from a reflection of a light signal from a surface of a skin covering the blood artery and near-surface tissues underlying the skin and covering the blood artery is kept unchanged.
• the additive contribution can be predetermined using a calibration process as described in U.S. Patent Application No. 14/738,711, titled "Pulse Oximetry,” filed on June 12, 2015, incorporated herein by reference for all purposes.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Cardiology (AREA)
• Biomedical Technology (AREA)
• Molecular Biology (AREA)
• Veterinary Medicine (AREA)
• Biophysics (AREA)
• Pathology (AREA)
• Engineering & Computer Science (AREA)
• Public Health (AREA)
• Heart & Thoracic Surgery (AREA)
• Medical Informatics (AREA)
• General Health & Medical Sciences (AREA)
• Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• Physiology (AREA)
• Vascular Medicine (AREA)
• Ophthalmology & Optometry (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Optics & Photonics (AREA)
• Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)

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• 2022
  • 2022-08-03 EP EP22863785.6A patent/EP4395635A1/de active Pending
  • 2022-08-03 WO PCT/IL2022/050840 patent/WO2023031906A1/en active Application Filing

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