Techniques for determining blood pressure based on morphological features of pulses preliminary class
Inventors
Rantanen, Antti Aleksi • Pärkkä, Juha Pekka • Koskimäki, Heli Tuulia • Heikkinen, Olli Petteri • Mäkinen, Jukka Tapani • Järvelä, Jussi Petteri • Koivisto, Hannu Hermanni • Ohukainen, Pauli Juhani • Syrjälä, Juha-Pekka
Assignees
Publication Number
US-11925441-B1
Publication Date
2024-03-12
Expiration Date
2043-03-24
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Abstract
Methods, systems, and devices for determining blood pressure based on morphological features of pulses are described. A system may include a wearable device that uses one or more light emitting components configured to emit light, one or more photodetectors configured to receive light, and a controller that couples the one or more light emitting components to the one or more photodetectors. The wearable device may transmit lights associated with multiple wavelengths, and acquire photoplethysmogram (PPG) data that includes one or more PPG waveforms associated with the respective wavelengths. The system may determine respective sets of morphological features associated with each of the PPG waveforms based on systolic and diastolic peaks corresponding to the heartbeat of the user. The system may determine one or more blood pressure metrics for the user based at least in part on a comparison of the respective sets of morphological features.
Core Innovation
The invention provides methods, systems, and devices for determining blood pressure based on morphological features of pulses collected via wearable devices. These wearable devices utilize one or more light emitting components configured to emit light at multiple wavelengths and photodetectors configured to receive the light. The system acquires photoplethysmogram (PPG) data that includes multiple PPG waveforms corresponding to different wavelengths. Morphological features associated with these PPG waveforms—such as systolic and diastolic peaks—are determined and compared to estimate blood pressure metrics for the user.
The problem addressed is the inaccuracy and inconvenience of traditional blood pressure measurement methods. Conventional wearable devices may fail to accurately measure blood pressure due to signal processing limitations and insufficient techniques relating hardware data to blood pressure. Clinical blood pressure devices, such as cuff-based monitors, are bulky and inconvenient for consistent use outside clinical settings, leading to infrequent measurements and unawareness of conditions associated with abnormal blood pressure.
The invention aims to provide an improved system enabling wearable devices, such as rings or watches, to measure blood pressure on a consistent basis via non-invasive PPG waveform analysis. By acquiring PPG data using multiple wavelengths of light, the system captures morphological features of pulses at different tissue depths. Comparisons of these morphological features, including correlation coefficients, delays between systolic and diastolic peaks, and timing differences of systolic peaks of different wavelength signals, are used to determine blood pressure metrics. This approach can adapt to variable conditions such as pressure applied to the wearable device against the tissue and compensate based on physiological data like acceleration, enhancing measurement reliability.
Claims Coverage
The patent includes one independent claim that discloses inventive features of a wearable device configured for blood pressure measurement using multi-wavelength PPG data and morphological feature analysis.
Emission and detection of multi-wavelength light for PPG data acquisition
The device includes light-emitting components configured to emit light at least at a first wavelength and a second wavelength and photodetectors configured to receive the light emitted by these components.
Morphological feature determination from second derivatives of multi-wavelength PPG waveforms
The device determines second derivatives of the acquired PPG waveforms for the first and second wavelengths and identifies peaks in these second derivatives corresponding to systolic peaks of the PPG waveforms.
Blood pressure metric determination based on comparison of morphological features and timing delays
The device determines first and second sets of morphological features associated with the respective PPG waveforms based on systolic and diastolic peaks, including the peaks of second derivatives, and calculates blood pressure metrics using a comparison of these features and delays between the second derivative peaks.
Use of baseline blood pressure metric for comparison and display
The device can determine a baseline blood pressure metric for a user, calculate differences between baseline and current metrics, and cause a graphical user interface to display this information.
Correlation coefficient analysis between PPG waveforms
Determination of a correlation coefficient between the first and second PPG waveforms to inform the blood pressure metric determination.
Acquisition of PPG data during varied pressure application and response analysis
PPG data is acquired while pressure between the wearable device and user tissue is selectively changed, using the morphological response to this pressure change as part of blood pressure measurement.
Adjustment of blood pressure metric based on acceleration data
Incorporation of acceleration data representing user movement to selectively adjust the determined blood pressure metric.
The claim covers a wearable device equipped with multi-wavelength light emission and detection, morphological analysis of PPG waveforms focusing on systolic and diastolic features derived from second derivatives, comparison techniques including correlation coefficients and timing delays, and use of pressure and acceleration data to enhance blood pressure metric determination and display.
Stated Advantages
Enables convenient and consistent blood pressure measurement using wearable devices without bulky equipment.
Improves accuracy of blood pressure measurements by leveraging morphological features of multi-wavelength PPG signals.
Allows non-invasive blood pressure monitoring outside clinical settings, supporting continuous or regular health assessments.
Incorporates adjustment for external factors such as applied pressure and physical activity to enhance measurement reliability.
Provides user feedback via graphical user interfaces including baseline comparisons and alert notifications.
Documented Applications
Wearable devices such as rings, watches, necklaces, chest-worn devices, and extremity monitors for continuous or periodic blood pressure measurement.
Monitoring cardiovascular health metrics including systolic and diastolic blood pressure in daily life outside clinical environments.
Calibration and adjustment of blood pressure measurement through user interaction, such as applying variable pressure to the wearable device.
Integration into health monitoring systems that track sleep stages, physiological parameters, and biological rhythms to contextualize blood pressure measurements.
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