Method and device for continuous, non-invasive determination of blood pressure
Inventors
Assignees
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Publication Number
US-10098554-B2
Publication Date
2018-10-16
Expiration Date
Abstract
The invention relates to a method and a device for continuously determining blood pressure in a non-invasive manner using a photoplethysmographic system which has at least one light source and at least one light detector that is arranged with a mount on a body part containing an artery. According to the invention, a device is provided with which the contact pressure of the mount on the body part can be adjusted and/or changed depending on the mean blood pressure.
Core Innovation
The invention provides a method for continuous, non-invasive determination of blood pressure by means of a photoplethysmographic system. The system includes a mounting element disposed on a body part containing an artery and comprising at least one light source and at least one light detector. The method obtains an initial photoplethysmographic signal and then obtains a photoplethysmographic signal for subsequent determination of blood pressure.
The method disposes the mounting element on the body part and varies a contact pressure of the mounting element depending on a mean arterial blood pressure. The rate of change of the contact pressure is smaller than that of pulsatile blood pressure changes in the artery. The contact pressure is varied by a control system departing from an initial contact pressure.
The control system uses a low-pass filter through which the photoplethysmographic signal is passed to generate a filtered photoplethysmographic signal, which is compared with the initial photoplethysmographic signal. Based on the comparison, the contact pressure is varied until the filtered photoplethysmographic signal again corresponds to the initial photoplethysmographic signal. An adaptive correction compensates physiological changes of the wall of an arterial vessel by accounting for vasomotoric changes such as vasoconstriction and vasodilatation.
Absolute blood pressure is obtained using an intermittent upper-arm measurement together with a transfer function applied to the photoplethysmographic signal. The claims further refer to compensating arterial-wall physiological changes via a second low-pass filter and comparing pulsatile signal components.
Claims Coverage
Independent claim coverage describes a continuous, non-invasive blood-pressure determination method using a photoplethysmographic system with adjustable mounting contact pressure, including an initial photoplethysmographic signal and closed-loop pressure adjustment based on low-pass filtering and comparison. Multiple inventive features support continuous absolute blood pressure determination.
Continuous non-invasive photoplethysmographic blood-pressure determination with contact-pressure control
A method for continuous, non-invasive determination of blood pressure by means of a photoplethysmographic system, disposing a mounting element on a body part containing an artery and continuously varying a contact pressure of the mounting element.
Contact pressure varied depending on mean arterial blood pressure with slower rate change
Varying a contact pressure of the mounting element depending on a mean arterial blood pressure, wherein a rate of change of the contact pressure is smaller than that of pulsatile blood pressure changes in the artery.
Low-pass filtered comparison to an initial photoplethysmographic signal
Varying the contact pressure by a control system departing from an initial contact pressure, wherein the control system uses a low-pass filter through which the photoplethysmographic signal is passed to generate a filtered photoplethysmographic signal, which is compared with the initial photoplethysmographic signal.
Adjust contact pressure until filtered signal corresponds to initial signal
Based on the comparison, varying the contact pressure until the filtered photoplethysmographic signal again corresponds to the initial photoplethysmographic signal.
Compensation of arterial-wall physiological changes via low-pass filtering and signal comparison
Accounting for physiological changes of the wall of an arterial vessel by passing the photoplethysmographic signal through a second low-pass filter and comparing pulsatile signal components.
Calibration using intermittent upper-arm blood pressure and signal components
Calibrating a blood pressure signal using a mean blood pressure of an intermittent upper arm measurement together with the contact pressure of the mounting element and pulsatile photoplethysmographic signal components.
The claims cover a closed-loop photoplethysmographic blood-pressure method in which mounting-element contact pressure is adjusted based on mean arterial blood pressure, with pressure control driven by low-pass filtering and comparison to an initial photoplethysmographic signal. Further features compensate arterial-wall physiological changes and support absolute blood pressure determination using intermittent upper-arm measurement together with a transfer function and signal components.
Stated Advantages
Continuous, non-invasive determination of blood pressure.
Documented Applications
Continuous blood-pressure monitoring/determination using a photoplethysmographic system with adjustable mount contact pressure.
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