Contactless system and method for measuring and continuously monitoring arterial blood pressure
Inventors
Assignees
Publication Number
US-11350825-B2
Publication Date
2022-06-07
Expiration Date
2037-08-24
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Abstract
A contactless system for measuring and continuously monitoring arterial blood pressure includes a light source configured to illuminate light having at least one predetermined wavelength at a predetermined area of a human subject having an artery therein. A detector responsive to reflected light from the predetermined area to continuously acquire images of the artery in the predetermined area. A processor processes the images and determines when an image at a proximal location of the predetermined area is darker indicating transition of a pulse wave into the artery at the proximal location and at a proximal time and when an image at a distal location of the predetermined area is darker indicating transition of the pulse wave into the artery at a distal location at a distal time to contactlessly and continuously calculate the arterial blood pressure for each cardiac cycle of the human subject.
Core Innovation
The invention is a contactless system and method for measuring and continuously monitoring arterial blood pressure in a human subject. The system includes a light source configured to illuminate light at at least one predetermined wavelength on a predetermined area of the subject where an artery is located. A detector continuously acquires images of the artery based on reflected light from the illuminated area. A processor analyzes these images to detect darker regions indicating the transition of a pulse wave at proximal and distal locations along the artery. Using the timing difference between these points, the processor calculates pulse transit time and length between the locations to derive arterial blood pressure continually for each cardiac cycle.
This contactless approach addresses limitations of conventional invasive arterial blood pressure measurement systems that require intravascular cannulae and pose risks such as thrombosis, infection, and bleeding, restricting use primarily to hospital intensive care settings. It also overcomes drawbacks of conventional photoplethysmography systems that rely on direct skin contact, which can be unsuitable for patients with exposed wounds, burns, or delicate skin, and are affected by motion artifacts from sensor contact.
Claims Coverage
The patent includes two independent claims, each covering a contactless system and a method for measuring and continuously monitoring arterial blood pressure with specific inventive features.
Contactless system for continuous arterial blood pressure measurement
A system comprising one or more light sources configured to illuminate light of at least one predetermined wavelength at a predetermined area containing an artery in a human subject; a detector configured to continuously acquire images of the artery from reflected light; and a processor configured to process the images to detect darker images at proximal and distal locations indicating pulse wave transition times, determine the length between these locations from the images, and contactlessly and continuously calculate the arterial blood pressure for each cardiac cycle.
Predetermined wavelength between green and near infrared light
The system utilizes light having one or more wavelengths between green light and near infrared (NIR) light that is sensitive to oxygenated or deoxygenated hemoglobin concentration in the blood.
Near infrared sensors as light sources
The one or more light sources include near infrared (NIR) sensors configured to emit appropriate wavelengths for illumination.
Detector comprising a charge coupled device camera
The detector includes a charge coupled device (CCD) camera responsive to the reflected light for image acquisition.
Creation of reference objects using spaced light emission
The system uses one or more light sources configured to emit spaced light to create reference objects in the predetermined area, allowing the processor to determine the proximal and distal locations and calculate the length between them.
Computer readable storage medium coupled to processor
The inclusion of a non-transitory computer readable storage medium coupled to the processor to store data and instructions.
Display and user interface for continuous blood pressure display
A display coupled to the processor configured to continuously display calculated arterial blood pressure for each cardiac cycle, further coupled to a user interface enabling user interaction.
Processor functions for blood pressure calculation
Processor configured to determine pulse transit time from timing differences, calculate pulse wave velocity by dividing length by transit time, determine artery diameters during systolic and diastolic phases, calculate pulse pressure and elastic modulus of the artery, and calculate arterial blood pressure using these parameters continuously for each cardiac cycle.
Contactless method for continuous arterial blood pressure measurement
A method that includes illuminating light of a predetermined wavelength at a predetermined area containing an artery, continuously acquiring reflected light images, processing images to detect darker images indicating pulse wave transition at proximal and distal locations, determining length between locations from images, and continuously calculating arterial blood pressure for each cardiac cycle.
Use of predetermined wavelength sensitive to hemoglobin concentration in method
Employing wavelengths between green and near infrared light sensitive to oxygenated or deoxygenated hemoglobin concentration in blood for illumination in the method.
Near infrared sensors for illumination in method
Using one or more near-infrared sensors to provide illuminating light in the method.
Spaced light sources creating reference objects in method
Providing one or more light sources configured to emit spaced light to create reference objects to determine proximal and distal locations and length between them in the method.
Continuous display of calculated arterial blood pressure in method
Providing continuous display of the calculated arterial blood pressure from the method.
Processor operations for blood pressure calculation in method
Processor operations including determining pulse transit time, calculating pulse wave velocity, determining artery diameters during systolic and diastolic phases, calculating pulse pressure and elastic modulus, and contactlessly and continuously calculating arterial blood pressure using these parameters.
The independent claims collectively describe a contactless system and method using specific light wavelengths, image acquisition and processing techniques, and physiological parameter calculations to continuously and contactlessly measure arterial blood pressure for each cardiac cycle of a human subject.
Stated Advantages
Contactless measurement allows use with patients who have exposed wounds, burns, or delicate and sensitive skin where contacting the skin is problematic.
Reduces risks associated with conventional invasive arterial blood pressure measurement systems such as thrombosis, infection, and bleeding.
Eliminates the need for close supervision due to risk of severe bleeding that could occur if an invasive line is disconnected.
Enables long distance measurements with multiple light sources and detectors mounted in a room to perform continuous monitoring of multiple patients simultaneously.
Simplifies network infrastructure by requiring minimal wires and cables compared to conventional contact systems.
Documented Applications
Monitoring arterial blood pressure in clinical settings including intensive care units and emergency rooms, particularly where multiple individual assessments are difficult or not feasible.
Use with patients where contact-based devices are unsuitable, such as patients with exposed wounds, burns, neonatal patients, or those with delicate skin.
Integration into standalone devices, wearable devices, smart watches, or mobile electronic devices for continuous and contactless arterial blood pressure monitoring.
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