Video Imaging Arterial Pulse Transit Time
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Solution Overview
Problem
Current methods for determining arterial pulse transit time require direct contact with the patient's skin, which is impractical for neonatal intensive care units, especially for premature babies with sensitive skin, and there is a need for non-contact, non-invasive solutions.
Innovation Solution
A system and method using video imaging to capture time-varying source signals from proximal and distal regions of the body, processing these signals to compute phase differences, and deriving arterial pulse transit time, which can then be used to calculate blood pressure, vessel dilation, blockage, flow velocity, or peripheral neuropathy without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes of an ECG device are attached directly to the patient's skin to obtain pulse transit time measurements, then measurement precision is improved, but ease of operation deteriorates due to the invasive nature and sensitivity concerns
Solution Approach 1:
The patent replaces the mechanical contact-based ECG electrode system with an optical imaging system using a video camera to capture blood volume changes in skin regions. This substitution eliminates the need for direct skin contact while maintaining measurement capability through non-contact optical detection of pulsatile blood volume changes.
Solution Approach 2:
The patent introduces video imaging as an intermediary between the measurement system and the patient. Instead of direct electrode-skin contact, the system uses video frames to capture and analyze blood volume changes in proximal and distal regions, with the intermediary processing steps including region identification, signal extraction, and phase difference computation.
2Ease of operation
If a non-contact video imaging system is used to measure pulse transit time, then ease of operation is improved by eliminating skin contact, but measurement precision may deteriorate due to signal extraction challenges
Solution Approach 1:
The patent segments the measurement process into distinct computational stages: identifying proximal and distal skin regions in video frames, extracting time series signals from each region, computing phases of extracted signals, and calculating phase differences. This segmentation allows each step to be optimized independently, maintaining precision through systematic signal processing.
Solution Approach 2:
The patent employs feedback mechanisms in the signal processing pipeline, where extracted time series signals are analyzed to compute phases, and the phase differences provide feedback for determining pulse transit time. The system uses the captured video data continuously to refine measurements, ensuring precision through iterative analysis of blood volume changes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables non-contact, non-invasive measurement of arterial pulse transit time, facilitating the assessment of cardiovascular health parameters, including blood pressure and vessel conditions, with high accuracy and without the need for direct skin contact.
Implementation Method 1
capture a time varying source signal of a proximal and distal region of a subject of interest
Implementation Method 2
capture time-varying source signals generated from video images
Data Source
AI summary
What is disclosed is a system and method for determining an arterial pulse transit time of a subject of interest in a remote sensing environment. A video imaging system is used to capture a time varying source images of a proximal and distal region of a subject intended to be analyzed for arterial pulse transit time. A time series signal for each of the proximal and distal regions is extracted from the source images and a phase of each of the extracted time series signals is computed. A difference is then computed between these phases. This phase difference is a monotonic function of frequencies in the signals. From the monotonic function, an arterial pulse transit time of the subject is extracted. The subject's arterial pulse transit time is then communicated to a computer system. The computer system determines blood pressure, blood vessel blockage, blood flow velocity, or a peripheral neuropathy.