Measuring capillary refill time
Inventors
Sheridan, David • Hansen, Matthew Lee • Kibler, Andrew • Baker, Steven D. • Sunderland, Richard Allen • Weitzel, Richard H.
Assignees
Promedix Inc • Oregon Health and Science University • Welch Allyn Inc
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Publication Number
US-11806114-B2
Publication Date
2023-11-07
Expiration Date
Abstract
A system for measuring capillary refill time includes a wearable device and a control unit. The wearable device includes a force sensor to obtain a force signal and an optical sensor to obtain an optical signal. The system ensures that an applied force is acceptable in both magnitude and duration, and that a duration over which the applied force is released or removed is acceptable. These factors can establish that a capillary refill time determined or calculated therein is accurate. The system can also determine the capillary refill time based on the force and optical signals obtained by the force and optical sensors, respectively.
Core Innovation
The invention relates to a device and associated techniques for measuring a capillary refill time (CRT). A wearable component includes a force sensor configured to generate a force signal representative of a force applied to a digit of a patient over time, and an optical sensor configured to generate an optical signal representative of optical energy received from an optical source over time.
A processor determines a timing parameter of the applied force within a force duration window, based on a characteristic of the force signal and a characteristic of the optical signal. The processor calculates the CRT based on the timing parameter and outputs a value of or data related to the CRT.
In the described implementation, CRT is calculated as the time from force release to when the optical signal returns to a baseline optical value level or within a threshold range or percentage. The system validates whether applied force magnitude and stability meet acceptance criteria and whether the force release or removal duration meets acceptance criteria, and provides corrective feedback such as retry or re-measure when data are invalid.
Claims Coverage
The document includes three independent claims: a device, a method, and a non-transitory computer readable medium. Each independent claim centers on determining a timing parameter within a force duration window or release window using both a force signal characteristic and an optical signal characteristic, then calculating CRT from that timing parameter and outputting CRT-related value or data.
Wearable CRT measuring device using force and optical timing characteristics
A wearable component comprising a force sensor configured to generate a force signal representative of a force applied to a digit of a patient over time, and an optical sensor configured to generate an optical signal representative of optical energy received from an optical source over time; and a processor programmed to determine a timing parameter of the applied force within a force duration window based on a characteristic of the force signal and a characteristic of the optical signal, calculate the CRT based on the timing parameter, and output a value of or data related to the CRT.
CRT determination method using a force duration release window timing parameter
Receiving a force signal representative of a force applied manually to a digit of a patient over time; receiving an optical signal representative of optical energy received from an optical source over time; determining a timing parameter of the applied force within a force duration release window based on a characteristic of the force signal and a characteristic of the optical signal; calculating the CRT based on the timing parameter; and generating an instruction to output a value of or data related to the CRT.
Non-transitory computer readable medium for CRT calculation from timing parameter
A non-transitory computer readable medium for calculating a capillary refill time (CRT), comprising machine-readable instructions that, when executed on one or more processors, perform operations comprising acquiring a force signal representative of a force applied manually to a digit of a patient over time, receiving an optical signal representative of optical energy received from an optical source over time, determining a timing parameter of the applied force within a force duration release window based on a characteristic of the force signal and a characteristic of the optical signal, calculating the CRT based on the timing parameter, and generating an instruction to output a value of or data related to the CRT.
Across the independent claims, the inventive focus is to determine a timing parameter within a force duration window or release window using both force-signal and optical-signal characteristics, calculate the CRT from the timing parameter, and output CRT-related value or data.
Stated Advantages
Validates applied force magnitude and stability against acceptance criteria and validates force release or removal duration against acceptance criteria.
Calculates CRT based on a timing parameter tied to force release and return of the optical signal to a baseline optical value level or within a threshold range or percentage.
Provides corrective feedback when data are invalid, including retry or re-measure.
Uses quality metrics for signal validation.
Outputs CRT-derived information as a value of or data related to the CRT.
Documented Applications
Smartphone, tablet, or hospital monitor application for measuring or outputting CRT-related value or data.
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