Atomfizikas un spektroskopijas institūts / Institute of Atomic Physics and Spectroscopy

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LU zinātniskais institūts / Scientific Institute of the University of Latvia

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Browsing Atomfizikas un spektroskopijas institūts / Institute of Atomic Physics and Spectroscopy by Subject "Capillary refill time"

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    Challenges in automated estimation of capillary refill time in dogs
    (SPIE, 2018-02-20) Cugmas, Blaž; Spīgulis, Jānis
    Capillary refill time (CRT) is a part of the cardiorespiratory examination in dogs. Changes in CRT can reflect pathological conditions like shock or anemia. Visual CRT estimation has low repeatability; therefore, optical systems for automated estimation have recently appeared. Since existing systems are unsuitable for use in dogs, we designed a simple, small and portable device, which could be easily used at veterinary clinic. The device was preliminarily tested on several measurement sites in two dogs. Not all measurement sites were suitable for CRT measurements due to underlying tissue optical and mechanical properties. The CRT measurements were possible on the labial mucosa, above the sternum and on the digit where CRT was in the range of values, retrieved from the color video of the visual CRT measurement. It seems that light penetration predominantly governs tissue optical response when the pressure is applied. Therefore, it is important to select a proper light, which reaches only superficial capillaries and does not penetrate deeper. Blue or green light is probably suitable for light skin or mucosa, on the other hand, red or near-infrared might be used for skin with pigmented or thick epidermis. Additionally, further improvements of the device design are considered, like adding a calibrated spring, which would insure application of consistent pressure.
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    Clinical evaluation of automated capillary refill time estimation in dogs and cats
    (SPIE, 2019-02-26) Cugmas, Blaž; Štruc, Eva; Spīgulis, Jānis
    In this study, we clinically evaluated a pulse oximeter-based device for automated capillary refill time (CRT) estimation in dogs and cats. CRT can reveal conditions like shock or anemia in dogs and cats. However, visual CRT estimation has low repeatability, and the available optical systems for automated estimation are not suitable for pets. We evaluated a custom-made portable CRT measuring device on various measurement sites of 12 dogs and 11 cats with parallel visual CRT estimation on the gum by treating veterinarian. The capillary refill was also recorded by a video camera for reference. The visual and video procedures were moderately correlated with the coefficient of 0.61; visual CRT values were on average for 0.18 s longer than the reference. On average, ~32% of measurements with the proposed device were successful. The rest failed due to excessive pigmentation, motion artifacts, and other pressure-induced effects. The measurement sites of the metacarpal pad, digit, and tail were moderately correlated with the reference values with coefficients of 0.53, 0.58, and 0.42, respectively.