Quantitative Capillary Refill Time with image-based finger force estimation

•Capillary refill time (CRT) is used as an indicator of the pathophysiology.•While the measurement of CRT is easy to perform, its evaluation is highly subjective.•This study proposes a method to aid quantified CRT measurement using an RGB camera.•Also, we estimate compression force by a finger from the nail color. Skin color observation provides a simple and non-invasive method to estimate the health status of patients. Capillary Refill Time (CRT) is widely used as an indicator of pathophysiological conditions, especially in emergency patients. While the measurement of CRT is easy to perform, its evaluation is highly subjective. This study proposes a method to aid quantified CRT measurement using an RGB camera. The procedure consists in applying finger compression to the forearm, and the CRT is calculated based on the skin color change after the pressure release. We estimate compression applied by a finger from its fingernail color change during compression. Our study shows a step towards camera-based quantitative CRT for untrained individuals.