Feasibility study of wearable capillary refill time measurement device

Capillary refill time (CRT) is an internationally accepted indicator of peripheral circulation. The CRT is measured by applying compression to the fingernail for a few seconds, releasing it, and observing the process of refilling of blood at the fingertip. The international guidelines for the management of sepsis and septic shock 2021 contains an additional new recommendation for CRT measurement to determine the peripheral circulation statuses of adult patients with septic shock. However, the current CRT measurement method lacks objectivity. Previous studies have reported the development of measurement devices and video analysis systems, which involve complex measurement environment construction and assume only in-hospital measurements. In addition, since medical workers are limited in the number of carrying medical devices, devices that can be used to obtain multiple biometric indicators in a single measurement are needed. Hence, a prototype wearable CRT measurement device was developed in this study, and its feasibility was evaluated by comparing the agreement, intra-class correlation coefficient, and coefficient of variation with those of a CRT measurement device developed in the past. The results indicated that mean CRTs between measurement methods were agreement, with moderate or better intra-rater reliability and no difference in coefficient of variation. Therefore, the results indicate the feasibility of the proposed wearable CRT device.