Development of models for robust determination of capillary refill time using video

• Grant number: 22/16344-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2023
• End date: December 31, 2023
• Field of knowledge: Engineering - Biomedical Engineering
• Principal Investigator: George Cunha Cardoso
• Grantee: Vanessa Ferreira de Lima
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Capillary Refill Time (CRT) is a technique for determining the quality of an individual's blood perfusion based on the metric of the color change after compression is exerted on a region of the patient's skin. The assessment of blood perfusion is used to diagnose diseases, including viral ones, such as dengue. However, this technique is subjective to the observer's evaluation, which can generate variability in the measurements, which is why there is a need for more precise alternatives. In previous works, the methodology called capillary filling time by reflection mode (rCRT) was developed, which is based on the computational analysis of the response of the RGB channels of a camera. ) of skin, and enabled the monitoring of hemoglobin in the compressed region as a function of time. Making an analogy to an electrical circuit, the increase in the concentration of oxygenated hemoglobin after removing the pressure applied to the area presents a behavior similar to that of charging a capacitor, with vascular resistance being related to the characteristics that alter blood pressure, such as heart rate and the skin temperature. Given this, this project aims to minimize the influence of compression applied to the skin on the CRT measurement, define an effective capillary resistance value and determine the fractal dimension of the vascular system in the region of interest, taking as a hypothesis the modeling of the temporal variation of the oxygenated hemoglobin by the capacitor charge model, these analyzes will be performed on materials already collected. In this project we will also vary the compression applied to the skin to assess the influence on vascular resistance values. All analyzes will be done using the Python script that will be developed in the project.