Measurement of capillary refill time with a handheld prototype device: a comparative validation study in healthy...

Validity and reproducibility of clinical capillary refill time (CRT) measurement depend on many factors in daily routine practice. We conducted a prospective validation study of an automatized handheld prototype device providing standardized CRT assessment (DiCART™) in 20 healthy volunteers. Three different methods of CRT measurement were compared before and during dynamic circulatory changes induced by venous and arterial occlusion tests at both upper and lower limb levels: CRT_CLIN corresponding to basic clinical assessment and considered as the reference method; CRT_VIDEO corresponding to off-line videos reviewed by investigators recorded by DiCART™; and CRT_DiCART corresponding to on-line videos analysed by a built-in proprietary mathematical algorithm included in DiCART™. Five subjects were excluded because of a DiCART™ dysfunction. ROC_AUC to detect arterial occlusion test changes at the upper limb level were 1.00 (95%CI 1.00; 1.00), 0.96 (95%CI 0.88; 1.00), and 0.92 (95%CI 0.79; 1.00) for CRT_CLIN, CRT_VIDEO, and CRT_DiCART, respectively. Precision of CRT_CLIN and CRT_VIDEO were significantly better than CRT_DiCART (0.18 and 0.20 vs. 0.28; P < 0.05). Percentages of error were 76% and 87% for CRT_VIDEO and CRT_DiCART, respectively. DiCART™ had an excellent discrimination to detect major changes in CRT induced by arterial ischemia. However, the perfectible precision, the poor agreement with clinical assessment and numerous device dysfunctions give leads to the development of a further version of the prototype before promoting its use in clinical practice.Trial registration clinicaltrial.gov. Identifier: NCT04538612.