Capillary refill time as a bedside perfusion indicator: associations with vital signs and triage acuity in the emergency department: a cross-sectional study

Abstract

Background: The capillary refill time (CRT) is the time it takes for a capillary bed to regain its color after being subjected to pressure. Capillary refill time (CRT) is a bedside perfusion indicator. We examined CRT across emergency department (ED) triage categories and identified independent correlates of CRT and prolonged CRT (> 2 s). Methods: In this cross-sectional study (July–September 2024), adults presenting to a tertiary ED were assigned green/yellow/red triage. CRT was measured in triplicate on the index-finger pulp after 10-s blanching and the mean was analyzed. Vital signs (SpO₂, heart rate, systolic/diastolic blood pressure, body temperature, skin temperature at the measurement site, and respiratory rate) were recorded. Associations were assessed using correlation and multivariable regression (overall and stratified by triage). Results: We included 313 patients (mean age 55.8 ± 20.9 years; 53.4% female). CRT repeatability was high (ICC = 0.972, 95% Cl). Mean CRT was 2.00 ± 0.94 s and was longer in the red vs. other triage groups (2.36 ± 1.01 s; p < 0.001). In stratified models, green: heart rate (β > 0, p = 0.031) and respiratory rate (β < 0, p < 0.001); yellow: age (β > 0, p = 0.001) and respiratory rate (β > 0, p = 0.039); red: age (β > 0, p = 0.001) and respiratory rate (β > 0, p = 0.026). In the overall model, age and heart rate were positively, and systolic blood pressure negatively, associated with CRT (all p < 0.05). Conclusion: CRT varies with ED triage acuity and behaves as a rapid, reproducible bedside perfusion indicator. Age, heart rate, respiratory rate and systolic blood pressure are independent correlates of CRT, supporting its utility in initial assessment. Prospective, multicenter validation and prediction-model performance reporting (AUC, calibration) are warranted. Clinical trial registration: The present study has been registered with the Clinical Trials Protocol Registration and Results System (ClinicalTrials.gov) under the registration number NCT07054151. The registration date is 26/06/2025.