Smartphone Application for Automated Measurement of Capillary Refill Time (CRT)
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- This is an observational study: the protocol does not assign a study treatment.
- Who it may be relevant to
- Registry conditions: Capillary Refill Time, Peripheral Tissue Perfusion. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- France
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Overview
This prospective, monocenter observational study aims to validate a smartphone application (CRTApp) that automatically measures capillary refill time (CRT) from a short video of a standardized finger compression. Sixty adult intensive care unit (ICU) patients will undergo a CRT measurement recorded with a professional Android smartphone. Clinical CRT will be determined from the video by three blinded observers (reference = median of the three measurements). The application will analyze the same video locally to provide an automated CRT measurement. Agreement between automated and clinical reference CRT will be assessed, and predefined subgroup analyses will explore performance across skin tone, ambient lighting, smartphone characteristics, and severity of peripheral hypoperfusion.
Detailed description
Capillary refill time (CRT) is a bedside indicator of peripheral perfusion, but visual assessment is prone to inter-observer variability. In this study, CRT is measured using a standardized method (10-second finger compression with a glass slide). A video of the fingertip is captured without audio; framing is strictly limited to the fingers. Files are pseudonymized at acquisition. Videos are transferred via USB to an AP-HP workstation and stored on an AP-HP server; no cloud or messaging is used, and videos are deleted from the smartphone after import. Automated CRT is computed locally from the video by CRTApp without network transmission and without retaining the video. Statistical analyses will include intraclass correlation coefficient and Bland-Altman analysis for agreement. Secondary analyses will evaluate agreement stratified by skin tone (Monk scale / ITA), ambient lighting (lux), smartphone characteristics, and severity of peripheral hypoperfusion.
Primary outcome measures
- Agreement Between Automated and Clinical Capillary Refill Time Measurement [Time frame: At inclusion (single assessment)]
Secondary outcome measures (5)
- Inter-Observer Variability of Clinical Capillary Refill Time Measurement [Time frame: Inter-observer variability of clinically measured capillary refill time assessed by three independent observers, expressed as the coefficient of variation.]
- Agreement Stratified by Skin Tone [Time frame: At inclusion (single assessment)]
- Agreement Stratified by Ambient Lighting Conditions [Time frame: Intraclass correlation coefficient between automated and clinical capillary refill time measurements stratified according to ambient light intensity measured in lux.]
- Agreement Stratified by Smartphone Model Characteristics [Time frame: Intraclass correlation coefficient between automated and clinical capillary refill time measurements stratified by smartphone type (iOS or Android) and camera resolution.]
- Agreement Stratified by Severity of Peripheral Hypoperfusion [Time frame: Intraclass correlation coefficient between automated and clinical capillary refill time measurements stratified by clinical capillary refill time (< 3 seconds versus ≥ 3 seconds).]
Eligibility criteria
Inclusion criteria
- Age ≥ 18 years
- Adult patients hospitalized in an intensive care unit
- Clinical indication for capillary refill time assessment (hemodynamic monitoring, suspected peripheral hypoperfusion, or therapeutic evaluation)
- No objection from the patient or legal representative
Exclusion criteria
- Skin lesions at the measurement site
- Known severe peripheral vascular disease
- Finger amputation
- Presence of distinctive skin marks on fingers (tattoos, significant scars, or prominent moles) that may interfere with measurement or increase the risk of patient re-identification
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Observational model
- Cohort
Study locations
France · 1 center
- CHU Bicêtre — Le Kremlin-Bicêtre
Identifiers
NCT: NCT07473869 · APHP251601