Background Capillary refill (CR) time is traditionally assessed by ‘naked-eye’ inspection of the return to original colour of a tissue after blanching pressure. Few studies have addressed intra-observer reliability or used objective quantification techniques to assess time to original colour. This study compares naked-eye assessment with quantified CR (qCR) time using polarisation spectroscopy and examines intra-observer and interobserver agreements in using the naked eye.
Method A film of 18 CR tests (shown in a random fixed order) performed in healthy adults was assessed by a convenience sample of 14 doctors, 15 nurses and 19 secretaries (Department of Emergency Medicine, Linköping University, September to November 2017), who were asked to estimate the time to return to colour and characterise it as ‘fast’, ‘normal’ or ‘slow’. The qCR times and corresponding naked-eye time assessments were compared using the Kruskal-Wallis test. Three videos were shown twice without observers’ knowledge to measure intra-observer repeatability. Intra-observer categorical assessments were compared using Cohen’s Kappa analysis. Interobserver repeatability was measured and depicted with multiple-observer Bland-Altman plotting. Differences in naked-eye estimation between professions were analysed using ANOVA.
Results Naked-eye assessed CR time and qCR time differ substantially, and agreement for the categorical assessments (naked-eye assessment vs qCR classification) was poor (Cohen’s kappa 0.27). Bland-Altman intra-observer repeatability ranged from 6% to 60%. Interobserver agreement was low as shown by the Bland-Altman plotting with a 95% limit of agreement with the mean of ±1.98 s for doctors, ±1.6 s for nurses and ±1.75 s for secretaries. The difference in CR time estimation (in seconds) between professions was not significant.
Conclusions Our study suggests that naked-eye-assessed CR time shows poor reproducibility, even by the same observers, and differs from an objective measure of CR time.
- acute care
- clinical assessment
- emergency department management
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Contributors DBW and RTJ conceived the study. DBW, RTJ and JH designed the trial. DBW obtained research funding. DBW and CDA supervised the conduct of the trial. RTJ and JH undertook recruitment of observers and managed the data with assistance from DBW. DBW and RTJ drafted the manuscript, and all authors contributed substantially to its revision. RTJ takes responsibility for the paper as a whole.
Funding This work was supported by two grants from Region Östergötland to author DBW (LIO-532001 and LIO-700271).
Competing interests RTJ and DBW have no conflicts of interest to declare. The bioengineering method TiVi is marketed by the company WheelsBridge AB. No financial support from WheelsBridge AB was involved in the conduct of the study. JH is employed by the Östergötland County Council but has a royalty agreement with WheelsBridge AB. CDA has a full-time academic position but also limited involvement in WheelsBridge AB.
Ethics approval This study was reviewed and approved by the Regional Ethical Vetting Board in Linköping, Sweden (permit number M200-07).
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.