Brief ReportImpact of patient and environmental factors on capillary refill time in adults
Introduction
Capillary refill time (CRT) has been taught as a rapid indicator of circulatory status. Normal CRT has usually been regarded as less than 2 seconds [1], [2]. However, there is considerable debate in the literature as to the definition of a normal CRT and the factors that may influence it.
Schriger and Baraff [3] reported that CRT was age and sex dependent, finding that children and adult men had significantly shorter CRT than adult women and elderly men and women. They advocated definition of the upper limit of normal for women as 3 seconds and for the elderly as 4 seconds. Watson and Kelly [4] confirmed that CRT varies significantly with age, sex, and environmental temperature.
In addition to these factors, it makes physiological sense that patient temperature and vasoactive medications might also impact CRT. No data defining normal CRT in the Australian population have been reported.
The aim of this study is to define normal CRT in the Australian context and the impact of defined environmental, patient, and drug factors on it.
Section snippets
Methods
This prospective, observational cohort study of healthy adult volunteers was undertaken at several sites including musculoskeletal outpatient clinics at a hospital, workplaces, universities, and local community groups. Inclusion criteria for this study were age older than 18 years, provision of verbal consent, and functioning independently in the community. Exclusion criterion was the inability to communicate in English and unavailability of a suitable translator.
The study period was from June
Results
Data were collected from 1000 participants. The median age fell in the 40- to 49-year-old age band, and the greatest percentage of participants (38%) was in the 18- to 29-year-old age band. There were no participants older than 90 years. There were more women (58%) in the study than men, and 90% of the sample was of white ethnicity.
Cardiac medications were taken by 213 (21%) of participants. Patient body temperature ranged from 34.3°C to 37.7°C, with a mean of 36.5°C (SD 0.5°C). Ambient
Discussion
Capillary refill time has been advocated for rapid assessment of circulatory status. However, the reliability of the test had been questioned because of the absence of agreed ranges for normal CRT values in a healthy adult population [3], [4]. In this study, we have defined the reference range for adult Australians and have investigated some of the factors that contribute to variability in the measurements.
Capillary refill time ranged from 0.8 to 6.1 seconds; and the upper limit of normal
Conclusion
Capillary refill time varies with environmental and patient factors, but these account for only a small proportion of the variability observed. Its suitability as a reliable clinical test is doubtful.
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