title: Impact of patient and environmental factors on capillary refill time in adults.
abstract: OBJECTIVE
  Capillary refill time (CRT) has been taught as a rapid indicator of circulatory status. The aim of this study was to define normal CRT in the Australian context and the environmental, patient, and drug factors that influence it.
  
  
  METHODS
  This prospective observational study included healthy adults at hospital clinics, workplaces, universities, and community groups. Volunteer participants provided their age, sex, ethnic group, and use of hypertensive or cardiac medications. Capillary refill time, ambient temperature, and patient temperature were recorded in a standard manner. Data were analyzed using descriptive statistics and regression analyses. The 95th percentile was used to define the upper limit of normal.
  
  
  RESULTS
  One thousand participants were included; 57% were women, 90% were white, and 21% were taking cardiac medications. The median CRT was 1.9 seconds (95th percentile, 3.5 seconds). The CRT increased 3.3% for each additional decade of age. The CRT was also on average 7% lower in men than in women. The CRT decreased by 1.2% per degree-Celsius rise of ambient temperature, independently of patient's temperature, and decreased by 5% for each degree-Celsius rise in patient temperature, independently of ambient temperature. On multivariant analysis, age, sex, ambient temperature, and patient temperature were statistically significant predictors of CRT, but together explain only 8% of the observed variability.
  
  
  CONCLUSIONS
  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.
authors: Monash University, Victoria 3800, Australia.
authors: Bronwyn
authors: B
authors: Anderson
authors: Anne-Maree
authors: AM
authors: Kelly
authors: Debra
authors: D
authors: Kerr
authors: Megan
authors: M
authors: Clooney
authors: Damien
authors: D
authors: Jolley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001831:Body Temperature; D002196:Capillaries / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012016:Reference Values; D012039:Regional Blood Flow; D013696:Temperature