title: Validity and reliability of measurement of capillary refill time in children: a systematic review.
abstract: BACKGROUND
  Most guidelines recommend the use of capillary refill time (CRT) as part of the routine assessment of unwell children, but there is little consensus on the optimum method of measurement and cut-off time.
  
  
  METHODS
  We searched Medline (from 1948), Embase (from 1980) and CINAHL (from 1991) to June 2014 to identify studies with information on the normal range of CRT in healthy children, the validity of CRT compared with reference standard measures of haemodynamic status, reliability and factors influencing measurement of CRT, such as body site, pressing time and temperature.
  
  
  RESULTS
  We included 21 studies on 1915 children. Four studies provided information on the relationship between CRT and measures of cardiovascular status, 13 provided data on the normal range of CRT, 7 provided data on reliability and 10 assessed the effect of various confounding factors. In children over 7 days of age, the upper limit of normal CRT is approximately 2 s when measured on a finger, and 4 s when measured on the chest or foot, irrespective of whether the child is feverish or not. Longer pressing times and ambient temperature outside 20°C-25°C are associated with longer CRT. Evidence suggests that the use of stopwatches reduces variability between observers.
  
  
  CONCLUSIONS
  We recommend use of the following standardised CRT method of measurement: press on the finger for 5 s using moderate pressure at an ambient temperature of 20°C-25°C. A capillary refill time of 3 s or more should be considered abnormal.
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors.forename: Susannah
authors.identifier: http://orcid.org/0000-0001-7205-2051
authors.initials: S
authors.lastname: Fleming
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK The Hospital for Sick Children, Department of Pediatrics, University of Toronto, Toronto, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Gill
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Jones
authors.affiliation: Child Health Institute, University of Washington, Seattle, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Taylor
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors.forename: Ann
authors.initials: A
authors.lastname: Van den Bruel
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors.forename: Carl
authors.initials: C
authors.lastname: Heneghan
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK Department of Family Medicine, University of Washington, Seattle, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Thompson
mesh_terms: D015415:Biomarkers; D002196:Capillaries / Q000502:physiology*; D002648:Child; D005385:Fingers / Q000098:blood supply*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers
keywords: Evidence Based Medicine; General Paediatrics; Measurement