Capillary refill time (CRT) in adult patients has found its way into modern medical practice in a seemingly haphazard way. Introduced by Beecher et al1 in 1947, it was defined as “normal”, “definite slowing” and “very sluggish”, correlating with “no”, “slight”/“moderate” and “severe” shock, respectively. No numerical values were placed on the definitions. The concept permeated into medical practice when it was revisited by Champion et al2 for their trauma score.

Champion and colleagues2 arbitrarily used a normal value of less than 2 seconds, although this was not based on experimental evidence. Schriger and Baraff3 in 1988 (and via a personal communication in 1987) were unable to uncover any publications at all that defined normal values of CRT and determined that the 2-second limit was based on personal experience only.

There are scant data on CRT in adults and what evidence there is shows little consensus with established practice.

Schriger and Baraff3 showed that a normal CRT, when measured using the pulp of the finger, …