Capillary refill

Capillary refill time (CRT) is defined as the time taken for color to return to an external capillary bed after pressure is applied to cause blanching.[1] It can be measured by holding a hand higher than heart-level and pressing the soft pad of a finger or fingernail until it turns white, then taking note of the time needed for the color to return once pressure is released.[2] Normal capillary refill time is usually less than 2 seconds. In newborn infants, capillary refill time can be measured by pressing on the sternum for five seconds with a finger or thumb, and noting the time needed for the color to return once the pressure is released. The upper normal limit for capillary refill in newborns is 3 seconds.[3] Capillary refill time can also be assessed in animals by pressing on their gums as opposed to the sternum which is generally covered with fur or inaccessible.

A prolonged capillary refill time may be a sign of shock and can also indicate dehydration and decreased peripheral perfusion.[4] Prolonged capillary refill time may also suggest peripheral artery disease.[2] It is generally accepted that the test is affected by many different external factors and therefore should not be relied upon as a universal diagnostic measure.[1]