Capillary refill time

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. 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. 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. 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. Prolonged capillary refill time may also suggest peripheral artery disease. 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.

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