capillary refilling, the process whereby blood returns to a portion of the capillary system after its blood supply has been interrupted briefly. Capillary refilling is tested by pressing firmly on a fingernail and estimating the time required for blood to return after pressure is released. In a normal person with good cardiac output and digital perfusion, capillary refilling should take less than 3 seconds. A time of more than 3 seconds is considered a sign of sluggish digital circulation, and a time of 5 seconds is regarded as abnormal.
