What does "capillary refill time" assess?

Capillary refill time is a critical assessment parameter that evaluates peripheral circulation and tissue perfusion. It measures how quickly blood reinfuses into the capillaries after capillary occlusion, typically tested by pressing on a fingertip or nail bed until it blanches and then measuring the time it takes for normal color to return once the pressure is released. A normal capillary refill time is generally considered to be less than 2 seconds and indicates that the patient has good blood flow to the extremities and adequate tissue perfusion.

On the other hand, factors such as blood pressure levels, heart rate variability, or neurological function are assessed using different methodologies and do not directly reflect peripheral circulation or the adequacy of blood flow to tissue at the capillary level. Thus, the assessment of capillary refill time specifically focuses on the circulatory system's ability to supply blood to peripheral tissues efficiently.