Capillary refill

A clinical test used to assess blood circulation in the body

Capillary refill is a quick and simple clinical test used to evaluate the circulatory status of a patient. It is commonly used in emergency medicine and by healthcare professionals to assess the adequacy of peripheral perfusion and cardiac output.

Physiology

Capillary refill time (CRT) is the time taken for color to return to an external capillary bed after pressure is applied to cause blanching. This test is based on the principle that when pressure is applied to the skin, it compresses the capillaries, causing them to empty of blood. Upon release of the pressure, the capillaries refill with blood, and the skin returns to its normal color.

Procedure

To perform the capillary refill test, the healthcare provider typically presses on the nail bed of a finger or toe until it turns white, indicating that the blood has been forced out of the capillaries. The pressure is then released, and the time it takes for the color to return is measured. A normal capillary refill time is usually less than 2 seconds.

Clinical Significance

Capillary refill time is used as a quick assessment tool for:

• Shock: Prolonged capillary refill time may indicate poor perfusion and shock.
• Dehydration: In cases of severe dehydration, capillary refill time may be delayed.
• Peripheral vascular disease: Conditions affecting blood flow can alter capillary refill time.

Limitations

While capillary refill is a useful initial assessment tool, it has limitations:

• It can be affected by ambient temperature, as cold environments can prolong refill time.
• It may not be reliable in patients with anemia or cyanosis.
• Variability in technique and interpretation can affect results.

Also see

• Peripheral perfusion
• Shock (circulatory)
• Vital signs
• Cardiac output