How to Correctly Test Capillary Refill Time in an Infant or Child

Capillary refill time is a quick and easy test that can provide important information regarding skin perfusion in an infant or child. Abnormal perfusion of the skin can indicate a number of worrisome medical conditions. The ability to immediately assess perfusion in children with a seconds-long test is invaluable to clinicians and concerned parents.

The capillary refill time is often done as part of the physical exam by nurses and physicians. When performing this painless test the capillaries (tiny blood vessels) are briefly compressed. The pressure on the arteriolar capillaries blanches or whitens the skin so that when the skin is uncompressed this allows blood to flow back in to the vessels and the skin returns to a normal color. The amount of time it takes for the skin to return to normal is the capillary refill time.

Despite the simplicity of this test, it is often performed incorrectly thus yielding useless results. The capillary refill test is often done by pressing on a finger or toe. In order to correctly perform a capillary refill test the extremity to be tested should be lifted to a level slightly above the heart. In an infant or child that is lying down, little effort is required to accomplish this. However, in an infant or child who is sitting or standing the tester must remember to lift the arm to just above heart level.

The capillary refill test is best performed in a room temperature environment. A cool environment can cause peripheral vasoconstriction and alter the results of the cap refill test. If it is not possible to test for capillary refill time in a room temperature environment then it is useful for the tester to time his or her own capillary refill time in that environment and extrapolate those results to the infant or child's cap refill time.

Once the environmental temperature has been accounted for and the child's extremity is in the correct position, pressure is applied to the finger or toe by compressing gently till the skin blanches. As soon is pressure is released from the digit the tester should count until the skin color returns to normal. The normal capillary refill time in an infant or child is less than 2 seconds.

Several medical issues can cause a delayed capillary refill time in children. Dehydration, hypothermia and most types of shock cause a sluggish or prolonged capillary refill time that is greater than 2 seconds.

Capillary refill time is a very simple and useful aspect of the physical exam. However, this test is easily done incorrectly. It is important that health care providers and concerned parents know how to correctly test the capillary refill time in infants and children.

Source: Pediatric Advanced Life Support. American Heart Association. 2006.