Capillary Refill Time (CRT) is a simple, non-invasive technique used to quickly gauge the status of a person’s peripheral circulation and hydration. This assessment measures how effectively blood is flowing to the extremities, providing immediate insight into overall tissue perfusion. It is a valuable tool in emergency and first-aid situations where a rapid assessment of cardiovascular health is necessary. The standard test, however, relies on observing the color change beneath a fingernail, which presents a common challenge when nail polish is present.
Understanding Capillary Refill Time
The standard procedure for checking capillary refill involves gently elevating the hand to a level at or above the heart. Next, firm but gentle pressure is applied to the nail bed for about five seconds, a duration sufficient to force the blood out of the capillaries and cause the tissue to blanch white. The pressure is then released, and the time it takes for the normal pink color to return is measured. This return of color signifies the capillaries refilling with oxygenated blood.
The presence of nail polish, especially dark or opaque shades, creates a visual barrier that makes this standard assessment impossible. The polish obscures the clear view of the nail bed, preventing the observer from accurately timing the return of the pink hue. This interference means the quick, observable change from white back to pink cannot be reliably seen. Therefore, when fingernails are unavailable, alternate sites must be utilized to gain the necessary information about blood flow.
Checking Circulation at Alternate Body Locations
When nail polish prevents the use of the fingernails, the assessment can be shifted to other areas of the body where the capillaries are close to the surface. One straightforward alternative is to use the toenail beds, provided they are free of polish or thick coverings. The technique remains identical to the standard finger test: apply firm pressure to the toenail for five seconds, release, and time the color return.
If the toenails are unavailable, a test for dermal refill on the skin itself can be performed. The sternum, the flat bone in the center of the chest, is one of the most reliable alternative sites for this assessment in adults. Apply pressure to the skin over the sternum for five seconds until the area turns pale. The time for the skin to return to its normal color is then recorded.
Other suitable dermal sites include the forehead, the plump pad (pulp) of an unpolished finger, or the thenar and hypothenar eminences on the palm of the hand. While these locations are effective, the skin’s natural pigmentation may require careful observation and adequate lighting to accurately identify the moment the color returns. The finger pulp, the soft underside of the fingertip, is a particularly reliable site as it bypasses the need for the nail plate entirely.
What Capillary Refill Results Indicate
A normal capillary refill time is considered less than two seconds, indicating healthy blood flow and adequate tissue perfusion. To estimate this, one can count “one-one-thousand, two-one-thousand” after releasing the pressure. If the color returns before finishing the count, the refill is brisk and suggests the heart is pumping effectively with sufficient blood volume circulating.
A delayed capillary refill time, defined as greater than two seconds, is a significant sign that indicates potential issues with peripheral circulation. This slow return of color suggests poor perfusion, which is reduced blood flow to the body’s tissues. Prolonged refill times may signal various conditions, including hypovolemia (low blood volume), dehydration, or the onset of shock.
Environmental factors can influence the result; for instance, cold ambient temperatures can naturally slow circulation to the extremities, leading to a slightly longer refill time. However, a CRT greater than three seconds, especially when accompanied by symptoms like pale skin, confusion, or a rapid heart rate, is a serious observation. If a delayed refill time is noted, immediate medical attention should be sought, as it may signify a life-threatening compromise to the circulatory system.