Capillary Refill Time in the Hands and Feet of Normal Newborn Infants

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Abstract
We measured capillary refill time (CRT) in a convenience sample of 137 healthy newborns between 1 and 120 hours of age and 36-42 weeks gestation in the well-baby nursery of a large community hospital. CRT was measured by applying moderate pressure to the dorsum of the right hand and right foot for 5 seconds. Pressure was released and the time for complete refilling of the blanched area noted. Each infant was studied only once. We also measured ambient temperature and the skin temperature of the dorsum of the hand and foot and tested interobserver agreement. Mean CRT was 4.23±1.47 s (SD) (range 1.63-8.78 s) in the hand and 4.64±1.41 s (range 2.15-9.94 s) in the foot (p=0.0001) and did not change significantly in the first 72 hours. CRT decreased with increasing temperature. Environmental temperature, axillary temperature, and temperature of the hand and foot were all significantly and indirectly related to CRT, the strongest relationship existing between CRT and the skin temperature of the hand (r=-0.59, 95% CI 0.69, 0.47 p<0.00001) and foot (r=-0.33, 95% CI 0.46, 0.16 p<0.0001). With triplicate measurements, there was a statistically significant, but clinically moderate, order effect, CRT decreasing with each successive measurement (p<0.0001). Interobserver agreement was fair, the correlation coefficient (r) ranged from 0.47 to 0.71. We conclude that CRT as measured in the hand or foot of a newborn infant in the first 5 days of life is a relatively subjective measurement with an endpoint that is not easy to define and a wide range of values in normal infants. It is influenced significantly by environmental, axillary, and skin temperatures. Since there is no accepted standard for measuring decreased perfusion in the newborn, it is impossible to document the clinical utility of CRT in this population. Further studies are necessary before CRT can be accepted as a useful measure of peripheral perfusion and circulatory status in the newborn infant.