Capillary Refill Time at the Nailbed and the Dorsum of Hand in Preterm and Term Infants

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The purpose of this study is to establish normal values for capillary refill time (CRT) in healthy full-term and preterm infants, and to compare CRT values at the nailbed and the dorsum of the hand. Healthy term and preterm infants without any major anomaly or cardiovascular problem were enrolled in the study. CRT was measured by applying moderate pressure to the nailbed or the dorsum of hand for 4-5 seconds, and the tune for complete refilling of the blanched area was recorded. Each test was repeated three times on the same subject. In addition, the CRT of 10 volunteer adults was measured for comparison. Our results showed that the mean CRT for the nailbed in premature infants, term infants and adults were 1.66+0.38 sec (SD), 2.00+0.47sec, and 1.55±0.37sec, and in the dorsum of the hand were 2.70 ± 0.65 sec, 3.11±0.56 sec, and 2.82 ± 0.28 sec, respectively. The CRT in the dorsum of hand was significantly longer than that of the nailbed in all three groups (p＜0.05). Full-term infants had longer CRT than preterm infants and adult at the nailbed (p＜0.05). The tests performed on the dorsum of the hand showed that the full term infants had a longer CRT than preterm infants and adults, but there was no significant difference between preterm infants and adults. Furthermore, the effect of ambient temperature was also analyzed, specifically preterm infants in incubators. In conclusion, the CRT values varied with the test sites and were influenced by environmental temperature. A standardized procedure to measure CRT is crucial to evaluate circulatory perfusion in premature and full-term newborn infants.