Determinants of Capillary Refill Time in Healthy Neonates

Objectives: Traditionally Capillary refilling time (CRT) has been used as a widely accepted method to assess cardiac output and peripheral circulation in neonates. There are only few studies describing normal values and the correct method of recording CRT. The value of CRT is affected by various factors like ambient or skin temperature, age, site of measurement, duration as well as amount of pressure and inter observer variation. However, none of these have been standardized. Hence, we conducted this study to establish the normal value and factors affecting Capillary Refilling Time (CRT) in healthy neonates in Varanasi. Design: Prospective observational study done over a period of 2 years. Setting: Maternity wards and Neonatal intensive care unit of Sir Sunderlal Hospital, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India. Participants: Healthy neonates between 35-42 weeks of gestation staying with their mothers and admitted in neonatal intensive care unit. Materials and Methods: CRT was measured by standard technique four times during first week of life on day 1, 3, 5 and 7. Statistics Analysis: Student t-test was used for analysis. A p-value less than 0.05 was taken as statistically significant. Results: The mean capillary refilling time (CRT) was 2.23 +/- 0.37 seconds in healthy neonates during first week of life. We studied each neonate four times in first week of life. Significantly lower values of CRT were noted in low birth weight babies throughout first week in healthy neonates. Babies under phototherapy and radiant warmer had also shorter CRT values. Values were not affected by age, sex and gestation. Conclusion: The normal value of capillary refilling time (CRT) in healthy neonate is less than three seconds. The major determinants of CRT in healthy neonate are birth weight, radiant warmer and phototherapy. CRT alone in neonatal age is less informative haemodynamic parameter; it should be evaluated along with either blood pressure or oxygen saturation with pulse oxymeter. Further studies are needed to assess the reliability and validity of CRT as a clinical tool to measure perfusion in neonates.