Reference values of perfusion indices in hemodynamically stable newborns during the early neonatal period

We aimed to determine reference values of perfusion index (PI) in healthy newborns during the early neonatal period. Preductal (right hand) and postductal (foot) PI values were assessed during the first 5 days of life by using a new generation pulse oximetry. A total of 241 newborn infants (196 [81.3 %] term and 45 [18.7 %] preterm) were enrolled to the study. On the first day, in term infants, the median (interquartile range [IQR]) preductal and postductal PI were 1.35 (1.02-1.91) and 0.88 (0.62-1.22), respectively (p = 0.001). These values were 0.88 (0.60-1.26) and 0.61 (0.35-0.92) in preterm infants, with the same respect (p = 0.001). From the first to third days, preductal PI remained significantly higher than the postductal PI (p < 0.001, for all comparisons). Both preductal and postductal PI of term newborns were significantly higher than those of preterm infants (p < 0.001, for both comparisons). These differences in PI disappeared on the fifth day of life. Conclusion PI values which reflect peripheral perfusion seem to reach to a steady state on the fifth day of life following physiological maturation.