Ductal flow ratio as a measure of transition in preterm infants after birth: a pilot study

Abstract

Background: Cardiovascular changes during the transition from intra- to extrauterine life, alters the pressure gradient across the ductus arteriosus (DA). DA flow ratio (R-L/L-R) has been suggested to reflect the infant's transitional status and could potentially predict neonatal outcomes after preterm birth.Aim: Determine whether DA flow ratio correlates with oxygenation parameters in preterm infants at 1 h after birth.Methods: Echocardiography was performed in preterm infants born < 32 weeks gestational age (GA), as part of an ancillary study. DA flow was measured at 1 h after birth. DA flow ratio was correlated with FiO(2), SpO(2), and SpO(2)/FiO(2) (SF) ratio. The DA flow ratio of infants receiving physiological-based cord clamping (PBCC) or time-based cord clamping (TBCC) were compared.Results: Measurements from 16 infants were analysed (median [IQR] GA 29 [27-30] weeks; birthweight 1,176 [951-1,409] grams). R-L DA shunting was 16 [17-27] ml/kg/min and L-R was 110 [81-124] ml/kg/min. The DA flow ratio was 0.18 [0.11-0.28], SpO(2) 94 [93-96]%, FiO(2) was 23 [21-28]% and SF ratio 4.1 [3.3-4.5]. There was a moderate correlation between DA flow ratio and SpO(2) [correlation coefficient (CC) -0.415; p = 0.110], FiO(2) (CC 0.384; p = 0.142) and SF ratio (CC -0.356; p = 0.175). There were no differences in DA flow measurements between infants where PBBC or TBCC was performed.Conclusion: In this pilot study we observed a non-significant positive correlation between DA flow ratio at 1 h after birth and oxygenation parameters in preterm infants.