Correlation of perfusion index with patent ductus arteriosus repercussion in premature newborns

The ductus arteriosus is a necessary structure in fetal circulation, and its patency can produce hemodynamic alterations. The diagnostic gold standard is echocardiography, not always available. In the neonatal intensive care unit (NICU), they have pulse oximetry that measures perfusion index (PI), which could be used as a diagnostic tool in hemodynamically significant patent ductus arteriosus (HSPDA).

The objective of the study was to correlate the PI increment (ΔPI) in 24 and 72 h after birth with HSPDA in premature newborns of NICU in a second-level hospital.

This is an analytic prospective study which included neonates of 26-34 weeks of gestational age, without comorbidities, who underwent echocardiography and measurement of PI in arm and leg, 24 and 72 h after birth. We did bivariate analysis with X2/exact Fisher's test and Student's t-test/Mann-Whitney U-test, besides Spearman correlation and linear regression for value prediction.

We included 39 premature newborns. We did not find significant differences between patients without and with HSPDA (median: 0.22 [0.06-0.58] vs. 0.03 [-0.27-0.2]; p = 0.09) at 24 h neither 72 h after birth (median: 0.2 [0-0.47] vs. 0.45 [-0.37-0.76]; p = 0.47). We found a positive correlation between ductus arteriosus diameter (DAD) and ΔPI (r: 0.78; confidence interval 95%: 0.6-0.88; p = 0.01). The prediction formula with linear regression is expressed this way: DAD = 1.31 + (2.05 × ΔIP).

The PI does not allow us to discriminate between patient without and with HSPDA. The ΔPI could be a tool for the monitorization of DAD in neonates 72 h after birth.