Perfusion index as a diagnostic tool for patent ductus arteriosus in preterm infants.

Background: Perfusion index (PI) could reflect peripheral flow. Preterm infants with hemodynamically significant patent ductus arteriosus (hsPDA) will have left-to-right shunt across PDA causing less blood flow to the lower legs.

Objective: To evaluate pre- and postductal PI differences (ΔPI) in hsPDA.