Relationship between perfusion index and patent ductus arteriosus in preterm infants

BACKGROUND: Perfusion index (PI) is a noninvasive measure of perfusion. Delta PI (difference between pre- and postductal PI) may identify hemodynamically significant PDA. However, studies are limited to brief and intermittent Delta PI sampling. Our objective is to assess the value of continuous high resolution API monitoring in the diagnosis of PDA. METHODS: Continuous Delta PI monitoring in preterm infants was prospectively performed using two high-resolution pulse oximeters. Perfusion Index measures (Delta PI mean and variability, pre- and postductal PI) were analyzed over a 4-h period prior to echocardiography. A cardiologist blinded to the results evaluated for PDA on echocardiography. Linear mixed regression models were utilized for analyses. RESULTS: We obtained 31 echocardiography observations. Mean Delta PI (-0.23 vs. 0.16; P < 0.05), mean pre-PI (0.86 vs. 1.26; P < 0.05), and API variability (0.39 vs. 0.61; P = 0.05) were lower in infants with PDA compared to infants without PDA at the time of echocardiography. CONCLUSION: Mean Delta PI, Delta PI variability, and mean pre-PI measured 4h prior to echocardiography detect PDA in pre-term infants. PI is dynamic and should be assessed continuously. Perfusion index is a promising bedside measurement to identify PDA in preterm infants.