Noninvasive peripheral perfusion index as a possible tool for screening for critical left heart obstruction

Aim: Peripheral perfusion index (PPI) has been suggested as a possible method to detect illness causing circulatory embarrassment. We aimed to establish the normal range of this index in healthy newborns, and compare it with newborns with duct-dependent systemic circulation. Design: We conducted a case-control study. Setting: Our study population comprised 10 000 prospectively recruited newborns from Vastra Gotaland, Sweden. Patients: A total of 10 000 normal newborns and 9 infants with duct-dependent systemic circulation (left heart obstructive disease [LHOD] group) participated in the study. Methods: We conducted single pre- and postductal measurements of PPI with a new generation pulse oximeter (Masimo Radical SET) before discharge from hospital. Results: PPI values between 1 and 120 h of age show an asymmetrical, non-normal distribution with median PPI value of 1.70 and interquartile range of 1.18-2.50. The 5th percentile = 0.70 and 95th percentile = 4.50. All infants in the LHOD group had either pre- or postductal PPI below the interquartile range, and 5 of 9 (56%) were below the 5th percentile cut-off of 0.70 (p < 0.0001, Fisher's exact test). A PPI value < 0.70 gave an odds ratio for LHOD of 23.75 (95% CI 6.36-88.74). Conclusion: PPI values lower than 0.70 may indicate illness and a value < 0.50 (1st percentile) indicates definite underperfusion. PPI values might be a useful additional tool for early detection of LHOD.