Diagnostic and prognostic value of serial perfusion index in neonates with suspected sepsis: A prospective observational study

Objectives: Perfusion index (PI), a non-invasive pulse oximetry-derived measure of peripheral perfusion, has shown promise as a marker of illness severity in neonatal sepsis, but most prior studies have relied on single time-point measurements. This study evaluated serial PI as a predictor of culture-positive sepsis, clinical deterioration and mortality in neonates with suspected sepsis. Material and Methods: In this prospective observational cohort study conducted in a tertiary care Neonatal Intensive Care Unit (April–July 2025), PI was measured at 0, 6 and 24 h from the time of clinical suspicion of early- or late-onset sepsis in 240 neonates. Diagnostic accuracy was assessed using receiver operating characteristic curve analysis, and independent predictors of deterioration and mortality were identified using multivariate logistic regression. Results: Blood culture was positive in 54 neonates (22.5%). PI did not differ significantly between culture-positive and culture-negative neonates at any time point ( p > 0.19). Sixty neonates (25.0%) developed deterioration and 24 (10.0%) died. PI showed good to excellent accuracy for deterioration (area under the curve [AUC] 0.905–0.910) and mortality (AUC 0.914–0.917), with PI rising over 24 h in stable/surviving neonates and falling in those who deteriorated or died. On multivariate analysis, PI at 0 h remained independently associated with mortality (odds ratio 0.102, 95% confidence intervals 0.015–0.712, p = 0.021), while only PI at 24 h showed a borderline independent association with deterioration ( p = 0.079). Conclusion: Serial PI did not distinguish culture-positive from culture-negative sepsis but showed good discriminative accuracy for deterioration and mortality in neonates, supporting its potential as a non-invasive bedside adjunct for early risk stratification, pending larger multicentre validation.