Peripheral perfusion index versus NEWS score in prehospital non-trauma adults: A prospective cohort study

Background

The Peripheral Perfusion Index (PPI), derived from pulse oximetry waveforms, is a non-invasive and easily obtainable parameter that reflects peripheral microcirculation. It has gained increasing attention for its potential role in early recognition of circulatory compromise and risk stratification in emergency settings. Despite its growing clinical relevance, studies investigating the prognostic value of PPI in non-traumatic adult patients presenting to the emergency department remain limited. In parallel, although the National Early Warning Score (NEWS) is widely used to predict acute clinical deterioration, its effectiveness in the prehospital setting and in undifferentiated patient populations continues to be debated. This study aimed to evaluate the prognostic value of the PPI in non-traumatic adult patients presenting to the emergency department. Additionally, it sought to compare the predictive performance of PPI with the NEWS in determining clinical outcomes such as discharge, ward admission, intensive care unit (ICU) admission, and 24-h and 30-day mortality.

Methods

This prospective observational study was conducted at Etlik City Hospital Emergency Department from January 13 to 20, 2025. Adult patients (≥18 years) arriving by ambulance with measurable PPI were included. Exclusions were trauma cases, cardiac arrest, alcohol/sedative use, pregnancy, and incomplete data. Vital signs, laboratory values, PPI (measured with MASIMO RAD-97), and NEWS scores were recorded at admission. Out of 1032 ambulance admissions, 452 patients met inclusion criteria and were analyzed.

Results

Between January 13–20, 2025, 452 emergency patients were evaluated for the predictive value of PPI and NEWS regarding patient disposition and mortality. ICU-admitted patients had significantly lower PPI and higher NEWS compared to ward-admitted and discharged groups (p < 0.001). Multivariable analysis identified PPI and NEWS as independent predictors of ICU admission. PPI showed excellent accuracy for predicting discharge (AUC 0.970) and ICU admission (AUC 0.942), outperforming NEWS. Additionally, PPI predicted 24-h mortality with high sensitivity and specificity (AUC 0.927).

Conclusions

PPI is a rapid, non-invasive, and reliable parameter that demonstrates superior prognostic performance compared to the NEWS in non-trauma adult patients presenting to the emergency department via ambulance. PPI effectively predicts patient disposition and early as well as late mortality, supporting its use as a valuable tool for early risk stratification and resource allocation. Further multicenter studies are needed to validate these findings and to establish standardized protocols for PPI integration into clinical practice.