Peripheral perfusion index for differentiating cardiac and pulmonary dyspnea in the emergency department: A...

Dyspnea is a common reason for emergency department (ED) visits, often caused by cardiac or pulmonary conditions with overlapping clinical presentations. Rapid differentiation between these etiologies is crucial for timely management and prognosis. The peripheral perfusion index (PPI), derived from pulse oximetry, has emerged as a non-invasive biomarker of tissue perfusion. This study aimed to evaluate the diagnostic performance of PPI in distinguishing cardiac from pulmonary causes of dyspnea and to assess its prognostic value for clinical outcomes.

We conducted a prospective observational study in the adult ED of Ankara Etlik City Hospital between March 1 and March 31, 2025. Adult patients presenting with dyspnea were consecutively enrolled, with predefined exclusion criteria applied. Demographic data, vital signs, laboratory parameters, and PPI values were collected within 30 min of presentation. Final diagnoses were established using clinical, laboratory, imaging findings, and specialist consultation. The primary outcome was the diagnostic accuracy of PPI in differentiating cardiac and pulmonary dyspnea. Secondary outcomes included ED disposition and 30-day mortality.

A total of 320 patients were included (median age: 73 years; 56.9% female). Pulmonary diseases accounted for 55.9% (n = 179), and cardiac diseases for 44.1% (n = 141). Median PPI was significantly lower in the cardiac group compared with the pulmonary group (1.8 [IQR 1.2-2.2] vs. 2.8 [IQR 2.0-4.3]; p < 0.001). PPI values were also lower in patients admitted to the ICU (1.5) and in 30-day non-survivors (1.5) compared with discharged patients (4.1; p < 0.001). Receiver operating characteristic analysis demonstrated good diagnostic performance for pulmonary disease prediction (AUC: 0.801; 95% CI: 0.749-0.844), with an optimal cutoff of >2.2 (sensitivity 71%, specificity 74%).

PPI is a simple, non-invasive, and rapidly obtainable parameter that may aid in differentiating cardiac from pulmonary causes of dyspnea in the ED. Lower PPI values were observed in patients with cardiac-origin dyspnea and were associated with ICU admission and 30-day mortality; however, the prognostic findings should be interpreted cautiously given the potential for residual confounding.