Background <p>Pulmonary embolism(PE) is a ventilation/perfusion(V/Q) disorder due to obstruction of the pulmonary artery, typically by a thrombus. The Pleth Variability Index(PVI) is a noninvasive measure reflecting dynamic changes in the perfusion index(PI), observed through photoplethysmography over at least one respiratory cycle. This study aims to investigate the prognostic value of plethysmographic parameters in patients with PE, hypothesizing that these parameters may serve as a reliable guide in a condition where impaired perfusion plays a critical role.</p> Methods <p>Data were collected from patients over 18 years old, diagnosed with PE in the emergency department, including demographic information, risk scores, and measurements. PVI and PI values were analyzed across mortality groups. A survival analysis was performed to assess the impact of PVI and PI on 1-year mortality. The study followed the STROBE checklist for evaluation.</p> Results <p>49-patients were included in this prospective, single-center study. The PVI was significantly higher, and PI was significantly lower in the deceased group compared to the survivors(<i>p</i> = 0.027, <i>p</i> = 0.011). AUC values for PVI, PESI score, and PI were 0.714, 0.820, and 0.745, respectively. The negative predictive value of PESI was 100%, while PVI showed the highest positive predictive value(53.5%). The mean survival time was significantly shorter for patients with PVI &gt; 40 and PI &lt; 1.9(<i>p</i> = 0.001, <i>p</i> = 0.002). An increase in PVI was associated with a ~ 5-fold higher risk of death(HR:5.04, 95% CI:1.50-16.92, <i>p</i> = 0.009).</p> Conclusions <p>PVI is a noninvasive, rapid, and objective tool for predicting mortality in PE patients in the emergency department. This study is the first to evaluate PVI in PE.</p> Trial registration <p>ClinicalTrials.gov Identifier: NCT06508112. Registered on 12 July 2024.</p>