Visual scoring of photoplethysmography morphology for risk stratification in hemorrhagic shock: a prospective observational study.

Purpose: Early recognition of high-risk patients with hemorrhage remains challenging, as conventional indicators may lack sensitivity during the compensated phase of blood loss. The study evaluated whether visual scoring of photoplethysmography (PPG) morphology could support bedside risk stratification during acute hemorrhage. Methods: In this prospective observational study conducted in the emergency department of West China Hospital between August and October 2025, 500 adults with hemorrhage were enrolled, of whom 461 were included in the final analysis. Three trained physicians independently scored PPG morphology using an ordinal 0-100 visual scale in 10-point increments. The final score was determined through majority voting. The primary outcome was 28-day all-cause mortality, while the secondary outcome was intensive care unit (ICU) admission. Moreover, lactate-related risk stratification was explored separately. Results: Inter-rater agreement was good to excellent based on pairwise linear weighted kappa (0.74, 0.99, and 0.75), whereas overall agreement was moderate based on Fleiss' kappa (0.58). The visual PPG score demonstrated good discrimination for both 28-day mortality (area under the curve [AUC] 0.81) and ICU admission (AUC 0.88), with numerically superior performance to the shock index, mean arterial pressure, lactate, and base excess. Adding the visual PPG score to routine clinical indicators increased the AUC for ICU admission from 0.82 to 0.90. Conclusion: Visual PPG scoring may support early bedside risk stratification in hemorrhagic patients and warrants external validation.