Volume 89, October 2025, 155167Author links open overlay panel, , , , , Section snippetsTechnical feasibility and clinical implementation

First, the retrospective nature of our signal processing algorithm currenlty limits clinical application. Real-time integration of PPG waveform analysis into bedside monitors is essential for emergency department use. The primary technical challenge is the computationally intensive template-based preprocessing required for signal quality assessment and feature extraction, which is technically only possible on a retrospective dataset. Nonetheless, beat-to-beat feature extraction, signal quality

Generalizability and validation

Second, the study was performed in an academic tertiary care center, which may limit external validity and, by extension, generalizability. However, our hospital has a substantial geographical spread in a rural area, ensuring a diverse population with diverse comorbidities that need either academic or non-academic care, reflecting real-world clinical complexity. This heterogeneity highlights the importance of predictive models detecting early sepsis across varied presentations. Sepsis remains

Predictive value of PPG compared to existing Scoring systems

Third, our study did not include a direct comparison between PPG-derived features and established triage scores such as NEWS or qSOFA. While the main aim was to assess whether PPG features differ between patients suffering deterioration and those not deteriorating, evaluating comparative predictive performance is an essential next step. To this end, we have now compared the PPG-derived features with MAP, qSOFA and NEWS (Fig. 1). PPG-derived features outperform traditional hemodynamic parameters

Future perspectives: toward intelligent, wearable early warning systems

PPG-derived features should be included as a core component of intelligent Early Warning Scoring systems, as this will enable continuous, non-invasive monitoring in both hospital and outpatient settings. When integrated with wearable technology, PPG-based monitoring could support early detection of patient deterioration, especially in resource-constrained environments [10]. In low- and middle-income countries, affordable, battery-operated devices incorporating PPG may improve triage and reduce

CRediT authorship contribution statement

Sanne Ter Horst: Conceptualization, Data curation, Formal analysis, Investigation, Visualization, Writing – original draft. Raymond J. van Wijk: Conceptualization, Writing – review & editing, Methodology. Anna D. Schoonhoven: Methodology, Conceptualization. Anouk de Lange: Data curation, Methodology. Jan C. ter Maaten: Conceptualization, Methodology, Supervision, Writing – review & editing. Hjalmar R. Bouma: Conceptualization, Investigation, Methodology, Supervision, Writing – review & editing.

Funding

The research is supported by a MD/PhD grant awarded to Ms. S. Ter Horst by the UMCG.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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