Endothelial Reactivation Test (ERT): Conceptual Framework for Norepinephrine Dose-Trend Monitoring in Septic Shock

Background: Assessing endothelial dysfunction and recovery of vasomotor tone in septic shock remains difficult at the bedside. Current practice relies on static clinical markers or invasive monitoring, which often miss dynamic vascular changes in real time.Objective: To present the conceptual framework of the Endothelial Reactivation Test (ERT), a bedside functional indicator based on tracking norepinephrine (NE) infusion requirements over time during stabilization and de-escalation of septic shock.Hypothesis: NE dose is modeled as a trend from ICU admission. Two prognostic pathways are proposed: Pattern A, a progressive and sustained fall in requirements, suggesting recovery of endothelial and vascular tone; and Pattern B, an escalating requirement, suggesting progressive vasomotor failure or refractory shock. A tentative operational threshold of 5 mcg/kg/min, under validation, separates the two.Significance: By shifting attention from single-point values to longitudinal infusion trends, the ERT offers a dynamic bedside functional indicator. This schematic defines the clinical logic intended to guide future algorithmic processing, real-time monitoring software and bedside decision-support devices.Note: Illustrative schematic and conceptual hypothesis under validation; figures are not patient data. Extends Zenodo v1 (doi:10.5281/zenodo.19097214). Clinical data integration and technical architecture are in preparation.© 2026 Eduardo J. Ortiz Bello. Licensed CC BY-NC-ND 4.0. Commercial use, or software/devices derived from this work, requires the author's written permission.