Physiological Stability Index (PSI): A Retrospective Computational Framework for Assessing Dynamic Physiological Instability

Background

Acute clinical deterioration in intensive care may be preceded by gradual changes in the dynamics of physiological signals. Current monitoring systems, however, are often based on static thresholds for individual vital signs and may not fully capture loss of systemic resilience before overt decompensation.

Objective

This study presents an open retrospective evaluation of the Physiological Stability Index (PSI) as an interpretable computational framework for assessing dynamic physiological instability from clinical and physiological time series. PSI is not proposed as a diagnostic device or a substitute for clinical judgment, but as a testable model of systemic fragility.

Methods