Directional Pressure Failure (DPF) is a geometric failure mode in which the body routes pressure and volume into the wrong compartment. Instead of stable partitioning across intravascular, interstitial, and intracellular spaces, signals become inverted: the system can behave dehydrated while retaining, clamp vascular tone while starving tissues, and flip states across timing windows. DPF is not defined by a single lab value; it is defined by directionality (where pressure is routed) and timing (when exits are lost and inversion begins). This preprint is a standalone DPF Series / Concept A definition object within the Lantern of Sulfur (LoS) Unified Version (v12 series). It provides a compact, citeable geometry that makes paradox presentations legible without conflating them with any single mechanism. The document includes: (i) a minimal three-compartment model, (ii) core paradox signatures, (iii) driver-agnostic framing that can integrate multiple Concept B mechanisms, and (iv) prediction/probe logic based on pattern behavior across time rather than one-number diagnosis. Related Concept A′ parent geometry: Hyperchloremia as a Directional and Timing Failure: The full geometry of pressure inversion when downward exits are lost (Lantern of Sulfur, Concept A′, v2026.04). DOI: 10.5281/zenodo.18202813.
Beth Ann Martell (Fri,) studied this question.