This is the 2D counterpart of the thigh-cuff dynamic-autoregulation simulator: it runs the identical second-order control model, but instead of an animated 3D vessel it draws the model's own native 2D spaces — a phase-plane trajectory and the classic pressure-flow autoregulation curve — which a 3D scene cannot show directly.
Let u = ΔMAP/MAP₀ be the normalized pressure step and y the resistance-vessel compensation state:
T² · y'' + 2·D·T · y' + y = K · u(t)
ΔCBFV/CBFV₀ = u(t) − y(t)
T (time constant), D (damping ratio) and K (gain) come from the Autoregulation Index (ARI, 0–9). The phase portrait plots y against its scaled velocity T·y' — for D < 1 (ARI 7–9) the trajectory spirals into the origin (oscillatory, underdamped recovery); for D ≥ 1 (ARI 0–4) it approaches monotonically (overdamped, no ringing). The pressure-flow curve plots the idealized static relationship between MAP and CBF — flat across the autoregulatory plateau (≈60–150 mmHg), pressure-passive below the lower limit, and rising again past the upper limit — with a marker showing where the live (MAP, CBFV) point sits; during the dynamic test the marker swings off the idealized curve and, if ARI is high enough, returns to it.
- Run Thigh-Cuff Test — steps MAP down by ~22% and holds it there, exactly as cuff release does.
- ARI slider — sets T, D and K from the standard 0–9 clinical scale (Tiecks-style parameters).
- PaCO₂ slider — hypercapnia blunts the myogenic gain K; hypocapnia sharpens it slightly.
- Baseline MAP — sets the resting operating pressure, and where the marker sits on the pressure-flow curve before the test.
Clinical relevance: a low measured ARI after stroke, subarachnoid hemorrhage or traumatic brain injury identifies pressure-passive cerebral flow — a key input to neuro-ICU blood-pressure targets.