Educational Use Only — Interactive walk-through of the Bühlmann/Haldane on-gassing equation.

Haldane Equation

A live, annotated walk-through of how a tissue compartment on-gasses over time.

pt(t) = palv + (pt,0palv) · ekt
 bar = + () ·
palv | alveolar N2 pressure
 bar
What the lungs are pushing into the blood at target depth.
pt,0 | tissue pressure at t=0
 bar
Where this compartment started, assumed equilibrated at start depth.
k | rate constant
= ln(2) / t1/2
 min⁻¹
Faster compartments → bigger k → catch up sooner.
e−kt | "fraction left to go"
= e−k · t
1.0 at t=0, decays toward 0. Half-gone every t1/2.
M-value check
M
pt,0
palv
pamb
pt
pt = 0.7510 bar | M = 2.50 bar within
M = a + pamb / b