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
0.7510 bar = 3.1218 + (0.75103.1218) · 1.0000
Palv | alveolar N2 pressure
= (Pamb − 0.0627) · FN₂
= (4.0133 − 0.0627) · 0.7902
3.1218 bar
What the lungs are pushing into the blood at target depth.
Pt,0 | tissue pressure at t=0
= (Pamb,start − 0.0627) · FN₂
= (1.0133 − 0.0627) · 0.7902
0.7510 bar
Where this compartment started, assumed equilibrated at start depth.
k | rate constant
= ln(2) / T½
= 0.6931 / 27.0
0.0257 min⁻¹
Faster compartments → bigger k → catch up sooner.
e−kt | "fraction left to go"
= e−k · t
= e−0.0257 · 0
1.0000
1.0 at t=0, decays toward 0. Half-gone every T½.
M-value check
M
Pt,0
Palv
Pamb
Pt
Pt = 0.7510 bar | M = 2.50 bar within
M = a + Pamb / b