Figure 1

A two compartment model. Two compartment model for the analysis of disaturated-phosphatidylcholine-palmitate kinetics. Compartment 1 is the alveolar space, compartment 2 is lung tissue. M₁ and M₂ are tracee disaturated-phosphatidylcholine-palmitate masses, P is disaturated-phosphatidylcholine-palmitate de novo synthesis, F₂₁ and F₁₂ are inter-conversion fluxes, F₀₁ and F₀₂ are irreversible loss fluxes, k₂₁ and k₁₂ are interconversion rate parameters, k₀₁ and k₀₂ are irreversible loss rate parameters, u is the tracer disaturated-phosphatidylcholine-palmitate input in compartment 1 and the dashed line with a bullet indicates the tracer to tracee ratio (ttr) measurement. It is assumed that loss from the alveolar space is 5–50% in controls and 5–100% in ARDS.