Stress-free equilibrium volume of the lung.
An experimental procedure was developed to measure the stress-free equilibrium volume of intact lobes from the lung of the dog. The procedure eliminates body, gravitational, interfacial, and externally applied forces to study the contribution of the tissue forces. The equilibrium gas volume was found to be 1.74 +/- 0.20 times the tissue volume and was independent of the volume history. This is smaller than the minimal air volume found by others and about one half the functional residual capacity (FRC) volume. The lung was found able to resist compressive loading implying a "finite buckling load" for the aveolar septa. A simple calculation shows the length-to-thickness ratio to be 7.1 at the stress-free equilibrium volume.
D000818:Animals; D004285:Dogs; D004548:Elasticity; D066298:In Vitro Techniques; D008176:Lung Volume Measurements / Q000379:methods*; D013314:Stress, Mechanical