Shear viscosity of the surfactant from dog lungs

Surface viscosity (eta S) was measured in the pulmonary lavage fluid obtained from 40 mongrel dogs. Two experimental methods were employed to determine surface viscosity: a) Fourt's "torsion pendulum" procedure; and b) the "viscous traction" viscosimeter. A satisfactory correlation (r = 0.88) between these two methods was obtained. The mean value for surface viscosity of the pulmonary lavage fluid was 3.8 X 10(-2) surface-poise (s.p.) with the torsion pendulum procedure, and 4.3 X 10(-2) s.p. with the viscous traction viscosimeter. The implications of surface viscosity in pulmonary mechanics is discussed, as well as the effects of blood plasma addition to the pulmonary lavage fluid. A significant increase of surface viscosity could be observed when blood plasma was added to the hypophase, in concentrations greater than 0.1%. This increase in surface viscosity might be of importance when related to the augmented respiratory work during the evolution of pulmonary edema.