The elasticity of sputum at low shear rates.

Elasticity of sputum. Elasticity of sputum has been determined using the Weissenberg 
rheogoniometer, by oscillatory testing, over frequencies from 0.01 to 0.8 c/s. 
Sputum was from patients with either asthma, chronic bronchitis, cystic fibrosis, 
or bronchiectasis and, macroscopically, mucoid, mucopurulent or purulent. As in the 
viscosity plot over this shear rate range two Zones with a 
junctional region can be distinguished. In Zone 1, over the lowest 
shear rates, elasticity increases slowly, changes little over a "plateau" region 
and then, in Zone 2, increases sharply. In contrast to the 
viscosity plot, the plateau does not show nothing. By 0.8 c/s 
some samples show decreasing elasticity. Although variance between samples is wide, 
there is no level of elasticity characteristic of each disease or 
of one macroscopic appearance. Elasticity and viscosity are correlated, most significantly 
at the lowest shear rates. Asthmatic and bronchiectatic sputa resemble each 
other in that this correlation is still significant at higher shear 
rates, cystic fibrosis and chronic bronchitic sputum in that it is 
not. Since in these last two mucous gland hypertrophy is present, 
it may be that the sputum has a higher mucus component. 
