Effect of experimental lung oedema on cough sound creation

We have assessed the importance of changes in lung structure on the pattern of cough sound and its creation with 13 anaesthetized cats. Acute lung injury with oedema was induced by i.v. administration of a mixture of fatty acids. Cough was elicited by mechanical stimulation of the mucous membranes of the airways and was evaluated by its intensities of effort and sound before and up to 2 h after administration of the fatty acids. Changes of cough sound pattern were not definitive, there being no typical alterations. The cough effort and sound intensities, induced from the trachea, consistently decreased (by 70-80% in both cases). The cough efforts immediately after induction of oedema were transiently abolished in some cats. The cough values induced from the larynx similarly decreased at 5 min (51-57%) but subsequently gradually returned to control values. There were significant correlations, both for coughs induced from the trachea and from the larynx, and for changes in intensity of efforts compared with sounds. Thus, pathological changes in the lungs modify the intensities both of cough efforts and their associated sounds.