[Deformation of the transpulmonary pressure plateau in experimental pulmonary emphysema]

Deformation of the transpulmonary pressure plateau occurring during the interruption of air flow for 0.5 s is described in 8 healthy rabbits and in 9 animals with experimental emphysema induced by the intravenous injection of licopodium spores. The greatest plateau deformity was seen in healthy animals during inspiration, averaging 20 cm H2O. In sick rabbits the degree of deformity was decreased by 13 cm H2O on the average. The plateau deformity was the same in expiration in healthy and sick animals, averaging 7 cm H2O. The direction of changes in the strain of respiratory muscles in response to inspiration or expiration during the air flow interruption was controlled by recording the pressure in the bronchus, whose amplitude of respiratory variations considerably exceeded such of transpulmonary pressure. Inspiratory plateau deformity is regarded to be the result of active sucking action of the lungs, and expiratory plateau deformity--as their active contraction under conditions of the air flow interruption.