気管支拡張剤の換気力学的検討

抄録

To investigate the mechanical behavior of the lungs in asthma, dynamic compliance and viscous resistance (esophageal balloon method), airway resistance and FRC (body plethysmographic method), and FEV 1.0 were measured following the inhalation of chemical mediators or allergen extract in 26 experiments on 22 asthmatic patients, and also after the administration of bronchodilators in 19 of those in whom the induced attacks were definite. They were calculated as the ratio of compliance (Cl) and conductance (reciprocal of viscous resistance=G_L, reciprocal of airway resistance=G_AW) to thoracic gas volume (TGV) and their changes were indicated in the per cent of initial values (these in saline inhalation). The provocation of asthmatic attack was induced by inhalation of nebulized solution of acetylcholine, histamine or allergen extract, with or without prior injection of atropine or propranolol, with increasing concentration of the solution until a definite change in transpulmonary pressure and FEV 1.0 was resulted.
Changes in the ratio of Cl, G_L and G_AW to TGV were simultaneous and of the same magnitude in the response to these mediators and allergen and did not demonstrate any definite difference in the mechanism of airway constrictions with these solutions. Prior treatment with atropine (3 cases) did not prevent the usual changes whilst intravenous injection of propranolol or two subjects induced attack in a patient and lowered the sensitivity to acetylcholine in the other.
Values after inhalation of 0.5% isoproterenol aerosol (7 cases), a isoquinoline derivative (0.5% AQ 110) (7 cases) or injection of epinephrine (1 case) were usually greater than those in the control state but the difference in the pattern of the response of the ratio to these bronchial spasmolytics was not apparent. Aminophylline differed from the above bronchodilators in that the intravenous injection (4 cases) induced immediate and pronounced increase in Cl but slow and mild one in G_AW. This suggest the difference of the affecting site (e. g., conducting or peripheral airways) in these drugs.
Measurement of FEV 1.0 was proved to be very useful for the evaluation of the reaction in provocation test and reliable to follow the response to bronchodilators.