[Mechanical properties of the lungs in bronchial asthma]

To evaluate basic parameters of elastic and nonelastic resistance of the lungs in patients with bronchial asthma (BA) with reference to severity of pulmonary ventilation disorder (PVD).

PVD was diagnosed in 92 BA patients aged 18 to 55 years (mean age 42 years, 50 males and 40 females). By PVD severity the patients were divided into 4 groups. The control group consisted of 65 healthy volunteers aged 18-54 years (mean age 45.6 years, 30 males and 35 females). PVD degree was assessed by reduction of respiratory capacity (RC) and forced expiratory volume per second (FEV1), volumes of the lungs, ventilation speed, bronchial resistance (Raw), total respiratory performance, total nonelastic resistance (TNR), total nonelastic pressure, dynamic lung compliance, static lung compliance (Cstat), elastic lung traction (ELT).

A RC fall in groups 2-4 was less significant than FEV1 reduction. Raw was elevated in all the groups: in group 2 the rise was more than in group 1, but in groups 3 and 4 the rise was similar. TNR at inhalation and exhalation increased from group 1 to group 3, was high in group 4. Cstat and ELT were similarly subnormal in all the groups.

Elevation of bronchial resistance does not influence PVD severity. Lowering of FEV1 only partially is related with Raw elevation. Subnormal lung compliance may represent a compensatory reaction directed to overcoming valvular bronchial obstruction and maintenance of normal lung ventilation. Low lung traction may result from high mechanical activity of the lungs in condition of its estimation.