Lung Function Tests
Forced expiratory volume in 1 s in liters and in percent of vital capacity (FEV,%VC) were measured with a Bernstein spirometer. Total lung capacity, functional residual capacity, residual volume, and vital capacity were studied by body plethysmography.
Lung resistance at an expiratory flow rate of 1 LA and at a pulmonary elastic recoil pressure of 7.5 cm HxO was measured together with the static elastic pressure volume curve from which static lung compliance was determined as previously described.
Dynamic measurements of lung mechanics were made at rest and at each work load during exercise.
The exercise test was performed on a bicycle ergometer. The initial work load was 50 W for men and 30 W for women with increments of 50 W and 30 W, respectively, every 5 min, and continued until exhaustion. buy birth control online
The patient was connected to a wide bore mouthpiece and a pneumotachograph. The signals for flow and transpulmonary pressure were A-D converted at 100 Hz by a computer. All complete breaths within the sampling period of 12 s were analyzed as is described below with omission of constants for conversion of units (eg, from seconds to minutes). Ventilation, tidal volume, and breathing frequency were calculated from the flow signal. Dynamic compliance of the lungs was calculated as the quotient between Vt and the Pl differences between end-expiration and end-inspiration.