Spirometric studies in non-smoking, healthy adults.

Reference spirometric values for vital capacity (VC), forced expiratory volume in one second (FEV1), forced vital capacity (FVC), forced expiratory volume in one second as percentage of vital capacity or of forced vital capacity (FEV%), the highest flow during forced inspiration (Vmax insp), the highest forced expiratory flow at 50% vital capacity (Vmax 50%), the highest forced expiratory flow when 75% of vital capacity has been expired (Vmax 25%), Vmax insp/Vmax 50% and peak expiratory flow (PEF) were determined in a series of 296 males and 257 females, 18-65 years old, who have never smoked. Equations were derived using height and age as predictors. The reproducibility was tested.

The effect of inhaled carbon dioxide and hypoxia mixtures on the electrical and mechanical activities of respiratory muscles in dogs.

The effects of hypercapnia and hypoxia on the regulation of breathing was studied in six mongrel dogs during pentobarbital anaesthesia with special reference to their action on the respiratory muscles. Carbon dioxide (5.5% in air) inhalation produced an increase of minute volume due to augmentation of respiratory frequency and tidal volume. The number of electrical impulses per breath remained unaffected despite the increase tidal volume. Therefore the mechanical ventilation increased more than the electrical output to the respiratory muscles indicating that the efficiency of the muscles increased. The tidal volume increased more than the pressure impulse (mechanical work by the respiratory muscles) suggesting that the airway conductance was increased during hypercapnia. During hypoxic stimulus (11% oxygen in nitrogen) the increase of minute volume was due to increase in respiratory frequency. The ratio of tidal volume to the number of electrical impulses in the respiratory muscles remained unaltered. During combined carbon dioxide and hypoxia stimulus the responses were similar to those of carbon dioxide stimulus alone. However, the increase of minute volume and the increase in the ratio of tidal volume and pressure impulse to the number of electrical impulses in the respiratory muscles were more pronounced. These findings suggest that carbon dioxide affects the regulation of breathing above the respiratory muscles and in the muscles themselves. Hypoxic stimulus seems not to have any direct effect on the respiratory muscles in dogs during pentobarbital anaesthesia.

Reappearance of Hering-Breuer reflex after bilateral autotransplantation of the lungs.

In combined heart-lung transplantation the afferent nerve pathways inevitably are transsected. In previous studies with en bloc heart-lung transplantation in dogs, we found altered regulation of breathing-abolition of Hering-Breuer reflex and response to hypercapnia inhalation stimulus consisting of augmented tidal volume with no change in respiratory rate-shortly after the operation. The long-term effects of pulmonary denervation on breathing regulation were now studied in dogs after staged bilateral pulmonary autotransplantation. Mechanical and electrical activities of the respiratory muscles were recorded during spontaneous breathing and after deflation and inflation with varying volumes of air. Five months postoperatively the duration of the respiratory cycle increased 2.5 times on inflation with 600 ml of air and occlusion of the airways, compared with tenfold prolongation in intact control dogs, indicating a partial return of the Hering-Breuer reflex after the autotransplantation. The duration of the EMG bursts in respiratory muscles increased in intact dogs and in those with bilateral lung autotransplants. In impulse frequency the response to stretching was less evident after autotransplantation. The mechanism mediating reappearance of Hering-Breuer reflex warrants further study.

Effect of lung autotransplantation on breathing regulation. Studies in dogs.

The effect of autotransplantation of the left lung on respiratory regulation was studied in four dogs in pentobarbital anaesthesia. In each dog the electrical and mechanical activity of the inspiratory muscles was studied before and 4-6 weeks, 3, 6 and 12 months after the transplantation. No or very little change was found in comparisons of spontaneous respiration or response to inhalation of carbon dioxide, hypoxia or combined hypercapnia and hypoxia. When the airways were closed after inflation with varying volumes of air, the increase in number and frequency of the electromyographic impulses in the intercostal muscles and the diaphragm (compared with the preceding unobstructed breaths) was greater before than after the lung autotransplantation. The duration of the first respiratory cycle after airway closure increased progressively with the volume of inflation in intact dogs and in dogs with autotransplanted left lung, though the increase was approximately halved following autotransplantation.

Inhaled budesonide influences cellular and biochemical abnormalities in pulmonary sarcoidosis.

In a randomized, double-blind study 19 patients with newly-detected pulmonary sarcoidosis were treated with either inhaled budesonide, 800 micrograms twice daily (n = 9), or placebo (n = 10) for 8-10 weeks. Before and after treatment, chest roentgenograms, lung function tests, bronchoalveolar lavage (BAL) and biochemical tests were performed. Angiotensin converting enzyme (ACE) activity and beta2-microglobulin (beta 2M) concentrations were measured in serum. The same tests, as well as albumin and hyaluronan were measured in the BAL-fluid. The total cell number in BAL-fluid, differential counts and lymphocyte subpopulations were determined (total T- and B-lymphocytes, T-helper/inducer (OKT-4) and T-suppressor/cytotoxic (OKT-8) lymphocytes). No significant changes in chest roentgenograms or lung function tests were observed during the short study time. However, a decrease in serum ACE (p less than 0.1) and beta 2 M (p less than 0.05) as well as in BAL-hyaluronan (p less than 0.01) was found in the budesonide-treated patients as well as a decrease in the percentage of BAL T-lymphocytes (p less than 0.05) and the T4/T8 ratio (p less than 0.1). No significant changes were seen in the placebo group. The findings suggest that treatment with inhaled budesonide influences biochemical and cellular findings in patients with early sarcoidosis in the same way as treatment with systemic corticosteroids. The results may also explain clinical effects seen in sarcoidosis patients treated with inhaled corticosteroids. However, further studies are required to determine the long-term clinical benefits of inhaled steroids in pulmonary sarcoidosis.

Obstructive lung disease in Behcet's syndrome.

Obstructive lung disease in two patients with Behcet's syndrome is presented. In both cases increased airways resistance, impaired PEF and FEV1.0 were found. In addition, diffusion capacity was slightly decreased in spite of enlarged total lung capacity and increased residual volumes. Both patients had mild hypoxaemia despite slight hyperventilation; a normal chest X-ray, and a decreased serum complement C3 level. Corticosteroids had a beneficial effect on VC in one of the two cases but failed to have any significant effect on the impaired ventilatory function in the other.