When airway smooth muscle is contracted in vitro, the airway lumen continues to narrow with increasing concentrations of agonist until complete airway closure occurs. Although there remains some controversy regarding whether airways can close in vivo, recent work has clearly demonstrated that, if the airway is sufficiently stimulated with contractile agonists, complete closure of even large car...

BACKGROUND Chronic obstructive pulmonary disease (COPD) is a common disease characterized by airflow obstruction and lung hyperinflation leading to dyspnea and exercise capacity limitation. OBJECTIVES The present study was designed to evaluate whether an extra-fine combination of beclomethasone and formoterol (BDP/F) was effective in reducing air trapping in COPD patients with hyperinflation....

The clinical features of hyaline membrane disease have been reviewed recently (1, 2). When the disease is fatal the lungs at autopsy are usually grossly atelectatic, suggesting the appearance of liver. Microscopically, this atelectasis is seen to be patchy and widespread; scattered through the lungs are dilated terminal bronchioles and alveolar ducts that are lined with an eosinophilic membrane...

Using a gamma camera, we quantified the topographical intrapulmonary distribution of inhaled 100 ml boluses of Technegas (TG), an ultrafine dispersion of carbon aggregates labelled with 99mTc, and 133Xenon (Xe) in six seated, normal subjects, inhaling from residual volume (RV) and from within a 1 l volume range above functional residual capacity (FRC) at a flow less than 0.5 l.s-1. Following in...

OBJECTIVE To compare the strength of polylactide-co-glycolide fiber-reinforced calcium phosphate bone cement (FRC) with nonreinforced calcium phosphate bone cement (NRC) subjected to simulated dural pulsations in defects larger than 25 cm(2). METHODS Seven NRC and 7 FRC specimens were set in both medium (37.5 cm(2)) and large (50.0 cm(2)) model skull defects while subjected to simulated dural...

We determined the effect of lung recruitment and oscillation amplitude on regional oscillation volume and functional residual capacity (FRC) in high-frequency oscillatory ventilation (HFOV) used in pre-term infants with respiratory distress syndrome (RDS). Changes in lung volume, oscillation volume and carbon dioxide levels were recorded in 10 infants during a stepwise recruitment procedure, an...

There are various ways of measuring absolute lung volume. These range from measurements derived from chest radiographs to the more common laboratory measurements employing either gas dilution or plethysmography. The principal difference between the latter two methods is that gas dilution techniques measure gas that is in free communication with the airway opening, whilst plethysmography measure...

Relationships between structural and functional variables in asthmatic lungs at local and global (or lobar) levels remain to be discovered. This study aims to investigate local alterations of structural variables [bifurcation angle, circularity, airway wall thickness (WT), and hydraulic diameter (Dh)] in asthmatic subjects, and their correlations with other imaging and pulmonary function test-b...

BACKGROUND Ventilated patients with asymmetry of lung or chest wall mechanics may be vulnerable to differing lung stresses or strains dependent on body position. Our purpose was to examine transpulmonary pressure (P TP) and end-expiratory lung volume (functional residual capacity (FRC)) during body positioning changes in an animal model under the influence of positive end-expiratory pressure (P...

1. The pattern of breathing in 12 patients with severe irreversible airflow obstruction has been studied during ventilatory stimulation by rebreathing CO2. Mean maximum tidal volume response was only 1.23 +/- 0.30 litres (mean +/- SD); this represented 65% of mean measured vital capacity and 82% of mean measured inspiratory capacity. During the course of rebreathing mean total breath duration w...