Clearance in Small Ciliated Airways in Allergic Asthmatics after Bronchial Allergen Provocation

Abstract

Background: Asthma tends to affect mucociliary clearance, as assessed from measurements in large airways. However, there is no knowledge about clearance in the smallest airways of the tracheobronchial region in acute exacerbation of asthma. Objective: The aim of the study was to investigate clearance from the bronchiolar region in patients with allergic asthma in a situation resembling a mild acute exacerbation of the disease. We also aimed to compare clearance data with corresponding data found for healthy subjects and asthmatics on therapy. Methods: Tracheobronchial clearance was studied twice in 9 patients with mild asthma of the allergic type after inhalation of 6 μm (aerodynamic diameter) monodisperse Teflon particles labelled with ¹¹¹In. At one exposure, inhalation was performed 4 h after bronchial provocation with an allergen the patients were allergic to. The second exposure was a control measurement. The particles were inhaled at an extremely slow flow, 0.05 liter/s, which gives deposition mainly in the small ciliated airways (bronchioles). Lung retention was measured at 0, 24, 48 and 72 h. Results: All patients demonstrated an early asthmatic reaction of varying degree after bronchial provocation. There was significant clearance of radioaerosol in each 24-hour period for both exposures, with the possible exception of the period between 24 and 48 h for the provocation exposure, with similar fractions of retained particles at all points of time. The retained fractions were significantly larger compared to a group of healthy subjects and asthmatics on regular treatment with anti-inflammatory drugs. Conclusions: Our results indicate that in allergic asthmatics a bronchial allergen provocation with an early asthmatic reaction does not significantly influence overall clearance from the bronchiolar region. However, in the present group of patients, retention in small ciliated airways was significantly higher compared to healthy subjects and asthmatics on regular treatment.

Long-term clearance from small airways in patients with cystic fibrosis

“…By using extremely slow inhalation flow (ESI) and rather large particles, the fraction deposited in small airways increases by sedimentation. Even if there was a difference in FEV1% pred and airway resistance between the CF patients and the healthy subjects the ESI has shown to be robust and rather insensitive to airway obstruction and uneven ventilation [28].…”

Total and Regional Deposition of Ultrafine Particles in a Mouse Model of Allergic Inflammation of the Lung

“…People with allergic asthma display a higher susceptibility to fine and ultrafine particle exposures (Pope, 2000). There are few human studies on UFP deposition during rest and exercise in healthy individuals and following various pulmonary pathologic conditions Brown et al, 2002;Frampton et al, 2004;Daigle et al, 2003;Svartengren et al, 1999). These studies show a relatively high pulmonary deposition rate of UFP, which increases inversely to particle size within the ultrafine range and with exercise.…”

Regional Distribution and Kinetics of Inhaled Pharmaceuticals

“…Particle charge and density are also strong factors in distribution, though this has received much more attention in the environmental science literature [9] than in drug distribution. Velocity of air flow during inhalation, [10][11][12][13] the timing of the device activation, and the degree of turbulence also can affect the distribution of drug in target tissues. These are in turn affected by the device used to deliver the drug [14,15].…”