Aerosol deposition in the lung with asymmetric airways obstruction: in vivo observation

Abstract

Both the total and regional aerosol deposition were measured in six adult sheep before and after an induction of asymmetric airway obstructions, either by local instillation of carbachol solution (CS, 0.1%) distal to the right main bronchus or inhalation challenge of the right lung with carbachol aerosol (CA, 10 breaths). Total lung deposition was determined by monitoring inert monodisperse aerosols [1.0 micron mass median aerodynamic diam (MMAD)] breath-by-breath, at the mouth, by means of a laser aerosol photometer. Cumulative aerosol deposition over the first five breaths as a percent of the initial aerosol concentration (AD5) was used as a deposition index. Regional deposition pattern was determined by scintigraphic images of sulfur-colloid aerosol (1.5 microns MMAD) tagged with 99mTc. Radioactivity counts in the right (R) and left lung (L) were expressed as a percent of the whole lung count. Half-lung AD5 was then determined by multiplying AD5 by fractional radioaerosol depositions in R or L. Pulmonary airflow resistance (RL mean +/- SE), as determined by an esophageal balloon technique, increased by 111 +/- 28 and 250 +/- 96% after CA and CS, respectively (P less than 0.05). AD5 also increased in all the sheep tested by 29 +/- 3 and 52 +/- 8%, respectively, after CA and CS (P less than 0.05). Radioaerosol deposition pattern was even at base line (R/L = 51:49) but shifted toward the unchallenged L after CS (R/L = 40:60). Deposition pattern after CA was variable: a shift toward L in three, no change in one, and a shift toward the R lung in two sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of airway obstruction induced by asthma attack on particle deposition

“…Therefore the efficacy of drug delivery will be low if the occluded airway is deep in the left lung airways and lead to acute overdose in the localised regions of the right lung airways unnecessarily. Studies published by Kim et al (1983), Kim et al (1989), and Kim (1989) corroborate the simulation findings where the aerosol deposition increased greatly in patients with obstructive airway disease without regard to type of obstructions.…”

“…The work by Longest, Vinchurkara, and Martonen (2006) however, included double bifurcation models of upper (G3-G5) and central (G7-G9) airways for a four-year-old child where the effects of asthma was modelled as a 30% constriction of the airway branches. Additional studies in obstructed airways (Kim, Brown, Lewars, & Sackner, 1983;Kim, Eldridge, Garcia, & Wanner, 1989;Kim, 1989;Kim & Kang, 1997b), showed that greater deposition occurred in the obstructed lung compared with a normal lung.…”

Extravascular fibrin, plasminogen activator, plasminogen activator inhibitors, and airway hyperresponsiveness

“…The observed exaggerated R n response is perhaps best explained by aerosol deposition dynamics. When airways constrict or close, more of a given aerosol deposits in the lung, and the distribution of aerosol deposition is changed such that more aerosol deposits in the central airways (44). Constriction or closure of the distal airways after exposure to methacholine aerosol, as we observed, will therefore have the effect of enhancing methacholine aerosol deposition in central airways, resulting in an exaggerated central airways, or R n , response.…”

Comparative measurement of lung deposition of inhaled fine particles in normal subjects and patients with obstructive airway disease.

“…Numerous studies have shown that in patients with obstructive airway disease, particle deposition patterns within the lung are very heterogeneous, showing marked enhancement of deposition in various local regions (3)(4)(5). Deposition enhancement at local sites has also been demonstrated systematically with various types of simulated airway obstruction imposed in animal models in vivo (6)(7)(8) as well as physical (Received in original form March t t, 1996 and in revised form November 6,1996) Although the researchdescribed in this article has been supported by the United States Environmental Protection Agency, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency, and no official endorsement should be inferred. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.…”