Inhalation systems | Ideal device | Patient Related Requisites | Morphology of Airways

Influence of obstruction in the respiratory system on aerosol deposition

Morphological alterations of airways in asthmatics do not seem to have much impact on the efficacy of inhaler devices in average. Interindividual variability of the anatomical conditions of the pharyngeal area play a more important role concerning lung deposition of aerosols. Comparative narrowing in this region leads to a higher rate of oropharyngeal particle deposition. Concerning spirometric measures in contrast to expiratory flow the peak inspiratory flow rate (PIF) in asthmatics normally does not differ considerably from the PIF generated in normal subjects. Even in people with chronic obstructive lung disease (COPD) and cystic fibrosis no significant differences are observed between patients and healthy volunteers. Only few studies exist exploring inspiratory parameters. Mostly variables like inspiratory flow rates are studied in trials on the efficacy of inhaler devices. However in these studies patients with obstructive lung diseases are assessed concerning their ability to generate sufficient inspiratory flows but rarely in comparison with normal subjects. One study investigated dynamic lung functions in patients with obstructive lung diseases compared with healthy people. Inspiratory manoeuvres performed against increasing resistive loads only slightly reduced the inhaled volumes probably due to fatigue. Simultaneously the degree of comfort experienced by the subjects decreased monotonically with increasing resistance. No significant differences were observed between patients and normal subjects in any variable studied.

Literature:

Colasanti RL, Morris J, Madgwick RG, Sutton L, Williams EM. Analysis of tidal breathing profiles in cystic fibrosis and COPD. 2004. Chest; 125:901-908

Hnatiuk OW, Sierra A, Chang AS. Evaluation of the normal inspiratory flow-volume curve. 1998. Respiratory Care; 43 (12): 1058-1063

Sarinas PSA, Robinson TE, Clark AR, Canfield J, Chitkara RK, Fick RB. Inspiratory flow rate and dynamic lung function in cystic fibrosis and chronic obstructive lung disease. 1998. Chest; 114: 988-992

Svartengren K, Lindestad PA, Svartengren M, Philipson K, Bylin G, Canner P. Deposition of inhaled particles in the mouth and throat of asthmatic subjects. 1994. European Respiratory Journal; 7 (8): 1467-1473

Deposition in mouth and throat dependent on characteristics of pharynx and larynx

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