Hasani, Amer Hasan; (1994) Studies of mucociliary clearance, cough and forced expiration in patients with lung disease. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Mucociliary clearance is one of the lungs' non-specific host defence mechanisms and together with cough helps to keep the conducting airways clean even when exposed to a polluted atmosphere. An objective, non-invasive radioaerosol technique was used for the measurement of lung mucociliary clearance. This technique involves inhalation of five micron polystyrene particles labelled with technetium-99m under strictly controlled conditions, followed by deposition and clearance measurements with a sensitive scintillation counter system and—for some studies—with a gamma camera. Lung mucociliary clearance was adversely affected in patients with pulmonary sarcoidosis. Sarcoid patients in apparent remission and those on oral corticosteroid therapy had better clearance than those on inhaled corticosteroids, but clearance was still reduced compared to healthy control subjects. Mucociliary clearance was also found to be substantially compromised in pigeon fanciers compared to healthy control subjects. The presence or absence of circulating blood precipitins appeared not to be related to the degree of mucociliary clearance impairment. During sleep lung mucociliary clearance in patients with stable asthma was significantly reduced compared to when the patients were awake. Two weeks' treatment with an oral controlled release beta agonist or slow-release methylxanthine did not enhance lung mucociliary clearance in asthmatic patients while asleep. The effect of cough and forced expiration technique (FET) on mucus movement within the lungs of patients with airways obstruction was studied by a gamma camera method giving regional lung data. Unproductive cough and FET compared to control significantly enhanced mucus clearance from all regions of the lungs with the exception of the forced expiration in the outer region. Productive cough and FET significantly enhanced mucus clearance from the tracheal, inner and intermediate regions of the lungs but not from the outer region. Regional and total mucus clearance did not correlate with the amount of sputum expectorated during the assessments nor with the daily sputum production of the patients. Neither peak flow, during the forceful exhalatory manoeuvres, nor viscoelasticity of sputa correlated with regional clearance suggesting that sputum viscoelasticity as well as peak flow provide no guide to clearance efficacy in humans in contrast to the in-vitro studies.

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