Effect of mannitol and repetitive coughing on the sputum properties in bronchiectasis

SummaryMucociliary clearance increases with increasing doses of mannitol and clearance is enhanced when mannitol inhalation is followed by repetitive voluntary coughing.The aim of the study was to investigate: 1) the effect of increasing doses of mannitol and repetitive coughing on the sputum physical properties; 2) if the changes in sputum properties can predict the efficacy of mucus clearance measured by radioaerosol technique in bronchiectasis patients.Sputum was collected from 14 patients, age: 63±6yr, who participated on the mucociliary and cough clearance studies at baseline, with mannitol (160, 320 and 480mg) and control (Daviskas et al. ERJ 2008; 31:765-772). Sputum was collected: 1) on the screening visit before and after mannitol challenge (635mg); 2) at the start and end of each clearance study after 100 repetitive voluntary coughs except on the control study (no mannitol or repetitive coughing). The sputum solids content, surface tension, contact angle and rheology were measured.Mannitol in association with coughing and coughing alone reduced the solids content, surface tension, contact angle and viscoelastic sputum properties (p<0.0001) and this effect, unlike mucociliary clearance, was not dose dependent. The control produced no effect. Total mucus clearance correlated only with the percentage reduction in surface tension on 480mg mannitol and with the reduction in solids content at baseline.In conclusion: Inhaled mannitol and voluntary repetitive coughing improved the sputum physical properties in bronchiectasis patients and this effect was not dose dependent. Changes in sputum properties do not predict efficacy of mucociliary and cough clearance

Mucociliary clearance in patients with chronic asthma: Effects of beta(2) agonists

Chronic asthma is characterized by airway inflammation, mucus hypersecretion and impaired mucociliary clearance (MCC). We investigated baseline MCC and the acute effect of terbutaline in chronic asthmatics with sputum production while on long-term treatment with salmeterol in combination with inhaled corticosteroids (ICS). MCC was measured at baseline and in response to 1 mg terbutaline (or placebo) on three visits over 80 min in 16 asthmatics (52 +/- 13 years of age). Subjects who had greater than 10% absolute increase in MCC above baseline and placebo, after terbutaline, were categorized in group A and subjects who had less than 10% in group B. In group A subjects (n = 6), MCC increased from 23.7 +/- 4.0% at baseline to 43.7 +/- 4.9% with terbutaline (P 0.05). Group B subjects withdrew from all beta(2) agonists for a week and MCC was remeasured. After withdrawal, baseline MCC (7.0 +/- 1.8%) was similar to the initial baseline value (P > 0.1) and MCC with terbutaline (15.8 +/- 4.9%) was greater than baseline (P < 0.005) but remained abnormal in most subjects. Baseline percentage predicted FEV1 and FEF25-75% were 77.3 +/- 7.2 and 41.7 +/- 5.6 in group A and 59.9 +/- 8.1 and 29.5 +/- 8.4 in group B subjects, respectively. MCC was impaired in most of these asthmatics with persistent airway obstruction and sputum production, despite regular treatment with ICS and salmeterol. In addition, there was little or no stimulation of MCC acutely after terbutaline in most of these asthmatics