The 24-h Effect of Mannitol on the Clearance of Mucus in Patients With Bronchiectasis

To investigate the acute effect ofmannitol on the clearance of mucus, and (1) the 24-h mucus retention, and (2) the mucus clearance rate and lung function 24 h afterinhalation of a single dose of mannitol. Clearance of mucus was measured on 3 consecutive days using99mTc-sulfur colloid radioaerosol and a gamma camera. Mannitol, 330 ± 68 mg (mean± SD), wasinhaled using a dry powder inhaler only on day 2. Eight patients with bronchiectasis (age range, 29to 70 years). On each day, lung images were collected over 2 h and at 24 h. Key findingsof the study are as follows: (1) the 24-h retention of mucus wasreduced the day after mannitol had been inhaled, compared to the daywithout mannitol (day 1) in the whole right lung (57.6 ± 6.2% vs68.1 ± 5.9%), central (47.5 ± 6.7% vs 56.9 ± 6.5%),intermediate (61.7 ± 5.6% vs 73.8 ± 5.5%), and peripheralregions (70.9 ± 4.3% vs 86.6 ± 4.6%)(p < 0.02); and (2)mannitol helped patients clear mucus within 2 h that mightotherwise take up to 24 h, from the whole right lung and definedregions. However, clearance over 60 min measured 24 h aftermannitol inhalation was not significantly different to baselineclearance without mannitol (8.7 ± 1.9% on day 1 vs 9.7 ± 3.7%24 h after mannitol; p > 0.8). The patients maintained the samelung function the day before and after mannitol had been inhaled: FEV1 (percent predicted), 79 ± 5 on day 1 vs 80 ± 5on day 3; and forced expiratory flow, midexpiratory phase (percentpredicted), 50 ± 6 on day 1 vs 51 ± 6 on day 3;p > 0.6). Mannitol inhalationacutely increases clearance of mucus, and this effect extends beyondthe acute study period, resulting in decreased mucus retention at24 h.