Prolonged airway retention of insoluble particles in cystic fibrosis versus primary ciliary dyskinesia

Patients with cystic fibrosis (CF) and primary ciliary dyskinesia (PCD) hav e been shown to have impaired large airway clearance of radiolabelled parti cles ar measured by external gamma camera scanning up to 6 hours post depos ition. Recent studies suggest that 24-hour retention of particles may refle ct some airway retention in addition to alveolar retention. In a retrospect ive study, rue analyzed the relationship between the deposition pattern and 24-hour retention (Ret(24hr)) of technetium 99- radiolabelled iron oxide ( Tc-99-Fe2O3) particles in 20 patients with CF, 12 patients with PCD, and 17 normal subjects. By gamma camera analysis, initial aerosol deposition was analyzed in terms of central-peripheral (CIP) activity within the lungs. Ga mma camera scanning was performed immediately following deposition and agai n at 24 hours to assess residual retention (Ret(24hr)) as a percent of init ial deposition. CIP analysis was also performed on the 24-hour scan (C/P-24 ). For all subjects, initial deposition pattern (CIP) was inversely related to lung function (forced expiratory volume in I second [FEV1]%pred vs. C/P , r = -.54). Ret(24r) was also inversely related to initial deposition patt ern for all subjects (Ret(24hr), vs. C/P ratio, r = -.42). Analysis of cova riance showed that for a given CIP ratio, CF patients had significant great er Ret(24hr) compared to normal subjects (9.8 +/- 28 [SE]%). In addition, t he CF patients had similar C/P-24 as the normal subjects (1.35 +/- 0.40 [SD ] vs. 1.10 +/- 0.39, respectively). These results suggest that small airway clearance is compromised in CF patients compared to normal subjects. On th e other hand, PCD patients had C/P-24 similar to their initial deposition C IP ratios (2.78 +/- 1.72 vs. 2.45 +/- 0.87, respectively), significantly gr eater than 1.0, and significantly greater than CF or normal subjects, sugge sting that PCD patients have prolonged particle retention associated with t heir large bronchial airways.