• Primary ciliary dyskinesia
• plethysmography
• HRCT
• bronchiectasis
• Bhalla score
• spirometry

Background
Primary ciliary dyskinesia is associated with progressive lung damage eventually culminating in chronic infection with Pseudomonas aeruginosa. Lung damage is usually evaluated by high-resolution computed tomography (HRCT).

Objective
To evaluate whether the presence of HRCT abnormalities and of Pseudomonas aeruginosa infection was better predicted by spirometry or plethysmography.

Methods
A cross-sectional study was performed in consecutive patients diagnosed with PCD.
All patients underwent sputum culture, spirometry, plethysmography and HRCT over a 48 hour period.

Results
Fifty patients (26 children) were studied. Pseudomonas aeruginosa infection was found in 40% of the patients and bronchiectasis in 88%. There was a significant correlation between infection with Pseudomonas aeruginosa and extent of bronchiectasis (p=0.009, r=0.367) and air-trapping (p=0.03 r=0.315). Moreover, there was a significant association between infection with Pseudomonas aeruginosa and RV values > 150% (p=0.04) and RV/TLC ratio > 140% (p=0.001), but not between infection with Pseudomonas aeruginosa and FEV1< 80%, or FEF25-75% < 70%, or FEV1/FVC < 70% (< 80% in children). Severity of the total lung impairment on chest HRCT inversely correlated with FEV1 (p= 0.02; r= -0.322), FVC (p= 0.007; r= -0.376) and directly correlated with RV (p= 0.003; r=0.423), and RV/TLC (p < 0.001; r= 0.513).

Conclusions
Plethysmography predicts better than spirometry HRCT abnormalities, and might be a useful test to reduce the number of HRCT scans performed in PCD.