Clearance of inhaled particles in ankylosing spondylitis

Patients with ankylosing spondylitis may uncommonly develop apical fibrobullous lung disease, the cause of which is unknown. It is postulated here that rigidity of the thoracic cage leads to reduced apical clearance of inhaled particles and may thereby predispose to chronic infection. Deposition and clearance of inhaled technetium-99m sulphur colloid particles were studied in eight male patients with ankylosing spondylitis who had chest wall rigidity (mean (SD) chest expansion 1.8 (1.07) cm) but normal chest radiographs. As a reference population eight healthy male volunteers were also studied. Particle deposition showed an increasing gradient from apex to base, with no significant difference between patients and controls. Clearance was assessed by comparing absolute counts, corrected for decay, at 24 hours with the baseline values. No delay in particle clearance in those with ankylosing spondylitis was apparent.