Pulmonary function and maximal transrespiratory pressures in ankylosing spondylitis

Area of Science:

• Pulmonary Medicine
• Rheumatology
• Physiology

Background:

• Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the spine.
• Respiratory complications can arise in AS due to chest wall and spinal rigidity.
• The impact of AS on respiratory muscle strength and lung volumes requires further investigation.

Purpose of the Study:

• To assess pulmonary function and respiratory muscle strength in patients with ankylosing spondylitis.
• To correlate clinical measurements with pulmonary function tests.
• To investigate the potential causes of respiratory impairment in AS.

Main Methods:

• Clinical measurements and pulmonary function tests were performed on 30 AS patients.
• Evaluated parameters included vital capacity (VC), forced expiratory volume in one second (FEV1), total lung capacity, and transfer factor for carbon monoxide (TLCO).
• Maximal expiratory pressures (PEmax) and inspiratory pressures (PImax) were measured to assess respiratory muscle strength.

Main Results:

• Patients exhibited slightly reduced lung volumes: VC at 79(16)%, FEV1 at 82(20)%, and total lung capacity at 85(13)%.
• Maximal expiratory pressures (PEmax) were significantly reduced to 56(17)%, and maximal inspiratory pressures (PImax) to 76(28)%.
• Reductions in lung volumes correlated with clinical measurements; respiratory muscle strength was more impaired than lung volumes.

Conclusions:

• Spirometrically determined lung volumes are relatively preserved in ankylosing spondylitis compared to respiratory muscle strength.
• Reduced respiratory muscle strength, particularly PEmax and PImax, is a significant finding in AS patients.
• Intercostal muscle atrophy is a potential contributing factor to the observed reduction in respiratory muscle strength in ankylosing spondylitis.