Lung function in progressive systemic sclerosis is dominated by poorly compliant lungs and stiff airways

Area of Science:

• Pulmonary Medicine
• Rheumatology
• Physiology

Background:

• Progressive systemic sclerosis (PSS) is an autoimmune disease known to affect multiple organs, including the lungs.
• Pulmonary involvement in PSS can lead to significant morbidity and mortality, necessitating a thorough understanding of its pathophysiology.

Purpose of the Study:

• To investigate pulmonary function abnormalities in patients with progressive systemic sclerosis.
• To characterize the parenchymal and bronchial properties affecting lung mechanics and gas exchange.

Main Methods:

• Pulmonary function tests including lung volumes (body plethysmography), pulmonary resistance, and elastic recoil pressure were performed.
• Pulmonary mechanics and arterial blood gases were assessed during graded exercise using a bicycle ergometer.
• Chest roentgenograms were used to evaluate lung fibrosis.

Main Results:

• Patients exhibited reduced lung compliance, lower total lung capacity (TLC), vital capacity (VC), and ventilatory capacity.
• A mild intrinsic bronchial obstruction was present, independent of smoking status.
• Seven patients showed stiff airways, evidenced by resistance not increasing towards residual volume.
• Arterial blood gas values remained normal at rest and during exercise.

Conclusions:

• Progressive systemic sclerosis is characterized by a stiff lung parenchyma and reduced lung volumes, leading to impaired ventilatory capacity.
• Mild airway obstruction and stiff airways are common findings in PSS patients.
• Despite significant mechanical changes, gas exchange is often preserved at rest and during exercise.