[Lung diffusion capacity of pulmonary tuberculosis patients]

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Infectious Diseases

Background:

• Tuberculosis (TB) is a major global health concern.
• Pulmonary function tests are crucial for assessing TB's impact on lung health.
• Diffusing capacity of the lungs for carbon monoxide (DLCO) is a key indicator of gas exchange efficiency.

Purpose of the Study:

• To investigate the impact of different forms of tuberculosis (focal, infiltrative, disseminated, and fibrocavernous) on various pulmonary function parameters.
• To identify the primary factors contributing to decreased DLCO in each TB subtype.

Main Methods:

• Pulmonary function tests were performed on 159 patients with different types of tuberculosis.
• Measurements included DLCO, DL/VA, Dm, Vc, lung volumes, and capacities.
• Analysis focused on correlating TB type with specific pulmonary function abnormalities.

Main Results:

• A decrease in DLCO was observed in 50% of patients with disseminated and fibrocavernous TB, and less than 20% with focal and infiltrative TB.
• In disseminated and fibrocavernous TB, reduced DLCO was primarily linked to a smaller lung respiratory surface due to decreased alveolar volume.
• Infiltrative TB showed reduced DLCO mainly due to decreased alveolocapillary membrane permeability.

Conclusions:

• The type of pulmonary tuberculosis significantly influences the mechanisms underlying DLCO reduction.
• Disseminated and fibrocavernous TB predominantly impair gas exchange through loss of lung surface area.
• Focal and infiltrative TB forms exhibit distinct pathophysiological changes affecting DLCO, with permeability being key in infiltrative disease.