Function of the Apparatus of External Respiration in Lung Cancer Developed with the Underlying Chronic Obstructive Pulmonary Disease

INTRODUCTION: Clinical observations ascertain a comorbid development of chronic obstructive pulmonary disease (COPD) and lung cancer (LC). Here, a more favorable prognosis for patients with LC depends on detection of the disease in early stages, when radical treatment is possible. This determines the importance of a detailed examination of the function of the external respiration using modern methods to identify predictors of lung cancer. AIM: To study the peculiarities of disorders in the apparatus of external respiration (AER) in patients with LC developed with the underlying COPD (LC + COPD). MATERIALS AND METHODS: A clinical and functional examination of 33 individuals was conducted — 10 healthy (control group), 12 patients with COPD and 11 patients with LC + COPD, using methods of spirography, pneumotachography and body plethysmography. RESULTS: In patients with COPD, as well as in those with LC + COPD, a statistically significant decrease in the median values of vital capacity of lungs (VCL), forced expiratory volume in 1 second (FEV1), flow-volume curve (PFER, MEF50, MEF75) and an increase in respiratory minute volume (RMV), residual lung volume (RLV), the ratio of residual lung volume to total lung capacity (RLV/TLC) and bronchial resistance (Raw) were revealed. It was found that in patients with LC + COPD, the median values of VСL, RLV/TLC, Raw did not differ, while the values of flow-volume curve were reduced as compared to patients with COPD. The observed decrease in the air flow rate parameters in the absence of differences in Raw indicates the extrapulmonary causes of these changes. CONCLUSION: In the course of the study, high reserve capacities of the apparatus of external respiration were found. The obtained parameters turned out to be of low informative value for diagnosis of development of LC with the underlying COPD. In patients with LC + COPD, the study of AER function, in addition to spirography and pneumotachography, should include body plethysmography, to avoid overdiagnosis of broncho-obstructive syndrome.