[Bioimpedansometry in patients with chronic lung diseases in the context of the pulmonary-cardio-renal continuum].

Bioelectrical impedance analysis is a method widely used to assess body composition and parameters related to health and its disorders, which has prognostic value in gastroenterology, endocrinology, nephrology, cardiology, pulmonology, oncology, surgery and critical care. The purpose of this study was to analyze bioimpedance measurements in patients with chronic lung diseases [interstitial lung diseases (ILD), chronic obstructive pulmonary disease (COPD)] in relation to clinical and biochemical parameters for assessing respiratory, cardiac and renal failure. Material and methods. An analysis of bioimpedance data obtained during diagnostics on the InBody 770 device was carried out in relation to clinical (heart rate, blood pressure, saturation before and after the 6-minute walk test) and biochemical parameters (serum creatinine and N-terminal prohormone of brain natriuretic peptide - NT-pro-BNP), in 197 patients with chronic lung diseases aged 25 to 60 years (117 patients with COPD, 86.0% men and 80 patients with ILD, 83.8% women). Results. A proportion of patients with COPD and ILD had changes in body composition, manifested by an increase in fat mass (57.3% of patients with COPD and 70% of patients with ILD) and a decrease in skeletal muscle mass (24.8% of patients with COPD and 27.5% of patients with ILD). The mean values of the phase angle (50 kHz) for the whole body in both groups were below the reference values. When analyzing the relationship between the phase angle (50 kHz) for the whole body and age, there was a weak inverse relationship according to the Evans scale (r=-0.23 in patients with COPD and r=-0.33 in patients with ILD). The NT-pro-BNP level was higher than reference values in both studied groups, which may indicate cardiac dysfunction. The whole-body phase angle in the ILD and COPD group had moderate and weak inverse relationships with NT-pro-BNP for men and women (r=-0.49 and -0.39; r=-0.25 and -0.22, respectively). After the 6-minute walk test, the saturation level decreased in patients of both groups. The body hydration index indicated moderate edema, more pronounced in women. The hydration index had a direct weak relationship with NT-pro-BNP level (r=0.21 and 0.38 in patients with COPD and ILD, respectively). Conclusion. A number of bioimpedance parameters (phase angle, hydration index) in patients with COPD and ILD had relationships with biochemical parameter of cardiac dysfunction (NT-pro-BNP). Assessment of body composition by bioimpedancemetry in patients with chronic lung diseases is necessary for a comprehensive analysis of health status with recommendations for correcting the identified changes.