Morphological and Functional Alterations of Respiratory Muscle Performance and Spirometry Parameters in Patients with Congestive Heart Failure

The purpose of the study. To identify structural changes and functional modifications in respiratory muscle performance in patients with congestive heart failure. Materials and methods. We conducted prospective observational study at the V.A. Almazov National Medical Research Center involving 118 subjects: 49 patients with congestive heart failure (CHF-group) and 69 healthy people (control group). NYHA functional classes of II to IV were taken as inclusion criteria in the CHF group, and respiratory diseases, abdominal pathology, morbid obesity, and anemia – as exclusion criteria. Ultrasound imaging was used to assess the structural (thickness) and functional (thickening and excursion indices) diaphragmatic impairments during quiet (resting) and deep breathing. Facemask spirometry was used to assess pulmonary function. Results. Patients with CHF were on average older than 59.0 years (53.0;70.0) vs. 25.0 years (24.0;26.0) in the control group, p=0.000001, had excessive body weight - 82.0 (73.0;95.0) vs. 68.5 (55.0;84.0) kg, p=0.000005 and higher body mass index - 28.4 (24.3;31.3) vs 21.8 (19.9;24.0) kg/m2, p =0.000001, but did not differ in height 173.0 (166.0;179.0) vs. 170.0 (165.0;183.0) cm, 0.97. Lower maximum inspiratory volume (MIV): 3000,0 (2300,0;4000,0) vs. 3684,1 (3392,5;4310,8) ml, p =0.0006, and negative inspiratory force (NIF) measured as max negative pressure generated by the respiratory muscles: 43,1 (-56,7; -33,0) vs. 53,5 (-58,8; - 50,9) mBar, p=0.000082, respectively were found in patients with CHF. The diaphragm was significantly thicker (mm) in patients with CHF during quiet (eupnea) and deep breathing compared to healthy subjects. The thickness at the end of quiet inspiration was 3,0 (2,2;3,6)/1,9 (1,5;2,2) in the right hemi-diaphragm, p <0.001; and 3,0 (2,4;3,5)/1,7 (1,4;2,0) – in the left, p =0.000001; thickness at the end of quite expiration - 2,2 (1,8;2,9)/1,5 (1,2;1,7) in the right dome, p =0.000001; and 2,0 (1,7;2,5)/1,4 (1,2;1,5) – in the left, p =0.000001. Thickness at the end of deep in spiration was 5.1 (4.4;6.1)/4.4 (3.6;5.1) in the right dome, p =0.0005, and 4,9 (4,2;6,2)/ 3,7 (3,1;4,8) – in the left, p =0,000007.The diaphragm thickening index during deep breathing was lower in the CHF group than in the control group: 131.1 (82.5;181.8) vs. 190.9 (150.0;240.0) in the right dome, p =0.000004; and 148.8 (112.5;190.3) vs. 175.2 (130.7;227.7) – in the left, p =0.03, respectively. Diaphragmatic excursions during quiet breathing were larger in patients with CHF than in healthy controls : 2,3 (1,6;2,8)/1,7 (1,5;1,9), p =0,0001 and 1,8 (1,5;2,2)/1,5 (1,3;1,9), p=0,03 of the right and left domes, respectively. Conclusion. Congestive heart failure contributes to the development of structural and functional impairments of the diaphragm.