Assessment of the respiratory muscles strength at patients with chronic obstructive pulmonary disease with various forms of comorbidity

The respiratory muscles (RM) strength is the main indicator of their functional state. However, RM strength is not used as criteria for chronic obstructive pulmonary disease (COPD) stratification.

Aim. To evaluate the RM power of COPD patients with various variants of comorbidity and to determine the role of comorbidity in the development of respiratory muscle dysfunction.

Materials and methods. RM strength of 64 men with exacerbation of COPD was studied. The severity of comorbidity was assessed by the Charlson index. Depending on the prevalence of comorbidity, patients were divided into 3 groups: cardiovascular, cerebrovascular and metabolic. Maximum inspiratory (MIP) and expiratory (MEP) pressures in the oral cavity, maximum rate of pressure development (MRPD), sniff nasal inspiratory pressure (SNIP), MEP/MIP and SNIP/MIP indexes were determined with MicroRPM device (UK). Measured values of MIP, MEP and SNIP were compared with the proper ones. The most noticeable decrease of RM strength was defined in the group of patients with severe comorbidity.

Results. In case of a mild comorbidity MEP and SNIP values were 68 and 78% of the predicted values and MIP value corresponded to the personified standard. RM strength of patients with COPD depended on the clinical variant of comorbidity. Thus, in the group of patients with cardiovascular variant of comorbidity auxiliary inspiratory muscles strength decreased. In the group of patients with cerebrovascular variant of comorbidity the expiratory muscles dysfunction predominated. In the group of patients with metabolic variant of comorbidity diaphragm dysfunction predominated.

Conclusion. The pathogenetic significance of various factors of COPD comorbidity in the development of RM dysfunction was confirmed by the results of the correlation analysis.