Evaluation of Respiratory Muscle Strength in Patients with Heart Failure

Abstract

Context: The estimated prevalence of heart failure (HF) is around 1% of the total population in India which is close by to 8–10 million individuals. Due to metabolic and structural skeletal muscle dysfunctions, peripheral muscles are impaired in the early stages of chronic HF (CHF). In experiments on rats with CHF, biopsies of respiratory muscles revealed histological abnormalities, such as atrophy of type 1 diaphragm fibers, resulting in decreased respiratory muscle strength and endurance. Aim: To determine the strength of respiratory muscle and pulmonary function in individuals having Class II and Class III HF. Settings and Design: Descriptive, observational, case–control study design. Subjects and Methods: Subjects included 37 HF patients having Class II and Class III in one group and controls in another group. The respiratory muscle strength (maximal inspiratory pressure [MIP] and maximal expiratory pressure [MEP]) was evaluated using respiratory pressure meter (RPM) and pulmonary function (forced expiratory volume at the end of 1 s [FEV1] and forced-vital capacity [FVC]) assessment using spirometry-Schiller (micro RPM). Statistical Analysis Used: Median and IQR were used to describe the study variables MIP, MEP, FVC, and FEV1, and the Mann-Whitney U test to compare the study variables between the two groups. Results: The outcomes were interpreted as the median values. The MIP and MEP were 59 and 70 cmH2O, respectively, in HF as compared to 97 and 96 cmH2O in the control group, significant at P < 0.001. The FEV1 and FVC in HF were 114 and 88% sequentially as compared to 130 and 99% in the control group, significant at P < 0.05. Conclusions: The respiratory muscle strength and pulmonary functions are impaired in individuals having Class II and Class III HF.