Evaluation of respiratory muscle strength and pulmonary function in heart failure patients

Background: Heart failure (HF) is the inability of the heart to pump enough blood to supply the necessities of the body. Pulmonary function and respiratory muscles can be affected and typical symptoms presented by the patients include discomfort at a minimal exertion. Objective: To verify pulmonary function and respiratory muscle strength in patients with class II and III HF as defined by the New York Heart Association (NYHA). Methods: The study was descriptive and observational, and comprised 12 class II and III HF patients in follow-up at the out-patient. Pulmonary function assessments [Forced Expiratory Volume in the first second (FEV1) and Forced Vital Capacity (FVC)] were performed using microspirometry and respiratory muscle strength [Maximal Expiratory Pressure (MEPmax) and Maximal Inspiratory Pressure (MIPmax)] were evaluated using a pressure transducer (Globalmed (TM)). Results: Differences were found between the functional classes II and III in relation to pulmonary function: FEV1 (II: 91.17 +/- 19.87, III: 68.17 +/- 21.78); FVC (II: 68.17 +/- 21.78; III: 73.67 +/- 22.94); and respiratory muscle strength: MIPmax (II: 77.67 +/- 40.70, III: 53.33 +/- 29.27) and MEPrnax (II: 98.83 +/- 34.56; III: 58.33 +/- 15.06). The class II were higher for all study parameters, only MEPmax revealed a statistically significant difference. Conclusion: The pulmonary function and respiratory muscle strength are impaired in heart failure patients class III patients, particularly in relation to MEPrnax.