Respiratory Muscle Strength Does Not Present Correlations with Lung Mechanics in GOLD II COPD Patients

Abstract

The diagnosis of COPD is based on spirometry, which is an effort-dependent test requiring good patient cooperation. Impulse oscillometry (IOS) is a lung mechanics measuring which does not requires effort and cooperation, presenting advantages, especially for geriatric population. A high prevalence of respiratory muscle weakness is associated to severity of airway obstruction, based in the spirometric evaluations. However, no study has investigated whether respiratory muscle strength may or not correlate with the levels of small airways obstruction, as evaluated by IOS, considering that small airways obstruction is a central characteristic of COPD patients. Then, 20 COPD GOLD II (70,53±4,73 years old) and 20 non-COPD patients (71,4±4,92 years old) were evaluated for lung function by spirometry, lung mechanics by IOS, maximum inspiratory (MIP) and expiratory (MEP) pressure by manovacuometer. Considering the spirometric parameters, the results showed that COPD patients presented reduced FEV1 and FEV1/FVC (p 0.05), while for oscillometric parameters, a reduced resistance of respiratory systems (R5Hz; p 0.05) and for reactance (X5Hz; p>0.05). However, while a positive correlation was found between the reduction of PIMax and PEMax with FEV1 (p 0.05). We conclude that IOS parameters does not correlate with muscular respiratory strength and are independent from effort.