Mauricio de Sant'Anna Jr1,a, Renata Ferreira Carvalhal2,b, Fernando da Franca Bastos de Oliveira3,c, Walter Araújo Zin4,d, Agnaldo José Lopes5,6,e, Jocemir Ronaldo Lugon7,f, Fernando Silva Guimarães8,g
J Bras Pneumol.2019;45(5):e20180311
Objective: To evaluate the different components of the resistance of the respiratory system, respiratory muscle strength and to investigate the occurrence of expiratory flow limitation (EFL) in patients with morbid obesity (MO) when seated. Methods: The sample was composed of MO (BMI≥40 kg/m2) and non-obese individuals (NO) with a BMI between 18 and 30 kg/m2. The protocol consisted of the anthropometric assessment and the following measures of respiratory function: spirometry, maximal inspiratory and expiratory pressures (MIP and MEP, respectively) and impulse oscillometry. The group comparison was performed using T-test for unpaired samples. The correlations were evaluated by the Pearson test with a significance level of 5%. Results: Fifty MO (age 40±10.4 years, 1.64±0.09 m, 138.8±33.6 kg and 50.7±8.9 kg/m2), and 30 NO (age 37.6±11.5 years, 1.67±0.09 m, 65.2±10.3 kg and 23.2±22 kg/m2) were evaluated. The MO showed higher values of total, peripheral, airways, tissue and central resistance when compared to the NO. No patient showed EFL. The waist circumference was associated with spirometric variables, MIP, and MEP. The waist-to-hip ratio was correlated to respiratory mechanics and spirometric variables, MIP, and MEP. Conclusion: Morbidly obese patients with no obstructive spirometric pattern show increased total, airway, peripheral, and tissue respiratory system resistance when compared to nonobese. These individuals, however, do not present with expiratory flow limitation and reduced respiratory muscles strength.
Keywords: Respiratory mechanics; Obesity; Impulse oscillometry; Pulmonary resistance; Respiratory system impedance.