Determining respiratory system resistance and reactance by impulse oscillometry in obese individuals

Abstract

Objective: To evaluate peripheral respiratory system resistance and reactance (Rrs and Xrs, respectively) in obese individuals. Methods: We recruited 99 individuals, dividing them into four groups by body mass index (BMI): < 30.0 kg/m2 (control, n = 31); 30.0-39.9 kg/m2 (obesity, n = 13); 40.0-49.9 kg/m2 (severe obesity, n = 28); and ≥ 50.0 kg/m2 (morbid obesity, n = 13). Using impulse oscillometry, we measured total Rrs, central Rrs, and Xrs. Peripheral Rrs was calculated as the difference between total Rrs and central Rrs. All subjects also underwent spirometry. Results: Of the 99 individuals recruited, 14 were excluded because they failed to perform forced expiratory maneuvers correctly during spirometry. The individuals in the severe obesity and morbid obesity groups showed higher peripheral Rrs and lower Xrs in comparison with those in the two other groups. Conclusions: Having a BMI ≥ 40 kg/m2 was associated with a significant increase in peripheral Rrs and with a decrease in Xrs.

Applications of oscillometry in clinical research and practice

“…High BMI can affect the frequency dependence likely indicative of obesity causing peripheral airway closure and hence, heterogeneity. 75,[94][95][96] The CV 5 is 11%, less than 15%, and hence the study is of acceptable quality. The R 5 is significantly above the reference value for a normal subject's R 5 with a Z-score over 3.…”

“…The R 5-20 is 2.85 cmH 2 O.s.L À1 and is well above the 1.0 cmH 2 O.s.L À1 threshold indicating the presence of significant small airways pathology providing the subject had a BMI < 40 and the cheeks were well supported during the test. 25,69,[72][73][74][75] The reactance curve is remarkable for a profound downward displacement of the X 5 and rightward shift of the F res beyond the stimulating frequencies, resulting in an A X significantly above the reference A X indicating severe ventilatory inhomogeneity and obstruction.…”

Efeito do treinamento muscular inspiratório em pacientes submetidos à cirurgia bariátrica: uma revisão sistemática

“…Despite the greater governmental and public health attention over the last decades on dietary and exercise interventions, the proportion of obese population has increased every year 8 . Morbid or severe obese patients frequently develop alterations in body mechanisms, especially in the respiratory system, including interference in the respiratory function, decreased pulmonary volumes and capacities [9][10][11][12][13] mechanical compression of the diaphragm, lungs and of the chest cavity 14 , reduced compliance and increased pulmonary resistance 10,15,16 besides reduced respiratory muscle strength 10,17,18 . Thus, due to chest and abdomen fat excess, the morbid obesity has effects on lung function, which leads to a mechanical disadvantage and influences the strength of respiratory muscles 17 .…”

Avaliação da função pulmonar, força e <i>endurance</i> muscular respiratória, resistência do sistema respiratório e capacidade funcional de pacientes com obesidade grau III e correlação com a percepção de dispneia e qualidade de vida

“…Alguns estudos observaram uma correlação da obesidade com a predisposição de desenvolvimento da asma brônquica e apneia obstrutiva do sono 15,16 . Outros estudos mostram que a espirometria não identificou nenhuma alteração da função pulmonar, questionando sua sensibilidade para este grupo específico [17][18][19] .…”

“…al 21 , originado a partir da técnica de oscilação forçada 22 que avalia as propriedades mecânicas das vias aéreas e do parênquima pulmonar, mediante a aplicação de pulsos de pressão em múltiplas faixas de frequência de ondas sonoras, sobre o sistema respiratório durante a respiração espontânea. Com isso, é possível detectar possível obstrução das vias aéreas periféricas, que muitas vezes não são observadas na curva fluxovolume, além de identificar alterações das vias aéreas centrais de forma regionalizada 17,23 .…”