Respiratory system impedance in different decubitus evaluated by impulse oscillometry in individuals with obesity.

BACKGROUND AND OBJECTIVE: The body posture can influence gas exchange, respiratory mechanics, and mucociliary clearance and different positions can be used as a therapeutic strategy to improve in gas exchange and can also help physiotherapists to assist patients who have difficult or restrictions to stay seated or the ones who stay in the same position for a long period. The objective of this study was to evaluate the effect of different positions on respiratory system impedance in obese and eutrophic subjects, using Impulse Oscillometry System (IOS). METHODS: The IOS parameters were evaluated in seated (Se), right lateral decubitus (RL), left lateral decubitus (LL), and supine (Su). RESULTS: Sixty two volunteers were allocated in obese group (OG) or eutrophic group (EG) according to BMI. In seated position, OG showed higher impedance than EG for R5: 0.55 (0.31; 0.93) and 0.33 (0.24; 0.52); R20: 0.39 (0.23; 0.54) and 0.32 (0.03; 0.41); R5-R20: 0.13 (0.02; 0.47) and 0.01 (-0.08; 0.27); X5: -0.20 (-0.51; 0.16) and -0,10 (-0.016; -0.04); Fres: 20.59 (11.54; 36.45 and 10.69 (7.56; 24.7) (p<0.05) and the impedance were higher in the Su for both groups. Compared to Se, there were differences with Su (R5, R5-20, X5), with RL (R20), and with LL (R5, R20) for OG; and with Su (R5, R5-20, X5, Fres), with RL and LL (X5) for EG. Compared to Su, there were differences with RL and LL (R5-20, X5) for OG; and with RL (R5, R5-20, X5, Fres), and LL (R5-20, X5, Fres) for EG. There were no differences between RL and LL for OG and EG. CONCLUSION: The respiratory system impedance is increased in OG, with greater contribution of peripheral resistance. The higher values of resistance and reactance were obtained in the supine position, in both groups, with lower differences obtained in the right and left lateral decubitus.

Correlation among clinical, functional and morphological indexes of the respiratory system in non-cystic fibrosis bronchiectasis patients.

BACKGROUND: Non-cystic fibrosis bronchiectasis (NCFB) is a heterogeneous disease, which assessment and severity can't be defined by one particular instrument but using a multidimensional score. Thus, in additional to traditional methods, alternative tools have been developed to assist these patients' evaluation. OBJECTIVE: To correlate functional and morphological indexes with severity and dyspnea in NCFB patients, focusing on the correlation between the impulse oscillometry system (IOS) and the quantitative analysis of computed tomography (CT). METHODS: Clinically stable NCFB patients, between 18 and 80 years old were submitted to clinical, functional and morphological evaluations assessed by Bronchiectasis Severity Index (BSI) and Medical Research Council (MRC) scale; spirometry and IOS; and subjective and quantitative Chest CT scans analysis, respectively. RESULTS: This study included 38 patients. The best correlations obtained between functional and morphological airway indexes were: resistance at 5 Hz-R5 and the normalized thickness of bronchial walls-Pi10 (r = 0.57), and the mean forced expiratory flow (FEF25-75%) and CT score (r = -0.39). BSI as well as MRC showed higher correlations with the quantitative automated analysis of CT (BSI and Pi10: r = 0.41; MRC and Pi10: r = 0.35) than with subjective CT score (BSI and CT score: r = 0.41; MRC and CT score: r = 0.15); and moderate and weak correlations were obtained on both functional airway indexes (BSI and peripheral airways resistance - R5-R20: r = 0.53; BSI and forced expiratory volume at the first second-FEV1: R = -0,64; MRC and R5-R20: r = 0.42; and MRC and VEF1: r = -0.45). CONCLUSION: In NCFB patients, compartmentalized methods for assessing the respiratory system (IOS and the automated quantitative CT analysis) have a good correlation with severity and dyspnea.

Increased airway resistance can be related to the decrease in the functional capacity in obese women.

BACKGROUND AND OBJECTIVE: Obesity can increase the airways resistance, mainly in the periphery, leading to dyspnea perception that can impair the functional capacity. This study aimed to analyze if airways resistance could be related to the walking capacity of women with morbid obesity. METHODS: Thirty-seven women with grade III obesity in preoperative bariatric surgery were evaluated using the spirometry test, impulse oscillometry system (IOS), and six-minute walk test (6MWT). Additionally, data about their daily dyspnea perception and physical activity level were collected. RESULTS: Variables of the spirometry test did not detect ventilator disorders. Compared to the predicted values, the IOS identified significant increase in airways resistance (kPa/L/s) (R5: 0.36 (0.34; 0.36) and 0.53 (0.47; 0.61); R20: 0.30 (0.28; 0.30) and 0.41 (0.35; 0.45); R5-20: 0.06 (0.06; 0.06) and 0.14 (0.10; 0.15); X5: -0.03 (-0.04; -0.01) and -0.20 (-0.27; -0.18), respectively). The distance walked in the 6MWT, 491.4±60.4m was significantly correlated to R5 (rho = -0.41, p = 0.01), R5-20 (rho = -0.52, p = 0.001), and X5 (rho = 0.54, p = 0.0006). CONCLUSION: The IOS is able to identify changes in airway resistance even before the onset of symptoms. When evaluated by IOS women with severe obesity and normal spirometry exhibited central and peripheral airways obstruction. The correlations between the IOS and six-minute walk distance suggest that increased peripheral airways resistance could be related to worsening functional capacity.

Comparative evaluation of expiratory airflow limitation between patients with COPD and BE using IOS.

Impulse oscillometry (IOS) allows evaluation of the compartmentalized resistance and reactance of the respiratory system, distinguishing central and peripheral obstruction. The IOS measurements are getting attention in the diagnosis and differentiation of chronic respiratory diseases. However, no data are available in the literature to differentiate between COPD and BE using IOS parameters. We aimed to evaluate the feasibility of IOS in the diagnosis of bronchiectasis non-cystic fibrosis (BE) in comparison to COPD. Whole breath, inspiration, expiration, and inspiratory-expiratory difference (Δ) were evaluated based on the IOS parameters: total resistance (R5), central airway resistance (R20), peripheral airway resistance (R5-R20), reactance (X5), reactance area (AX), and resonance frequency (Fres). Fifty-nine subjects (21 Healthy, 19 BE, and 19 COPD) participated in this study. It was observed a significant difference in the comparison of healthy and pulmonary disease groups (BE and COPD) for total breathing (R5-R20, X5, AX, and Fres), inspiratory phase (R5 and R5-R5), and expiratory phase (R5-R20 and X5). The comparison between BE and COPD groups showed significant difference in the expiratory phase for resistance at 5 and 20 Hz and, ΔR5 and ΔR20. The IOS evidenced an increase of R5, R20 and R5-R20 in patients with BE and COPD when compared to healthy subjects. Expiratory measures of IOS revealed increased airway resistance in COPD compared to BE patients who had similar FEV1 measured by spirometry, however, further studies are needed to confirm these differences.

Effects of Controlled Voluntary Increase in the Ventilatory Demand on Respiratory System Resistance in Healthy and Non-Cystic Fibrosis Bronchiectasis Subjects: A Cross-Sectional Study.

INTRODUCTION: Bronchiectasis patients may present a reduced functional capacity due to an increase in the ventilatory demand during exercise. OBJECTIVE: To evaluate the effects of controlled voluntary hyperinflation and increased respiratory rate on the mechanics of the respiratory system, simulating what happens during exercise, in bronchiectasis and healthy subjects. METHODS: Bronchiectasis (n=30) and healthy (n=16) subjects were evaluated by impulse oscillometry (IOS) during a baseline condition, and in controlled conditions with baseline (b) tidal volume (V) and hyperinflation (H), with respiratory rates at 30(R30) and 40(R40) bpm, in a random order. The mixed effects and a significance level at 0.05 were used for comparisons. RESULTS: Resistance at 5Hz (R5), and at minus 20Hz (R5-R20), in kPa/L/s, were higher in subjects with bronchiectasis in all experimental conditions (p<0.05). For the bronchiectasis group, R5 and R5-20 increased with R increase at V (VRb versus VR30 and VR40; VR30 versus VR40; R5, R20 and R5-20 increased with R increase at H (HRb versus HR40; HR30 versus HR40). For the same R, there was a decrease with H compared to V (HRb versus VR30 and VR40; and HR30 versus VR30 and VR40). For the healthy group, only R20 showed differences (HR30 versus HR40; HR40 versus VR40). CONCLUSION: The tachypnea increases the resistance and reactance of the respiratory system in bronchiectasis patients, and the voluntary hyperinflation caused attenuates this increase. These results can guide the development of strategies to reduce the limitation of physical activity in patients with bronchiectasis.

Effects of Controlled Voluntary Increase in the Ventilatory Demand on Respiratory System Resistance in Healthy and Non-Cystic Fibrosis Bronchiectasis Subjects: A Cross-Sectional Study.

INTRODUCTION: Bronchiectasis patients may present a reduced functional capacity due to an increase in the ventilatory demand during exercise. OBJECTIVE: To evaluate the effects of controlled voluntary hyperinflation and increased respiratory rate on the mechanics of the respiratory system, simulating what happens during exercise, in bronchiectasis and healthy subjects. METHODS: Bronchiectasis (n=30) and healthy (n=16) subjects were evaluated by impulse oscillometry (IOS) during a baseline condition, and in controlled conditions with baseline (b) tidal volume (V) and hyperinflation (H), with respiratory rates at 30(R30) and 40(R40) bpm, in a random order. The mixed effects and a significance level at 0.05 were used for comparisons. RESULTS: Resistance at 5Hz (R5), and at minus 20Hz (R5-R20), in kPa/L/s, were higher in subjects with bronchiectasis in all experimental conditions (p<0.05). For the bronchiectasis group, R5 and R5-20 increased with R increase at V (VRb versus VR30 and VR40; VR30 versus VR40; R5, R20 and R5-20 increased with R increase at H (HRb versus HR40; HR30 versus HR40). For the same R, there was a decrease with H compared to V (HRb versus VR30 and VR40; and HR30 versus VR30 and VR40). For the healthy group, only R20 showed differences (HR30 versus HR40; HR40 versus VR40). CONCLUSION: The tachypnea increases the resistance and reactance of the respiratory system in bronchiectasis patients, and the voluntary hyperinflation caused attenuates this increase. These results can guide the development of strategies to reduce the limitation of physical activity in patients with bronchiectasis.

Peak expiratory flow in obese subjects in different positions.

Objective: To analyze the peak expiratory flow (PEF) in obese subjects in standing (ST), seated (SE), supine (SU), prone (PR), and right and left lateral decubitus (RL and LL) positions. Methods: 36 obese volunteers, aged between 18 and 54 years, and nonsmokers, were evaluated by anthropometric data; spirometry; international physical activity questionnaire (IPAQ); and PEF in ST, SE, SU, PR, RL, and LL positions, randomly. Results: The mean age was 27.3 ± 7.4 years and BMI of 38.7 ± 3.2 kg/m2; IPAQ results: active (50%), irregularly active (25%), very active (16.7%), and sedentary (08.3%); spirometry results: FVC = 100.33%, FEV1 = 92.83%, FEV1/FVC ratio = 0.95, FEF25-75% = 85.55%. The PEF (L/min) were within the normal range and there was no difference between the ST and SE (428.6 ± 100.9 and 430.0 ± 100.1). Comparing ST and SE to the other positions, in absolute and percent of predicted values (L/min and %), there was a decrease in the SU (85.4 ± 14.9), PR (401.1 ± 92.4 and 84.1 ± 14.4), RL (398.6 ± 94.7 and 83.3 ± 14.9) (p < 0.05), and there was no difference to SU (409.4 ± 102.8) and LL (410.3 ± 93.9 and 85.8 ± 14.5). Conclusion: The PEF of healthy obese are similar in the standing and seated positions. The PEF decreases in the lying positions, except for the LL, that could be used as an alternative for measurements.

The Influence of Different Mouthpieces on Impulse Oscillometry Results.

BACKGROUND: Impulse oscillometry is a method of airway assessment and diagnosis that provides data on lung mechanics. In the literature, studies have used different types of mouthpieces or did not describe the model used for the tests. We sought to compare the 3 most commonly described mouthpieces in terms of test results, comfort, and subject preference. METHODS: Thirty-nine healthy volunteers were evaluated with spirometry and impulse oscillometry, assessing the resistance at 5 Hz and 20 Hz (R5 and R20, respectively), reactance at 5 Hz (X5), reactance area, and resonant frequency. A filter heat exchanger with a circular mouthpiece (B1), a filter heat exchanger with an oval mouthpiece (B2), and a filter heat exchanger with a circular mouthpiece coupled with a free-flow piece (B3) were compared using an acceptability and tolerance scale, and subjects noted their preference. RESULTS: Statistical analysis showed differences between all the mouthpieces and the predicted values for R5, R20, and X5. The mouthpiece comparison showed differences in R5 between a filter heat exchanger with an oval mouthpiece (B2) and a circular mouthpiece coupled with a free-flow piece (B3) (P = .007); resonant frequency between a filter heat exchanger with a circular mouthpiece (B1) and a filter heat exchanger with an oval mouthpiece (B2) (P = .004) and between a filter heat exchanger with a circular mouthpiece (B1) and a circular mouthpiece coupled with a free-flow piece (B3) (P = .003); and reactance area between a filter heat exchanger with a circular mouthpiece (B1) and a circular mouthpiece coupled with a free-flow piece (B3) (P = .01). In the subjective evaluation, acceptability and tolerance differences were found in the ease of carrying out the evaluation, and no difference was found with regard to the degree of discomfort. Ten subjects preferred a filter heat exchanger with a circular mouthpiece (B1), 15 preferred a filter heat exchanger with an oval mouthpiece (B2), and 14 preferred a circular mouthpiece coupled with a free-flow piece (B3). CONCLUSIONS: A circular mouthpiece coupled with a free-flow piece (B3) appeared to be the most suitable mouthpiece for the impulse oscillometry tests. It assured smaller impedance values for the respiratory system, and subjects expressed the most confidence in using this mouthpiece.