Reliability, validity and minimal detectable change of computerized respiratory sounds in patients with chronic obstructive pulmonary disease

INTRODUCTION

Computerized respiratory sounds (CRS) are closely related to the movement of air within the tracheobronchial tree and are promising outcome measures in patients with chronic obstructive pulmonary disease (COPD). However, CRS measurement properties have been poorly tested.

OBJECTIVE

The aim of this study was to assess the reliability, validity and the minimal detectable changes (MDC) of CRS in patients with stable COPD.

METHODS

Fifty patients (36♂, 67.26 ± 9.31y, FEV₁ 49.52 ± 19.67%predicted) were enrolled. CRS were recorded simultaneously at seven anatomic locations (trachea; right and left anterior, lateral and posterior chest). The number of crackles, wheeze occupation rate, median frequency (F50) and maximum intensity (Imax) were processed using validated algorithms. Within-day and between-days reliability, criterion and construct validity, validity to predict exacerbations and MDC were established.

RESULTS

CRS presented moderate-to-excellent within-day reliability (ICC_1,3  ≥ 0.51; P < .05) and moderate-to-good between-days reliability (ICC_1,2  ≥ 0.47; P < .05) for most locations. Negligible-to-moderate correlations with FEV₁ %predicted were found (-0.53 < r_s  < -0.28; P < .05), and the inspiratory number of crackles were the best discriminator between mild-to-moderate and severe-to-very severe airflow limitations (area under the curve >0.78). CRS correlated poorly with patient-reported outcomes (r_s  < 0.48; P < .05) and did not predict exacerbations. Inspiratory number of crackles at posterior right chest, inspiratory F50 at trachea and anterior left chest and expiratory Imax at anterior right chest were simultaneously reliable and valid, and their MDC were 2.41, 55.27, 29.55 and 3.98, respectively.

CONCLUSION

CRS are reliable and valid. Their use, integrated with other clinical and patient-reported measures, may fill the gap of assessing small airways and contribute toward a patient's comprehensive evaluation.

Design of Wearable Breathing Sound Monitoring System for Real-Time Wheeze Detection

In the clinic, the wheezing sound is usually considered as an indicator symptom to reflect the degree of airway obstruction. The auscultation approach is the most common way to diagnose wheezing sounds, but it subjectively depends on the experience of the physician. Several previous studies attempted to extract the features of breathing sounds to detect wheezing sounds automatically. However, there is still a lack of suitable monitoring systems for real-time wheeze detection in daily life. In this study, a wearable and wireless breathing sound monitoring system for real-time wheeze detection was proposed. Moreover, a breathing sounds analysis algorithm was designed to continuously extract and analyze the features of breathing sounds to provide the objectively quantitative information of breathing sounds to professional physicians. Here, normalized spectral integration (NSI) was also designed and applied in wheeze detection. The proposed algorithm required only short-term data of breathing sounds and lower computational complexity to perform real-time wheeze detection, and is suitable to be implemented in a commercial portable device, which contains relatively low computing power and memory. From the experimental results, the proposed system could provide good performance on wheeze detection exactly and might be a useful assisting tool for analysis of breathing sounds in clinical diagnosis.

Regional Lung Sound Asynchrony in Chronic Obstructive Pulmonary Disease Patients

<b><i>Background:</i></b> Regional lung sound distribution in chronic obstructive pulmonary disease (COPD) is reported to be asynchronous. Mathematical analyses using vibration response imaging (VRI), such as left and right lung asynchrony (gap index; GI) and regional lung asynchrony (asynchrony score; AS), are useful measures to evaluate lung sound asynchrony. <b><i>Objectives:</i></b> The aim of this study was to investigate the association of lung sound asynchrony with pulmonary functions and emphysematous lesions in COPD patients. <b><i>Methods:</i></b> VRI recordings and pulmonary function tests were performed in 46 stable male COPD patients and in 40 healthy male smokers. Lung sound asynchrony was evaluated using GI, AS of the left and right lung (AS L-R), and AS of the upper and lower lung (AS U-L). In 38 patients, computed tomography taken within 6 months was available and analyzed. <b><i>Results:</i></b> AS L-R and AS U-L were significantly higher in COPD patients than in healthy smokers, with no significant difference in GI. There were no significant correlations with either AS and pulmonary functions, excluding a negative correlation between AS U-L and diffusion capacity. Although there were no significant correlations between both AS and severity of emphysema, significant positive correlations were observed between heterogeneity of emphysematous lesions and AS L-R (&#x03C1; = 0.38, p < 0.05) or AS U-L (&#x03C1; = 0.51, p < 0.005). <b><i>Conclusions:</i></b> Regional lung sounds are distributed more asynchronously in COPD patients than in healthy smokers, which correlates with the heterogeneous distribution of emphysematous lesions.

Oscillating Positive Expiratory Pressure on Respiratory Resistance in Chronic Obstructive Pulmonary Disease With a Small Amount of Secretion: A Randomized Clinical Trial

This study aims to evaluate the acute effects of an oscillating positive expiratory pressure device (flutter) on airways resistance in patients with chronic obstructive pulmonary disease (COPD).Randomized crossover study: 15 COPD outpatients from Asthma Lab-Royal Brompton Hospital underwent spirometry, impulse oscillometry (IOS) for respiratory resistance (R) and reactance (X), and fraction exhaled nitric oxide (FeNO) measures.Thirty minutes of flutter exercises: a "flutter-sham" procedure was used as a control, and airway responses after a short-acting bronchodilator were also assessed.Respiratory system resistance (R): in COPD patients an increase in X5insp (-0.21 to -0.33 kPa/L/s) and Fres (24.95 to 26.16 Hz) occurred immediately after flutter exercises without bronchodilator. Following 20 min of rest, a decrease in the R5, ΔR5, R20, X5, and Ax was observed, with R5, R20, and X5 values lower than baseline, with a moderate effect size; there were no changes in FeNO levels or spirometry.The use of flutter can decrease the respiratory system resistance and reactance and expiratory flow limitation in stable COPD patients with small amounts of secretions.

The correlation between lung sound distribution and pulmonary function in COPD patients

Background

Regional lung sound intensity in chronic obstructive pulmonary disease (COPD) patients is influenced by the severity and distribution of emphysema, obstructed peripheral airways, and altered ribcage and diaphragm configurations and movements due to hyperinflation. Changes in the lung sound distribution accompanied by pulmonary function improvements in COPD patients were observed after bronchodilator inhalation. We investigated the association of lung sound distribution with pulmonary functions, and the effects of emphysematous lesions on this association. These studies were designed to acquire the basic knowledge necessary for the application of lung sound analysis in the physiological evaluation of COPD patients.

Methods

Pulmonary function tests and the percentage of upper- and lower-lung sound intensity (quantitative lung data [QLD]) were evaluated in 47 stable male COPD patients (54 - 82 years of age). In 39 patients, computed tomography taken within 6 months of the study was available and analyzed.

Results

The ratio of lower QLD to upper QLD showed significant positive correlations with FEV₁ %predicted (%FEV₁; ρ = 0.45, p<0.005) and MEF₅₀ %predicted (%MEF₅₀; ρ = 0.46, p<0.005). These correlations were not observed in COPD patients with dominant emphysema (% low attenuation area >40%, n = 20) and were stronger in less emphysematous patients (n = 19, %FEV₁; ρ = 0.64, p<0.005, %MEF₅₀; ρ = 0.71, p<0.001).

Conclusions

In COPD patients, the ratio of lower- to upper-lung sound intensities decreased according to the severity of obstructive changes, although emphysematous lesions considerably affected lung sound distribution.

Left and right lung asynchrony as a physiological indicator for unilateral bronchial obstruction in interventional bronchoscopy

BACKGROUND

In patients with bronchial obstruction, pulmonary function tests may not change significantly after intervention. The airflow asynchrony in both lungs due to unilateral bronchial obstruction may be applicable as a physiological indicator. The airflow asynchrony is reflected by the difference in the left and right lung sound development at tidal breathing.

OBJECTIVES

To investigate the usefulness of left and right lung asynchrony due to unilateral bronchial obstruction as a physiological indicator for interventional bronchoscopy.

METHODS

Fifty cases with central airway obstruction were classified into three groups: tracheal, bronchial and extensive obstruction. The gap index was defined as the absolute value of the average of gaps between the left and right lung sound intensity peaks for a 12-second duration.

RESULTS

Before interventional bronchoscopy, the gap index was significantly higher in the bronchial (p<0.05) and extensive obstruction groups (p<0.05) than in the tracheal group. The gap index in cases with unilateral bronchial obstruction of at least 80% (0.18±0.04 seconds) was significantly higher than in cases with less than 80% obstruction (0.02±0.01 seconds, p<0.05). After intervention for bronchial obstruction, the dyspnea scale (p<0.001) and gap index significantly improved (p<0.05), although no significant improvements were found in spirometric assessments. The responder rates for dyspnea were 79.3% for gap indexes over 0.06 seconds and 55.6% for gap indexes of 0.06 seconds or under.

CONCLUSIONS

Assessment of left and right lung asynchrony in central airway obstruction with bronchial involvement may provide useful physiological information for interventional bronchoscopy.

The application of impulse oscillation system for the evaluation of treatment effects in patients with COPD

There are only a few reports of the use of impulse oscillation system (IOS) for the evaluation of COPD treatment. In this study, we applied IOS and spirometry to evaluate the effectiveness of fluticasone propionate and salmeterol (SFC) combined with tiotropium (TIO) in COPD patients. Following a 4-week run-in period with TIO (18 μg once daily) treatment, COPD patients were randomized to SFC (250/50 μg twice daily; SFC+TIO group, n=25), or TIO alone (TIO group, n=31). Pulmonary functions were recorded by IOS and spirometry before and after the study period. The SFC+TIO group showed significant improvements in inspiratory resistance at 5 Hz and resonant frequency, as well as in FVC and FEV1, after the 12-week treatment (p<0.05). Since there were no significant correlations between improvements in IOS measurements and FVC or FEV1, IOS may provide a physiological point of view that is different from spirometry and seemed to be applicable as an additional assessment tool targeting COPD patients.