Impulse Oscillometry May Be Useful in Evaluation of Bronchiectasis Severity and Prediction of Airway Reversibility.
Cuiyan TanDonghai MaKongqiu WangChangli TuMeizhu ChenXiaobin ZhengYingjian LiangYiying HuangZhenguo WangJian WuJin HuangJing Liu
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Abstract Background Impulse oscillometry (IOS) can be used to evaluateairway impedance in patients with obstructive airway diseases. Previous studies have demonstrated that IOS parameters differ betweenbronchiectasis patients and healthy controls. This study aims to explore the usefulness of IOS in assessing disease severity and airway reversibility in bronchiectasis. Method Seventy-four patients with non-cystic fibrosis bronchiectasis who visited our Respiratory Medicine outpatient clinic were consecutively recruited. Spirometry, plethysmography and IOS tests were performed. Patients were stratified into mild, moderate and severe disease according to Reiff, Bhalla, BSI, FACED, and BRICS scores. Airway reversibility was measured by bronchodilation test (BDT) and the result was classified as positive or negative.. ROC curves of IOS parameters was used to assess the usefulness of IOS parameters in predicting airway reversibility. Correlations between the IOS, spirometric lung function and bronchiectasis severity parameters were analysed. Results Many IOS parameters, such as airway resistance at 5Hz (R5), small airways resistance (R5–R20), total airway reactance (X5), resonance frequency (Fres), total airway impedance at 5Hz (Z5), and peripheral resistance (Rp) increased with increased bronchiectasis severity according to the FACED, BSI and Reiff scores. Large airway resistance (R20) and central resistance (Rc) were not significantly different among groups with differentbronchiectasis severity. The difference between R5 and R20 (R5-R20) showed 81.0% sensitivity, and 69.8%specificity in predicting the airway reversibility in bronchiectasis with AUC of 0.794 (95%CI, 0.672-0.915). Conclusion IOS measurements are useful indicators of bronchiectasis severity and may be useful for predicting the airway reversibility.Keywords:
Plethysmograph
Background: Airway resistance can be measured by different techniques of body-plethysmography and impulse oscillometry (IOS). So far there has been no systematic study comparing validity of these techniques in relation to clinical condition of the patients reported.
Aims and objectives: We investigated correlation between these techniques in assessment of airway resistance and asthma control test.
Methods: In 92 patients with asthma selected on the basis of ATS criteria for diagnosis of asthma and GINA asthma control test (ACT) questionnaire completed. Pulmonary function tests including body-plethysmography with airway resistance measurement and impulse oscillometry measuring total airway resistance at 5 Hz and 20Hz was done using IOS.
Results: ACT score has a significant correlation with a r value of - 0.34 with total airway resistance measured by body-plethysmography (p=0.003) and also significant correlation with r value of - 0.31 (p=0.002) with airway resistance measured by IOS at 5Hz but no significant correlation with airway resistance measured by IOS at 20 Hz. There is a significant correlation between airway resistance measured by body plethysmography and airway resistance measured by IOS at 5 Hz and at 20 Hz.
Conclusion: These finding indicates a good correlation of total airway resistance measured by body plethysmography and by IOS at 5 Hz as well as 20 Hz, which is stronger with the first, Also significant negative correlation between ACT score and airway resistance centered in peripheral airways measured by IOS at 5 Hz but not with the resistance at central airways measured mainly by IOS at 20Hz.
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We compared specificity and sensitivity of the forced oscillation technique with the standard methods of body plethysmography and spirometry in children suffering from asthma (age 5-8 yrs). We investigated 60 healthy and 66 asthmatic children by forced oscillation, plethysmography and spirometry. Mean FEV1% pred was 99.7 and 82.4% in the healthy and asthmatic subjects, respectively, and mean SRaw was 0.68 and 1.18 kPa*s, respectively. Forced oscillation and plethysmography could be measured in all children, whereas 29% of the investigated children failed to perform valid spirometry. Discriminant analysis was used to compare the optimal classification which could be obtained from the measured data with the clinical one. Fixing specificity to 95%, we computed sensitivities of 66% (forced oscillation), 68% (body plethysmography), and 76% (spirometry). We conclude that the diagnostic value of the three methods in young children with asthma is similar. However, the value of spirometry is limited by cooperation in these young children.
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Rational. Lung function (LF) testing is considered as hallmark to get objectivity of functional deficits and their severity. The question is whether simple spirometry is an appropriate tool for that purpose in asthmatic children. Objectives. Selectivity to detect abnormal in asthmatic children comparing spirometric with plethysmographic parameters. Methods. An asthma database was prospectively built-up during the past 3 years comprising measurements of 168 children (98 males, 70 females). Target parameters of spirometry were forced expiratory indices (FEV 1 , MEF 50 ), those of plethysmography functional residual capacity (FRC pleth ), and effective total airway resistance (sR tot ). Data were analysed as standard deviation scores (SDS) using reference equations. Results. Normal were found in 11.8% of patients. 19.8% presented with pulmonary hyperinflation (FRC pleth >2 SDS), 22.7% with bronchial obstruction (sR tot >2 SDS), and 48.2% with bronchial obstruction and pulmonary hyperinflation. A small group of 9.4% presented only with a decrease of MEF 50 , considered as “small airway dysfunction. Best detection rate of abnormal LF was found for sR tot (72.3%) followed by MEF 50 (51.6%). FEV 1 was abnormal only in 14.7% of patients, especially with a very low rate in patients with pulmonary hyperinflation (6.9% and those with both pulmonary hyperinflation and bronchial obstruction (23.1%). Conclusions. The assessment of lung function disorders in asthmatic children should not be based on spirometry only, because airway patency is not well reflected by flow-volume curves in children, especially when pulmonary hyperinflation is present.
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Using a constant-volume infant whole-body plethysmograph containing a heated rebreathing bag, we have been able to measure airway resistance (Raw) throughout the respiratory cycle using a computer-based technique. Data from the plethysmograph transducers are sampled at 60 Hz for the calculations and Raw is calculated at each point sampled during the breath, with appropriate corrections for absolute lung volume. It was found that in most cases Raw varied less with respect to tidal volume than to tidal flow. Various patterns of Raw change in relation to tidal volume were found. These included an elevated but relatively constant resistance, a progressively rising expiratory resistance, and in 3 infants with laryngomalacia, a progressively rising inspiratory resistance. It was also found that the dynamic performance of the rebreathing bag was such that considerable errors would occur if apparatus resistance was assumed to be constant and so the actual apparatus resistance at each point was subtracted from the total resistance to give Raw· In conclusion, Raw is not constant throughout the respiratory cycle in infants and the pattern of change conveys additional information.
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Small airway dysfunction (SAD) is associated with poorly controlled asthma and frequent exacerbations. Objective: To assess the prevalence of SAD in asthmatics using spirometry, body plethysmography, and impulse oscillometry (IOS). Materials and methods: The observational cross-sectional study of 61 patients with asthma was performed. Conclusion available SAD was made on the basis of identifying one of the criteria or their combination: 1) slow vital capacity (SVC) - forced vital capacity (FVC) >10% according spirometry; 2) "air trapping" according body plethysmography; 3) presence of pathological frequency dependence of the resistance (R) at 5 and 20 Hz (R5-R20 > 0,07 kPa•sec/l) according IOS. Results: The analysis was performed for the entire group as well as for patients with FEV1 > 80 %pred. and FEV1/SVC < 0,7 (group 1) and patients with FEV1 > 80 %pred. and normal FEV1/SVC (group 2). SAD was most often diagnosed using IOS and the selected criterion R5-R20>0,07 kPa •sec/l since 75% of patients had this deviation in the entire group, 65% of patients in group 1 and 55% of patients in group 2 whereas only in 48% and 24% of cases in the entire group according body plethysmography and spirometry, respectively. Conclusion: SAD is definitely observed in patients with asthma. IOS is a more effective method of diagnosing SAD compared to spirometry and body plethysmography and can serve as a supplement functional method, especially in cases of normal parameters of spirometry and body plethysmography in asthmatics.
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Abstract The role of emotions as potential triggers of asthmatic airway obstructions was examined by whole body plethysmography. Three affectively homogeneous picture series (IAPS) were presented with video glasses to induce pleasant, unpleasant, and neutral emotional states in 32 asthmatic and 32 nonasthmatic participants while they were seated in a Jaeger Bodytest plethysmograph. Airway resistance, specific airway resistance, thoracic gas volume, and mood were measured immediately after each presentation, in addition to specific airway resistance before and during each presentation. Airway resistance and specific airway resistance were significantly increased after and during pleasant and unpleasant stimulation compared to neutral stimulation in asthmatic patients and also, but less pronounced, in nonasthmatic controls. The results show that the experience of pleasant and unpleasant emotions can provoke increased airway resistance especially in asthmatic patients.
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To examine whether the complicated method of body plethysmography can be replaced by non-plethysmographic methods, such as oscilloresistometry (Ros), the closing pressure method (Run) or the forced expiration volume method (FEV1), the authors studied the results obtained with 247 hospitalised patients between 18 and 81 years of age suffering from, or free from, airway obstruction. Although satisfactory correlations were obtained by linear and curvilinear regression analysis, considerable differences were seen in individual patients suffering from obstructions to a higher degree. Oscilloresistometry showed at the standard value limit of the airway resistance applicable in body plethysmography (0.30 kPa/l/s) a sensitivity of 89%, whereas the specificity was only 62%. Almost identical values of sensitivity (92%) and specificity (61%) were attained by the closing pressure method only if the standard value limit was set a little higher, namely, at 0.35 kPa/l/s. FEV1, which is easiest to measure, was able to objectivate an airway obstruction in a manner comparable to that of Ros and Run; there was in fact even a closer statistical correlation between the body plethysmographic resistance mographic methods are suitable for screening examinations on account of their sensitivity. However, if the results on the examination are not in keeping with the overall clinical findings, further diagnostic clarification must be sought by performing a body plethysmographic measurement.
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