Impulse Oscillation Technique Research Articles

Diagnostic Value of Oscillation Technique for Chronic Obstructive Pulmonary Disease: A Meta-Analysis

Many studies have investigated the usefulness of oscillation technique, including forced oscillation technique (FOT) and impulse oscillation technique (IOS), for the diagnosis of chronic obstructive pulmonary disease (COPD). However, the overall diagnostic accuracy of oscillation technique for COPD remains unclear. The aim of the present meta-analysis was to determine the overall accuracy of oscillation techniques for diagnosis of COPD. We performed a systematic search in PubMed and Embase. Data on sensitivity, specificity, positive/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR) were pooled. Summary receiver operating characteristic (SROC) curves and area under the curve (AUC) were used to summarize overall test performance. Six studies met our inclusion criteria. Summary estimates for oscillation technique in the diagnosis of COPD are as follows: sensitivity - 0.77 (95%CI 0.70-0.83; I 2 = 87.6%); specificity - 0.85 (95%CI 0.81-0.88; I 2 = 58.4%); PLR - 5.99 (95%CI 2.91-12.34); NLR - 0.16 (95%CI 0.005-0.47); DOR - 47.95 (95%CI 9.99-230.17) and AUC - 0.96. Pooled estimates for FOT were as follows: sensitivity 0.94 (95% CI 0.86-0.98), specificity 0.94 (95% CI 0.86-0.98), PLR 11.48 (95% CI 5.17- 25.48), NLR 0.08 (95% CI 0.03-0.17), DOR 221.8 (95% CI 58.39-842.5), and AUC 0.98. Given its easy to perform and subject-independent nature, our meta-analysis suggests a potential role for oscillation technique in diagnosis of COPD, especially FOT.

Comparison Study of Airway Reactivity Outcomes due to a Pharmacologic Challenge Test: Impulse Oscillometry versus Least Mean Squared Analysis Techniques

The technique of measuring transpulmonary pressure and respiratory airflow with manometry and pneumotachography using the least mean squared analysis (LMS) has been used broadly in both preclinical and clinical settings for the evaluation of neonatal respiratory function during tidal volume breathing for lung tissue and airway frictional mechanical properties measurements. Whereas the technique of measuring respiratory function using the impulse oscillation technique (IOS) involves the assessment of the relationship between pressure and flow using an impulse signal with a range of frequencies, requires less cooperation and provides more information on total respiratory system resistance (chest wall, lung tissue, and airways). The present study represents a preclinical animal study to determine whether these respiratory function techniques (LMS and IOS) are comparable in detecting changes in respiratory resistance derived from a direct pharmacological challenge.

Effectiveness of Omalizumab in a Patient with Severe Asthma, Low Serum IgE Level, and Lack of Sensitized Allergens Induced by Oral Steroid Therapy: The Usefulness of Impulse Oscillation for Assessment of Omalizumab Therapy

Background. Omalizumab is a humanized monoclonal anti-IgE antibody that was recently approved for the treatment of severe allergic asthma. However, omalizumab is not licensed for allergic asthma in patients with a low serum IgE level (<30 IU/mL) or negative results for specific allergen tests. Case history. We present a patient with severe asthma and low serum IgE levels who had negative results for specific allergens induced by oral steroid therapy. Omalizumab administration improved asthma exacerbated forced expiratory volume in 1 s (FEV1) and respiratory resistance measurements based on the impulse oscillation technique (Mostgraph-01). The response to omalizumab therapy was evidenced by a decrease in airway resistance at 1 month. Conclusions. The findings of this case report indicate that omalizumab treatment had beneficial effects in a patient with severe asthma and low total serum IgE levels with negative results for specific IgE, which may have been induced by long-term corticosteroid administration.

Impulse Oscillation Technique May Help to Better Discriminate Between Asthmatic Preschool Children and Healthy Controls When Combined with Conventional Spirometry on The Basis of Their Bronchodilator Response

Impulse Oscillation Technique May Help to Better Discriminate Between Asthmatic Preschool Children and Healthy Controls When Combined with Conventional Spirometry on The Basis of Their Bronchodilator Response

Useful Parameters of Bronchial Hyperresponsiveness Measured with an Impulse Oscillation Technique in Preschool Children

Background. There are few studies focused on bronchial challenge testing using the oscillation technique, and results from the test in preschool children have been inconsistent. Objectives. The aim of this study was to explore which level of provocative concentration (PC) is appropriate for bronchial challenge testing using the impulse oscillometry system (IOS) for assessing asthma. The authors also compared variable diagnostic cutoff values of PC expressed in different ways. Methods. A methacholine challenge test was performed using an IOS and the mean baseline value, resistance (Rrs), reactance (Xrs), resonance frequency (Rf), and area of reactance (AX) of the respiratory system were recorded simultaneously over a frequency spectrum of 5 to 35 Hz in 50 preschool children with asthma and 41 children with chronic cough, serving as controls. Results. The results of the methacholine challenge test by IOS, expressed as percent changes of the predicted value (Δ%Pred), were significantly different between the two groups, whereas results expressed as actual data or Z-score were not. PC80_Xrs5 was a valuable diagnostic cutoff level for asthma with acceptable sensitivity (80.0%) and specificity (82.9%). The areas under the ROC curves of Xrs5 for both actual (0.867; p < .001) and predicted values (0.877; p < .001) were larger than those for Rrs5 (0.746 and 0.730, respectively). Conclusions. The authors suggest PC80_Xrs5 might be a useful parameter for IOS-assessed bronchial challenge testing in preschool children with asthma.

Impulse oscillometry in comparison to spirometry in pregnant asthmatic females: Table 1—

To the Editors: Asthma complicates 3–8% of pregnancies 1, 2 and early diagnosis and optimal management of the condition seems necessary. However, spirometry as a clinical measure of airway disease mainly depends on subjects efforts during forced expiratory manoeuvres. Considering the high prevalence of respiratory symptoms and breathlessness in pregnancy and the limited functional capacity and mobility of the diaphragm because of the growing foetus 3, an easier, more rapid screening test that does not require patient cooperation would be ideal. Our study aimed to evaluate the correlation between spirometry and impulse oscillation technique (IOS) parameters to reveal the utility of IOS parameters in diagnosis of airflow obstruction in pregnant females. In total, 125 pregnant females were categorised in …

Multi-frequency forced oscillation technique [FOT] for assessment of lung allograft function: a pilot study

Introduction: The forced impulse oscillation technique [FOT] measures impedance of the respiratory system to forced acoustic oscillations. Resistance [Rrs; Normal: 1.8-3 cm H2O/L/s] and reactance [Xrs], the vector of elastic and inertial tissue forces, can be determined with 7-10% variability. Normative data exist for normal subjects, smokers and both healthy and asthmatic children. We postulate that FOT may allow enhanced discrimination of larger versus smaller airway dysfunction after LT.

Observer variability of lung function measurements in 2-6-yr-old children.

The aim of this study was to assess the within-observer and between-observer variability of lung function measurements in children aged 2-6 yrs. Two observers examined 22 asthmatic children independently according to a predefined protocol. Each observer obtained duplicate measurements of respiratory resistance by the interrupter technique (Rint), respiratory resistance (Rrs,5) and reactance (Xrs,5) at 5 Hz by the impulse oscillation technique and the specific airway resistance (sRaw) by whole body plethysmography. The within-subject SD (SDw) was not significantly different in the two observers. The ratio SDw between observers/mean SDw within observers was 0.94, 1.25, 1.35 and 2.86 for Xrs,5, Rrs,5, sRaw and Rint, respectively, indicating greater between-observer variability of the latter. The systematic difference between observers assessed by the difference between observer means (expressed as a percentage of their mean value) was 11, 7, 6 and 2% for Xrs,5, sRaw, Rrs,5 and Rint, respectively. These differences were statistically significant, except that for Rint. In conclusion, specific airway resistance, impulse oscillation technique and respiratory resistance assessed by the interrupter technique measurements in young children are subject to influence by the observer, and the random variability between observers appears to be particularly great for respiratory resistance assessed by the interrupter technique. The authors suggest that the between-observer variability should be investigated when evaluating novel methods for testing lung function.

Lung function and short-term outcome in young asthmatic children.

The aims of this study were to investigate lung function in 2-5-yr-old stable asthmatic children consecutively referred from general practitioners and to analyse the outcome on the basis of their requirement for antiasthmatic treatment and symptoms after 1.6-4.5 yrs. Lung function was measured in 110 children with a mean+/-SD age of 3.8+/-1.0 yrs using the interruptor technique (resistance assessed using the interruptor technique (Rint)), whole body plethysmography (specific airway resistance (sRaw) and respiratory resistance (Rrs,5)and reactance at 5 Hz (Xrs,5) using the impulse oscillation technique. Rint, sRaw, Xrs,5 and Rrs,5 were suggestive of impaired lung function in 44%, 14%, 11% and 7.5% of the children, respectively, with a predominance of children aged 2-3 yrs. Sixty-five per cent were treated with inhaled steroids, and 35% were treated only with beta2-agonists as needed; lung function was not significantly different between these two groups. Outcome after 2.9+/-0.7 yrs was not significantly different between children with Rint measurements above and those children with Rint measurements within the reference range at enrolment. Of these children, 58 and 59% were currently on antiasthmatic treatment, and 40% and 49% had current symptoms, respectively. Impairment of lung function may be a common finding in stable young asthmatic children, but apparently this is not a risk factor for persistence of asthmatic symptoms.

Specific airway resistance, interrupter resistance, and respiratory impedance in healthy children aged 2-7 years.

We report data on respiratory function in healthy children aged 2-7 years in whom we measured respiratory resistance by the interrupter technique (Rint); total respiratory impedance (Zrs), respiratory resistance (Rrs), and reactance (Xrs) by the impulse oscillation technique; and specific airway resistance (sRaw) by a modified procedure method in the whole body plethysmograph. Measurements were attempted in 151 children and were successfully obtained in 121 children with a mean (SD) age of 5.3 (1.5) years; no measurements were possible in 30 children (mean age 3 (0.9) years). The repeatability of measurements was independent of the age of the subjects, and the within-subject coefficient of variation was 11.1%, 8.1%, 10.8%, and 10.2% for sRaw, Rint, Zrs, and Rrs at 5 Hz (Rrs5), respectively. All lung function indices were linearly related to age, height, and weight. A significant negative correlation with age, height, and weight was found for Rint, Zrs, and Rrs5. Xrs5 was positively correlated to age and body size. The mean values of Rint, Rrs5, Xrs5, and Zrs in children younger and older than 5 years were 1.04, 1.38, -0.5, and 1.48 kPa x L(-1) x s and 0.9, 1.18, -0.37, and 1.23 kPa x L(-1) x s, respectively. sRaw showed no significant correlation with body size or age and the mean sRaw in children younger and older than 5 years was 1.09 and 1.13 kPa x s, respectively. None of the indices of respiratory function differed between boys and girls. Xrs and Rrs exhibited a significant frequency dependence in the range of 5-35 Hz. The techniques applied in this study require minimal cooperation and allow measurement of lung function in 80% of our population of awake young children. Further studies are needed to evaluate the potentials of the presently established reference values for clinical and epidemiological purposes.

Measurement of respiratory impedance in healthy calves using the impulse oscillation technique—Physiological and methodological aspects

The aim of the present study was to investigate methodological and physiological aspects of complex respiratory impedance measurements in calves using the impulse oscillation technique. To apply the system to animals, a tightly fitting face mask was used. The measuring system was modified by placing a flexible tube between the pneumotachograph and the loudspeaker. Complex respiratory impedance measurements were not significantly influenced by the modification. Linear correlations were found between body weight and respiratory impedance; as body weight increased, resistance decreased and reactance increased. The methodological variability of impedance measurements using the impulse technique was found to be extremely small. Diurnal variations of respiratory impedance were considered to be the main source of intra-individual variability. When comparing different animals (even when healthy and matched for age and body weight) our results suggest that inter-individual biological variability must be carefully considered.

Repeatability of methacholine challenges in 2- to 4-year-old children with asthma, using a new technique for quantitative delivery of aerosol.

To determine the repeatability of bronchial responsiveness in awake young children, two methacholine challenge tests were performed on separate days in 16 children with stable asthma (mean age, 3 3/4 years). Methacholine was administered using a new method for quantitative delivery of aerosol that eliminates the effect of dilution of the aerosol by entrainment of air and enables quantitative delivery of aerosol according to body weight. Respiratory function was monitored by measurement of respiratory resistance by the interrupter technique (Rint), respiratory resistance and reactance at 5 Hz (Rrs5, Xrs5) by the impulse oscillation technique, transcutaneous measurements of oxygen (PtcO2), and specific airway resistance (sRaw). Repeatability was evaluated by determining the provocative dose that caused a defined percentage of change relative to baseline (PD%: Rint PD30, Rrs5 PD30, Xrs5 PD80, PtcO2 PD10, and sRaw PD80. Repeatability was estimated from the difference between the PD% obtained at the time of the two tests. Using the numeric value of these differences, the repeatability of Xrs5 PD60, PtcO2 PD10, and sRaw PD50 was [mean (SD)]: [0.8 (0.5)] [0.5 (0.4)] and [0.7 (0.6)] doubling doses, respectively. Rint PD30 and Rrs5 PD30 proved to be less reproducible: [1.2 (1)] and [1.6 (0.9)] doubling doses, respectively. The new method of aerosol delivery offers a means of standardizing the bronchoconstrictor stimulus, and the results show that estimates of bronchial responsiveness in young children can be obtained reproducibly within one doubling dose of methacholine.

The impulse oscillation technique applied for measurements of respiratory function in young children.

The impulse oscillation technique applied for measurements of respiratory function in young children.

Measurement of lung function in awake 2–4‐year‐old asthmatic children during methacholine challenge and acute asthma: A comparison of the impulse oscillation technique, the interrupter technique, and transcutaneous measurement of oxygen versus whole‐body plethysmography

Measurement of lung function in awake 2–4‐year‐old asthmatic children during methacholine challenge and acute asthma: A comparison of the impulse oscillation technique, the interrupter technique, and transcutaneous measurement of oxygen versus whole‐body plethysmography

Lung function measurement in awake young children

The aim of the study was to evaluate methods applicable in a clinical setting for monitoring of changes in lung function in awake young children. Impedance measurements by the impulse oscillation technique (ZIOS), respiratory resistance measurements by the interrupter technique (Rint) and transcutaneous measurements of oxygen tension (Ptc,O2) were compared with concomitant measurements of specific airway resistance (sRaw) and forced expiratory volume in one second (FEV1) by whole body plethysmography and spirometry, respectively, during methacholine challenge in 21 young children aged 4-6 yrs, with suspected asthma. Measurements with each technique were repeated after each challenge step. A special face-mask was developed with an integrated mouthpiece which ensured mouth breathing during the measurements. The order of sensitivity of the techniques to assess methacholine-induced changes in lung function was ZIOS > sRaw > Ptc,O2 > FEV1 > Rint. ZIOS was significantly more sensitive than all subsequent methods, and Ptc,O2 was significantly more sensitive than FEV1. ZIOS, sRaw and Rint, but not Ptc,O2 and FEV1, detected the subclinical increase in bronchial muscle tone in the children during baseline, which was revealed by the significantly reduced airway obstruction after inhalation of a beta 2-agonist as compared to baseline. It is concluded that ZIOS, Rint and Ptc,O2 change in parallel with sRaw and FEV1 and with a comparable sensitivity during simultanoeous measurements of the response to methacholine in young children aged 4-6 yrs. This implies that ZIOS, Rint and Ptc,O2 provide convenient indices of changes in lung function. Their combined use will be useful for monitoring airway diseases of young children.