Impulse oscillometry and free-running tests for diagnosing asthma and monitoring lung function in young children

Predictive Value of Impulse Oscillometry Combined with Fractional Expiratory Nitric Oxide Test for Asthma in Preschool Children

Objective

Prediction of asthma in preschool children is challenging and lacks objective indicators. The aim is to observe and analyze the variances between impulse oscillometry (IOS) and fractional expiratory nitric oxide (FeNO) in preschool children with wheezing, establish a joint prediction model, and explore the diagnostic value of combining IOS with FeNO in diagnosing asthma among preschool children.

Patients and methods

This study enrolled children aged 3-6 years with wheezing between June 2021 and June 2022. They were categorized as asthmatic (n=104) or non-asthmatic (n=109) after a 1-year follow-up. Clinical data, along with IOS and FeNO measurements from both groups, underwent univariate regression and multiple regression analyses to identify predictive factors and develop the most accurate model. The prediction model was built using the stepwise (stepAIC) method. The receiver operating characteristic curve (ROC), calibration curve, Hosmer-Lemeshow test, and decision curve analysis (DCA) were employed to validate and assess the model.

Results

During univariate analysis, a history of allergic rhinitis, a history of eczema or atopic dermatitis, and measures including FeNO, R5, X5, R20, Fres, and R5-R20 were found to be associated with asthma diagnosis. Subsequent multivariate analysis revealed elevated FeNO, R5, and X5 as independent risk factors. The stepAIC method selected five factors (history of allergic rhinitis, history of eczema or atopic dermatitis, FeNO, R5, X5) and established a prediction model. The combined model achieved an AUROC of 0.94, with a sensitivity of 0.89 and specificity of 0.88, surpassing that of individual factors. Calibration plots and the HL test confirmed satisfactory accuracy.

Conclusion

This study has developed a prediction model based on five factors, potentially aiding clinicians in early identification of asthma risk among preschool children.

Impulse oscillometry bronchodilator response in preschool children

BACKGROUND

In preschoolers, performing an acceptable spirometry and measuring bronchodilator response (BDR) is challenging; in this context, impulse oscillometry (IOS) represents a valid alternative. However, more studies on the standardization of BDR for IOS in young children are required.

OBJECTIVE

The objective of the study was to identify optimal thresholds to define a positive BDR test with IOS in preschoolers with suspected asthma.

METHODS

Children aged 3-6 years with suspected asthma and their lung function investigated with both IOS and spirometry pre- and post-BDR were retrospectively analyzed. The spirometric BDR was defined as positive when the change of FEV1 was ≥12% or ≥200 mL. The oscillometric BDR was defined as positive in case of change of at least -40% in R5, +50% in X5, and -80% in AX.

RESULTS

Among 72 patients, 36 (age 5.2 ± 1 years; 64% boys) were selected for the subsequent analysis according to ATS/ERS quality criteria of measurements; specifically, 19 patients did not meet IOS and 36 did not meet spirometry criteria. The spirometric BDR was found positive in seven subjects (19.4%); conversely, a positive oscillometric BDR was identified in four patients (11.1%). No patient presented a positive BDR response with both methods. In IOS, the mean decrease in R5 and AX was 19.9% ± 10% and 44% ± 22.1%, and the mean increase in X5 was 23.3% ± 17.8%, respectively. A decrease in R5 of 25.7% (AUC 0.77, p = .03) and an increase in X5 of 25.7% (AUC 0.75, p = .04) showed the best combination of sensitivity and specificity to detect an increase of FEV1 ≥ 12% and/or ≥200 mL.

CONCLUSION

The IOS represents a valid alternative to spirometry to measure BDR in preschool children and should be the gold standard in this age group. We are considering a decrease of 26% in R5 and an increase of 26% in X5 as diagnostic threshold for BDR.

Window of opportunity for respiratory oscillometry: A review of recent research

Oscillometry has been around for almost 70 years, but there are still many unknowns. The test is performed during tidal breathing and is therefore free from patient-dependent factors that could influence the results. The Forced Oscillation Technique (FOT), which requires minimal patient cooperation, is gaining ground, particularly with elderly patients and children. In pulmonology, it is a valuable tool for assessing obstructive conditions (with a distinction between central and peripheral obstruction) and restrictive disorders (intrapulmonary and extrapulmonary). Its sensitivity allows the assessment of bronchodilator and bronchoconstrictor responses. Different lung diseases show different patterns of changes in FOT, especially studied in asthma and chronic obstructive pulmonary disease. Because of these differences, many studies have analysed the usefulness of this technique in different areas of medicine. In this paper, the authors would like to present the basics of oscillometry with the areas of its most recent clinical applications.

Current and Optimal Practices in Childhood Asthma Monitoring Among Multiple International Stakeholders

Importance

Childhood asthma control largely depends on rigorous and regular monitoring. Although various clinical parameters, biomarkers, and patient-reported outcomes are helpful for monitoring purposes, there is no consensus on the minimum and/or optimal set of parameters and their relative priority.

Objective

To assess actual and perceived optimal childhood asthma monitoring practices used globally.

Design, Setting, and Participants

This international, multistakeholder survey study surveyed health care professionals and clinical academics with a professional interest in and exposure to childhood asthma between April 12 and September 3, 2021, to test for differences between the frequency that different techniques are actually used in practice vs optimal practice, between-group differences, and differences across medical settings and country economies.

Main Outcomes and Measures

Outcomes were frequency of duration of asthma monitoring visits as well as actual and perceived optimal use and importance of monitoring tools and domains.

Results

A total of 1319 participants with expertise in childhood asthma from 88 countries completed the survey. Participants included 1228 health care professionals with a balanced distribution across different care settings (305 [22.7%] primary care, 401 [29.9%] secondary, and 522 [38.9%] tertiary care) and 91 researchers. Children with mild to moderate asthma attended regular monitoring visits at a median (IQR) of 5.0 (2.5-8.0) months, with visits lasting a median (IQR) of 25 (15-25) minutes, whereas severe asthma required more frequent visits (median [IQR], 2.5 [1.0-2.5] months; median [IQR] duration, 25 [25-35] minutes). Monitoring of symptoms and control, adherence, comorbidities, lung function, medication adverse effects, and allergy were considered to be very high or high priority by more than 75% of the respondents. Different patterns emerged when assessing differences between actual and perceived optimal use of monitoring tools. For some tools, current and optimal practices did not differ much (eg, spirometry), whereas in others, there was considerable space for improvement (eg, standardized control and adherence tests). The largest gap was observed for between-visit monitoring with electronic trackers, apps, and smart devices. Differences across country economies, care settings, and medical specialties were modest.

Conclusions and Relevance

These survey results suggest that pediatric asthma monitoring is performed generally homogeneously worldwide, in most cases following evidence-based standards. Wider use of standardized instruments and the intensification of continuous between-visit monitoring, supported by electronic devices, is needed for further improvement of disease outcomes. The results of this survey, in conjunction with the available evidence base, can inform recommendations toward further optimization.

The effect of applied force and device design on skin prick test performance

BACKGROUND

Skin prick tests (SPTs) are difficult to standardize, and SPT performance mainly relies on the clinician's expertise. So far, the effect of various factors such as device types, shape, variety of material type, and applied force on the performance of SPT has not been extensively investigated.

OBJECTIVE

To investigate the effect of various factors, including type or shape of devices, material type, and applied force, on the performance of SPT.

METHODS

Four SPT devices with different shapes and materials were applied on 12 subjects under 3 different applied forces (30, 45, and 60 g). The results were compared with standard method using an ALK lancet pricked by an experienced clinician.

RESULTS

A total of 480 pricks were conducted on 12 subjects. The wheal sizes and sensitivities of all devices increased with higher applied forces. The thinner lancets with a long sharp tip had relatively higher analytical sensitivities and provided 100% sensitivity at applied forces of 45 g and above. The pain scores of all devices at applied forces of 30 to 60 g ranged from 1.00 to 1.81 with minimal incidences of bleeding (0%-4.17%), whereas the pain score of the standard method by the ALK lancet was 2.08 with much higher incidences of bleeding at 27.08%.

CONCLUSION

The type/shape of the SPT device and applied force are the essential factors affecting the performance of SPT. The study result could pave the way toward higher performance and standardized SPT.

TRIAL REGISTRATION

The Thai Clinical Trials Registry identification number: TCTR20220627004 (https://www.thaiclinicaltrials.org/show/TCTR20220627004).

Impulse Oscillometry System for the Diagnosis of Wheezing Episode in Children in Office Practice

Background and Objective

Objectively differentiating between wheezing episodes and other respiratory disorders will be helpful in treatment in office practice. The impulse oscillometry system has been useful in assessing airway resistance in children 3–6 years old. As the reference values are different in geographical regions the use of the impulse oscillometry is still limited. Comparison between the percent change in IOS parameters as compared to reference standards and changes in actual IOS parameters was done to diagnose wheezing episodes.

Methodology

Three to six years old children with a history of fever, cough, cold, and/or breathlessness with noisy breathing and who were not on any regular medications, whose parents gave consent were recruited in the study. The children underwent an impulse oscillometry system examination as per the guidelines. The test was repeated after they were given nebulization by salbutamol (2.5 mg) (before COVID 19 pandemic). Final diagnosis was done by following patients for 7 days.

Results

About 106 children were recruited in the study. Five children could not perform the IOS test. Eighteen children did not complete the follow-up. Hence, 83 children were analyzed. There were 47 males and 36 female patients. The change in actual values of AX, R5, and X20 showed statistically significant difference in wheezing episode group (p-value<0.001). The percentage change as compared to predicted values of R5 and X20 also showed a statistically significant difference in the wheezing episode group and the others group (p-value<0.001).

Conclusion

The change in actual values of AX, R5, X20, and resonant frequency may help to differentiate wheezing episode from other respiratory diseases.

Managing the allergy and asthma epidemic in 2020s-Lessons from the Finnish experience

In Finland, a systematic public health programme was implemented from 2008 to 2018 to mitigate the burden of allergic disorders by revisiting the prevention strategy. Allergy health and contacts with natural environment were emphasized to promote immunological and psychological resilience instead of poorly justified avoidance. Allergy management practices were improved and low‐valued recommendations for care, for example for food allergy, were revised. Patients and families were empowered to use guided self‐management to proactively stop symptom exacerbations. A professional non‐governmental organization implemented the nationwide education for healthcare and patient NGOs for patients, families and lay public. In healthcare, the work supporting allergic patients and families was organized towards common goals and integrated into everyday work without extra costs. Reaching the predefined goals was followed by employing the national healthcare registers and questionnaire surveys. Governmental bodies contributed with kick‐off funding, which was supplemented by private funding. International collaboration, for example with the European patient organization (EFA), increased awareness of the Finnish action and predisposed it for peer review. The 10‐year results are favourable, patients are less disabled, practices and attitudes in healthcare have changed, and major cost savings have been obtained. Views of the lay public and patients are slow to move, however. Local multidisciplinary allergy teams were set up to continue the activities also after the Programme. Changes in environment and lifestyle in the last 50 years are the main reasons for the allergy rise. The Finnish experience may help to manage allergic diseases, improve nature relatedness in the fast‐urbanizing world, combat nature loss and reduce the disease burden.