The urgency of diagnosing asthma stems from two primary factors. Firstly, it’s estimated to impact 300 million individuals globally. Secondly, the treatment of asthma imposes significant financial burdens on both healthcare institutions and patients. 

 

Despite current asthma guidelines employing clinical and spirometry-based criteria to assess and manage its severity, a substantial number of children and adults experience inadequate control of the condition, even under specialized care. 

 

This article offers a concise examination of the hurdles specialists encounter in promptly diagnosing asthma and assessing treatment efficacy. Within this article, you’ll discover the scientific evidence supporting the role of oscillometry as a supplementary test alongside spirometry. 

 

Asthma is Underdiagnosed 

 

Research indicates that asthma misdiagnosis is prevalent, with an estimated underdiagnosis rate ranging from 19-73% of cases. Precise diagnosis is vital to prevent patients from receiving inappropriate treatments, as well as to avert exacerbations and long-term damage to their airways. 

 

Since the turn of the millennium, significant efforts have been dedicated to formulating and spreading global guidelines on asthma. This endeavor has undoubtedly enhanced asthma management worldwide by facilitating the identification and treatment of new asthmatic cases. However, it may also have contributed to a rise in instances of improperly diagnosed asthma, resulting in unnecessary or misguided treatments. This escalation heightens the likelihood of patients experiencing adverse effects without deriving any therapeutic benefits. 

 

International Clinical Practice Guidelines (CPGs) recommend that asthma diagnosis be grounded in both symptomatic manifestation and objective assessments of variable airflow limitation. Consequently, there is a substantial probability that physicians may incline towards commencing treatment in patients exhibiting asthma symptoms without conducting supplementary diagnostic evaluations. Recent research suggests that many asthma diagnoses in primary care rely solely on clinical assessment and/or treatment response. 

 

Spirometry stands as the cornerstone for asthma diagnosis in both children and adults, although there exists another supplementary test that can be highly beneficial: oscillometry. Before delving into the advantages of employing both tests, it’s essential to grasp why their combined use is optimal. 

 

The Missing Piece for Proper Asthma Diagnosis 

 

A contributing factor to the misdiagnosis of asthma in both children and adults stems from the underestimation of peripheral airways (PA), where luminal diameter is ≤ 2 mm. These airways constitute primary sites of obstruction and inflammation in individuals with persistent asthma. Consequently, conventional treatments, such as inhaled corticosteroids of large particles (ICLP), may prove insufficient in reaching these crucial areas. 

 

Historically, PA have been overlooked, largely due to their inaccessibility using conventional diagnostic methods. However, a novel non-invasive technique, oscillometry (OS), offers an accurate means of assessing them. 

 

Oscillometry functions by measuring lung mechanics during normal breathing, evaluating airway impedance to detect obstruction in both central airways and PA, as well as reactance, which gauges the elasticity of PA. Recent studies have demonstrated its utility as a complementary tool in diagnosing and monitoring asthma and various other respiratory conditions. 

 

Notably, oscillometry presents an advantage as it solely necessitates normal breathing into the oscillometer’s mouthpiece, making it well-suited for older adults, young children, individuals with cognitive impairments, or those facing difficulties in understanding and adhering to instructions. 

 

The Solution for Obtaining a Precise and Accurate Asthma Diagnosis 

 

As demonstrated, the significance of small airways in asthma cannot be overstated. Consequently, oscillometry holds promise as a valuable adjunct to spirometry. Integrating both tests into routine diagnostic protocols and asthma management strategies could prove highly beneficial for patients in several ways: 

 

Treatment Customization: Not all inhaled medications effectively target small airways, potentially leading to treatment inefficacy, particularly in individuals with pathology in those regions. Oscillometry offers a means to identify asthma sufferers who might benefit from small particle aerosols, which can penetrate deeper into peripheral airways. 

 

Monitoring: Oscillometry serves as a valuable tool for assessing therapeutic efficacy and forecasting exacerbations. Moreover, oscillometry readings exhibit strong correlations with asthma control metrics, encompassing patient-reported outcomes such as ACQ (Asthma Control Questionnaire) scores. Additionally, this diagnostic approach can detect declining function in peripheral airways, even among patients deemed to have well-managed conditions. 

 

SCHILLER has introduced tremoflo®, an Airwave Oscillometry platform that assesses lung function by superimposing a multifrequency wave onto the patient’s spontaneous breathing, thereby computing airway resistance and reactance. 

Oscillometry + Spirometry

 

Asthma is a prevalent and persistent respiratory condition impacting both children and adults alike. It is distinguished by varying respiratory symptoms and restriction of expiratory airflow that can be reversed, either spontaneously or through treatment. Despite effective therapies being available, diagnosing and managing the condition remains a challenge. 

 

The SCHILLER-Ganshorn pulmonary function line comprises the airway oscillometer, tremoflo®, and the ultrasonic spirometer, SpiroScout. When physicians utilize these two complementary assessments, they obtain additional insights into the patient’s lung function. This is invaluable as it enables accurate asthma diagnosis and facilitates the provision of appropriate treatments to enhance patients’ quality of life. 

 

Click the button to download the tremoflo® and SpiroScout brochure. 

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REFERENCES 

[1] Contoli, M., & Papi, A. (2010). When asthma diagnosis becomes a challenge. European Respiratory Journal, 2010; 36: 231–233 DOI: 10.1183/09031936.00053010  

[2] Stanley P. Galant, MD., Tricia Morphew, MSc. Adding oscillometry to spirometry in guidelines better identifies uncontrolled asthma, future exacerbations, and potential targeted therapy. Annals of Allergy, Asthma & Inmunology. Volume 132, ISSUE 1, P21-29, January 2024. https://doi.org/10.1016/j.anai.2023.08.011 

[3] Kavanagh J et al. Breathe (Sheff). 2019;15(1):e20-e27. 

[4] Global Initiative for Asthma. Global strategy for asthma management and prevention, 2023. Updated July 2023. Available from www.ginasthma.org 

[5] Desiraju K, Agrawal A. Lung India. 2016;33(4):410-6 

[6] Lundblad LKA et al. Can J Respir Crit Care Sleep Med. 2021;5:54-68. 

[7] Cottini M et al. Clin Mol Allergy. 2021;19(1):7. 

[8] Galant SP et al. Ann Allergy Asthma Immunol. 2017;118(6): 664-71.