Relationship between acoustic breath sounds and spirometry
Research type
Research Study
Full title
A comparative single centre study assessing the relationship between acoustic breath sounds as measured by a commercially available sound recording device against standard of care (spirometry) in the assessment of airflow obstruction in patients who plan to undergo spirometry testing.
IRAS ID
312339
Contact name
Brendan Cooper
Contact email
Sponsor organisation
University Hospitals Birmingham NHS Foundation Trust
Clinicaltrials.gov Identifier
Duration of Study in the UK
1 years, 6 months, 0 days
Research summary
Research Summary: The purpose of this study is to assess a commercially available acoustic breath sound (ABS) recording device called the "Wheezo" against spirometry with respect to detecting airflow obstruction.
Expiratory airflow and volume can be measured during a spirometry test. When performing spirometry, (after inhaling maximally) individuals exhale with maximal force and duration into a spirometer. The spirometry measures the speed of airflow and volume of air exhaled with respect to time. These values are then compared to what is expected, which is based upon an individual’s age, height and sex.
Airflow obstruction refers to reduction in the fraction of air exhaled in the first second of the test, relative to the volume of air exhaled in the entirety of the test. Airflow obstruction is associated with abnormal airway function (narrowed airways) and is a common finding in asthma and chronic obstructive pulmonary disease (COPD).
Thus, spirometry is performed routinely to aid diagnosis and monitor asthma and COPD over time. Spirometry has limitations as it can only be performed by trained healthcare professionals, which reduces the clinical utility outside of a clinical environment.
The Wheezo is a commercially available non-invasive sound recording device that is placed against the trachea and records the proportion of breath sounds that contain wheeze (known as the Tw/Ttot%). Wheeze is an abnormal breath sound that is generated by airflow interacting with abnormally narrow airways. Therefore, the aim of this project is to identify whether the device is able to identify and quantify airflow obstruction by comparing Tw/Ttot% against spirometry.
Currently it is unknown if the measurements taken by the device are comparable to that measured by spirometry. If there is agreement, this device may have pre-hospital utility by patients to aid guide therapy and need for medical intervention.
Summary of Results: The study demonstrated that wheeze rate was unable to discriminate between participants with and without airflow obstruction (AUC: 0.570 and 0.572 for all and asthmatic participants, respectively). Although wheeze had a higher incidence in participants with severe/very severe airflow obstruction, a greater proportion of participants across all severity categories of airflow obstruction did not wheeze. Overall, 22.5% of participants with airflow obstruction wheezed, compared to 8.3% without airflow obstruction. The optimal wheeze rate detecting airflow obstruction was 3%, which had a sensitivity of 37.5% (95% CI: 22.5%, 52.5%) and specificity of 79.7% (95% CI: 72.9%, 86.5%). Using the standard ≥5% threshold, sensitivity was lower at 22.5% (95% CI: 9.6%, 35.4%) and specificity increased to 91.7% (95% CI: 87.1%, 96.4%). Whilst abnormal ACT and ACQ scores obtained from asthmatics were not associated with wheeze rate, wheeze incidence or spirometric findings, there was a link between wheeze and cough (p=0.031), excess sputum production (p=0.012), and elevated FeNO (p=0.009). Similar to wheeze during tidal breathing, forced expiratory wheeze rate (FEWR) failed to discriminate between participants with normal and abnormal spirometry, with very similar wheeze rates in participants with and without airflow obstruction (11.5% [4.8,18.3], vs. 8.4 [3.1,19.7], respectively, p=0.522). However, limitations in deriving FEWR were acknowledged, and further methodological consideration is suggested to reevaluate the data. Taken together, wheeze rate measured during tidal breathing was unable to accurately identify airflow obstruction and cannot be used as a surrogate for this purpose. Notably, 70% of participants reporting wheeze were not wheezy when assessed, consistent with previous findings and suggesting that that the device may be able to enhance the accuracy of participant reported wheeze. Further longitudinal research could evaluate wheeze rate and symptoms over time, to determine whether ongoing or episodic wheeze, objectively measured, correlates with symptom burden or disease control, potentially highlighting a role for the device in disease monitoring rather than diagnosis.
REC name
West Midlands - South Birmingham Research Ethics Committee
REC reference
22/WM/0247
Date of REC Opinion
24 Oct 2022
REC opinion
Favourable Opinion