Oscillometry Solution for Clinical Trials

The procedure is simple. Each maneuver takes 20-30 seconds, resulting in a total test time of 10-20 minutes. A minimum of three maneuvers is required. The patient is asked to sit upright and breathe normally through a sterile mouthpiece while wearing a nose clip. The patient or technician places hands on cheeks to support the soft tissue in the face. Additional support may be needed to ensure a tight seal of the lips around the filter mouthpiece to prevent air leaks.

During normal tidal breathing, the oscillometry device (which contains a loudspeaker or vibrating mesh) superimposes gentle, inaudible sound waves (pressure oscillations) into the airways. These waves cause changes in airflow and pressure, which are measured by sensors in the device. The ratio of pressure to flow determines the respiratory system’s impedance.

The oscillometry test is often selected over traditional lung function tests, such as spirometry, primarily because it is effort-independent and more sensitive to small airway dysfunction.

Key advantages of oscillometry:

• Minimal patient cooperation: The test requires only normal, quiet breathing through a mouthpiece, unlike spirometry which requires forceful inhalation and exhalation maneuvers. This makes oscillometry ideal for patient groups who struggle with forced maneuvers:
  • Young children
  • The elderly
  • Patients who are critically ill or on ventilators
  • Individuals with physical, cognitive, or neuromuscular impairments
• Higher sensitivity to small airways: Oscillometry can detect early changes and abnormalities in the small (peripheral) airways, which are often the first site of diseases like asthma and COPD, even when traditional spirometry results appear normal.
• Differentiation of airway location: The test uses different sound wave frequencies to provide insights into both central and peripheral airway mechanics, helping clinicians pinpoint the site of the respiratory problem (e.g., central obstruction shows uniform resistance; peripheral issues are seen in the difference between high and low frequency resistance).
• Better assessment of bronchodilator response: Studies show oscillometry is more sensitive than spirometry in detecting a patient’s response to bronchodilator medication, which aids in optimizing treatment plans.
• Reduced risk of bronchospasm: The lack of a required deep inhalation maneuver during oscillometry may reduce the risk of inducing bronchospasm (airway constriction) in highly reactive patients, which can sometimes occur during spirometry.

Oscillometry is valuable in clinical trials primarily because its high sensitivity and minimal patient effort requirements make it an effective tool for measuring subtle physiological changes and for use across diverse patient populations.

Key uses in clinical trials:

• Sensitive endpoint for drug efficacy: Oscillometry parameters, especially those related to small airway function, often show a significant response to treatment even when traditional spirometry measures (like FEV1) do not. This increased sensitivity makes it a useful endpoint for trials of new therapies, particularly those targeting the peripheral airways.
• Assessing Small Airway Dysfunction (SAD): Many respiratory diseases, such as asthma and COPD, begin in the small airways, which are difficult to assess with spirometry alone. Oscillometry’s ability to detect SAD earlier allows researchers to:
  • Identify patients with early-stage disease for inclusion in trials
  • Determine if a new drug specifically targets the small airways
  • Monitor disease progression and the impact of therapies on different lung regions
• Inclusion of diverse patient populations: Since oscillometry is effort-independent and performed during normal breathing, it can be used reliably in patient groups who struggle with forced breathing maneuvers required for spirometry. This is particularly crucial for clinical trials involving:
  • Young children
  • The elderly
  • Patients with neuromuscular disorders or physical disabilities
• Bronchodilator and bronchoprovocation testing: Oscillometry can be used as an alternative or complement to spirometry during bronchial challenges and bronchodilator response (BDR) testing. It can often detect airway hyperresponsiveness or a positive BDR with greater sensitivity than spirometry, potentially allowing for the use of lower provocative doses in a trial setting and providing more robust data.
• Objective monitoring and biomarker identification: The test offers objective, reproducible measurements that can be tracked over time to monitor disease stability, predict future exacerbations, and correlate with other biomarkers of inflammation or lung damage (e.g., imaging results or serum C-reactive protein levels).
• Translational research: The technique is used in both human studies and animal models, providing a way to bridge preclinical research findings with human clinical trials and better understand how pathologies affect the lung at different levels across species.

Oscillometry provides a more physiological and objective measure of the entire respiratory system’s mechanical properties during natural breathing, while spirometry relies on forced maneuvers to derive flow and volume metrics that indicate general obstruction. They are considered complementary tools that offer different perspectives on lung health.

Oscillometry provides detailed information about both the large (central) and, critically, the small (peripheral) airways. By using different sound frequencies, it can differentiate between central airway resistance (measured at higher frequencies like 20 Hz) and peripheral airway resistance (the difference between low frequencies like 5 Hz and 20 Hz). This makes it more sensitive for detecting early-stage diseases where small airway dysfunction (SAD) is present but might not show up on a standard spirometry test.

Spirometry predominantly assesses airflow limitation in the central airways. The forced expiration maneuver can cause dynamic compression of the smaller airways, potentially masking peripheral airway issues or making their assessment less reliable. Spirometry detects if there is a flow problem but does not provide granular information on where the resistance is originating within the lung’s structure.