Oscillometry Healthcare Provider Toolkit

• Be used across the lifespan
• Assess young children
• Monitor an individual’s environmental or occupational exposures over time
• Provide insight into airway caliber
• Assess reduced lung compliance
• Detect small airway dysfunction
• Track treatment response after bronchodilator or anti-inflammatory therapy
• Predict COPD exacerbations
• Manage disease long-term

Oscillometry may lead to improved health outcomes by:

• Predicting COPD exacerbations. 
• Informing treatment responsiveness and treatment plans during an asthma exacerbation 
• Reactance parameters were found to be more sensitive in identifying poor asthma control than spirometry, supporting the use of oscillometry to complement spirometry in the clinical management of asthma
• By assessing lung abnormalities early, oscillometry may then reduce the need for medications which could then reduce healthcare costs and the long-term effects of high-dose inhaled corticosteroids.  

The current gold standard test used to diagnosis asthma and COPD is spirometry. For this reason, most experts recommend that oscillometry should not be used as a standalone diagnostic tool but rather in conjunction with spirometry, plethysmography, and clinical history and other investigations such as chest imaging and appropriate blood work.

However, oscillometry can be clinically useful as outlined above in the “What Is the Clinical Usefulness of Oscillometry in the Assessment and Management of Lung Disease” section.

Indications for oscillometry use include:

1. If the patient is unable to perform spirometry, oscillometry is recommended (i.e. too young, too old, or situations where patient is unable to follow instruction to perform spirometry; presence of contraindication to forced expiratory maneuvers but at risk for undiagnosed lung disease). Normal oscillometry can rule out underlying lung disease. Abnormal oscillometry indicates need for further assessment. 
2. If results from spirometry are normal, but the patient remains symptomatic, oscillometry is recommended and subsequent follow up is indicated. 
3. Oscillometry can be helpful in early detection and diagnosis of lung disease as it is more sensitive than spirometry at assessing small airway dysfunction.
4. Oscillometry can be used to monitor medication treatment response.
5. Monitor an individual’s environmental or occupational exposures over time. 
6. Oscillometry can also help predict COPD exacerbations and can be used during an exacerbation to inform treatment. 

When implementing oscillometry in clinical practice, consider the following:

1. Have at least one clinic staff adequately trained in performing the procedure. 
2. Establish written protocols and procedures to match the intended use and audience 
3. Testing can be performed in an exam or procedure room. Some devices are portable and can be performed at bedside.
4. Oscillometry should be conducted first, if other lung function tests such as spirometry are planned during the same clinic visit. This ensures that oscillometry is evaluated at FRC. Tests that require deep breaths and forced maneuvers will change the lung volume.
5. Testing generally takes 15 minutes if it measures a patient’s baseline lung function.   If obtaining a pre- and post-bronchodilator response, 30 minutes should be allocated.

See “How to conduct an oscillometry test” section in the downloadable “Oscillometry:  A toolkit for healthcare professionals” for more information.  

Steps to conduct an oscillometry test include:

1. Equipment and software set up
2. Patient preparation
3. Quality control during the test
4. Determine acceptable measurements
5. Determine measurement exclusion
6. Ensure measurement repeatability
7. Post-bronchodilator response – optional
8. Reporting results

GRAPH PLACEMENT

Steps to Oscillometry Interpretation:

Please refer to the video above and the downloadable Oscillometry: A toolkit for healthcare professionals for further details on oscillometry test result interpretation.

Steps to interpretating oscillometry test results include:

1. Check quality metrics (COV1 coherence)
   1. Coefficient of Variation: <10% for adults, <15% for children (R5 parameter)
   2. Repeat at least 3 tests for a valid session
2. Review R5, total resistance
   1. R5 (resistance at 5Hz) reflects the total respiratory system resistance from central and peripheral airways
   2. Increased R5 suggests overall airway narrowing, as in asthma, COPD, or acute bronchoconstriction.
   3. Normal R5 means total airway resistance is within expected limits
3. Review R5-R20, small airway resistance
   1. R20 (resistance at 20 Hz) primarily reflects large/central airways
   2. R5-R20 means small airway narrowing, often the earliest sign of obstructive lung disease
   3. A normal R20 but elevated R5-R20 can indicate isolated small airway disease
   4. R19 and R5-19 can be interpreted in the same way as R20 and R5-20
4. Review X5:   Small airway reactance
   1. X5 (reactance at 5 Hz) reflects the elastic and inertial properties of peripheral airways
   2. More negative increased X5 values means stiffer, less compliant small airways
   3. This is seen in restriction, such as fibrosis or interstitial lung disease) and in severe small airway obstruction, such as asthma and COPD
5. Review AX:   Area under the Reactance Curve
   1. AX is the integrated area under the reactance curve from 5 Hz to Fres (resonant frequency or zero-crossing)
   2. Increased AX indicates greater small airway dysfunction and can amplify findings from X5
   3. AX is highly sensitive to early changes in small airways
6. Identify the pattern (peripheral, restrictive, obstructive)
7. Add within-breath analysis, expiratory flow limitation or inspiratory flow limitation detection
8. Consider reversibility, pre- and post-bronchodilator

According to technical standards supported by the American Thoracic Society (ATS) and European Respiratory Society (ERS), oscillometry (FOT) is used to detect asthma through measures of increased respiratory resistance (R) and reactance (X).   Recommended bronchodilator responsiveness (BDR) thresholds for asthma, based on the 95^th percentile in healthy individuals, are defined as:

• R5 ↓ by ≥40%
• X5 ↑ by ≥50%
• AX ↓ by ≥80%

• Lack of reference equations
• Lack of device and software standardization
• Growing guideline support
• Efficacy of clinical use in different populations and disease states
• Need to define bronchodilator response thresholds
• Provider familiarity with interpretation of results
• Inability to bill for both oscillometry and spirometry at the same visit.  
• Cost and equipment availability

1. Ensure that the patient is free of any active or suspected transmissible respiratory infection, such as coronavirus or tuberculosis.
2. Ensure that the patient has not had any recent dental or facial surgeries, such as tooth extractions, and can form a proper tight seal around the mouthpiece.
3. Ensure that the patient is as relaxed as possible, is not wearing tight-fitting clothing, and withholds from tobacco use and vigorous exercise at least 1 hour prior to testing.
4. Perform oscillometry prior to other pulmonary function tests, such as spirometry.
5. Ensure that the patient withholds bronchodilators prior to testing, unless instructed by a referring physician to continue bronchodilator medication. 

1. Verify the resistance load of the oscillometry device by using a valid factory calibrated mechanical test load prior to patient testing.
2. Remove the dust caps at both ends of the mechanical test load and attach them onto the oscillometry device.
3. Upon successful verification, save and proceed with testing.
4. Have multiple 'single-patient-use-bacterial/viral' filters and nose clips readily available.
5. Have personal protection equipment (PPE), such as gloves and masks, and disinfectant wipes available.

1. Verify the patient's information: first and last names, date of birth, birth sex, and height.
2. Measure the patient's height without shoes, with feet together, standing as tall as possible with the eyes level and looking straight ahead, and the back flush against a wall or flat surface.
3. Record patient's usage of bronchodilators, dosage, time/date of last administration, and any medication allergies.

1. Ask the patient to sanitize their hands prior to entering the testing station.
2. Outline the test duration of 30 seconds and the minimum requirement of three trials.
3. Explain the sensation generated by oscillations such as 'vibrations' or 'fluttering.'
4. Ensure that the patient is seated properly in a slight 'chin-up' position with both feet on the floor. Avoid slouching against the back of the chair or leg crossing.
5. Instruct the patient to breathe normally while holding their cheeks with their palm and fingers and using their thumbs to support the soft tissue of the jaw during measurements. If they are unable to hold their cheeks themselves, you may hold it for them.
6. Explain to the patient that swallowing should be avoided and the tongue must be below the mouthpiece during the test.

1. Please refer to the manufacturer's instruction manual for individual instructions.
2. Select New Patient, if appropriate, and enter the patient's information such as first and last names, date of birth, birth sex, height, weight, and smoking history.
3. Ensure that the correct wavelength setup is selected. 
4. Ensure the appropriate set of reference values is selected.  

1. Click on Select Patient and choose the correct patient's file by verifying their information such as first and last names and date of birth.
2. Ensure the patient's weight and height are updated prior to the start of testing.

1. Attach a 'single-patient-use-bacterial/viral' filter to the oscillometry device.
2. Ensure the oscillometry device is ready in the testing mode.
3. Remind the patient of the 30 second test duration and the minimum requirement of three measurements.
4. Instruct the patient to wear a nose clip.
5. Adjust the oscillometry device to the patient's head level.
6. Instruct the patient to wet their lips before wrapping them around the mouthpiece to form a proper, tight seal. Instruct the patient to begin to breathe normally.
7. Observe the patient's breathing pattern and start recording following a minimum of three stable tidal breaths. Provide adequate rest time in between each measurement and adjust accordingly, based on the patient.

1. Administer bronchodilator via a valued-holding chamber.
2. Record the method and number of doses administered.
3. Wait for at least 15 minutes.
4. Repeat above testing steps to assess post-bronchodilator response

What is an acceptable oscillometry test?

1. Ensure that the measurements have a validity greater than 70%.
2. Inspect each measurement for anomalies or artefacts that may be caused by coughing, tongue obstruction, glottis closure, air leakage around the mouthpiece, attempting to talk, swallowing, and taking a deep breath.
3. Exclude any unacceptable measurement with anomalies.
4. Validity: Variation in consecutive R₅ values < 15%

What is a repeatable oscillometry test?

1. Ensure that a minimum of three acceptable measurements are recorded.
2. The Coefficient of Variation (CoV) of Rrs for these measurements must be within the set limits:
   • Adults: CoV ≤ 10%.
   • Children: CoV ≤ 15%.

1. Discard patient's mouthpiece and nose clip.
2. Use disinfectant wipes to clean the oscillometry device and patient's chair.

1. Include patient's first and last names, height, age, and birth sex.
2. Include input signal frequencies and duration of individual recordings.
3. Report the mean of acceptable and reproducible measurements and the CoV for these reported measurements.
4. Select and report reference equations.
5. Include impedance graph demonstrating Rrs and Xrs versus oscillation frequency.
6. Include post-bronchodilator response with dosage and method of administration including z-scores and absolute percentage change - optional