Respiratory telemetry is a different modality of the pulmonary function testing that is now increasingly used in the clinical and research setting. Oscillometry is conducted through tighter breathing with three acceptable measurements, and can be performed with minimal contraindications. The main advantage of respiratory oscillometry is that it requires minimal cooperation and may be even more sensitive to picking up changes in the peripheral airways than conventional pulmonary function tests.
The goal of this video is to provide a training manual for clinicians, technologists, and research personnel on the appropriate conduct of oscillometry following international standard protocols and quality control guidelines. Our laboratory uses a device from a particular manufacturer, but the technique is the same regardless of the manufacturer. The software programs are different for each manufacturer in the same way that different commercial spirometers have unique proprietary software for data collection and display.
The protocol is applicable for all respiratory oscillometry devices. Viewers are directed to the manuals of their commercial devices for specific instructions regarding software use. Equipment and materials used in this video are detailed in the table of materials and regions.
Ensure patient is free of any active or suspected transmissible respiratory infection, such as coronavirus or tuberculosis. Ensure patient does not have any recent dental or facial surgeries, such as tooth extractions, and must be able to form a proper tight seal around the mouthpiece. Ensure patient is as relaxed as possible, is not wearing tight fitted clothing, and withholds from tobacco use and vigorous exercise at least one hour prior to testing.
Oscillometry must be performed prior to conventional PFTs, such as spirometry, if requested by a referring physician. Please refer to supplemental table one for contraindications for spirometries and PFTs. Ensure patient withholds from bronchodilator usage prior to testing, unless instructed by a referring physician to continue bronchodilator medication.
Please refer to supplemental table two for bronchodilator withholding times for PFTs and supplemental table three for bronchodilator withholding times for methacholine challenge test. Ensure the resistance load of the oscillometry device is verified by using a valid factory-calibrated mechanical test load prior to patient testing. Remove the dust caps at both ends of the mechanical test load and attach onto the oscillometry device.
Select calibration from the oscillometry software menu and proceed with impedance test load verification. Upon successful verification, save and proceed with testing. Have multiple single patient use bacterial filters and nose clips readily available.
Ensure proper protection equipment such as gloves and masks and disinfectant wipes are available. Ensure patient's information is correct, such as first and last names, date of birth, birth sex, height, weight, and gender identity if applicable. Patient's height must be measured 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 a flat surface. For patients age 25 years and are older where height measurement has been made previously in the same laboratory, remeasuring height at subsequent visits within one year may not be necessary. Update weight measurement at each visit.
Record patient's use of bronchodilators, dosage, time and date of last administration, and any medication allergies, such as salbutamol. Ask the patient to sanitize their hands prior to entering the testing station. Outline the test duration at 30 seconds and the minimum requirement of three trials.
Explain the sensation generated by the oscillations using words such as vibrations or fluttering. Ensure 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.
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. Cheek and floor of the mouth support is enforced to avoid upper airway shunt. If the cheeks in the soft tissue of the mouth are not supported, flow measured at the mouth is lost in the motion of the upper airway wall.
Explain to the patient that swallowing should be avoided and the tongue must be below the mouthpiece during the test. The instructions above apply to both children and adults. For adults with cognitive impairment, consider having an accompanying person nearby to coach and calm the patient to breathe normally.
For patients with physical impairment, some oscillometry devices are portable and can be brought to the patient's bedside or wheelchair. Also consider asking the accompanying person to provide cheek and jaw support during tests. Select new patient and enter the patient's information, such as first and last names, date of birth, birth sex, height, weight, ethnicity if applicable, and smoking history.
Check that all information entered is correct prior to selecting standard test. Ensure that the correct wavelength setup is selected. In this demonstration, airwave oscillometry is selected from the template dropdown menu.
The choice of specific wavelengths and wavelength combinations will be different amongst the different manufacturers. Follow the software instruction manual for your specific device. Ensure the appropriate set of reference values is selected.
The preferred and availability of reference values may differ depending on each laboratory's policy and oscillometry device manufacturer. Click on select patient and choose the correct patient's file by verifying the patient's information, such as first and last names and date of birth. Select standard test and choose airwave oscillometry from the template dropdown menu.
Step 4.1.3 in the protocol applies here as well. Attach a single patient use bacterial filter to the oscillometry device. Ensure the oscillometry device is ready in testing mode.
Remind the patient of the 30-second test duration and the minimum requirement of three measurements. Instruct the patient to wear a nose clip and provide instructions described in steps 3.2.4 and step 3.2.5 in the protocol. Adjust the oscillometry device to the patient's head level.
Instruct the patient to wet his or her lips before wrapping them around the mouthpiece to form a proper tight seal. Instruct the patient to begin to breathe normally. Inspect for potential air leaks around the mouthpiece and nose clip.
Observe the patient's breathing pattern and start recording following a minimum of three stable tidal breaths. During the test, inform the patient of the time remaining during each measurement. Provide adequate rest time in between each measurement and adjust accordingly based on the patient.
Following a minimum of three measurements, proceed to step six to assess acceptability and reproducibility. Administer bronchodilator via a spacer. Record the method and number of doses administered.
Wait for 10 minutes post-salbutamol or albuterol and 20 minutes post-ipratropium bromide inhalation. Repeat step 5.2 in the protocol to assess post-bronchodilator response. Remind the patient that each test duration is 30 seconds and a minimum of three measurements will be obtained.
Ensure the correct wavelength setup for intra breath measurement is selected. Repeat steps 5.2.2 to 5.2.6 in the protocol. Ensure measurements have a validity greater than 70%Check that the symbol beside the measurement has obtained a check mark.
If a caution simple is present, the measurement is unacceptable. Inspect each measurement for anomalies or artifacts that may be caused by coughing, tongue obstruction, glottis closure, air leakage around the mouthpiece, attempting to talk, and taking a deep breath. If the patient is observed taking a deep breath, reset the oscillometry device because forceful breaths disruptive motors and the quality of subsequent measurements.
To reset, stop testing and then click zero channels. Review measurements automatically excluded by the software. These include anomalies or artifacts such as cough or glottis closure.
Exclude any unacceptable measurement with anomalies outlined in step 6.1.3, and repeat step 5.2 in the protocol to obtain additional measurements. Ensure the minimum of three acceptable measurements are recorded. Ensure the coefficient of variance of resistance of respiratory system is less than or equal will do 10%in adults and less than are equal to 15%in children.
Repeat step 5.2 to obtain additional measurements. if the three acceptable measurements have a coefficient variance greater than 10%in adults and greater than 15%in children. Repeat step 6.1 in the protocol to determine acceptability and report three acceptable measurements.
Discard the patient's mouthpiece and nose clip into the waste bin. Use disinfectant wipes to clean the oscillometry device and patient's chair. Throw off gloves and sanitize hands.
Place the red dust cap back onto the oscillometry device to avoid any contamination. Shown he year is a standard template for reporting oscillometry. Include patient's first and last names, height, weight, age, birth sex, BMI, and smoking history.
Include the device name, model, software version, and manufacturer. Include input signal frequencies and duration of individual recordings. Report the mean of acceptable and reproducible measurements and the coefficient of variants for these reported measurements.
If the coefficient of variants is higher than the specified upper limit, the results should be flagged so that the interpreting physician may interpret the results with caution. Select reference equations. Include an impedance graph demonstrating RS and XRS versus oscillation frequency.
Include post-bronchodilator response with dosage and method of administration, including Z scores and absolute percentage changes. Perform regular audits, weekly or monthly, depending on the volume of oscillometry testing in the laboratory. Assess each operator using a standardized checklist to ensure oscillometry tests are conducted accurately and professionally.
Provide regular feedback to operators and hold quarterly quality assurance meetings to reflect on laboratory matters. Ensure biological calibrations are conducted weekly with at least two healthy non-smoking subjects, and measurements are within two standard deviations of their mean baseline. This is extremely important for validating testing equipment and procedures when there are multiple oscillometry devices in the laboratory.
Conduct quarterly self-inspection and annual factory maintenance of oscillometry devices for calibration and quality checks. From October 17th, 2017 to April 6th, 2018, we conducted the first quality assurance and quality control audit of 197 oscillometry tests. Although all of the operators were trained prior to testing patients with a one hour seminar and onsite testing, 10 unacceptable and/or reproducible measurements were identified.
In other words, 5.08%of the measurements were deemed unacceptable. At this point biological quality control, or bio QC, was not conducted regularly. The research personnel underwent additional oscillometry training and developed a standard operating protocol to ensure proper ERS guidelines and medical professionalism were in place.
The importance of bio QC, a tool to validate testing equipment and procedures, was highlighted to the research personnel, who were reminded to perform regular bio QC tests. Improvements were found in subsequent quality assurance and quality control audits. Of the 1, 930 oscillometry tests conducted from April 9th, 2018 to June 30th, 2019, only three, or 0.0016%of the tests, were invaLid measurements.
Between July 2nd, 2019 and March 12th, 2020, 1, 779 oscillometry tests were performed, and nine, or 0.005%of the tests, were considered unacceptable Refer to table one for additional information. This video outlined and demonstrated the standard operating protocol for the contact of respiratory oscillometry in the outpatient setting. We highlighted the key steps to ensuring acceptable and reproducible quality measurements according to the recommended European Respiratory Society, or the ERS guidelines.
Potential problems and pitfalls were also discussed with suggestions to resolve technical errors.