ATS Pulmonary Function Laboratory Manual

ATS Pulmonary Function Laboratory Management & Procedure Manual | 3rd Edition

Test Procedure

Step Action 1.

Explain and demonstrate the procedure to the patient. Emphasize the following: a. The importance of relaxing and breathing “normally” between measurements b. The need to “pant” while supporting the cheeks with the fingertips. The panting maneuver (during open and closed shutter) requires that the breaths are: • Small ( ≃ 50 to 100 ml)

• Slow (Raw ≃ 1.5 to 2.0 breaths/s) • Uniform (equal volume in and out)

Use descriptive phrases such as • Open shutter: panting like a “little piston,” or “like a dog” • Closed shutter: “like panting with your hand over your mouth”

Reassure the patient constantly, to reduce anxiety associated with the test or from sitting in the closed booth, emphasizing that the test should take less than 5 minutes. If the patient desires, the test can be stopped at any time and the door opened to allow him/her to relax before subsequent measurements are made. The door may be released from the inside at any time (manufacturer specific). Assure the communication device is operational (manufacturer specific). Close the plethysmograph door and allow thermal equilibration. Observe the plenum (or similar device) to assure thermal equilibration (4). 2. Instruct the patient to insert the mouthpiece into the mouth, assuring the tongue and/or teeth are not blocking the mouthpiece port. Have the patient apply the nose clip on the nose, support the cheeks using the fingertips, and relax the shoulders and breathe “normally.” 3. Activate the computer 4. Instruct the patient to begin panting small ( ≃ 50 to 100 ml/pant), uniform pants and at a frequency between 1.5 and 2.0 breaths/s. Open-shutter loops should be closed (or nearly so), and linear (non-elliptical), par- ticularly within the range of +0.5 to -0.5 L/s ( see Figures 9.3–9.5). The entire tracing should be visible and within the calibrated pressure range. Once two to three acceptable open-shutter loops have been collected, close the mouth shutter and instruct the patient to continue panting. The displayed Pao/Pbox loop should be closed or nearly so. Acceptable pressure changes should be within the calibrated pressure range of each transducer. The entire tracing should be visible. Pressure changes that are too large or too small may yield erroneous results. During closed-shutter loop data collection, the shutter should be closed for only a brief period of time (e.g., ≃ 2 seconds) as longer time may cause undue patient discomfort. 5. Repeat open- and closed-shutter panting maneuvers until four or five technically acceptable tests are obtained. Assure the patient returns to tidal breathing between maneuver performance. Discourage deep inspiration as lung inflation could provide a bronchodilatory or bronchoconstrictive effect. Encourage patient’s performance during each attempt, offering suggestions on how to improve on subsequent maneuvers (e.g., “slow the panting frequency,” “pant using smaller volumes,” “do the same on the next attempt”). Ask the patient if he/she is able to continue or does he/she need a rest period. 6. Visually inspect each maneuver to ensure it meets acceptability criteria, there was no evidence of thermal drift and the panting frequencies were similar. Some individual’s Raw values get worse at higher pant- ing frequencies, possibly because of uneven time constants within the airways (“frequency dependence of resistance”) (13) If serial measurements are to be performed, the panting frequency should be kept the same to aid in the interpretation (4). 7. Adjust computer measured open- and closed-shutter slopes, if necessary.

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