ATS Pulmonary Function Laboratory Manual

chapter  10

8.

If clinically acceptable, supplemental O 2 this cannot be done safely, O 2

should be discontinued for 10 minutes before beginning the test. If should be adjusted appropriately and recorded so that the results can be inter-

preted accordingly.

9. The patient’s race or ethnicity should be determined from questioning the patient. While not currently included in published reference equations (which are usually based on Caucasian populations), it can be useful for interpretive purposes. Assessment of Patients 1. Assess each patient for physical and developmental status to determine ability to perform the diagnostic test and if special arrangements are required. If there is a language barrier, an interpreter will be used. 2. Patients should be asked if they have complied with the preparation criteria including: 2.1. If they have recently smoked, and if so, what was the time? 2.2. If they have consumed alcohol within 4 hours of test starting time. 2.3. If they have eaten within 2 hours of test starting time. 2.4. If they have exercised within an hour of test starting time. 3. Postponement may be necessary if the patient has not complied with the preparation criteria. The ordering physician is to be contacted to determine if rescheduling is necessary. 4. In order to properly interpret the test results, relevant clinical information should be provided in writing by the ordering physician (i.e., diagnosis and type of treatment). A recent measurement of hemoglobin concen- tration should also be obtained. Information on use of respiratory medications in the past 24 hours should also be noted. If the Dl CO is measured following the administration of bronchodilators for spirometry test- ing, this should be noted as well. Special safety precautions The following may pose a relative danger to the patient and/or affect the validity of the test: 1. More than five maneuvers will likely increase the COHb level by approximately 3.5% (10), which in turn will likely decrease the Dl CO value by approximately 3–3.5%, and is not recommended (7). 2. A large meal or vigorous exercise immediately before the test (unless using exercise to assess Dl CO “recruita- bility”). 3. Mental confusion or poor muscular coordination that prevent the patient from adequately performing the maneuver or the inability to adequately seal their lips on the instrument mouthpiece. Equipment Preparation and Calibration Checks 1. Preparation 1.1. Ensure CO 2 and H 2 O absorbers (if applicable) are replaced at a frequency recommended by the manu- facturer, when saturated (as indicated by color change), or sooner. Additionally, they should be placed in the proper order (i.e., the CO 2 absorber should precede H 2 O absorber). If selectively permeable tub- ing is used, ensure it has been replaced at appropriate intervals as recommended by the manufacturer. 1.2. Turn on the equipment to ensure adequate warm-up time, usually at least 30 minutes. 1.3. For Dl CO systems using a volume-type spirometer, a leak test of the spirometer should be done accord- ing to the manufacturer’s specifications.

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