ATS Pulmonary Function Laboratory Manual

chapter  19

1.2. Pulmonary function tests, blood gas data, chest radiograph, blood chemistry results, etc. 1.3. Current symptoms including chest pain, discomfort, or wheezing 1.4. The patient’s usual exercise program, exercise limitations and activities of daily living 2. Assess each patient for physical and development status to determine ability to perform the diagnostic procedure. Postponement may be necessary if the patient has not complied with the preparation criteria. Contact the ordering physician to determine if rescheduling is necessary. 3. If there is a language barrier an interpreter should be used. 4. Ask each patient if he/she complied with the preparation procedures. 4.1. Time of the last meal 4.2. Medication was taken as instructed 4.3. If they exercised recently Quality Control A quality control program starts with routine equipment calibration and maintenance, with appropriate documen- tation. In addition, a biological control program is highly recommended to both document the accuracy of equip- ment and early detection of problems. 1. Biologic controls (BioQC; one or two healthy, non-smoking laboratory personnel) 1.1. Obtain consent to repeated testing. 1.2. Test weekly (or at least monthly) depending on the volume of testing performed (30, 31). 1.3. The biologic standards should initially perform a maximal study, then use 40 to 50% of the maxi- mum workload as their steady-state work rate. As long as the subject is in a steady state, ˙ V o 2 and other parameters should be reproducible. 1.4. For the steady-state tests, collect gas exchange and work intensity data on each biologic control as 6 minutes of constant work rate is performed. 1.5. If the ˙ V o 2 or ˙ V co 2 value obtained by averaging the last 2 minutes of the 6-minute test are outside the 95% confidence limits (i.e., mean ±1.96 × SD) for a historical average for a particular biologic control, repeat the test or use another biologic control. Another approach for the limits of variation have been reported by the AHA (22) and are:

O 2

uptake

±5.0% ±6.0% ±5.5% ±3.0%

output

CO 2

Minute ventilation

RER

1.6. Take corrective action if the repeat values or other biologic control’s values are also outside the 95% confidence limits, and repeat the test of the biologic standard to verify adequacy of the corrective procedure. 1.7. Add data to the quality control database only after the system is again performing properly. Recalcu- late averages and SD to obtain updated values for the 95% confidence limits. 1.8. The time of day used to test the biologic control should be consistent from session to session. 1.9. These procedures test the reproducibility, but not the accuracy of the gas exchange measurements.

217