ATS Pulmonary Function Laboratory Manual

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

Equipment Preparation and Calibration Check (Verification) 1. Preparation 1.1. All components should be assembled according to the manufacturer’s instructions (i.e., tubing, connectors, flow-sensors, valves, and adapters). 1.2. A new in-line bacteria filter (if used), disposable mouthpiece, or disinfected reusable mouthpiece should be in place; a clean or new flow-sensor should be used (for some flow-based spirometers). 1.3. Turn on the system to ensure adequate warm-up. 1.4. Perform diagnostic spirometry only at ambient temperatures between 17 and 40° C (temperatures outside this range may cause problems for both volume-based and flow-based spirometers). 1.5. Volume-displacement spirometers should be checked for leaks each day of use (6) (application of at least 3 cm H 2 O to the system with the outlet occluded should result in a volume change of less than 30 ml/min). Leaks are the most commonly detected problem in volume-displacement spirometers. 1.6. Flow-sensors should be checked for holes in the sensor, clogging, channel plugging, or excess mois- ture. Care must be taken when “zeroing” a flow-sensing spirometer as zero errors, typically caused by sensor motion or inadvertent air movement, can cause falsely elevated or reduced volumes. 1.7. Environmental data (i.e., internal spirometer temperature or ambient temperature, relative humid- ity [if applicable] and PB) from an accurate source representative of the laboratory should be entered before calibration checks. A 3-L syringe should be used for calibration checks of spirometers; the syringe should have an accuracy of ±15 ml or ±0.5% of full scale (15 ml for a 3-L syringe), whichever is greater (6). The syringe should be checked at least annually to include a leak check and, if appropriate, to ensure the adjustable stop has not moved. A dropped or damaged syringe should be considered out of calibration until it is checked. 2.2. Calibration checks (verification) should be performed at least once for each day of testing; for large- screening surveys or other situations in which a large number of tests are performed, calibration checks (verification) should be repeated more frequently. 2.3. Calibration checks should produce a measured value within 3.5% of the syringe volume (i.e., ±0.105 L for a 3-L syringe). Flow-sensing spirometers that measure flow at the mouth may require separate correction factors for inspiratory and expiratory volumes. 2.4. For flow-based spirometers, the 3-L syringe should be discharged at least three times to give a range of flows varying between 0.5 and 12 L/sec (injections of < 1sec, 3 sec, and 6 sec). The volume achieved at each of these flows should meet the accuracy requirement of ±3.5%. For devices with dis- posable flow sensors a new and different sensor, taken from those that might be used for patient tests, should be tested each day. 2.5. The calibration syringe should be maintained at the same temperature and humidity as the spirom- eter (6). 2.6. Spirometers that do not require calibration still need routine accuracy checks. 2. Calibration Check (verification) 2.1.

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