IN THE NAME OF GOD

1. IN THE NAME OF GOD SPIROMETRY UPDATE

2. ATS 1994 Update • Areas pertinent to occupational pulmonary function testing • Critical role of technician in obtaining accurate results. • Recommended changes in testing procedure. • Equipment validation. • Quality control • Infection control and hygiene concerns

3. Spirometric testing

4. Lung Volumes and Capacities • Pulmonary volumes are measured • Pulmonary capacities are calculated

6. INDICATIONS FOR SPIROMETRY

7. Indications • Primary prevention • Pre-placement and fitness-for-duty examinations • Physical demands of a job (heavy manual labor, fire fighting); • Characteristics of respiratory use (prolonged use of negative-pressure mask under conditions of heavy physical exertion and/or heat stress - not required by OSHA); • Research and monitoring of health status in groups of workers.

8. Indications • Secondary prevention • Medical surveillance programs – workers at risk of developing occupationally related respiratory disorders • Baseline and periodic evaluations • Mandated OSHA regulations (asbestos, cadmium, coke oven emissions or cotton dust) • Local mandated medical surveillance program • Component of workplace health promotion program

9. Indications • Tertiary prevention • Clinical evaluation of symptomatic individuals • Restrictive • Obstructive • Combined ventilatory defects • Disability under Social Security Administration • Federal Coal Mine Health and Safety Act • Workers’ compensation setting

11. Technician Training • From Preamble to OSHA Cotton Dust Standard, 1978: • “The key to reliable pulmonary function testing is the technician’s way of guiding the employee through a series of respiratory maneuvers; • The most important quality of a pulmonary function technician is the motivation to do the very best test on every employee;

12. Technician Training • The technician must also be able to judge the degree of effort and cooperation of the subject; • Test results obtained by a technician who lacks these skills are not only useless, but also convey false information which could be harmful to the employee.”

13. Quality Control • Technician needs to be aware of patient-related problems when performing FVC maneuvers • Submaximal effort • Leaks between lips and mouthpiece • Incomplete inspiration or expiration (prior to or during forced maneuvers) • Hesitation at start of the expiration

14. Quality Control • Cough ( particularly within the first second of expiration) • Glottis closure • Obstruction of mouthpiece by the tongue • Vocalization during forced maneuver • Poor posture

17. Problematic examples compared with well-performed maneuvers.

18. Quality Control • Errors that inflate test results • Poor testing technique • Extra breath through nose • Slight submaximal expiratory effort • Accept/save curve with large hesitation, even when flagged by spirometer • Flow-type spirometer malfunctions during subject test • Inaccurate zeroing of sensor (performed before each expiration; or • Sensor characteristic change between expirations due to warming, deposition of mucous, or condensation of water vapor.

19. Problematic examples compared with well-performed maneuvers.

22. Quality Control • Error that reduce test results • Leaks in volume spirometer or breathing tubes • Reduce FVCs significantly but are not visible in spirograms until leak is very large • Checking for leaks at least daily in the calibrations check is essential

24. Quality Control • Hygiene and Infection Control • Recommendation: • Direct contact • Potential for transmission of URI, enteric infections, and blood borne infections; • Most likely surface for contact are mouthpieces and immediate proximal surface of valves or tubing.

25. Quality Control • Recommendation: • Indirect contact • Potential for transmission of TB, various viral infections, and possible opportunistic infections and nosocomial pneumonia; • Possible contamination of mouthpieces and proximal valves and tubing.

26. Quality Control • Prevention • Proper hand washing and/or use of barrier device. • Use of disposable mouthpieces, nose clips, etc. • Spirometers using close circuit technique should be flushed at least five time over entire volume range. • Provide proper attention to environmental engineering control where TB or other diseases are spread by droplet nuclei might be encountered.

27. Quality Control • Prevention • Take special precaution when testing patients with hemoptysis, open sores on oral mucosa, or bleeding gums. • Extra precautions with know transmissible infectious diseases. • Regular use of in-line filters (not mandated). • Manufacturers encouraged to design instrumentation that can be easily disassembled for disinfection.

28. Quality Control • Equipment quality control • Volume • Must be checked at least daily with a 3-liter calibrated syringe. • Syringe accuracy • Calibration syringe must have an accuracy of at least 15 ml or at least 0.5% of full scale (15 ml for a 3-liter syringe. • Leak test • Volumetric spirometry systems must be checked daily.

29. Quality Control • Equipment quality control • Linearity • Volume spirometers must have their calibration checked over the entire volume range quarterly (in one liter increments). • Time • Assessing mechanical recorder time scale accuracy with a stopwatch must be performed at least quarterly. • Other QA procedures • Calibration with physical standard (practice of using laboratory personnel as “known subjects”) • Adhere to ATS recommendations for computer software for spirometers.

30. Quality Control • Equipment Quality Control

31. Spirometry Parameters

32. Spirometry Parameters • Forced Vital Capacity • FVC • Forced Expiratory Volume in One Second • FEV1 • Forced Expiratory Volume in One Second Expressed as a Percentage of the Forced Vital Capacity • FEV1/FVC % • Mean Forced Expiratory Flow during the Middle Half of the Forced Vital Capacity • FEF 25-75%

33. FVC • Definition: • Defined as the maximal amount of air that can be exhaled forcefully after a maximal inspiration or the most air a person can blow out after taking the deepest possible breath.

34. FVC - forced vital capacity • defines maximum volume of exchangeable air in lung (vital capacity) • forced expiratory breathing maneuver • requires muscular effort and some patient training • initial (healthy) FVC values approx 4 liters • slowly diminishes with normal aging • significantly reduced FVC suggests damage to lung parenchyma • restrictive lung disease (fibrosis) • loss of functional alveolar tissue (atelectasis) • FVC volume reduction trend over time (years) is key indicator • intra-subject variability factors • age • sex • height • ethnicity

35. FVC • End of Test Criteria • The volume time curve show an obvious plateau • Plateau defined as no change in volume for at least one second. • Subject cannot or should not continue further exhalation. • The forced expiration is of reasonable duration.

37. PEF

38. FEV1 • Definition: • The volume of air exhaled during the first second of a forced expiratory maneuver. • normal FEV1 about 3 liters • FEV1 needs to be normalized to individual’s vital capacity (FVC)

39. FEV1 • Steps for determination of the FEV1: • Determine Time Zero using the back extrapolation technique; • Measure over one second from Time Zero; • Draw a straight line up from the point where Time = one second and the point where the straight line intersects is the FEV1.

41. PEF

42. FEV1/FVC% • Definition: • The value expresses the volume of air the worker exhales in one second as a percent of the total volume of air that is exhaled. • Calculated by using largest valid FEV1 and largest FVC even if they are not from the same tracing. • Find largest valid FEV1 • Find largest valid FVC • Divide FEV1 by FVC • Multiply by 100 to obtain percentage.

43. FEF25-75% • Definition: • The mean expiratory flow during the middle half of the FVC • More sensitive than FEV1. • Considerably more variability than FVC and FEV1. • ATS recommends only be considered after determining presence and clinical severity of impairment and should not be used to diagnosis disease in individual patients

44. PEF - Peak Expiratory Flow rate • measures airflow limitations in large (central) airways • large airways are rate-limiting for airflow in healthy patients • large airway flow limitations important in asthma • PEF measurements recommended for asthma management • spirometry is recommended to help make the diagnosis of asthma • PEF not recommend to evaluate patients for COPD • cannot measure small airway airflow limitations • advantages of PEF tests • measurements within a minute (three short breaths) • uses simple, safe, hand-held devices that typical, costs $20 • disadvantages of PEF tests (compared to spirometry) • insensitive to obstruction of small airways (mild or early obstruction) • PEF is very dependent on patient effort (large intra-subject variability) • mechanical PEF meters are much less accurate than spirometers

45. BTPS • Definition: • Gas (air) at: • Body Temperature (37°C) • Ambient Pressure (surrounding air pressure) • Saturated with water vapor (relative humidity = 100% as is the case in the lungs)

46. BTPS • Spirometric test requiring conversion to BTPS • FEV1, FVC, and FEF25-75% all represent volume (volume per unit of time) – must be converted to BTPS. • FEV1/FVC% is ratio of volumes – doesnot have to be converted.

47. Points to remember: Temperature Ambient temperatures should be recorded to within 1°C. Spirometric testing should only be done with ambient temperatures between 17° - 40°C. BTPS

48. Reproducibility (Variability) • ATS recommends obtaining three (3) valid tracings with reproducible FVC’s and FEV1. • The two largest valid FVC’s are examined to determine there is no more than a .2 liter (200 ml) difference between them. • The two largest valid FEV1 are examined to determine there is no more than a .2 liter (200 ml) difference between them.

50. Points to Remember • FVC • Convert answer to BTPS when needed. • FEV1 • Excessive variability and extrapolated volume must be calculated to determine if additional maneuvers are needed. • Convert to BTPS when needed. • FEV1 and FVC • Always use largest volume from an acceptable tracing to ensure maximal results.