Spirometry in Occupational Health—2020

Home , Exhalation, Mucus, Spirometry

7 8 . as well as 5 and in 2016, the 12 Fourth, OSHA promul- 9 Fifth, in 2014, the US Effective July 15, 2019, 1 and explanation of an error 6 10,11 13,14 and on Standardized Pulmonary 2 However, since these statements Volume 62, Number 5, May 2020 2020 Topics — 2020 made in the 2005 Spirometry Statement. OSHA updated the(29 Cotton CFR Dust 1910.1043), the Standard tion landmark regula- in which OSHA first specified how Second, the USHealth Occupational Administration Safety (OSHA)Best and issued Practices its Testing Guidance in Occupational Health on Programs Third, Spirometry the ATSStandards issued Official on Technical Testing Occupational Spirometry a correction, National Institute forand Occupational Health Safety (NIOSH) began approvingics clin- to test coalWorker miners as Health part(CWHSP). of the Surveillance Coal Program 1926.1153) and forCFR general 1910.1053) industry and1915.1053). (29 maritime (29 CFR gated theStandards Respirable for Crystalline Silica construction (29 CFR were published, there haveof been developments a which affect number occupational spirometry testing.Thoracic First, Society (ATS) and theRespiratory the Society American European (ERS) issuedcial an Technical Offi- Statementtion of on Spirometry 2019 Standardiza- Update, Function Reports. Mine Safetyadded and spirometry Health tosurveillance Administration coal exams, miner medical — JOEM or elevated TATEMENT S 1,3,4 UIDANCE Spirometry in Occupational Health If uncorrected, these problems , Forced Expiratory Volume in One Second; LLN, Lower Limit of Normal; A, Quality Assurance. 1 Physicians and other health care pro- Recognizing the central role of spi- Mary C. Townsend, DrPH FEV (a) Spirometry Testing Quality(b) and Frequency Test and Variability Duration(c) of Determination Testing of Abnormally Reduced or Highly Variable FEV (a) Spirometer Specifications and(b) Validation Spirometer Testing Accuracy Recommendations Checks (c) Avoid Sensor Errors during Subject Tests (a) Technician Training (b) Conducting the Test (c) Testing Goal for(d) a Reporting Valid Results Test (e) Quality Assurance (QA) Reviews (a) Reference Values (b) Race-Adjustment of Predicted(c) Values Interpretation and Algorithm LLNs test results. Whatever their level ofment involve- in the actual testing,need spirometry users to befrom aware many that othersince spirometry medical it differs measurements dependsits results on to multipleflawed, be equipment factors is valid. not for Ifnicians accurate, subject or fail tech- effort toand is elicit effort, results maximal can be cooperation falsely testing maypresence also of beworkers. impairment used Used for in to both screeningcal and symptomatic assess clini- evaluations, the spirometryformed in tests a variety are ofsmall per- venues ranging clinical from facilities practices and multiple plant to medical depart- ments large within an testing industry. fessionals maythemselves, conduct supervise spirometrythe tests others tests, or be conducting involved only in interpreting the American College of OccupationalEnvironmental Medicine and (ACOEM) developed three spirometryin position the statements past twoadvances decades, of particular which relevance summarize totional occupa- health practice. reduced. may profoundly impactare conclusions drawn that function about with aquences potentially worker’s for adverse workers pulmonary (Table conse- 1). rometry in workplace respiratory programs, 3. Comparing Results with Reference Values 4. Longitudinal Interpretation 5. Further Evaluation of6. Spirometric Recordkeeping Abnormalities TABLE 1. 1. Equipment Performance 2. Conducting Tests ACOEM G Spirometry in Occupational Health The primary aim of 1,2 2020 American College of Occupa- ß pirometry, theformed most frequently pulmonary per- function test Elk Grove Village, IL 60007 ([email protected]). its documents to discloseing any potential interests, compet- whichACOEM are carefully emphasizesexpressed considered. herein that representevidence at the the the bestbe time considered available the of judgments positionthe publication of individual ACOEM and opinions and of shall contributing not authors. ACOEM, 25 Northwest Point Blvd, Suite 700, Environmental Medicine, Elk Grove, Illinois. under the auspices ofAdvisors. It the was Council reviewed of byPolicy, the Scientific Procedures, Committee on andapproved Public by Positions, theACOEM ACOEM and requires all Board substantive of contributors to Directors. tional and Environmental Medicine e208 spirometry testing changes into its recommendations to provide current informationof for all spirometry users test results,form from or those who superviseinterpret per- or testing review results. to those who only S decades, which summarized advancesular of partic- relevance toHowever, occupational since these health statements were practice. published, there have been important developmentseral in regulations fed- andracic in official Society American Tho- occupational recommendations which spirometryACOEM affect guidance testing. statement incorporates This these 2020 Spirometry in theplays occupational a critical healthand role tertiary setting prevention in of workplace-related the lung disease. primary, Recognizing secondary, the central roleetry of spirom- inAmerican workplace College of Occupational respiratory andmental Environ- programs, Medicine (ACOEM) developed three the spirometry position statements in the past two possible disease.of Consistency testing techniques, equipment, over andpretation inter- time approaches are essentialpational in occu- testingevaluated since over workersTesting are decades is often of requiredbased employment. by on some employee work regulations exposures and workplace spirometry is to identify workers who should have further evaluation for (PFT), is therespiratory cornerstone of evaluation occupational occupational programs. health Inplays a the setting, critical role inary, spirometry the and primary, tertiary second- preventionrelated lung of disease. workplace- Copyright The author declares noAddress conflicts correspondence of interest. to: Marianne Dreger, MA, From the American College ofThis Occupational and position paper was developed by ACOEM DOI: 10.1097/JOM.0000000000001851 Copyright © 2020 American College of Occupational and Environmental Medicine. Unauthorized reproduction of this article is prohibited Copyright © 2020 American College of Occupational and Environmental Medicine.

Downloaded from https://journals.lww.com/joem by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3JfJeJsayAVVA0tuPeWF8+fcCByaszlArA0/85mOoxJ79CzoKGQxNkw== on 05/27/2020 Downloaded from https://journals.lww.com/joem by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3JfJeJsayAVVA0tuPeWF8+fcCByaszlArA0/85mOoxJ79CzoKGQxNkw== on 05/27/2020 JOEM Volume 62, Number 5, May 2020 Spirometry in Occupational Health—2020

TABLE 2. Major Spirometry Developments Since Publication of ACOEM’s 2011 Statement4

1. Effective July 15, 2019, OSHA updated the Cotton Dust Standard (29 CFR 1910.1043), the landmark regulation in which OSHA first specified how occupational spirometry testing must be conducted.15 2. OSHA issued Best Practice Guidance for Occupational Spirometry Testing.8 3. NIOSH-approved spirometry courses for technicians are required by the Cotton Dust Standard,15 Respirable Crystalline Silica Standards,10,11 and the NIOSH Coal Worker Health Surveillance Program (CWHSP),13 and recommended by OSHA Guidance.8 4. NIOSH maintains a list of spirometers approved for use in the CWHSP.17 5. NIOSH released spirometry training videos.18 6. OSHA and NIOSH promulgate record-keeping requirements,10,13,15,16 and ATS and OSHA make record-keeping recommendations.2,8 7. ATS/ERS states that ‘‘There is no requirement for minimum FET’’ (length of exhalation).5 Subjects who are young, have small thoracic cavities, or have restrictive impairment often have spirometry maneuvers with plateaus and repeatable results, but with exhalation times less than 6 s.5,6,8,9 Such maneuvers are now recognized as acceptable and can be used to meet requirements for a valid test. 8. ATS/ERS confirms that the occupational spirometry testing protocol which records only maximal expiration meets the requirements of the 2019 Update of the ATS/ERS Spirometry Standards.19-21 This permits occupational settings to maintain essential consistency in their testing procedures over time. 9. ATS/ERS confirms that for occupational spirometry testing in the United States, the use of the NHANES III22 spirometry reference values is in full compliance with the 2019 Update of the ATS/ERS Spirometry Standards.19-21 Since consistency over time is essential, NHANES III remains the required or recommended reference value set for occupational testing in the United States.2,8,9,15 22 10. A 0.88 scaling factor, applied to NHANES III Caucasian reference values for FVC and FEV1, is recommended or required when testing Asian- 2,8,15 American workers. However, the Caucasian FEV1/FVC reference values are not adjusted. 11. Spirometry abnormality is assessed using the 5th percentile LLN, but values close to the LLN should be interpreted with caution.9 12. Especially for workers with initial FEV1 above 100% of predicted, longitudinal evaluation of FEV1 can be used as a tool to determine whether more evaluation for possible disease is indicated.2 13. ATS recommends further medical evaluation steps when screening abnormalities are found.2

ACOEM, American College of Occupational and Environmental Medicine; ATS, American Thoracic Society; CWHSP, Coal Worker Health Surveillance Program; ERS, European Respiratory Society; nnnnnnnnnn Occupational Safety and Health Administration; LLN, Lower Limit of Normal; NHANES III, National Health and Nutrition Examination Study, Round III; NIOSH, National Institute for Occupational Safety and Health.

occupational spirometry testing must be comprehensive current information for all Major recommendations are summarized conducted.15 And finally, OSHA has issued users of spirometry test results, from those at the end of the document in ACOEM a Letter of Interpretation regarding respon- who perform or supervise testing to those Recommendations—2020. To assist read- sibility for maintaining medical records who only interpret or review results. The ers in understanding the material, particu- under the Silica and Respiratory Protection document allows those with specific inter- larly in sections on Equipment Performance Standards.16 Table 2 summarizes these ests to review those sections that are rele- and Conducting Tests, Fig. 1 presents a major developments since publication of vant to them. As shown in Table 1, six spirogram from a valid test, to compare the last ACOEM spirometry statement major topics are covered in this statement: with the flawed test results shown in in 2011. (1) Equipment Performance; (2) Conduct- Figs. 2 and 3, as discussed below. ACOEM has developed this 2020 ing Tests; (3) Comparing Results with Ref- statement to incorporate these spirometry erence Values; (4) Evaluating Results over EQUIPMENT PERFORMANCE testing changes into its recommendations. Time; (5) Further Evaluation of Spirometric Four elements contribute to accurate The goal of this statement is to provide Abnormalities; and (6) Recordkeeping. spirometer performance: (1) ATS/ERS5,7

FIGURE 1. Valid test. Flow-volume curve (left) emphasizes start of test, rising immediately to a sharp peak and smoothly descending to zero flow. Volume-time curve (right) emphasizes end of test, initially rising rapidly, and then gradually flattening out and reaching 1 second of no visible volume change, at the FVC plateau. To permit effective subject coaching, ATS/ERS recommends using spirometers that show both graphical displays real-time and of sufficient size to clearly reveal technical errors.5,7

ß 2020 American College of Occupational and Environmental Medicine e209

FIGURE 2. (A). Sensor contaminated or blocked by condensation, mucus, or fingers. DISCARD THIS CURVE. The last curve (#8) shows the impact of blockage or contamination of the sensor after the 7th maneuver was recorded. The FVC and FEV1 values are falsely increased on curve #8, exceeding values from the earlier maneuvers (curves #1 and #7) by more than 0.40 L. Technicians must replace the sensor if it becomes contaminated during the test. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8 FIGURE 2. (B) Error: Inconsistent Zero-Flow Errors Causing Flows to be Over-Recorded. DELETE THIS TEST. This spirometer’s zero-flow reference point was set at different incorrect levels before the first two maneuvers, causing the volume-time curves (bottom figure) to be splayed apart and extended tails to be drawn to the right on the flow-volume curves (top figure). FVC is increased more than FEV1, falsely reducing the FEV1/FVC and probably leading to an erroneous ‘‘obstructive impairment’’ pattern. Block sensor when the spirometer is zeroed and hold sensor still during subject testing to avoid this problem. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8

e210 ß 2020 American College of Occupational and Environmental Medicine

Copyright © 2020 American College of Occupational and Environmental Medicine. Unauthorized reproduction of this article is prohibited JOEM Volume 62, Number 5, May 2020 Spirometry in Occupational Health—2020

FIGURE 2. (C) Error: Zero-Flow Error Causing Flows to be Under-Recorded. DELETE THIS TEST. FVC is much more reduced than FEV1, falsely increasing the FEV1/FVC and possibly masking true airways obstruction. Block the sensor when the spirometer is zeroed and hold sensor still during subject testing to avoid this problem. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8 FIGURE 2. (D) Error: Consistent Zero-Flow Error Causing Flows to be Over-Recorded (left). DELETE THIS TEST. This spirometer’s zero-flow reference point was set only once per test, before a complete set of maneuvers. The test on the left shows a zero-flow error, while the test on the right shows valid results; both tests were recorded by the same subject. The zero-flow error on the left produced erroneous but consistent results for all maneuvers, elevating the FVC more than the FEV1 and falsely reducing the FEV1/FVC. This zero-flow error may erroneously indicate an ‘‘obstructive impairment’’ pattern. Consistency of the flawed curves on the left may make this error difficult to detect, but technicians should watch out for extended tails that are drawn to the right on the flow-volume curves (top figure), and volume- time curves that climb at a constant rate without reaching a plateau, until the spirometer terminates data collection (bottom figure). Block the sensor when the spirometer is zeroed and hold sensor still during subject testing to avoid this problem. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8 OSHA; Occupational Safety and Health Administration.

ß 2020 American College of Occupational and Environmental Medicine e211

FIGURE 3. (A) Error: Excessive Hesitation (solid curves). Discard this curve. Because the worker’s initial blast is delayed, the peak of the flow-volume curve (top figure) is displaced to the right, and a gradually climbing tail is seen at the start of the volume-time curve (bottom figure). Coach the worker: ‘‘blast out as soon as you are ready.’’ Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8

and ISO23 recommend minimum perfor- of coal miners, NIOSH evaluated documen- coal mining workforce and periodically mance-based standards for spirometers of tation submitted by manufacturers for inclu- throughout the miner’s coal mining career. all types; (2) prototype spirometers and sion in its CWHSP. As discussed below, NIOSH approves facilities to test miners their software should undergo validation though the list of spirometers approved by and has established requirements for testing, preferably by an independent test- NIOSH for their CWHSP is not exhaustive the spirometers used at these facilities. ing laboratory, to demonstrate they meet and includes some program-specific require- Spirometers used in NIOSH-approved clin- these specifications5,7; (3) spirometer users ments, it does provide some possible con- ics must17: should perform daily accuracy checks (ie, crete guidance for spirometer selection by ‘‘calibration checks’’) of the spirometer so clinics for whom no specific recommenda- 1. Comply with ATS performance stand- that defective spirometers can be removed tions have been available previously. NIOSH ards for accuracy and precision and from service until they are repaired5,7; and requires that spirometers used in its CWHSP real-time display size.7 (4) if sensor errors develop during subject meet the criteria listed below, as presented in 2. Meet NIOSH requirements for the con- testing, users need to recognize the errors an online NIOSH table of spirometers tent of spirometry test reports. and delete the resulting invalid tests even if approved for CWHSP.17 3. Produce output data in standardized not labeled as errors by the spirometer’s ATS/ERS, ACOEM, and OSHA rec- electronic spirometry data file format software.5,24 ommend that facilities performing occupa- which allows NIOSH to reconstruct Though these elements of accurate tional spirometry tests maintain a procedure individual spirometry curves for quality spirometer performance have not changed manual documenting the details of equip- review of the coal miner spirometry test. significantly since 2011, increasing atten- ment type, spirometer configuration, manu- Though the third item is specific to tion has been paid to their implementation. facturer’s guidelines, calibration log, NIOSH’s coal miner clinic requirements, The OSHA Guidance document endorses service and repair records, personnel train- meeting the first two criteria means that the these elements as best practice for assuring ing, and standard operating procedures.5,8 spirometer meets ATS/ERS recommenda- accurate equipment performance and Such a manual will permit troubleshooting tions, as recommended or required by presents a list of recommended features if problems with anomalous test results ACOEM4 and OSHA.8,10,15 Specifically, for newly purchased spirometers.8 In arise. NIOSH criteria include17: nonmandatory Appendix B, the OSHA Respirable Crystalline Silica Standards rec- Spirometer Specifications and 1. Obtaining written verification docu- ommend following these elements in occu- Validation Testing menting spirometer validation testing pational spirometry testing.10 But even Recommendations by a third-party laboratory. The letter though general comments about desirable ACOEM4 and OSHA8,10,15 recom- should be obtained from the spirometer spirometer properties are available, until mend or require selecting spirometers that manufacturer and indicates that a spi- now there has been little information about meet the ATS/ERS recommendations for rometer model prototype measured at specific manufacturers and models of spi- occupational testing.7 In addition, NIOSH least 21 of the 24 ATS waveforms with rometers that might be appropriate for the operates the CWHSP to conduct mandated acceptable accuracy and precision.7 In occupational health setting. surveillance of working US coal miners’ 2019, the ATS/ERS recommended As NIOSH developed requirements respiratory health. As part of CWHSP, spi- using ISO standard waveforms23 to for its clinics approved for spirometry testing rometry is performed upon entry into the evaluate spirometers.5

e212 ß 2020 American College of Occupational and Environmental Medicine

FIGURE 3. (B) Error: Cough in 1st Second (solid curves). DISCARD THIS CURVE. Because cough in the first second repeatedly interrupts the airflow early in the expiration, the flow-volume curve (top figure) clearly shows steep changes (interruptions) in the flow rate, while the volume-time curve (bottom figure) shows only subtle steps in the first second. A drink of water may solve this problem. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’OSHA3637- 2013.8 FIGURE 3. (C) Error: No Blast (solid curves). This worker failed to blast out initially, so the expiratory speed was never rapid. The flow-volume curve (top figure) is very small and has no sharp peak, and the volume-time curve (bottom figure) shows a slanted start of expiration. Such a weak push reduces the FEV1 and FEV1/FVC, and may be caused by the worker trying to ‘‘save’’ air so that they can exhale for many seconds. This error causes false spirometer interpretations of ‘‘obstructive impairment.’’ Coach ‘‘blast out hard and fast’’ to solve this problem. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8

2. The spirometry system has a dedicated 4. The spirometer software automatically 5. The spirometer can: (a) store values from calibration check routine consistent performs quality assurance checks on at least eight maneuvers within one testing with the 2005 ATS/ERS recommenda- expiratory maneuvers during each spi- session; and (b) the spirometry software tions.2,5,7,8 rometry test.2,5,9 ‘‘However, technicians can save and recall curves and results from 3. Graphical displays meeting a minimum should be trained not to rely exclusively at least three acceptable maneuvers and size requirement provide real-time vol- on these quality-control prompts, since preferably from all curves.8,9 ume-time and flow-volume curves dur- technical errors may occur that are not 6. The spirometry data file retains results ing the test to enhance technician among those recognized by the soft- for all parameters defined in the coaching.4,5,7,8 ware.’’25 2005 ATS/ERS recommendations.7

ß 2020 American College of Occupational and Environmental Medicine e213

FIGURE 3. (D) Error: Sub maximal Inspiration (solid curves). The solid volume-time curve (bottom figure) resulted from a worker failing to inhale maximally before the forced expiration. The solid curve is considerably lower than the dashed curve that was drawn when the worker inhaled maximally before the forced exhalation, and this very low curve is not ‘‘acceptable.’’ An incomplete inspiration can give theappearanceofreducedFEV1 and FVC, and may cause false spirometer interpretations of ‘‘restrictive impairment.’’ Coach the worker: ‘‘fill your lungs.’’ Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637- 2013.8 FIGURE 3. (E) Error: Early Termination (solid curves). When expiration stops before the volume-time curve flattens into a 1- second plateau, the FVC may not be fully recorded. The solid lines show expirations for a subject with airways obstruction who terminated the exhalations early. Such incomplete recordings falsely increase the FEV1/FVC and may cause the spirometer interpretation to be ‘‘normal’’ even when airways obstruction is present. The dashed line shows the increase in FVC that would have occurred with only 5 more seconds of expiration for this subject. The resulting higher FVC and the lower, more accurate FEV1/FVC would trigger a correct interpretation of ‘‘airways obstruction.’’(Note: though not shown here, subjects should try to exhale to a1-second plateau when possible. However, curves longer than 15 seconds should not be recorded.5) Coach ‘‘keep blowing until I tell you to stop.’’ Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8

e214 ß 2020 American College of Occupational and Environmental Medicine

FIGURE 3. (F) Acceptable Test for Young Worker with FVC Plateau. Because the subject recorded 1-second FVC plateaus and the curves are repeatable, the maneuvers are acceptable.5,6,9 Spirometer error messages about ‘‘early termination’’ or ‘‘unacceptable test’’ should be ignored. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.‘‘ OSHA 3637-2013.8 FIGURE 3. (G) Error: Extra Breath through the Nose at End of Test (solid curves). DISCARD THIS CURVE. At the end of the forced expiration, this worker inhaled additional air through the nose and quickly exhaled it into the spirometer mouthpiece. The flow-volume curve (top figure) shows multiple maneuvers and the volume-time curve (bottom figure) shows additional expirations in increasing steps at the end of the test. This error erroneously elevates the FVC, greatly reduces the FEV1/ FVC, and causes a false spirometer interpretation of ‘‘airways obstruction.’’ Solution: have the worker wear nose clips. 27 Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-2013.8 OSHA; Occupational Safety and Health Administration.

ß 2020 American College of Occupational and Environmental Medicine e215

accuracy, ie, performing ‘‘calibration TABLE 3. Daily Calibration Checks4,5,8 checks,’’ daily when spirometers are in Flow Spirometers: use. They also recommend saving calibra- 1. Inject 3 L of air at three different speeds (taking approximately 0.5 s, 3 s, and 6 s). tion records indefinitely and keeping a log 2. Verify that the recorded value is between 2.91 and 3.09 L at all three speeds (ie, 3% of 3.00 of technical problems found and solved, as L).5 well as all changes in protocol, computer Volume Spirometers: software, or equipment. As noted earlier, 1. Check that there are no leaks causing an air loss > 0.030 L/min (30 mL/min.). the purchase of spirometers with dedicated 2. Inject 3 L of air and verify that the recorded value is between 2.91 and 3.09 L (ie, 3.0% of 5 calibration check routines for use in the 3.00 L). occupational setting is recommended. And Quarterly checks of linearity are also needed for volume spirometers—see reference8 for details. Do not conduct spirometry tests if the spirometer fails any calibration checks, until the cause of supplementing calibration checks by using standard subjects as biological controls is failure is identified and corrected. 2,5 Adapted from ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare valuable. Professionals.’’ OSHA 3637-2013.8 Avoid Sensor Errors during OSHA; Occupational Safety and Health Administration. Subject Tests Even though a spirometer passes its check of calibration accuracy, subject test 7. For use in a NIOSH-approved CWHSP become inaccurate and repeatedly fail their results can be invalidated by equipment clinic, spirometers must provide elec- calibration checks, and there are no obvious errors occurring during subject tests.5,24 tronic transfer of spirometry data files mechanical causes for the inaccuracy, they Two errors that can occur during subject using a NIOSH-approved procedure for must be recalibrated by the manufacturer. testing using some flow-type spirometers the format, content, and data structure But some spirometers require recalibration are contamination or blockage of a spirom- specified by the 2005 ATS/ERS recom- 7 on a regular basis. In this case, the techni- eter sensor, and incorrect setting of the mendations. cian must carefully follow the manufac- zero-flow reference point. Items 1 to 5 have also been recom- turer’s instructions since the spirometer’s First, if a subject’s fingers, secre- mended or required by ACOEM4 and by 8,15 calibration factor will be reset by this pro- tions, or water vapor block or contaminate OSHA and an image made to scale of cedure. Once the spirometer is recalibrated, a flow-type spirometer’s sensor, increasing the minimum recommended display size is 4,8 technicians should then perform the cali- its resistance, the test results will be falsely available in Appendix A. An online bration checks listed in Table 3. Technicians increased and become invalid. The impact NIOSH table of spirometers approved for 17 should use spirometer software programs of this problem is seen by comparing a valid use in the CWHSP is available. Though designed for calibration checks whenever test (Fig. 1) with a test having sensor con- this list is not an exhaustive compilation of possible.8 tamination (Fig. 2A). Even though such spirometers that meet ATS recommenda- ACOEM, ATS,ATS/ERS, and OSHA contaminated sensor problems are not iden- tions, it may provide a useful starting point recommend saving these calibration check tified as errors by the spirometer, the tech- for clinics that need to purchase spirometers. records indefinitely.2,4,5,8 ‘‘Availability of nician needs to identify the error when it ACOEM recommends that spiro- such records permits later troubleshooting occurs and discard the erroneous curve meters used for all occupational spirometry of problematic spirometry test results, which immediately so that the results are not tests meet NIOSH criteria 1 to 5 above. is particularly important when conducting reported as the largest results from the Meeting these criteria will ensure that periodic spirometry testing.’’2 ATS also rec- test session. occupational spirometers comply with 5,7,8 ommends performing calibration checks Second, most flow-type spirometers the ATS/ERS recommendations. For when spirometry software is updated and set a zero-flow reference point before each NIOSH-approved clinics that test coal min- ‘‘supplement[ing] calibration checks by maneuver, or before each set of maneuvers. ers, criteria 1 to 5 are currently in place and 17 using standard subjects as biological con- All flows during a subject’s subsequent criteria 6 to 7 will soon be fully in place. trols.’’2,5 expiration(s) are measured relative to this ACOEM, ATS, and OSHA recom- reference point. The ‘‘zero’’ flow reference Spirometer Accuracy Checks mend or require checking spirometer baseline can be incorrect if: (1) a gravity- ATS/ERS,2,5,7 ACOEM,4 OSHA,8,15 and NIOSH13 all recommend or require daily checking of spirometer accuracy when the spirometer is in use, more frequently TABLE 4. Spirometry Test Acceptability Requirements for Adults when the ambient conditions change, and 1. Maximal inhalation at least every 4 hours when many tests are 2. A good start of exhalation with extrapolated volume <5% of FVC or 0.10 L, whichever is 8 performed throughout the day. Such fre- greater, that is, no excessive hesitation5 quent ‘‘calibration checks’’ ensure that spi- 3. Free from artifacts rometers are accurate when in use, 4. No cough during first second of exhalation (for FEV1) preventing interpretation of erroneous test 5. No glottis closure or abrupt termination (for FVC) results caused by inaccurate equipment. 6. No early termination or cutoff (for FVC). Timed expiratory volumes can be reported in Details of the checks given by ATS/ERS,5 maneuvers with early termination, but FVC should be reported only with qualification. 4 8,15 7. Maximal effort provided throughout the maneuver: inhalation, blast, complete exhalation ACOEM, and OSHA are summarized in 8. No obstructed mouthpiece Table 3. Further details were given by ATS/ 9. No extra breaths taken through the nose ERS in Tables 3 and 4 of the 2019 Spirome- 10. No zero-flow errors try Standardization document.5 For many models of spirometers, the FVC and FEV1 are each considered separately for acceptability. FEV1 acceptability does not consider anything calibration is checked but cannot be after the first second, whereas FVC does. Adapted from Ref. [9]. adjusted by the user. If these spirometers

e216 ß 2020 American College of Occupational and Environmental Medicine

sensitive pressure-transducer moves employee. The technician must also be and troubleshooting of technical errors during the subject test; (2) pressure tubing able to judge the degree of effort and and the interpretation of spirometry is disconnected or loose; (3) a sensor is cooperation of the subject. The test results.’’8 degrading; (4) electronics are unstable; or results obtained by a technician who (5) very slow airflow passes through lacks these skills are not only useless, OSHA requires that individuals con- the sensor in either direction while ‘‘zero- but also convey false information which ducting spirometry tests required by the ing’’ is in progress. Such airflow might could be harmful to the employee. Respirable Crystalline Silica or Cotton be caused by slight sensor motion, back- Dust Standards maintain a current certifi- ground fans, or forced air ventilation. NIOSH was designated as the cate from a NIOSH-approved course.10,11,15 Blocking the sensor and holding it still next agency responsible for reviewing and NIOSH requires completion of such a to the subject’s face often prevents these approving occupational spirometry training course when technicians test coal miners errors.5,24 courses, based on topics addressed by in NIOSH’s CWHSP.13 ACOEM4 and Unless a zero-flow error is large, Appendix D of OSHA’s Cotton Dust Stan- OSHA8 recommend that all technicians most spirometers do not alert the user to dard (29 CFR 1910.1043). NIOSH appro- conducting occupational spirometry tests this problem. Zero-flow errors can be rec- ves both initial Spirometry courses and should complete NIOSH-approved courses. ognized by the apparently constant flow Spirometry Refresher courses, which must And ATS/ERS2,25 recommend that courses rate that appears near the end of the be taken every 5 years (in addition to similar to Initial and Refresher NIOSH- maneuver in both the flow-volume and allowing for a 7 month additional grace approved courses should be taken to volume-time curves, as can be seen in period) to maintain the certificate of com- develop and maintain technician skills. Fig. 2B to D. Even though such zero-flow pletion from a NIOSH-approved course. problems may not be identified as errors NIOSH conducts on-site course audits Conducting the Test by available spirometers, the erroneous and periodic reviews of course approval ‘‘Perhaps the most important com- curves should be discarded immediately status to monitor the quality of its approved ponent in successful pulmonary function (not saved), so that their results are not courses. The NIOSH web page lists a testing is a well-motivated, enthusiastic reported as the results from the test ses- schedule of NIOSH-approved courses,26 technician.’’25 ATS/ERS,5,7 ACOEM,4 sion. and NIOSH spirometry training videos and OSHA8 emphasize that technicians Since neither of these types of errors are available.18 ATS/ERS has endorsed explain, demonstrate, and coach subjects are typically detected by spirometer soft- NIOSH-approved courses as prototypes throughout their maneuvers, even when ware, health professionals need to recog- for technician training,2,25 and more workers have performed the test previously. nize the effects of contaminated sensors and recently stated that ‘‘Technicians should Consistent with decades-long occupational zero-flow errors on test results and curve undergo initial practical training and spirometry testing protocol, technicians shapes. Both errors can produce very incon- refresher courses to maintain their skills.’’2 need to encourage maximal inhalations, sistent results (failing to meet repeatability Most recently, ATS/ERS stated that ‘‘Oper- hard initial blasts, and complete exhala- criteria, as discussed below), sometimes ator training and attainment and mainte- tions. In 2019, the ATS/ERS presented along with large percent of predicted val- nance of competency must be integrated separate protocols for testing that measures ues, exceeding 130% to 140%. Tests with in any spirometry testing service.’’5 the forced expiration only, as has been done zero-flow errors often are falsely inter- Since 2016, both OSHA’s Respirable in occupational testing since 1978, and for preted by the spirometer as indicating Crystalline Silica Standards for Construc- testing that measures forced expiration fol- obstructive impairment. tion, General Industry, and Maritime and lowed by a maximal inspiration.5 ATS/ERS ACOEM and OSHA recommend that NIOSH’s CWHSP have required that spi- has confirmed that the former protocol, users of flow-type spirometers become rometry tests conducted under these regu- used in occupational testing and required familiar with the flawed patterns shown lations must be conducted by individuals by OSHA15 and NIOSH,13 meets the in Fig. 2, and institute protocols of preven- who have a current certificate from a requirements of the 2019 Update of the tive actions as well as corrective actions if NIOSH-approved course.10,11,13 Such train- ATS/ERS Spirometry Statement.19–21 those patterns are observed. Such protocols ing is also required by OSHA’s Cotton Dust Occupational spirometry tests tradi- might include occluding sensors5 during Standard.15 The Cotton Dust Standard tionally have been conducted with workers premaneuver sensor ‘‘zeroing,’’ frequent requires persons other than licensed physi- in the standing posture, permitting maximal checks for sensor moisture and mucus cians to complete the NIOSH approved inspirations and blasts on expiration, and 1,4,8 deposits, maintaining sensors in an upright course, while the Silica Standard requires yielding maximal FEV1s and FVCs. position to minimize accumulation of con- all technicians to complete the NIOSH ATS/ERS has noted that subjects with densation, and keeping subjects’ fingers far approved course. An OSHA Letter of Inter- ‘‘excessive weight at the mid-section’’ from the sensor outlet. pretation has recently stated that under the achieve larger inspirations when stand- silica standard, OSHA views all medical ing,25 and ATS also ‘‘recognize[ed] that CONDUCTING TESTS personnel (eg, physicians, physicians’ standing may yield slightly increased val- assistants, nurses) who administer spirom- ues.’’2 A chair without wheels is to be Technician Training etry testing as technicians.11 placed behind the subject, and the techni- In 1978 and again in 2019, the In 2013, OSHA’s Guidance also rec- cian must be ready to assist the subject into OSHA Cotton Dust Standard stated that ommended that: the chair if the subject begins to feel faint. If the goal of spirometry training courses is All technicians and other persons con- there is a history of fainting or if the subject to provide technicians with ‘‘the basic ducting occupational spirometry tests is deemed to be at risk from fainting or knowledge required to produce meaningful obtain certification by completing a falling, the test should be conducted in the test results.’’15 In the regulation’s preamble, NIOSH-approved course; and that sitting position. In all cases, the test posture OSHA noted that: ‘‘Supervisors and/or interpreters of should be documented and kept consistent The most important quality of a pulmo- test results also complete a NIOSH- over time whenever possible. Changes in nary function technician is the motiva- approved spirometry course or equiva- test posture need to be taken into account tion to do the very best test on every lent training that emphasizes recognition when interpreting results over time.2

ß 2020 American College of Occupational and Environmental Medicine e217

The subject’s head is to be slightly spirometers will continue to flag curves maximal inhalation as they demonstrate elevated and he/she needs to stand or sit as incomplete and unacceptable if they performance of the test. Failure to achieve upright. The tongue cannot block the are recorded for <6 seconds (until testing repeatability does not rule out interpretation mouthpiece, and lips are to be tightly sealed software is updated), users should now of results, since it may also occasionally be around it. ATS/ERS recommends that nose ignore those messages and determine caused by underlying respiratory disease.9 clips be used for all spirometry tests,5,7 whether one of the 3 EOFE criteria above Lack of repeatability needs to be docu- which prevents extra breaths through the has been met. Fig. 3E shows the impact of mented and taken into account during the nose, a technical error that invalidates early termination for a worker with airways interpretation process. results,27 but is not detected by most spi- obstruction: the FVC is under-recorded, the ACOEM recommends that occupa- rometry software—see Fig. 3G. FEV1/FVC ratio is falsely elevated, and tional spirometry tests strive to meet ATS/ ACOEM, ATS/ERS, and OSHA rec- true airways obstruction may be missed. ERS criteria for a valid test, that is, record- ommend that technicians explain, demon- Since working populations are often ing three or more acceptable curves, with strate, and actively coach workers to younger and healthier than clinic patients, FVC and FEV1 repeatability of less than or perform maximal inspirations, hard and the decision by the ATS/ERS to no longer equal to 0.15 L (150 mL.) The recent deci- fast expiratory blasts, and complete expi- require a minimum FET for an acceptable sion by the ATS/ERS to no longer require a rations. Occupational testing should be curve permits many workers to be labeled minimum FET5 means that healthy workers conducted standing, unless workers have correctly as having achieved valid tests. who reach their FVC plateau in a short time experienced problems with fainting in the The time taken to achieve a plateau gener- will now be labeled as having valid tests past, or are deemed to be at risk from ally increases with age, decreases with when the FVCs are consistent among fainting or falling. Testing posture should body size, and decreases in the presence curves. Failure to achieve FVC repeatabil- be recorded on the spirometry record and of restrictive lung disease, so that young ity is often caused by inhalations that are the same posture should be used for serial workers, adults with small body frames (eg, not maximal. tests over time. Disposable nose clips are Asian females), and patients with restrictive recommended. lung disease may reach plateaus quickly, Reporting Results before 6 seconds has elapsed. Their results Testing Goal for a Valid Test [can] be considered acceptable in such Values to be Reported ATS/ERS5,7,9 continues to define a cases and an appropriate comment by the The largest FVC and the largest 6,9 valid spirometry test as having two compo- reviewer should be made.’’ Until spirom- FEV1 from all acceptable curves are nents: (1) at least three ‘‘acceptable’’ eter software is updated, if a curve that reported as the test results even if they curves that are free of technical flaws; plateaued in less than 6 seconds is labeled are taken from different curves. The and (2) ‘‘repeatable’’ results for the FVC as unacceptable, technicians should mark FEV1/FVC is calculated using these two 4,5,7,8,15 and FEV1 among the acceptable curves, as such curves as ‘‘acceptable’’ so that the values. To permit thorough review defined below. Most healthy workers can results will be included in the final test of a spirometry test, results from all accept- achieve this testing goal, and up to eight results. Similar to the worker shown in able curves, or at least the three best curves, maneuvers ‘‘is generally a practical upper Fig. 3F, 54% of 4568 healthy nonsmoking should be shown on the spirometry report. limit for most adults.’’5,7 subjects aged 19 or older in the NHANES As discussed below, ATS continues to III study group reached their FVC plateau strongly discourage evaluating the forced Acceptable Curves before 6 seconds elapsed.9,28 Examples of a expiratory flow (FEF) rates, recently saying The components of ‘‘acceptable’’ valid test with an exhalation less than 6 sec- that ‘‘forced expiratory flow at 75% of FVC occupational spirometry maneuvers— max- onds in length, and of unacceptable curves (FEF75%) and FEF25% to 75% have not dem- imal inhalations, hard initial blasts, and com- caused by flawed testing technique are onstrated added value for identifying plete exhalations—have not been shown in Fig. 3A to G. Acceptability crite- obstruction ... and therefore are not rec- changed.4,7,9,19–21 However, since some ria are summarized in Table 4. ommended for routine use.’’6,9 But if subjects experience difficulty in fully record- reported, all FEF, except for the Peak Expi- 5,7 ing their FVCs, ATS/ERS recognized that Repeatable FVC and FEV1 ratory Flow (PEF), are to be drawn from curves that do not completely record the Since 2005, ATS/ERS5,7,9 has one acceptable curve with the highest sum exhalation may be ‘‘usable’’ for FEV1 mea- defined the level of consistency to be of (FEV1 þ FVC). The highest PEF surement if they are free of hesitation and achieved among test results as a difference recorded from among all acceptable curves cough in the first second (Fig. 3A and B). of up to 0.15 L (150 mL) between the is to be reported.4,6,8 ATS/ERS has recently stated that largest and second largest values of the ‘‘there is no [longer a] requirement for a FVC and the FEV1. In general, up to eight Test Report Format minimum Forced Expiratory Time total maneuvers can be attempted, empha- ATS recently issued an Official (FET),’’5 though other End of Forced Expi- sizing maximal inhalation, if repeatability Technical Standard on ‘‘Recommendations ration (EOFE) criteria are still applied to among acceptable curves exceeds 0.15 L. for a Standardized Pulmonary Function ‘‘ensure the best estimate of FVC.’’6 The As ATS recently stated: Report.’’9 Key points from that standard goal for an acceptable EOFE is still: (1) to ‘The most common reason for low FVC, relevant to occupational spirometry reports 4,5,6,8,9 reach a one-second FVC plateau, or FEV1, and PEF values is an incomplete include: (2) to exhale for 15 seconds, or (3) ‘‘if the inhalation. Achievement of maximal patient cannot expire long enough to reach inhalation is best assessed by measures 1. Keep the reports simple: Include subject a plateau (eg, children with high elastic of repeatability and also by the consis- identification number, sex, date of birth, recoil or patients with restrictive lung dis- tency of the shape of the flow-volume or height, weight, ethnicity, date of test, ease)...to repeatedly achieve the same volume-time curve.9 (See Fig. 3D). normal reference source, Lower Limit FVC.’’5 Length of exhalation should be of Normal (LLN), flow-volume and limited to 15 seconds since longer exhala- To emphasize the importance of a volume-time graphs showing technical tions will not affect clinical decisions made complete inhalation in a valid spirometry quality, percentage of Predicted values,9 about the subject.5,7,8 Though many test, technicians should exaggerate the and test posture.2 Scales of the graphs

e218 ß 2020 American College of Occupational and Environmental Medicine

have been previously defined,4,7,8 and can be adjusted as needed ‘‘to maximize TABLE 5. Importance of a Valid Test: Summary the image within the available space for 9 Z Some spirometry errors falsely elevate FVC and/or FEV1: excessive hesitations (Fig. 3A), extra the report.’’ -scores of the results (the inhalations through the nose (Fig. 3G), contaminated sensors (Fig. 2A), and over-recorded flows number of standardized residuals below 9 caused by zero-flow errors (Fig. 2B and C). It is especially important to reject these curves the predicted value) are optional. because spirometers use the largest test results to interpret the test. Exclude parameters with no clinical Other errors, such as submaximal inhalations (Fig. 3D) and weak expiratory pushes (Fig. 3C) value, limiting parameters to FVC, often falsely reduce FVC and/or FEV1. Spirometers usually discard such falsely low values FEV1, FEV1/FVC, [PEF,] and FET for when good coaching leads to higher, more accurate results on subsequent maneuvers. technical quality assessment. ‘‘Limiting However, even if it leads to reduced FEV1, coughs in the first second of exhalation (Fig. 3B) 6 the number of parameters reported and make the maneuver unusable. showing the LLN next to the measured Interpretation of falsely elevated or reduced results may indicate incorrectly that impairment value should improve interpretive accu- exists when a worker is normal, or that a worker is normal when impairment in fact exists. racy, particularly for those less experi- Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ 9 enced.’’ OSHA 3637-2013.8 There should be a ‘‘place for technician OSHA; Occupational Safety and Health Administration. comments on the test session, any quality issues, date of last calibration or 8 calibration check, and other relevant and the OSHA Best Practices Guidance repeatability; and tests with grade F should information that may aid in interpreta- 8 9 9 document. not be used.’’ tion.’’ In 2017, ATS stated that ‘‘quality ACOEM, ATS, and OSHA recom- 2. Specify whether the reference values review of PFTs needs to move beyond mend that technicians ‘‘receive on-going are adjusted for race (and what adjust- 2,9 ‘did, or did not, meet ATS standards,’ but feedback about the quality of the tests they ment factor is used). a grading system is most helpful if the perform, and how to correct problems in 3. ‘‘Standardized electronic formats for grades have a common meaning; therefore test performance.’’2 The frequency of such the saving of all PFT data, including adoption of a uniform system is desirable.’’ reviews should be at least quarterly, and each individual maneuver, are ... rec- A standard scheme for grading spirometry more often if technicians are inexperienced ommended. This will allow reviewers tests on a scale of A-F was recom- or if poor technical quality is observed. It is the flexibility to see additional detail or mended,5,9 with the grades incorporating recommended that reviews be conducted by to reanalyze previous PFTs or apply both acceptability and repeatability. ‘‘A those experienced in recognizing and cor- new reference values as they become 29 9 grading system allows the user to evaluate recting flawed spirometry tests results. available.’’ the likelihood that spirometry results are When used with caution, test quality grades Many of these recommendations representative of true values in the face of may be helpful in evaluating spirometry test have also been made by ACOEM4 and by 9 8 test performance that is not ideal.’’ But as results. OSHA. noted above, ‘‘technicians should be trained ACOEM, ATS, and OSHA recom- not to rely exclusively on spirometer qual- COMPARING RESULTS WITH mend or require that occupational spirom- ity-control prompts, since technical errors REFERENCE VALUES etry test reports include values and curves may occur that are not among those recog- After establishing the technical from all acceptable curves (or at least the 25 nized by the software,’’ and incorporated validity of a test, spirometry results are three best curves) and that the largest FVC into the letter grade (Table 5). evaluated at the time of the test, comparing and largest FEV be interpreted, even if 1 ‘‘While strict application of the grad- the worker’s results with the normal range they come from different curves. Default ing criteria can be done by computer soft- expected for his/her current demographic spirometer configurations often need to ware, the reviewer’s role is to apply characteristics. The likely presence or be adjusted to meet these recommenda- judgment by reviewing the individual absence of impairment is based on this tions. Technicians should also check to be curves, which may change the scoring evaluation and details are presented below. sure that ambient conditions are correctly 9 and allow interpretation.’’ The grades are In addition, a worker’s results are often recorded. 9 summarized in Table 6. ‘‘In general, tests evaluated longitudinally, comparing their with grades of A, B, or C are usable; tests Quality Assurance (QA) Reviews current results with their previous test with grade D are suspect; tests with grade E results. This assessment serves as a helpful In addition to technician training, might be used by the interpreter only to adjunct to traditional cross-sectional evalu- ATS recently emphasized the importance show values ‘within the normal range’ or at ation since increased change over time may of periodic technical review of spirograms ‘at least as high as,’ without demonstrated indicate that further medical assessment is to provide on-going feedback on the quality of each technician’s testing.2,9,25 Samples of randomly selected tests, all invalid tests, TABLE 6. Test Quality Categories for FVC or FEV1 in Adults and tests with abnormally low or improba- Grade No. of Acceptable Curves Repeatability bly high results (FEV1 or FVC >130% of predicted) can be reviewed. Around 80% or A 3 0.150 L more of an occupational health program’s B 2 0.150 L spirometry tests should be technically 8,29 C 2 0.200 L acceptable. Figures illustrating some D 2 0.250 L of the technical errors that can affect spi- E 1 N/A rometry test results are presented in Figs. 2 F 0 N/A and 3 in this statement, in the 1994 ATS 30 Adapted from Official American Thoracic Society Technical Statement: Recommendations for a Standardized Spirometry Update, the 2019 ATS/ERS 9 Spirometry Statement Online Supplement,5 Pulmonary Function Report. AJRCCM. 2017;196:1463–1472.

ß 2020 American College of Occupational and Environmental Medicine e219

appropriate for a worker even though he/she III)22 for occupational testing in the US. Guidance document.8 If not calculated by is not impaired based on traditional evalua- NHANES III tested large random samples older spirometers, NHANES reference val- tion. Updated recommendations for longi- of nonsmoking asymptomatic US Cauca- ues can be calculated using a Reference tudinal interpretation are summarized in the sians, African Americans, and Mexican Value Calculator.39 Since reference values Longitudinal Interpretation section. Americans. Equipment and testing protocols can vary significantly and affect the percent Three critical aspects of traditional were held constant and quality control was of predicted values, the selected reference pulmonary function evaluation influence strictly maintained, so that observed differ- values should always be identified on the cross-sectional interpretation: (a) the ences between groups reflect biological dif- spirometry printout, as noted earlier. source of the reference values used; (b) ferences and not simply varying equipment how the reference values are adjusted when or testing techniques. Race-specific Race-Adjustment of Predicted a worker’s race/ethnicity differs from the NHANES III reference equations are avail- Values and LLNs reference study subjects; and (c) selection able for Caucasians, African-Americans, If a worker’s self-reported race/ethnic- of the interpretation algorithm used to cat- and Mexican-Americans (Hispanics). ity is the same as the referencevalue group, no egorize pulmonary function as normal or However, uncertainty about whether adjustment of the reference values is required. abnormal, that is, the choice of lung func- the NHANES III values were a good fit for Since NHANES III reference values were tion parameters to be evaluated and the countries outside of the United States pre- generated specifically for Caucasians, Afri- sequence in which they are examined. vented the ATS/ERS from recommending can-Americans, and Mexican Americans NHANES III for use in Europe and other (used for Hispanics), the predicted values Reference Values countries. To meet the need for reference and LLNs are not adjusted when workers As stated by the ATS 1991, ‘‘A refer- values for Europe and other parts of the of these race/ethnicity groups are tested. ence population should, ideally, be represen- world, and for subjects younger and older However, when Asian-American workers tative of the general population from which than the NHANES population, the Global (ie, Chinese, Japanese, Indian, or Pakistani) the clientele of the laboratory comes.’’31 Lung Function Initiative (GLI) combined are tested, race-specific NHANES reference Reference values define the average and data from 70 research studies in 26 countries values are not available. To determine appro- the lower boundary of the normal range (mostly outside of North America) and pub- priate Asian-American reference values, Cau- 38 for individuals similar to the tested worker lished the GLI-12 equations. Though ATS/ casian values for FVC and FEV1 should be for factors related to the size and shape of the ERS recently recommended use of the GLI multiplied by a scaling factor to account for thoracic cavity, that is, age, height, race, and equations in Europe, Australia, New Zea- the larger average thoracic cavities observed sex. Obtaining accurate information on these land, and North America,5,9 particularly in in Caucasians compared with Asian-Ameri- characteristics for the worker is critical to clinical research studies to permit compar- cans of the same age, height, and sex. The accurately interpreting spirometry results, isons with international studies, they stated scalingfactorrequiredbyOSHAin2019and and inaccurate information can lead to incor- that the NHANES III values ‘‘remain appro- recommended by ATS/ERS in 2014, 0.88, rect assessment of a worker’s pulmonary priate where maintaining continuity is was based on recent evidence indicating that function. Referencevalues are obtained from important,’’9 as it is the occupational set- it minimizes false positives when used research studies of asymptomatic never ting.2 Also in November, 2019, the ATS/ERS to calculate Asian-American reference val- smokers of varying ages, heights, and sex, stated that ‘‘for occupational spirometry test- ues.2,8,15,40 and optimally, varying ethnic/racial back- ing in the United States, the use of the ACOEM and ATS/ERS recommend grounds. Subject ethnic/racial group should NHANES III spirometry reference values that race-specific NHANES III reference be based on self-report and standing height is in full compliance with the 2019 Update values be used whenever possible, basing in stocking feet should be measured period- of the ATS/ERS Spirometry Standards.’’19– the worker’s race/ethnicity on self-report. To ically and not simply reported by the sub- 21 Effective July 15, 2019, OSHA mandated evaluate Asian-American workers, ACOEM ject.5 The worker’s sex should be sex use of the NHANES III reference values recommends applying a scaling factor of assigned at birth,5,32,33 though this might when workers are tested under the updated 0.88 to Caucasian predicted values and 15 misclassify some transgender workers who cotton dust standard. And since ‘‘a refer- LLNs for FVC and FEV1. Forcotton-exposed began gender-affirming hormone therapy ence population should, ideally, be represen- workers, OSHA requires that the 0.88 scal- before the onset of puberty. (Defining best tative of the general population from which ing factor be used for Asian-American work- 31 practices to elicit an accurate sex designation the [subjects come],’’ workers who are ers. Note that FEV1/FVC predicted values from transgender workers warrants further tested in the United States are best compared and LLNs are not adjusted. research.) The relationships of pulmonary with values obtained from the highly stan- function parameters with these four demo- dardized NHANES III research study con- Interpretation Algorithm graphic variables are summarized in regres- ducted in the United States. For almost three decades, ATS has sion equations, which produce average OSHA mandates use of the NHANES recommended applying a stepwise algo- ‘‘predicted’’ values and 5th percentile III (Hankinson 1999) reference values for rithm to three pulmonary function parame- LLN. (Note that LLN is equivalent to a Z- occupational spirometry testing required by ters to interpret spirometry results.2,9,31,34 score of 1.645). Since predicted values and the updated Cotton Dust Standard15 and ACOEM endorsed this approach in its pre- LLNs describe the average and the bottom of recommends NHANES III normal values vious statements1,4 and OSHA adopted it in the normal range based on a single research for use8 in occupational testing under other their Guidance document.8 Since consensus study, both indices need to be drawn from a regulations, unless a regulation mandates exists on how to distinguish normal from single source of reference values.31,34 another specific set of reference values. abnormal results, and which measurements Many reference values studies have ACOEM, ATS/ERS, and the AMA Guides identify obstructive or possible restrictive been conducted in a single geographical 6th edition endorse use of the NHANES III impairment, these determinations are pre- location,35,36 but ATS/ERS,2,9,19–21,34 reference values in occupational testing in sented in Fig. 4. Since recommendations ACOEM,4 OSHA,8,15 and the AMA Guides the United States.22 Most spirometers cal- for grading severity of impairment are quite 6th edition,37 support using reference val- culate NHANES III reference values, and disparate,34,41 this statement’s interpretation ues from the National Health and Nutrition tables of NHANES III predicted values and algorithm (Fig. 4) does not grade severity Examination Study, Round III (NHANES LLNs are in Appendix A of the OSHA of impairment.

e220 ß 2020 American College of Occupational and Environmental Medicine

FIGURE 4. Spirometry interpretation algorithm. Based on ‘‘Spirometry Testing in Occupational Health Programs: Best Practices for Healthcare Professionals.’’ OSHA 3637-013.8 LLN, lower limit of normal; OSHA; Occupational Safety and Health Administra- tion.

ß 2020 American College of Occupational and Environmental Medicine e221

LLN Defines Abnormality obstructive defect will result in false nega- whether expiratory airflow is slowed Since 1991, ATS has officially tive results for younger workers, and false- (obstructive impairment), and finally, con- 2 endorsed using the 5th percentile, the point positive results in older workers.’’ Using sider whether expired lung volumes might below which only 5% of nonexposed asymp- the 5th percentile LLN to define abnormal- be reduced (restrictive impairment). It is tomatic subjects are expected to fall, as the ity for the major spirometry measurements important to follow the steps in the order 43,44 LLN range.2,9,31,34 (As previously noted, the avoids such problems. specified to minimize false positive find- LLN corresponds to a Z-score of 1.645.) ‘‘Spirometry values that are below ings when interpreting spirometry test Determining what constitutes an abnor- the fifth percentile LLN are considered results. All three steps should be evaluated mal versus a normal spirometry result is abnormal, and may reflect a pulmonary for every set of test results. particularly important when spirometry problem. However, by definition, 5% of a The algorithm shown in Fig. 4 is is performed related to the workplace. In healthy population will also fall below the used to classify the worker as having: 2 addition to prompting further evaluation fifth percentile LLN’’ and so false posi- of a worker and workplace exposures, tives are possible. According to ATS, Obstructive impairment (airways an ‘abnormal’ spirometry result can also ‘‘interpreters should be aware of uncer- obstruction); impact a worker’s job (eg, determining tainty when interpreting values near any Possible restrictive impairment; job placement). The ATS/ERS and dichotomous boundary ... and so caution Possible mixed impairment (both ACOEM recommend using the fifth is indicated when interpreting values close obstructive and possible restrictive 9 percentile lower limit of normal to the LLN.’’ ATS gives a practical exam- impairments); or (LLN) to differentiate normality from ple of how clinical circumstances affect a Normal spirometry results (no obstruc- abnormality, rather than a fixed value, diagnosis of impairment: tive or restrictive impairment). For example, consider the meaning of a Each of these classifications is such as 80% of predicted for the FEV1 and FVC, or 0.70 for the observed ratio spirometric study that shows FEV1 val- described below, following the sequence 2 ues and other expiratory flow rates to be in Fig. 4.’’8 of FEV1/FVC.’ just above the lower limit of normal. If Because the Global Initiative for the patient were a healthy male who Is Test Valid? Chronic Obstructive Lung Disease criteria sought medical assistance because he As shown in Fig. 4, the first step in have been used in the primary care setting was disqualified for life insurance on interpreting spirometry test results is to to screen smokers and symptomatic the basis of his spirometry, it would be determine whether a valid test has been patients for chronic obstructive pulmonary appropriate to interpret his spirometry performed or if more maneuvers may be disease,42 clinics may erroneously adopt as within normal limits. If, in contrast, needed. ATS/ERS has cautioned that the fixed cut-point of a measured ratio of the same data were obtained from a ‘‘omitting the quality review and relying less than 0.70 to indicate the presence of smoker with complaints of intermittent only on numerical results for clinical deci- airways obstruction for all individuals. coughing and occasional wheezing, it sion making is a common mistake, which is Since the measured ratio declines by about would be appropriate to suggest that the more easily made by those who are depen- 10% across the decades from 20 to 70, a study is consistent with mild obstructive dent upon computer interpretations.’’34 fixed cut-point is only accurate in the mid- dysfunction, although it could also rep- dle of that age range and not in younger or resent a variant of normal. In both of Obstructive Impairment older individuals. As an example, for Cau- these instances, computer printouts, or Once test validity is established, casian males, the NHANES III LLN for the robotic physician interpretation that FEV1/FVC is the first measurement to be FEV1/FVC ratio equals 0.70 at about age simplistically declare the results to be evaluated, to ‘‘distinguish obstructive from 40. But at age 20, the ratio LLN is 0.74 and ‘normal’ or ‘abnormal’ on the basis of nonobstructive patterns.’’31 When the at age 70, it is 0.64. This means that young whether the observed values fall to one FEV1/FVC and FEV1 are both less than people who should be exhaling 74% or side or the other of a single number, LLN, airways obstruction is present. How- more of their volume in the first second could give information that does not ever, when FEV1/FVC is less than LLN, but will not be labeled with ‘‘airways obstruc- perform a useful service to the patient[- FEV1 is greater than LLN, borderline tion’’ until their ratio is less than 0.70 if the emphasis added].31 obstruction or ‘‘possible physiologic vari- GOLD criterion for obstruction is used. In ant’’ may exist.31,34 occupational settings, where the goal is to ATS/ERS cautions that FEV /FVC Applying the Interpretation 1 identify impairment at an early stage, these less than LLN combined with FEV1 greater are unacceptable false negatives. The older Algorithm than equal to 100% of predicted is ‘‘some- subject has the opposite problem: many Spirometry interpretations should times seen in healthy subjects, including older people who are not obstructed will specify whether the worker’s lung function athletes’’ and ‘‘is probably due to ‘dysanap- exhale less than 0.70 of their volume in the is in the normal range, or shows an obstruc- tic’ or unequal growth of the airways and first second. These false positives may tive, restrictive, or mixed impairment pat- lung parenchyma.’’34 This pattern is labeled result in unnecessary job restrictions tern. Merely stating which values are as a ‘‘possible physiologic variant,’’31,34 and or treatment. normal or low, without concluding if is not unusual among physically fit non- As ATS has stated: ‘‘The fixed val- there is an impairment pattern, is not smoking emergency responders, firefighters, ues commonly used...are estimates based helpful.34 and police. However, if these healthy work- on middle-aged adults, and therefore erro- ‘‘OSHA recommends following the ers are exposed to known hazardous sub- neous clinical decisions based on these algorithm pictured in Fig. 4 to interpret lung stances, the possibility of obstructive fixed cutoffs are more likely to occur’’2,9 function. This general approach has previ- impairment needs to be considered when a 4 in young workers and in those with small ously been recommended by ACOEM, reduced FEV1/FVC is observed. lung volumes, ie, older, shorter, and/or ATS/ERS,34 and NIOSH.45 Figure 4 lists female adults. And ‘‘because the FEV1/ three steps to be followed in interpreting Restrictive Impairment FVC ratio declines with age, using a fixed spirometry test results: first, evaluate the FVC, the forced expiratory measure- value, such as 0.70, to determine an validity of the test results, second, assess ment of vital capacity, is next evaluated to

e222 ß 2020 American College of Occupational and Environmental Medicine

determine whether restrictive impairment ACOEM and OSHA recommend that of follow up; and definition of excessive may exist. If FVC less than LLN, restrictive occupational medicine practitioners follow decline. The primary measurement used to impairment is possible, and true restriction the algorithm pictured in Fig. 4 to separate assess longitudinal change should be the will need to be confirmed using additional normal from abnormal test results. This FEV1, as it is less affected by technical pulmonary function tests, such as lung general approach has also been recom- factors than the FVC.’’2,4,34 volume measurements. mended by ATS/ERS34 and NIOSH.45 Pres- However, in the presence of airways ence of airways obstruction is indicated by Spirometry Testing Quality and obstruction (FEV1/FVC air trapping.6,34 Changes in weight over time should be LONGITUDINAL recorded, since weight gain can contribute INTERPRETATION to decline in lung function.2,3,9 Maintaining Normal Spirometry Results Since ‘‘workers can undergo peri- calibration check records and tracking spi- odic, often annual, spirometry tests in If FEV1/FVC LLN, there is no rometry results for groups of workers over obstructive impairment and if FVC greater mandated or recommended medical sur- time (eg, mean FEV1, within-person varia- than equal to LLN, there is no restrictive veillance programs, it is important to eval- tion, proportions of high or low values) can impairment: the worker has normal spirom- uate such measurements not only relative to help identify ongoing health hazards and etry results. Since the LLN is defined so normal ranges [based on predicted values also anomalous results possibly resulting that 5% of healthy individuals will fall and LLNs], but also relative to the workers’ from technical issues.’’2,3,8 below it, spirometry results from a worker baselines, particularly when lung function without any apparent health problems are values are within the normal range. Many Frequency and Duration of occasionally found to be slightly below the workers have FVC and FEV1 that exceed Testing LLN. As noted above, such values, just their predicted values. Such individuals ‘‘As length of follow up increases, above or just below the LLN should be must lose a significant portion of their lung real decline in pulmonary function becomes interpreted with caution. The worker should function before their spirometry results fall easier to distinguish from background mea- be retested at a later date to confirm the below the LLN, and they are identified as surement variability. The precision of the abnormal. Longitudinal evaluations of peri- results and, if still abnormal, the complete estimated rate of FEV1 decline improves clinical presentation should be evaluated. odic spirometry testing may detect exces- with increasing frequency of measurement Additional tests of pulmonary function sive lung function loss due to an exposure and duration of follow-up.2,53 Because or underlying condition earlier than using a should be done if clinically indicated. 2 chronic occupational respiratory diseases single spirometry test’’ for these individu- (such as chronic obstructive pulmonary Forced Expiratory Flow Rates als. However, while an FEV1/FVC or FVC disease and pneumoconioses) typically (FEF) less than LLN is widely recognized as develop over many years, spirometry per- As presented above, because of the indicating obstructive or possible restrictive formed less frequently than annually (eg, wide variability of the FEF25% to 75% and the lung impairment, interpreting a greater than every 2 to 3 y) should be sufficient to instantaneous flow rates, both within and expected loss in FEV1 is less well standard- monitor for the development of such dis- between healthy subjects, ATS/ERS con- ized and should not be used to label workers eases.2 However, for diseases that can tinues to discourage their use for diagnos- as impaired, but rather as a guide to desig- develop more rapidly (such as flavoring- ing small airway disease in individual nate workers who may need more medical related lung disease or occupational 6,9,31,34 patients, or for assessing respiratory follow-up. asthma), more frequent follow up at inter- impairment. Interpretation of FEF25% to 75% ‘‘How to evaluate loss of lung func- vals of 6 months to 1 year may be appro- and other flow rates is not generally rec- tion over years [had] not been directly 2 2,34 priate.’’ ommended if the FEV1 and the FEV1/FVC addressed by the ATS or ERS,’’ so an are within the normal range.46,47 If flow ATS committee ‘‘performed an evidence- Determination of Abnormally rates are interpreted at all, ‘‘the wide vari- based systematic literature review to iden- Reduced or Highly Variable FEV1 ability of these tests in healthy subjects tify evidence relevant to the question of ‘‘Great care is required in determin- must be taken into account in their inter- how to evaluate excessive decline in lung ing what constitutes an ‘excessive’ FEV1 pretation.’’34 ‘‘The practice of using 80% of function.’’2 Results from that review are decline [or unusually variable measure- predicted as the lower limit of normal for summarized here. ‘‘Assessment of decline ments] when evaluating periodic testing FEF25% to 75% or the instantaneous flows in lung function is affected by several fac- in worker populations. It is important to will cause important errors since, for these tors [which are considered below], includ- avoid the consequences of either false-pos- flows, the lower limits of normal are closer ing: spirometry technical quality and test itive or negative findings. The purpose of to 50% of predicted’’31,34 variability; testing frequency and duration such periodic testing is to detect

ß 2020 American College of Occupational and Environmental Medicine e223

progressive lung disease at an earlier stage, For example, if a worker’s initial up at intervals of 6 months to 1 year may be 2 which might otherwise be missed, espe- FEV1 was 120% predicted, his decline appropriate.’’ cially when lung function values are above might be considered excessive or his results But as ATS cautions, ‘‘these small LLN.’’2 extremely variable if he falls to 105% pre- short-term longitudinal changes (5 years) Due to ‘‘the relatively large technical dicted (a decrease of 15% of predicted), may be difficult to interpret because of the variability often encountered in spirometry even though he is still above average and relatively large inherent FEV1 technical var- testing,’’ longitudinal evaluation ‘‘methods remains well above the LLN. First his tests iability in spirometry testing.’’2 It is essential are most effective for evaluating declines in would be reviewed for technical quality and that the assumptions that underlie applica- FEV1 over relatively long time periods (5 the follow-up test possibly repeated. If the tion of a computerized program are under- y).’’2 ‘‘Excessive shorter-term (<5 y) lon- conclusion remained the same, a medical stood. For example, Spirola requires gitudinal FEV1 declines have been shown evaluation would be considered as specification of a within-subject variability to presage long-term losses, but can be described in section 5 below. of measurements and a reference rate of loss difficult to interpret in any individual Though a ‘‘volume method’’2 was of function. Spirola’s recently used default worker. ... Despite this variability, to pro- originally described as ‘‘Method 2 for setting of 4% variability and 40 mL/y are not tect lung health among workers with dis- Baselines less than equal to 100% Pre- universally appropriate, and the assumed eases that develop rapidly, clinicians may dicted,’’3 it is more cumbersome than the within-person variability, in particular, dra- need to identify individuals who may have percent predicted method and the two matically impacts the number of subjects experienced declines in FEV1 over shorter approaches ‘‘provide very similar thresh- flagged as having an abnormal FEV1 decline 2 2 57 time periods (months to a few years).’’ olds for excessive decline in FEV1.’’ Sim- or abnormally variable measurements. 1,3 But ATS cautions that ‘‘the greatest ilarly, regression of FEV1 on time It is important to note that NIOSH errors occur when one attempts to interpret requires greater than or equal to 5 years now recommends setting Spirola’s defaults serial changes in subjects without disease of follow-up, is not appropriate if FEV1 to match ‘‘the ACOEM-recommended lon- because test variability will usually far decline is not linear, and a fixed mL/y gitudinal limit based on a decline of 15% exceed the true annual decline, and reliable threshold will flag workers with low base- from baseline in excess of that expected due rates of change for an individual subject line FEV1s sooner than workers with higher to aging. [This] can be specified by select- 2 cannot be calculated without prolonged FEV1s. Therefore, in clinical settings, ing a 6% pairwise-within person variation follow-up. Thus, ‘‘yearly changes [in ACOEM recommends adopting the simpler and 30 mL/y referential rate of decline in FVC or FEV1] of 15% or more were gen- ‘‘Percent of Predicted’’ method instead of the Options tab. Those defaults will be used erally thought by the [ATS] Workshop to be the ‘‘volume’’ or regression methods. in the next release of SPIROLA.’’58 clinically important.’’31,54 The ‘‘Percent Predicted’’ approach Though the Percent Predicted method In 2014, ATS concluded that ‘‘The and more complicated computerized can be used to monitor ‘‘decline in FEV1 most practical thresholds for clinicians to approaches ‘‘are quantitatively similar’’ from baseline to follow up for longer periods 2 use in comparing longitudinal FEV1 meas- when within-person testing variability is of time’’ the computerized LLD method is urements are based on a 15% loss from about 6%, as is probably common in not recommended for follow-up greater than baseline, taking into account expected age- real-world testing scenarios.31,54 And ‘‘spi- 5 to 8 years. For these longer follow-ups, the related loss. ...A threshold of 15% decline rometry programs with more variability computerized LLD method should be in FEV1 from baseline to follow up for should evaluate if it is due to technical replaced by the Percent of Predicted method. longer periods of time, beyond the expected issues or increased prevalence of disease, And finally, it must be borne in mind loss due to aging during the follow-up and should use the 15% approach above to that an ‘‘abnormal’’ decline must be ‘‘con- period, has been recommended by NIOSH evaluate individual results.’’2 So for most sidered together with other information (eg, to monitor coal miners55 and by occupational testing, use of the ‘‘Percent spirometry quality, respiratory symptoms, ACOEM.’’3,4 As also noted by the Califor- Predicted Method’’ is recommended2 and it exposure to respiratory hazards such as nia Department of Health,29 and OSHA,8 is appropriate for any length of follow-up.55 tobacco smoking or occupational expo- this cut-off is chosen to avoid the false However, ‘‘for diseases that develop sures, radiological findings). Before mak- positives that may occur when pulmonary rapidly, declines in FEV1 of less than 15% ing a final decision, the quality of the function is measured in many nonstandar- over shorter time periods may be clinically baseline and final spirometry tests should dized, real-world clinic situations. This important,’’2 if they identify workers who be evaluated, and if needed, spirometry 59 approach will identify FEV1s that are lower should have further evaluation for possible should be repeated.’’ The ATS caveat than expected due to aging, whether due to disease. If spirometry programs maintain about avoiding errors ‘‘when one attempts steeper declines in function or unusually tighter QA programs and their measure- to interpret serial changes in subjects with- variable measurements over time. And as ments have less within-person technical out disease’’31 must always be considered. noted above, this method was designed to variability, declines of 10% to 15% may ACOEM recommends that the inter- monitor FEV1 from baseline on, regardless indicate a problem. One computerized pretation of pulmonary function change over of the length of follow-up.2,55 approach, Spirola, accounts for variability time start with an evaluation of technical The easiest way to calculate the among measurements as it determines a quality of the tests and an adequate length of allowed FEV1 decline of 15% beyond that threshold for abnormal decline or measure- follow-up. When high quality spirometry expected due to aging is to apply the ‘‘Per- ment variability.56 For follow-ups less than testing is in place, ACOEM recommends cent Predicted Method’’2 (previously or equal to 5 to 8 years, the computerized further medical evaluation for workers known as ‘‘Method 1 for Baselines greater lower limit of longitudinal decline (LLD) whose FEV1 falls more than 15% below that than 100% Predicted’’3): method,56 may flag smaller declines as which is expected due to aging. The Percent Baseline (initial) FEV1% of predicted ‘‘abnormal’’ when within-person variabil- Predicted method is the easiest way to assess minus current FEV1% of predicted; ity is minimal. This may be particularly FEV1 longitudinally for usual occupational Interpretation: If 15%, then observed important when ‘‘diseases that can develop health clinic measurements and can be used decline in FEV1 may be excessive, or more rapidly (such as flavoring-related for all lengths of follow-up. variability of measurements may be lung disease or occupational asthma),’’ Smaller declines of 10% to 15%, increased.2 are of concern, and ‘‘more frequent follow after allowing for the expected loss due

e224 ß 2020 American College of Occupational and Environmental Medicine

ensure that medical records in the PLHCP’s TABLE 7. Workers Referred for Further Evaluation possession (eg, written medical report) are 1. Assess technical quality of spirometry and repeat testing if indicated based on spirometry quality, retained. To meet the second obligation, and other relevant information below employers can include the retention 2. Obtain comprehensive medical and occupational history and physical exam including: requirement in a written agreement with (a) Work and exposure history the PLHCP, or the employer can otherwise (b) Smoking history specifically communicate OSHA’s record- (c) Respiratory symptoms, timing in relationship to work retention requirements to the PLHCP.10 A (d) Physical exam, including lung exam and chest wall deformities recent Letter of Interpretation on this topic (e) SDSs, results of workplace measurements, if available describes the limited amount of information 3. Review preemployment, follow-up questionnaires and spirometry, if available 4. Possible additional diagnostic testing: that may be given to the employer under (a) If airflow obstruction, spirometry with bronchodilator response both the Silica and Respiratory Protection (b) If restrictive pattern, full pulmonary function tests (lung volumes, diffusing capacity) Standards, stating that these standards ‘‘do (c) Chest imaging (chest x-ray, CT scan) not authorize the transfer of spirometry test (d) If asthma, consider peak flow recordings at and away from work or other medical records to employers.’’16 (e) If interstitial lung disease, consider high resolution chest CT scan These issues and others are addressed in (f) If nonreversible airflow obstruction, consider occupational etiologies, even in smokers (eg, OSHA’s Occupational Exposure to Respi- occupational COPD, bronchiolitis obliterans) rable Crystalline Silica 29 CFR §1910.1053 5. If a possible work-related problem is identified, consider other at-risk workers and §1926.1153: Frequently Asked Ques- tions for General Industry and for Construc- SDS, Safety Data Sheet. 62,63 Reprinted with permission of the American Thoracic Society. Copyright ß 2019 American Thoracic Society. tion. Redlich C, Tarlo S, Hankinson J, Townsend MC, et al. Official American Thoracic Society Technical Standards: 2. Equipment Maintenance Records: Spirometry in the Occupational Setting. AJRCCM; 189(8):984–994, 2014. The American Journal of Respiratory and 2 ‘‘Since equipment maintenance records sup- Critical Care Medicine is an official journal of the American Thoracic Society. port the accuracy of the spirometry test results in the medical record, OSHA recom- to aging, may be important in diseases that the lung function abnormality and/or decline mends saving the equipment calibration progress rapidly and have tests performed over time, and the clinical context.’’2 check log and information about the spirom- more frequently than annually.60 These Detailed suggestions from ATS are shown eter. Availability of such records permits smaller declines must first be confirmed, in Table 7.2 Moreover ‘‘in addition to man- later troubleshooting of problematic spirom- and then, if the technical quality of the agement of the individual worker, the analy- etry test results, which is particularly impor- pulmonary function measurement is ade- sis of aggregate worker data (from the same tant when conducting periodic spirometry quate, acted upon. In such cases, a com- workplace, company, job, or industry), both testing.’’ Details of the recommended equip- puterized approach may detect small but cross-sectional and longitudinal, can offer ment maintenance records to be retained are important early changes in function if the significant benefit.’’2 given elsewhere.8 Record storage methods spirometry testing is of very high technical should be updated as technology changes to quality. RECORDKEEPING assure future record access. ‘‘Adequate recordkeeping is a criti- 3. Personnel Training and Evalua- FURTHER EVALUATION OF cal component of a good spirometry pro- tion Records: OSHA recommends that per- gram. To improve the quality of spirometry SPIROMETRIC sonnel qualifications be documented and testing programs, OSHA makes recommen- available for review. Records should ABNORMALITIES dations below on three recordkeeping com- include: technician continuing medical Although ACOEM has stated that ponents: (1) spirometry test reports; (2) education, certificates from completed ‘‘excessive declines’’ in FEV1 should trig- equipment maintenance records; and (3) NIOSH-approved spirometry training ger further medical surveillance once the personnel training and evaluation courses, and results of evaluation and feed- 8 declines were confirmed, the details of records.’’ ATS and ACOEM recommend back to technicians. medical follow-up were not specified.4 that ‘‘to protect worker confidentiality, pro- But in 2014, ATS described an ‘‘Action viders must not disclose individual work- ACOEM Recommendations— Plan for Spirometry in the Work Setting.’’2 ers’ personal health information to 2020 Steps in evaluating workplace spirometry employers without employee consent.’’2,61 results and further medical evaluation plans 1. Spirometry Test Reports: Most 1. Equipment Performance were given in detail. Those details are OSHA standards require employers to ACOEM recommends that facilities presented in this section. ensure that medical records for each performing occupational spirometry ‘‘Workers with values below the worker, including the spirometry test tests maintain a procedure manual LLN and/or an excessive decline in FEV1 results, are maintained for at least 30 years documenting equipment type, spi- should be further evaluated for potential following the end of employment (see 29 rometer configuration, manufac- causes and preventable risk factors. Factors CFR 1910.1020).8 Details of the recom- turer’s guidelines, calibration check such as work exposures, respiratory symp- mended spirometry report format are given log, service and repair records, per- toms, and medical information (eg, diagno- elsewhere.8 Record storage methods should sonnel training, and standard operat- ses, medications) should always also be be updated as technology changes to assure ing procedures. Such a manual will considered, as spirometry values or rates future record access. permit troubleshooting if problems of decline can remain ‘‘normal’’ when other Under the OSHA silica rule, employ- arise with test results. factors may indicate that further evaluation ers must: (1) retain medical records which a. Spirometer Specifications is needed.’’2 are in their possession (eg, the Physician or 1. ACOEM recommends that spiro- ‘‘The specific steps to be taken will Licensed Health Care Practitioner’s meters of all types meet or exceed rec- depend on several considerations, including (PLHCP) written medical opinion about ommendations made by ATS/ERS 2005 the exposures of concern, the magnitude of any limitations on respirator use); and (2) and by ISO 26782:

ß 2020 American College of Occupational and Environmental Medicine e225

Performance-based criteria for spi- d. Avoiding Sensor Errors during Sub- are valid, even if the spirometer flags rometer operation, including, for ject Tests the effort as unacceptable or invalid. example, accuracy, precision, linear- Users of flow-type spirometers need There is no longer a minimum ity, frequency response, expiratory to recognize the flawed curves and length of exhalation required for an flow impedance, and other factors; test results that may be caused by acceptable test,5 though it is unlikely Minimum sizes and aspect ratios for sensor contamination or zero-flow that spirometer software will be real-time displays of flow-volume errors (Fig. 2), and updated immediately to reflect this and volume-time curves (Appendix Protocols need to be established and change. A); and used to prevent these errors from ATS test acceptability requirements Standard electronic spirometer out- occurring and to correct the errors are presented in Table 4. Importance put of results and curves. if they do occur. See text for of a valid test is summarized in 2. It is also recommended that spiro- specific suggestions. Table 5. meters which will be used in the occu- 2. Conducting Tests d. Reporting Results pational setting: a. Technician Training Spirometry test reports need to pres- Store all information from up to eight All technicians conducting occupa- ent values and curves from all (or at maneuvers in a subject test session; tional spirometry tests should suc- least the best three) acceptable Permit later editing and deletion of cessfully complete a NIOSH- maneuvers to permit technical qual- earlier flawed test results; approved spirometry course initially, ity to be fully evaluated, and Be capable of including flow-volume and a NIOSH-approved refresher The largest FVC and largest FEV1 and volume-time curves and test course every 5 years. Such training are interpreted, even if they come results from at least the 3 best is mandatory if cotton dust- or respi- from different ‘‘acceptable’’ curves. maneuvers, and preferably from all rable crystalline silica-exposed Default spirometer configurations saved efforts, in the spirometry test workers are tested. NIOSH-approved often need to be adjusted to meet report; courses are also mandatory for those these recommendations. Provide computer-derived technical testing coal miners in the NIOSH e. QA Reviews quality indicators; CWHSP program. ACOEM recommends that facilities Provide a dedicated routine for veri- performing occupational spirometry fying spirometer calibration; and b. Conducting the Test tests need to establish on-going pro- Save indefinitely a comprehensive Consistent with decades-long occu- grams providing QA reviews electronic record of all calibration pational spirometry testing protocol, of spirograms. and calibration verification results. technicians need to explain, demon- Reviews need to be conducted at b. Validation Testing of Spirometers strate, and actively coach workers to least quarterly, and more often if If spirometers are purchased for use in perform maximal inspirations, hard technicians are inexperienced or if the occupational health setting, and fast expiratory blasts, and com- poor technical quality is observed. ACOEM recommends that: plete expirations. ATS/ERS has con- The goal of such reviews is to assure The manufacturer provides written firmed that this protocol meets the that 80% or more of an occupational verification that the spirometer suc- requirements of the 2019 Spirometry health program’s spirometry tests are 19–21 cessfully passed its validation test- Update. technically acceptable. ing, preferably conducted by an Testing should be conducted stand- It is recommended that QA reviewers independent testing laboratory, and ing, positioning a sturdy chair with- be experienced in recognizing and that the tested spirometer and soft- out wheels behind the subject, unless correcting flawed spirometry test ware version correspond with the the subject has previously sat for the results. model and software version being test or experienced a problem with Table 6 presents ATS test quality purchased; and fainting or is deemed to be at risk of categories for FVC and FEV1. The spirometer meets the ATS/ERS fainting or falling. 3. Comparing Results With Reference recommended minimum real-time Record test posture on the spirometry Values display for flow-volume and vol- record and use the same posture for a. Reference Values ume-time curves and ISO minimum all serial tests over time. ACOEM recommends that the aspect ratios for these displays, as Disposable nose clips are recom- NHANES III (Hankinson) reference well as providing a standard spirom- mended. values22 be used for occupational eter electronic output (Appendix A). c. Testing Goal for a Valid Test spirometry in the United States c. Spirometer Accuracy Checks To achieve a valid test, occupational unless a regulation mandates another ACOEM recommends that: spirometry should attempt to record specific set of reference values. Spirometer accuracy be checked or more three acceptable curves, with OSHA mandates use of NHANES daily when in use, following the FVC and FEV1 repeatability of 0.15 III in the recently updated Cotton steps summarized in Table 3; L (150 mL) or less. See text for def- Dust Standard.15 NHANES III val- Tracings and records from these initions of terms. ues are recommended for the United checks be saved indefinitely; Failure to achieve repeatability is States when continuity over time is A log is kept of technical problems often caused by submaximal inhala- important, as it is in occupational found and solved, as well as all tions, though very poor repeatability health, and ATS/ERS has confirmed changes in protocol, computer soft- (eg, >0.50 L) may indicate sensor that use of NHANES III reference ware, or equipment; and contamination or zero-flow errors. values is in full compliance with the Spirometers purchased for use in the Workers who are young, have small 2019 ATS/ERS Spirometry Stan- occupational setting have dedicated body frames, or restrictive lung dis- dardization Statement.19–21 calibration check routines (as noted ease often reach their FVC plateaus It is essential to obtain accurate above.) very quickly. Such tests, if repeatable, worker information on factors that

e226 ß 2020 American College of Occupational and Environmental Medicine

are related to the size and shape of Evaluate technical quality of the spi- If restrictive pattern, full pulmo- their thoracic cavity, that is, age, rometry tests and the adequacy of the nary function tests (lung volumes, height, sex, and race. Details of gath- follow-up period before interpreting diffusing capacity) ering this information are presented in change in pulmonary function over Chest imaging (chest x-ray, CT the section Comparing Results With time. scan) Reference Values; Reference Values, ACOEM recommends that FEV1 If asthma, consider peak flow and new recommendations are made losses of greater than equal to 15% recordings at and away from work for testing transgender workers.5 since baseline, after allowing for If interstitial lung disease, consider b. Race-Adjustment of Predicted Val- the expected loss due to aging, high resolution chest CT scan ues and LLNs trigger further medical evaluation If nonreversible airflow obstruc- Use NHANES III race-specific ref- when spirometry is of high technical tion, consider occupational etiol- erence values, basing a worker’s quality. The simplest method to ogies, even in smokers (eg, race/ethnicity on self-report. use is the Percent of Predicted occupational chronic obstructive As recommended by ACOEM and method, comparing the baseline pulmonary disease, bronchiolitis required by OSHA’s Cotton Dust FEV1% Predicted with the follow- obliterans). Standard,15 a scaling factor of 0.88 up FEV1% predicted, as described in If a possible work-related problem is should be applied to Caucasian pre- Section 4c. identified, consider other at- dicted values and LLNs for FVC and The Percent of Predicted method and risk workers. computerized methods give virtually FEV1 to obtain appropriate reference 6. Recordkeeping values for Asian-American workers. identical results when the length of Spirometry Test Reports: Under most follow-up is less than or equal to 5 to The predicted FEV1/FVC and its OSHA regulations, medical records, LLN are not race-adjusted. 8 years. For longer follow-ups with including spirometry test results, many measurements, ACOEM rec- c. Interpretation Algorithm must be maintained for at least ommends use of the Percent of Spirometry results should always be 30 years following the end of Predicted Method. interpreted in light of the full clinical employment (see 29 CFR ACOEM recommends that a con- 8 picture of the worker. 1910.1020). A recent Letter of firmed FEV decline of 10% to Figure 4 presents a three-step inter- 1 Interpretation on this topic describes 15% since baseline, after allowing the limited amount of information pretation algorithm to use when dis- for the expected loss due to aging, tinguishing normal from impaired that may be given to the employer would trigger further medical evalu- under both the Silica and Respiratory workers. ation in rapidly developing diseases To separate normal from abnormal Protection Standards, stating that with very frequent measurements. these standards ‘‘do not authorize test results, first examine the FEV1/ For short-term follow-ups when high the transfer of spirometry test or FVC to determine whether obstruc- technical quality of testing is main- tive impairment is present, and then other medical records to employ- tained, a computerized algorithm ers.’’16 evaluate the FVC to determine if may be recommended. restrictive impairment may exist. Equipment Maintenance Records: Assumptions that underlie applica- Since spirometer maintenance The FEV1 is examined if the FEV1/ tion of a computerized program must FVC indicates possible obstructive records support the accuracy of the be understood and evaluated for spirometry test results, OSHA rec- impairment, as shown in Fig. 4. appropriateness. NIOSH now recom- All three indices of pulmonary func- ommends saving the equipment cali- mends setting Spirola defaults to be bration check log and information tion are considered abnormal if they consistent with ATS recommenda- th about the spirometer to support the fall below their 5 percentile LLN. tions: 6% within-person measure- Fixed cutoff points for abnormality accuracy of the medical record. ment variability and 30 mL/y Personnel Training and Evaluation such as 80% of the predicted value or expected loss of FEV1 over time.58 an observed FEV /FVC ratio less Records: Records of technician 1 5. Further Evaluation of Spirometric continuing medical education, certif- than 0.70 should not be used in the Abnormalities2 occupational health setting since icates from completed NIOSH- Assess technical quality of spirome- approved spirometry training they are known to cause known false try and repeat testing if indicated positives and false negatives. courses, and results of evaluation based on spirometry quality, and and feedback to technicians should An FEV /FVC that is barely abnor- 1 other relevant information below. be documented and available mal, in the presence of FEV greater 1 Obtain comprehensive medical and for review. than100% of predicted, may indicate occupational history and physical a ‘‘possible physiologic variant’’ in exam including: (a) work, exposure, ACKNOWLEDGMENTS healthy individuals. However, if such and smoking histories; (b) respiratory ACOEM would like to acknowledge healthy workers are exposed to known symptoms, timing in relationship to the invaluable input from several reviewers: respiratory hazards, clinical judgment work; (c) physical exam, including Drs Susan Tarlo, John Hankinson, and Bill is needed to evaluate the possibility of lung exam and chest wall deformities; Eschenbacher, and Kathleen Rogers, RRT, early airways obstruction. and (d) SDSs, results of workplace CPFT. Others too numerous to list also Values that are either just above or measurements, if available. provided valuable input. just below the LLN should be inter- Review preemployment, follow-up preted with caution. questionnaires and spirometry, if REFERENCES 4. Evaluating Results Over Time available. 1. American College of Occupational and Envi- Spirometry results should always be Possible additional diagnostic testing: ronmental Medicine. Spirometry in the occupa- interpreted in light of the full clinical If airflow obstruction, spirometry tional setting. J Occup Enivron Med. 2000; picture of the worker. with bronchodilator response 42:228–245.

ß 2020 American College of Occupational and Environmental Medicine e227

2. Redlich C, Tarlo S, Hankinson J, Townsend MC, 9f55f5b4ad0d8d41f84eeb&mc=true&node=- interpretative strategies. Am Rev Resp Dis. et al. Official American Thoracic Society Tech- se29.6.1910_11043&rgn=div8. Accessed Febru- 1991;144:1202–1218. nical Standards: spirometry in the occupational ary 22, 2020. 32. Haynes JM, Stumbo RW. The impact of using setting. AJRCCM. 2014;189:984–994. Available 16. Occupational Safety and Health Administra- non-birth sex on the interpretation of spirometry at: http://www.thoracic.org/statements/resources/ tion, (OSHA). Letter of Interpretation from data in subjects with air-flow obstruction. eold/OccupSpiromTechStds.pdf. Reprinted with Patrick, J. Kapust to Mary, C. Townsend. Sep- Respir Care. 2018;63:215–218. permission of the American Thoracic Society. tember 18, 2019. Available at: https://www.osh- 33. Al-Hadidi, N, Baldwin JL [2017]. A625 Spi- Copyright ß 2019 American Thoracic Society. a.gov/laws-regs/standardinterpretations/2019- rometry considerations in transgender patients. 3. American College of Occupational and Envi- 09-18. Accessed February 22, 2020. J Allergy Clin Immunol 139(2, Supplement) ronmental Medicine. Evaluating pulmonary 17. NIOSH. Coal Worker Health Surveillance Pro- AB198 (2017 American Academy of Allergy, function change over time. J Occup Enivron gram (CWHSP) Spirometer Manufacturer Asthma, and Immunology (AAAAI) Annual Med. 2005;47:1307–1316. Model Information for, Clinics. Available at: Meeting, Atlanta, GA, March 3-6, 2017). Avail- 4. Townsend MC, Occupational and Environmen- https://www.cdc.gov/niosh/topics/cwhsp/Man- able at: https://www.jacionline.org/article/ tal Lung Disorders Committee. Spirometry in ufModelInfoClinics.html. Accessed February S0091-6749(16)32160-1/pdf. Accessed Febru- the occupational health setting— 2011 update. J 22, 2020. ary 22, 2020. Occup Environ Med. 2011;53:569–84. 18. Learning Curves—Technical Procedures for 34. American Thoracic Society/European Respi- 5. Graham BL, Steenbruggen I, Miller MR, et al. Spirometry in the Occupational, Setting. ratory Society. Interpretative strategies for Official American Thoracic Society and Euro- NIOSH. Video Publication, No. 2017-167. lung function tests. Eur Respir J. 2005;26: pean Respiratory Society Technical Statement: Available at: https://www.cdc.gov/niosh/ 948–968. Standardization of Spirometry 2019 Update. topics/spirometry/videos.html. Accessed Feb- 35. Crapo RO, Morris AH, Gardner RM. Reference AJRCCM. 2019;200:e70–e88. ruary 22, 2020. spirometric values using techniques and equip- 6. American Thoracic Society–European Respi- 19. Graham B, Committee Chair of 2019 ATS/ERS ment that meet ATS recommendations. Am Rev ratory Society: standardisation of lung function Spirometry Statement: Personal Communica- Resp Dis. 1981;123:659–664. testing: the authors’ replies to readers’ com- tion, November, 2019. 36. Knudson RJ, Lebowitz MD, Holberg CJ, Bur- ments. Eur Respir J. 2010;36:1496–1498. 20. Townsend MC. The ATS/ERS 2019 Spirometry rows B. Changes in the normal maximal expi- Available at: http://www.thoracic.org/state- Statement and Occupational Spirometry Testing ratory flow-volume curve with growth and ments/resources/pft/clarification-12-2010.pdf. in the U.S. (Letter to Editor). AJRCCM. 2020. aging. Am Rev Resp Dis. 1983;127:725–734. Accessed February 22, 2020. doi: 10.1164/rccm.201911-2267LE. [Epub 37. American Medical Association. Guides to the 7. American Thoracic Society/European Respira- ahead of print]. Evaluation of Permanent Impairment. 6th edn. tory Society. Standardisation of spirometry. Eur 21. Graham BL, Steenbruggen I. Reply to Arce: On Chicago: American Medical Association; 2008. Respir J. 2005;26:319–338. Available at: the 2019 Spirometry Statement. AJRCCM. 38. Quanjer PH, Stanojevic S, Cole TJ, et al., ERS https://www.thoracic.org/statements/resources/ 2020;201:627. pfet/PFT2.pdf. Accessed February 22, 2020. Global Lung Function Initiative. Multi-ethnic 22. Hankinson JL, Odencrantz JR, Fedan KB. Spi- reference values for spirometry for the 3-95 year 8. Spirometry Testing in Occupational Health Pro- rometric reference values from a sample of the age range: the global lung function 2012 equa- grams: Best Practices for Healthcare Professio- general U.S. population. Am J Resp Crit Care tions. Eur Respir J. 2012;40:1324–1343. nals. Occupational Safety and Health Med. 1999;159:179–187. Administration, OSHA 3637-2013. Available 39. Reference Value Calculator. Available at: http:// at: http://www.osha.gov/Publications/OSH- 23. ISO 26782:2009 Anaesthetic and respiratory www.occspiro.com/RefCal.html. Accessed A3637.pdf. Accessed February 22, 2020. equipment – spirometers intended for the mea- February 22, 2020. surement of time forced expired volumes in 40. Hankinson JL, Kawut SM, Shahar E, Smith LJ, 9. Official American Thoracic Society Technical humans. Available at: http://webstore.ansi.org/ Stukovsky KH, Barr RG. Performance of Amer- Statement: Recommendations for a Standard- RecordDetail.aspx?sku=ISO+26782%3A2009. ican Thoracic Society-recommended spirome- ized Pulmonary Function Report. AJRCCM. Accessed February 22, 2020. 2017;196:1463–1472. Available at: http:// try reference values in a multiethnic sample of www.thoracic.org/statements/resources/pft/ 24. Townsend MC, Hankinson JL, Lindesmith LA, adults: the multi-ethnic study of atherosclerosis standardized-pulmonary-function-report.pdf. Slivka WA, Stiver G, Ayres GT. Is my lung (MESA) lung study. Chest. 2010;137:138–145. Accessed February 22, 2020. function really that good? Flow-type spirometer problems that elevate test results. Chest. 41. American Thoracic Society. Evaluation of 10. Occupational Safety & Health Administration 2004;125:1902–1909. impairment/disability secondary to respiratory [OSHA]. (2016). Regulations (Standards-29 disorders. Am Rev Respir Dis. 1986;133:1205– CFR 1910.1053, 1915.1053, and 1926.1153). 25. American Thoracic Society/European Respira- 1209. tory Society. General considerations for lung Available at: https://www.osha.gov/laws-regs/reg- 42. Global Initiative for Chronic Obstructive Lung ulations/standardnumber/1910/1910.1053, https:// function testing. Eur Respir J. 2005;26:153– 161. Disease (GOLD): Global Strategy for Diagno- www.osha.gov/laws-regs/regulations/standard- sis, Management, and Prevention of COPD number/1915/1915.1053, and https://www.osha.- 26. NIOSH Spirometry Training Course Schedule. (2020 Report). Available at: https://goldcop- gov/laws-regs/regulations/standardnumber/1926/ Available at: https://wwwn.cdc.gov/niosh-rhd/ d.org/. Accessed February 22, 2020. 1926.1153. Accessed February 22, 2020. spirometry/TrainingSchedule.aspx. Accessed February 22, 2020. 43. Hansen JE, Sun XG, Wasserman K. Spirometric 11. OSHA. Standard Interpretations: Who can per- criteria for airway obstruction: use percentage form a pulmonary function test (PFT) in com- 27. Graham BL, Steenbruggen I. Reply to: on the of FEV1/FVC ratio below the fifth percentile, pliance with the Respirable Crystalline Silica 2019 spirometry statement. Am J Respir Crit not < 70%. Chest. 2007;131:349–355. Standards? Available at: https://www.osha.gov/ Care Med. 2019 [Epub ahead of print] Available laws-regs/standardinterpretations/2018-07-30, at: https://www.atsjournals.org/doi/pdf/ 44. Townsend MC. Conflicting definitions of air- Accessed February 22, 2020. 10.1164/rccm.201911-2161LE. ways obstruction: drawing the line between normal and abnormal. Chest. 2007;131:335– 12. 30, CFR. 72 Health Standards for Coal, Mines. 28. Hankinson JL, Eschenbacher B, Townsend M, 336. Available at: https://www.ecfr.gov/cgi-bin/text- Stocks J, Quanjer PH. Use of forced vital idx?SID=af715502f522bc117aebae583e6347- capacity and forced expiratory volume in 1 45. National Institute of Occupational Safety and de&mc=true&node=pt30.1.72&rgn=div5#se30.1. second quality criteria for determining a valid Health (NIOSH). Spirometry Training Guide. 72_1100. Accessed February 22, 2020. test. Eur Respir J. 2015;45:1283–1292. December 1, 2003. Available at: http:// www.cdc.gov/niosh/docs/2004-154c/pdfs/ 29. Medical Surveillance for Flavorings: Related 13. 42 CFR 37 Specifications for Medical Exami- 2004-154c.pdf. Accessed February 22, 2020. nations of Coal Miners. Available at: https:// Lung Disease among Flavor Manufacturing www.ecfr.gov/cgi-bin/retrieveECFR?&- Workers in California 05/12. Available at: 46. Quanjer PH, Weiner DW, Pretto JJ, et al. Mea- n=42y1.0.1.3.21&r=PART&ty=HTML. https://www.cdph.ca.gov/Programs/CCDPHP/ surement of FEF25-75% and FEF75% does not Accessed February 22, 2020. DEODC/OHB/CDPH%20Document%20Li- contribute to clinical decision making. Eur Respir J. 2014;43:1051–1058. 14. Reynolds LE, Wolfe AL, Clark KA, et al. Letter brary/flavor-guidelines.pdf. Accessed February to the editor: strengthening the coal workers’ 22, 2020. 47. Pellegrino R, Brusasco V, Miller MR. Question health surveillance program. J Occup Environ 30. American Thoracic Society. Standardization of everything (Editorial). Eur Respir J. Med. 2017;59:e71. spirometry, 1994 update. Am J Resp Crit Care 2014;43:947–948. Med. 1995;152:1107–1136. 15. Cotton Dust Standard Update: 1910.1043 Cotton 48. Pennock BE, Rogers RM, McCaffree DR. Dust Standard Update. Available at: https:// 31. American Thoracic Society. Lung function test- Changes in measured spirometric indices. What www.ecfr.gov/cgi-bin/text-idx?SID=24c1a801ab ing: selection of reference values and is significant? Chest. 1981;80:97–99.

e228 ß 2020 American College of Occupational and Environmental Medicine

49. Hruby J, Butler J. Variability of routine pulmo- healthy nonsmokers. Am Rev Respir Dis. 60. Department of Health & Human Services, Cen- nary function tests. Thorax. 1975;30:548–553. 1986;133:974–980. ters for Disease Control, National Institute 50. Rozas CJ, Goldman AL. Daily spirometric var- 55. USDHHS, PHS, CDC, NIOSH. Criteria for a for Occupational Safety and Health. HETA iability: normal subjects and subjects with Recommended Standard: Occupational Expo- 2007-0033 Interim Report March 29, 2007. chronic bronchitis with and without airflow sure to Respirable Coal Mine Dust. September Available at: www.cdc.gov/niosh/hhe/reports/ obstruction. Arch Intern Med. 1982;142: 1995. pdfs/2007-0033-letter.pdf. Accessed February 22, 2020. 1287–1291. 56. NIOSH Spirometry Monitoring Technology 51. Nickerson BG, Lemen RJ, Gerdes CB, et al. Web Page. Spirometry Longitudinal Data Anal- 61. ACOEM Position Statement: Confidentiality of Within-subject variability and per cent change ysis (SPIROLA) Software. Available at: Medical Information in the Workplace. 11-06- for significance of spirometry in normal sub- www.cdc.gov/niosh/topics/spirometry/spiro- 2012. Available at: https://acoem.org/acoem/ jects and in patients with cystic fibrosis. Am Rev la.html. Accessed February 22, 2020.57. media/News-Library/Confidentiality-of-Medi- cal-Information-in-Workplace.pdf. Respir Dis. 1980;122:859–866. 57. Townsend MC. Personal Communication. 52. Dawson A. Reproducibility of spirometric April 2019. 62. Occupational Exposure to Respirable Crystal- line Silica 29 C.F.R. § 1910.1053: Frequently measurements in normal subjects. Am Rev 58. CDC—NIOSH: Spirometry Longitudinal Data Respir Dis. 1966;93:264–268. Asked Questions for General Industry. Avail- Analysis (SPIROLA) Software. [Last paragraph able at: https://www.osha.gov/dsg/topics/silica- 53. Berry G. Longitudinal observations: their use- of text before Download bars]. Available at: https:// crystalline/generalindustry_info_silica.html. fulness and limitations with special reference to www.cdc.gov/niosh/topics/spirometry/spirola- Accessed February 22, 2020. the forced expiratory volume. Bull Physiopa- software.html. Accessed February 22, 2020. 63. Occupational Exposure to Respirable Crystal- thol Respir (Nancy). 1974;10:643–656. 59. CDC—NIOSH: Spirometry Quick assessment of line Silica 29 C.F.R. § 1926.1153: Frequently 54. Burrows B, Lebowitz MD, Camllli AE, Knud- longitudinal FEV 1 decline in adults (20-80 years Asked Questions (FAQs) for the Construction son RJ. Longitudinal changes in forced expira- of age). Available at: https://www.cdc.gov/niosh/ Industry. Available at: https://www.osha.gov/ tory volume in one second in adults. topics/spirometry/spirola-quick-calcula- dsg/topics/silicacrystalline/construction_info_- Methodologic considerations and findings in tion.html. Accessed February 22, 2020. silica.html. Accessed February 22, 2020.

ß 2020 American College of Occupational and Environmental Medicine e229

Appendix A

e230 ß 2020 American College of Occupational and Environmental Medicine