The 2019 ATS/ERS Spirometry Standards were recently released. The standards are open-access and can be downloaded without charge from the October 15^th issue of the American Journal of Respiratory and Critical Care Medicine. Supplements are available from the same web page.

The 2019 Spirometry Standards have been extensively re-organized with numerous updates. Notably, a number of sections that were previously discussed in the 2005 General Considerations for Lung Function Testing have been updated and included in the 2019 Spirometry Standards. Also notably, a number of stand-alone spirometry tests, including the Flow-Volume Loop, PEF and MVV are not included in the 2019 Standards.

An overview of changes and updates from the 2005 Spirometry Standards are detailed within the 2019 Spirometry Standards (page e71, column 1, paragraph 2) and in the Data Supplement (pages E2-E3). In more detail these include:

◆ The list of indications for spirometry (page e73, table 1) was updated primarily with changes in language.

• “To measure the effect of disease on pulmonary function” was updated to “To measure the physiological effect of disease or disorder”
• “To describe the course of diseases that affect lung function” was updated to “To monitor disease progression”
• “To monitor people exposed to injurious agents” was updated to “To monitor people for adverse effects of exposure to injurious agents”

◆ Items added to indications:

• “Research and clinical trials”
• “Preemployment and lung health monitoring for at-risk occupations”

◆ Contraindications were previously mentioned in the 2005 General Considerations rather than the 2005 Spirometry Standards and these have been extensively updated and expanded. Although the list of contraindications (page e74, table 2) is fairly inclusive (and should be reviewed by all concerned) there were items mentioned in the body of text that were not in the table:

• “Spirometry should be discontinued if the patient experiences pain during the maneuver.”
• “…because spirometry requires the active participation of the patient, inability to understand directions or unwillingness to follow the directions of the operator will usually lead to submaximal test results.”

◆ Notably, abdominal aortic aneurysm (AAA) was not included as a contraindication in the 2019 standards. (page e72, column 3, paragraph 1)

◆ “Ambient temperature, barometric pressure, and time of day must be recorded.” (page e72, column 3, paragraph 2) This was mandated in the 2005 General Considerations and is now included in the 2019 Spirometry Standards.

◆ Patient testing considerations (page e72, column 3, paragraph 3) have been expanded and now includes:

• “Testing should preferably occur in a quiet and comfortable environment that is separated from the waiting room and other patients being tested.”
• “Drinking water should be available. Tissues or paper towels should be offered to help patients deal with secretions.”
• “A smaller chair or a raised footstool should be provided for children and small adults.”

◆ The effects of testing in different positions is discussed (page e73, column 1, paragraph 1) and “If testing is undertaken with the patient in another position, this must be documented in the report.”

◆ Although mentioned in the 2005 General Considerations (pages 155-157) an abbreviated version of hygiene and infection control has been included in the 2019 Spirometry Standards (page e73, column 1, paragraph 1 and page e78, table 6).

◆ Spirometer specifications must meet ISO 26782 standards. (page e73, column 3, paragraph 3) There are however, no significant differences in spirometer accuracy (± 3%) from the 2005 Spirometry Standards. However the 2005 Spirometry Standards noted that “if the [calibration] syringe has an accuracy of 0.5%, a reading of ±3.5% is appropriate whereas in the 2019 Spirometry standards it is assumed that it is a “±3% accuracy tolerance, ±2.5% for spirometers plus ±0.5% for calibration syringes”.

◆ The specifications for digitization of analog flow or volume signals are higher than the 2005 Standards (“…sampling rate must be ≥100 Hz with a minimum resolution of 12 bits.”, (page e74, column 1, paragraph 1)). This sampling rate was indirectly specified in the proposed reporting format in the 2005 Spirometry Standards (page 335, column 1, paragraph 2) but was not specifically part of the spirometry equipment requirements.

◆ Manufacturers are now required to provide an alert if a calibration is ± 2SD from the mean calibration factor or ± 6% from the previous calibration factor (page e75, column 1, paragraph 2).

◆ A summary of mandated alert signals is included in the Data Supplement (pages E30-E31).

◆ Quality assurance now includes the statement “Precalibrated spirometers cannot be recalibrated by the operator but must still undergo a calibration verification. Manufacturers must specify the action to be taken if a precalibrated device fails the calibration verification.” (page e75, column 1, paragraph 1)

◆ Quality assurance now includes the statement “Spirometry software must include the ability to generate a report of calibrations that includes the results of all verifications, the number of failed calibration verifications in each session, and the changes in calibration factors.” (page e75, column 1, paragraph 1)

◆ The 2019 Standard mandates that “The spirometry system must determine the zero-flow level with the spirometer blocked before calibration, calibration verifications, and patient tests.” (page e75, column 1, paragraph 3). Zero-flow levels were not discussed in the 2005 Standards.

◆ Quality assurance now includes “Verification of reference value calculations after software updates”. (page e74, table 3)

◆ Biological QC is mentioned (page e75, column 2,paragraph 3) but it is also indicated that “A biological control is not a substitute for the use of a calibration syringe.” and that “In some jurisdictions, including a biological control in quality control reporting may constitute a breach of employee privacy protection.”

◆ Age must now be reported in years to one decimal point. Height must now be reported in centimeters to one decimal point. Weight must now be reported in kilograms to the closest 0.5 kg. (page e75, column 3, paragraph 2)

◆ Estimating height from arm span or ulna length with reference equations is discussed in the Data Supplement. (pages E27-E28).

◆ Patient details now includes the statement “In persons aged 25 years or older, for whom a reliable height measurement has been made previously in the same facility, remeasuring height at subsequent visits within 1 year may not be necessary.” (page e75, column 3, paragraph 2)

◆ Patient details now includes a statement acknowledging transsexual / transgender patients: “When requesting birth sex data, patients should be given the opportunity to provide their gender identity as well and should be informed that although their gender identity is respected, it is birth sex and not gender that is the determinant of predicted lung size. Inaccurate entry of birth sex may lead to incorrect diagnosis and treatment.” (page e75, column 3, paragraph 3)

◆ In the 2005 Standards the only smoking was indicated as an activity that should be avoided prior to testing (page 327, column 3, paragraph 3). The 2019 Standards indicates a number of additional activities that should be avoided prior to testing (page e77, table 5).

◆ Like the 2005 Spirometry Standards, the 2019 Spirometry Standards notes “Well-fitting dentures are usually left in place.” but also notes that “…a larger 2018 study found that FVC was an average of 0.080 L higher when dentures were removed” (page e76, column 2, paragraph 2)

◆ The FVC maneuver now includes a fourth phase “inspiration at maximal flow back to maximum lung volume” not present in the 2005 Standards. (page e76, column 3, paragraph 3)

◆ Expiratory time is now either until EOT (End of Test) criteria has been met or when the expiratory reaches 15 seconds. The 2005 Spirometry Standard of “…and the subject has tried to exhale for ≥3 s in children aged >10 yrs and for ≥6 s in subjects aged >10 yrs” no longer applies. (page e77, column 1, paragraph 2)

◆ The 2019 Standard now mandates that “The spirometry system must signal the operator when a plateau has been reached or forced expiratory time (FET) reaches 15 seconds.” (page e77, column 1, paragraph 2)

◆ The 2019 Spirometry Standard now indicates that “With appropriate coaching, children as young as 2.5 years old with normal cognitive and neuromotor function are able to perform acceptable spirometry” (page e77, column 2, paragraph 3) whereas the 2005 Standard stated “children as young as 5 yrs of age are often able to perform acceptable spirometry”.

◆ The back-extrapolation method has been updated to “At the point of PEF on the volume–time graph, a tangent is drawn with a slope equal to PEF, and its intersection on the abscissa defines Time 0, which becomes the start for all timed measurements.” (page e77, column 3, paragraph 4)

◆ Extrapolated Volume (EV) has been updated to Back Extrapolated Volume (BEV). (page e77, column 3, paragraph 4)

◆ The minimum acceptable level of back extrapolation has been updated to “<5% of the FVC or 0.100 L, whichever is greater” from “<5% of the FVC or 0.150 L, whichever is greater” (page e77, column 3, paragraph 4)

◆ Hesitation time, which is not mentioned in the 2005 Standards and is “…defined as the time from the point of maximal inspiration to Time 0, should be 2 seconds or less” (page e77, column 3, paragraph 4)

◆ End of Test (EOT) acronym has been replaced with End of Forced Exhalation (EOFE). (page e78, column 2, paragraph 1)

◆ EOFE is considered acceptable when an expiratory time of 15 seconds has been reached. Test equipment must acknowledge this expiratory time with a double beep. (page e78, column 3, paragraph 2)

◆ EOFE is considered acceptable when “The patient cannot expire long enough to achieve a plateau (e.g., children with high elastic recoil or patients with restrictive lung disease). In this case, the measure of whether EOFE has been reached is for the patient to repeatedly achieve the same FVC.” (page e78, column 3, paragraph 3)

◆ The 2019 Spirometry standards include a discussion of the criteria differences between acceptability and usability of spirometry efforts. (page e79, table 7)

◆ The 2019 Spirometry Standards notes “Maneuvers that do not meet any of the EOFE acceptability criteria will not provide acceptable FVC measures. However, an acceptable FEV1 measurement may be obtained from a maneuver with early termination after 1 second.” (page e79, column 1, paragraph 2)

◆ The 2019 Spirometry Standards includes the FIVC in the assessment of the FVC. Specifically “If the volume of the maximal inspiration (i.e., FIVC) after EOFE is greater than FVC, then the patient did not start the maneuver from TLC. FEV1 and FVC measurements from a maneuver with FIVC-FVC > 0.100 L or 5% of FVC, whichever is greater, are not acceptable.” (page e79, column 3, paragraph 2)

◆ The 2019 Standards indicates that “The spirometry system software must provide explicit feedback to the operator indicating FEV1 and FVC acceptability at the completion of each maneuver.” (page e80, column 2, paragraph 2) This was suggested in the 2005 Standards but was not mandatory.

◆ The 2005 Standards included repeatability criteria based on FVC volume (“For those with an FVC of 1.0 L, both these values [the difference between the largest and next largest FVC and FEV1] are 0.100 L (page 325, column 1, paragraph 7)). The 2019 standard uses this repeatability criteria for ages ≤ 6 years, but not for any value of FVC. (page e80, column 3, paragraph 2)

◆ Both the 2005 and 2019 Spirometry Standards indicate that the maximum number of FVC maneuvers in adults should be eight. The 2019 Standards, however, suggests that “When testing children, more than eight attempts may be required because each attempt may not be a full maneuver.” (page e81, column 1, paragraph 1)

◆ The list of medications that should be withheld prior to reversibility testing has been updated with significantly different withholding times. (page e82, table 8).

◆ Recommended reversibility testing protocols are detailed in the Data Supplement (pages E32-E35).

◆ The 2005 Spirometry Standard discussed a variety of values that could be reported whereas the 2019 Standard mandates those that must be reported (page e82, table 9)

◆ The 2019 Spirometry Standard requires that FIVC be reported. (page e82, table 9).

◆ The selection and limitations of FEF25-75 is discussed in the 2019 Standards. (page e82, column 2, paragraph 2)

◆ The 2019 Standards recommends that the 2017 ATS reporting standards and the GLI reference equations be used for reporting spirometry results. (page e82, column 3, paragraph 2)

◆ The 2005 Spirometry Standards included a section on performing a flow-volume loop as a maneuver separate from spirometry (pages 326-328). The 2019 Standards mandates that the flow-volume loop is an integral part of spirometry. (page e82, column 3, paragraph 2)

◆ The 2005 Standards includes a section on normal and abnormal flow-volume loops with 7 examples (pages 327-328). This was not present in the 2019 Standards. Flow-volume loop examples are included in the Data Supplement (pages E4-E20).

◆ The 2019 Spirometry standards suggests but does not mandate that reports should be exported as a .PDF file and that data should be exported using the Clinical Document Architecture Release 2 standard of HL7 International or Fast Healthcare Interoperability Resources. (page e82, column 3, paragraph 2)

◆ Database elements are mandated and detailed in the Data Supplement (pages E35-E38). The ability to export data in .XML format is mandated.

◆ The date and time for each maneuver must be recorded ((page e82, column 3, paragraph 3)

◆ The 2019 Standard suggests that all reported spirometry efforts be graded by repeatability. (page e83, table 10) (page e83, column 1, paragraph 2)

◆ The stability of tidal breathing prior to a slow VC maneuver is defined and its effect on IC is discussed in the 2019 Standards (“Stability is defined as having at least three tidal breaths with end-expiratory lung volume within 15% of the VT”). (page e84, column 1, paragraph 2). This was not previously discussed in the 2005 Standards.

◆ The 2019 Standards mandates that during a slow VC maneuver “The test system must provide both a visual and an audible signal (single beep) when a stable end-expiratory tidal lung volume is detected or there have been 10 tidal breaths…” (page e83, column 1, paragraph 3)

◆ The 2019 Standards also mandates that during a slow VC maneuver the test system must provide “…for expiration to RV in either IVC or EVC maneuvers, a double beep when a plateau is reached (≤0.025 L in the last second) or the expiration time reaches 15 seconds.” (page e83, column 2, paragraph 1)

◆ The 2005 Standards included the procedure for PEF testing (pages 330-331). This was not discussed in the 2019 Standards.

◆ The 2005 Standards included the procedure for MVV testing (page 331). This was not discussed in the 2019 Standards.

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This is a welcome update to the previous 2005 ATS/ERS Spirometry Standards. Many deficiencies in the prior Standards have been corrected and the new standards are more pertinent to the current level of technology. As usual, it will probably take a while before the existing software is updated to reflect the new standards and in some cases this may never occur.

I was particularly pleased to see a discussion concerning the acceptability and usability of spirometry efforts. A spirometry effort does not have to be acceptable to be able to provide clinically useful information.

Although the selection criteria for reported results (largest FVC and largest FEV1 from any acceptable effort) has not changed from the 2005 Standards (which is okay) there was no discussion on how to indicate that reported results are a composite nor how to link graphical results (flow-volume loops and volume-time curves) to composite efforts nor how to select other values (such as PEF) for a composite result.

I would have liked to see some movement in the Standards towards performing FEV1 and VC maneuvers separately. Interestingly this was discussed very briefly in the 2005 Standards (page 326, column 2, paragraph 3) but I could find no similar discussion in the 2019 standards.

Although ethnicity was discussed in the Data Supplement (page E29) I would have liked to see a more in-depth discussion. Ethnicity was acknowledged by both the 2005 and 2019 Standards as being critical to the selection and use of reference equations but the guidelines are somewhat vague and many ethnicities are not represented in existing reference equations.

I am slightly disappointed that the technical requirements for spirometry systems has not changed from the 2005 Standards. This however is probably realistic since measuring the flow and volume of exhaled air is technically quite difficult and we’ve likely reached a plateau in our ability to do this.

Despite all this I am pleased overall with the 2019 Standards. They are a distinct step forward and should be welcomed by all.

References:

Brusasco V, Crapo R, Viegi G. ATS/ERS task force: standardisation of lung function testing: General considerations for lung function testing. Eur Respir J 26: 153-161.

Brusasco V, Crapo R, Viegi G. ‘‘ATS/ERS task force: standardisation of lung function testing: Standardisation of spirometry. Eur Respir J 2005; 26: 319-338.1

Culver BH, Graham BL, Coates AL, et al. Recommendations for a standardized pulmonary function report. Am J Respir Crit Care Med 2017; 196(11): 1463-1472

Graham BL, et al. Standardization of Spirometry 2019 Update. Am J Respir Crit Care Med 2019; 200 (8): e70-e88.