10 steps to checking your spirometry result


Lindsay Zurba - Education for Health Africa, e-mail: linds@educationforhealth.africa

Peter Stanyer - Stanyer Electroserve, e-mail: peter@stanyersa.com


The 10-step process, outlined in Figure 1, ensures that best practices for data ­validation, interpretation and record ­keeping are adhered to in the assessment of every spirometry test. This 10-part ­series briefly outlines each step, one-by-one.

Figure 1. The recommended 10-step process to ensure your spirometry result derives from best practices for data validation, interpretation and record keeping

Figure 2: Examples of unacceptable spirometry flow volume loops when compared to acceptable flow volume loops1




Acceptability is the guideline for checking the performance of each individual blow. The ATS/ERS Guidelines of 2005 suggest that three acceptable manoeuvres should be achieved. An acceptable manoeuvre is one in which the following is achieved:

• An explosive start (no hesitation or sigmoid curve) with a back-extrapolation volume < 150 ml or 5%, whichever is higher

• A maximal inspiration and expiration

• No glottis closure or cessation of airflow (e.g. by hesitation or blocking the mouthpiece)

• No coughs (particularly during the first second), inspirations during the trace, or evidence of leaks

• The end-of-test criteria are met (exhaling for ≥ 6 s with < 50 mL being exhaled in the last two seconds)



When every effort has been made to achieve three acceptable blows, but acceptability criteria have not been met, the technician may assess the tests for usability.

There are two usability criteria:

• The start of the test must be smooth and unhesitating;

• There must be no cough or artefact in the first second of the blow.

Usability criteria should be used with caution. The technician should be sure they have done at least eight blows first. He/she should record why acceptability criteria could not be met. The person interpreting the test is to decide if this blow should be used for interpretation.

The most common reason for inconsistent readings is subject technique. Errors may be detected by observing the subject throughout the manoeuvre and by examining the resultant trace.



1: Johns D, Pierce R. Pocket Guide to Spirometry, 2nd ed: McGraw-Hill Australia; 2007.


Founded 22 years ago, Stanyer Electroserve is a South African-based company that provides sales, service and calibration of audiometers, spirometers and vision screeners, across the African continent. Our technicians have both the experience and the qualifications to assure you the highest quality and standards of service.

We offer a variety of occupational health-related short courses including: 
Spirometry, Audiometry, Vision Screening, Wellness, HIV & Counselling, Health Risk Assessment, Family Planning, Physical Examination and Health Assessment, Occupational Health Auditing Training, Peak Flow.

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