Spirometry – what is it and what is it for?

By Priya Pattni Clinical Physiologist (Post-grad CRFS)
Spirometry is a primer for decision makers in respiratory care. Just as hypertension cannot be diagnosed without measuring blood pressure, lung problems should not be diagnosed without spirometry testing. Spirometry is a valuable tool to evaluate any unexplained breathlessness/wheeze, abnormal chest x-ray, query of effect of medication or simply as a follow up for asthma or COPD, or to diagnose, screen or monitor lung disease.
Spirometry testing has widely come into practice since the 1970s. It is a simple, non-invasive and affordable breathing test. Spirometry is an essential tool to assess volume and how well the lungs ventilate. In addition, it is a convenient tool used for monitoring, screening and diagnosing respiratory issues. It measures the effects of occupational and environmental exposure on lung function. For instance, spirometry is helpful when there is shortness of breath, reduced breath sounds, abnormal chest x-ray or to measure effect of disease on the lungs.
Spirometry is a manoeuvre that is performed forcefully and rapidly. It requires the patient to be able to coordinate instructions in a timely manner, be fit enough to sit up straight and have energy for the hard and fast breathing test. This should not be mistaken for incentive spirometry or breathalyser test that are done slowly. The patient takes a big breath in and then instantly, forcefully 'blasts' the air out and keeps breathing out until he or she cannot or should not breath any further, then takes a rapid deep breath in at the end. The resultant is displayed as a flow-volume loop and a volume time graph.
The measurements obtained through this are used to assess information on airflow resistance created by airway obstruction if present. In addition, the patterns of the graph achieved through the manoeuvre are also clinically important in recognising some lung pathological abnormalities. This is one of many assessments made from the spirometry test results.
Some of the contra indications to consider when performing this test include any recent major surgery, eye surgery, unstable cardiac/angina status, haemoptysis or acute illness like nausea/vomiting.
Testing techniques, equipment and patient manoeuvres have become widely standardised throughout the world through efforts of professional societies. Advancements in computer technology have improved the ease of use and portability of the spirometers. Despite this, it is crucial for the equipment to be maintained and used within the standards established.
These days spirometry is undertaken by many health care and allied health care professionals. However, the usefulness of spirometry relies on the proficiency of the operator. Currently Asthma Waikato conducts spirometry testing approximately every second Saturday at Tui Medical Centre in Rototuna, Hamilton by a qualified clinical physiologist.
Talk to your GP about whether a referral to Asthma Waikato for a spirometry is right for you.


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