Asthma is a common chronic inflammatory lung disease, which can be controlled but not cured. Asthma is defined by the presence of both the following:

• Excessive variation in lung function (variable airflow limitation e.g. variation in expiratory airflow that is greater than that seen in people without asthma)
• Respiratory symptoms (e.g. wheeze, shortness of breath, cough, chest tightness) that vary over time and may be present or absent at any point in time

The underlying pathophysiology involves airway hyper-responsiveness and intermittent airway narrowing due to bronchoconstriction, small airway oedema, mucus hypersecretion, smooth muscle hypertrophy and epithelial desquamation.

The prevalence of asthma in Australia is relatively high, by international standards. 11% of the Australian population has asthma — about 1 in 10 adults and about 1 in 9 or 10 children.

Asthma is more common in Aboriginal and Torres Strait Islander peoples. 16% of Aboriginal and Torres Strait Islander people have asthma. The prevalence is 1.6 times that in non-indigenous Australians.

Asthma tends to be more prevalent in people living in lower socioeconomic areas.

There is a strong link between asthma and allergy and asthma and allergic rhinitis.

Asthma is more common in people with a family history of asthma.

Despite the known additional health risks, just as many non-smokers have asthma as smokers.

It is sometimes be difficult to distinguish between asthma and chronic obstructive pulmonary disease (COPD).

There is no 'gold standard' for the diagnosis of asthma. The diagnosis of asthma is based on history, physical examination, considering other diagnoses and documenting variable airflow limitation.

Spirometry is the lung function test of choice for diagnosing asthma and for assessing asthma control in response to treatment.Young children cannot perform spirometry. Spirometry can usually be performed from age 6 years and older.

A diagnosis of asthma can be made in an adult when:

• The person has variable symptoms (especially episodes of cough, chest tightness, wheeze and shortness of breath)
• Variable airflow limitation is demonstrated on spirometry
• There are no findings that suggest an alternative diagnosis.

It can sometimes be difficult to differentiate between asthma and COPD and there can sometimes be overlap in older adults.

A normal physical examination does not exclude asthma.

Spirometry should be performed by trained staff using calibrated equipment.

Before an appointment for spirometry is booked:

• Patient should be advised to bring their own spacer and reliever
• Without bronchodilators as per Spirometry Quick Reference Guide - a guide to performing high quality spirometry National Asthma Council

The staff member should:

• Check spirometer is set up correctly and perform calibration
• Attach disposable filter and mouth piece
• Enter patient information:
  • Height
  • Weight
  • Date of birth
  • Sex at birth
  • Ethnicity
  • Smoking status
• Record time patient last used bronchodilator
• Give clear instructions and demonstrate correct postures and process
• Explain to patient that they will need to repeat the process at least 3 times to get a reliable result (maximum 8).
• Offer a nose clip for patient to use (recommended but not essential)

For open circuit method, which measures expiration only, the patient should:

• Sit upright with feet firmly on the floor and not lean forward
• Breathe normally for 2-3 breaths
• Breathe in rapidly and deeply to completely fill their lungs
• Put the mouthpiece in their mouth and close their lips, forming a good seal Without pausing for more than 2 seconds, blast air out as hard and fast as possible and for as long as possible, until the lungs are completely empty. They need to keep blowing until they cannot blow any more.
• Remove mouth piece
• Breathe normally and relax

Acceptable blows must be smooth continuous expiration of maximal lung volume:

• Expiration been performed with a good start, without coughing
• Forced expiration has been maintained throughout the test

Repeat the test until you obtain three reproducible and acceptable measures, where:

• The 2 largest values for FVC should be within 150 mL of each other
• The 2 largest values of FEV1 should be within 150 mL of each other.

Testing is complete when acceptability and reproducibility criteria are met. 8 is the maximum number of trials in adults.

Recording the results

Record the best forced expiratory volume in one second (FEV1) and FVC obtained.

Assessing for reversibility

• Perform baseline spirometry as per above instructions
• Administer bronchodilator- use patient's own inhaler and spacer
  • give four separate doses of salbutamol 100 mg via a metered-dose inhaler (MDI) and large-volume spacer. (A large-volume spacer is more efficient.)
• Wait 10-15 minutes
• Repeat spirometry
  • Repeat the test until you obtain three reproducible and acceptable measures, where:
    • The 2 largest values for FVC should be within 150 mL of each other
    • The 2 largest values of FEV1 should be within 150 mL of each other.
  • Testing is complete when acceptability and reproducibility criteria are met. 8 is the maximum number of trials in adults.

Recording the results post-bronchodilator and calculate reversibility

Record the best forced expiratory volume in one second (FEV1) and FVC obtained post-bronchodilator.

Calculate percentage and absolute increase in FEV1

Airflow limitation is judged to be reversible if either of the following applies:

• Baseline FEV1 >1.7 L and post-bronchodilator FEV1 at least 12% higher than baseline
• Baseline FEV1 ≥1.7 L and post-bronchodilator FEV1 at least 200 mL higher than baseline

Results should be expressed as absolute values and also as a percentage of predicted values, based on the patient's age, height and sex.

National Asthma Council (2020). Spirometry. Asthma Management Handbook.
Visit website

National Asthma Council Australia. (2020). Spirometry quick reference guide.
View guide

Medicare billing:

To claim a 11505 to diagnose asthma, spirometry must be recorded both pre and post bronchodilator. This can only be claimed once in a 12-month period.

MBS Online: 11505
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In an Australian study, 75% patients using an inhaler for an average of 2–3 years reported they were using their inhaler correctly but, on objective checking, only 10% demonstrated correct technique. (*1)

To help patients use their inhaler correctly:

• Ensure your own knowledge of inhaler technique is up-to-date
• Ensure inhaler is appropriate for the patient
• Ask the patient to bring in their devices and observe their technique
• Give patients verbal instructions (not just a leaflet)
• Give a physical demonstration (placebo devices are often available in practices or, if not, from pharmacies and drug representatives)

Be aware of common errors for each type of inhaler
e.g. Keep chin up and inhaler upright (not aimed at roof of mouth or tongue)

• Ask about use of complementary medicines and advise patients about potential hazards.
• Encourage a good therapeutic partnership with the patient by asking the patient use of complementary therapies in an open, non-judgemental approach.
• There is insufficient evidence to support complementary therapies as asthma treatments and in some cases insufficient safety data.
• Some complementary medicine such as royal jelly may cause severe reactions and should be used with caution in asthmatics.

Penny is already on high-dose inhaled corticosteroid (ICS) medication. ICS medications have a flat dose-response curve; increasing the dose at the top end of the curve produces relatively small improvements in lung function.

Consider adding a long-acting beta₂agonist (LABA) to a medium-dose ICS before using a high-dose ICS for uncontrolled asthma. The dose for Penny would be salmeterol 50 micrograms twice a day, or eformoterol 12 micrograms twice a day.

As Penny has not achieved control with a high dose ICS, it would be important to assess other factors that may be contributing:

• We have discussed checking technique and triggers.
• Has there been a recent viral exacerbation? If so, consider a course of oral steroids.
• Are her symptoms really due to asthma or could they be due to GORD or anxiety?

Before considering stepping up, check:

• Symptoms are due to asthma
• Inhaler technique is correct
• Adherence is adequate
• Trigger avoidance is being attempted

Consider stepping up if good control is not achieved.

When asthma is stable and well controlled for 2-3 months, consider stepping down (e.g. reducing inhaled corticosteroid dose, or stopping long-acting beta₂agonist if inhaled corticosteroid dose is already low).