Spirometry in primary care

A good reading requires co-operation from the patient. By Jane Scullion and Dr Steve Holmes.

Ensure there is a good seal around the mouthpiece (Photograph: SPL)
Ensure there is a good seal around the mouthpiece (Photograph: SPL)

Over the past 10 years, more GP practices have started to perform spirometry. With an emphasis on early and accurate diagnosis of asthma and COPD, competency in spirometry is ever more important.

The clinician can then recommend pulmonary rehabilitation if appropriate and instigate pharmacological interventions to improve symptoms and quality of life.

When choosing a spirometer for the practice, consider factors such as ease of use, reproducibility of results, price and running costs. The calibration requirements and how the spirometer interfaces with other clinical software are also worth considering.

A normal flow volume loop has a rapid peak expiratory flow rate with a gradual decline in flow back to zero. The inspiratory portion of the loop is a deep curve plotted on the negative portion of the flow axis. Inspiratory data can be undertaken but is often overlooked.

Spirometry should be used in conjunction with a history and examination. When undertaking spirometry adequate training and familiarity with the equipment is vital. Equipment needs to be well maintained and accurate and the patient's recent history, including food intake, recent flare ups or infections, and recent medication history should all be recorded.

Patient co-operation
Spirometry results are user and operator dependent. A good spirometry reading is highly dependent on patient co-operation and effort, and is normally repeated at least three times to ensure reproducibility. Record if it has been difficult for a patient to co-operate.

It is important to highlight this as often clinicians look back at results produced to check for trends. Due to the patient cooperation required, spirometry can only be used on children old enough to comprehend and follow the instructions given (typically about 7-8 years old).

As there is a normal age- related decline in the FEV/FVC ratio, elderly patients without airway obstruction will often have a ratio below 70-80 per cent so it is important to combine the procedure with a good history.

Despite being an easy test, spirometry can be unreliable and confusing if performed incorrectly. Spirometry can be part of a bronchial challenge test, but concerns have been expressed about the quality of spirometry in primary and secondary care. It is vital that the primary care team is trained in undertaking and interpreting spirometry.

Systems must be developed to ensure spirometry is readily available and reliably undertaken in order to optimise care for patients with respiratory conditions.

  • Ms Scullion is a respiratory nurse consultant at the University Hospitals of Leicester and Dr Holmes is a GP in Somerset and education lead for the Primary Care Respiratory Society
  • This is an abbreviated version of a previously published article
The spirometry procedure

1. Explain the procedure to the patient.

2. Enter data into the spirometer (height/weight/date of birth/gender/ethnicity/recent history). Record recent history and medications taken.

3. Attach a new disposable mouthpiece or a bacterial filter if there is any risk of infection.

4. Ask the patient to sit comfortably and loosen any restrictive clothing.

5. Ensure there are no contraindications to performing procedure.

6. Use a nose clip or allow patient to pinch their nose.

7. Instruct patient to breathe in and out normally then take a deep breath in and then to blow out slowly into the mouthpiece until empty. This is a slow (relaxed) manoeuvre and is good practice for the forced manoeuvre and prevents sudden collapse of the small airways which can occur with a forced manoeuvre.

8. Instruct the patient to breathe in and out normally and then to take the biggest breath in until full, and then while holding their breath, to seal their lips tightly around the mouthpiece and then to blow out hard and fast until empty.

9. Encourage patient through the procedure and watch that the blows are good, there are no coughs and that there is a good seal around the mouthpiece. Look for a smooth tracing and a plateau on the tracing.

10.Continue until repeatability standards have been reached - this means that the two largest FEV1 and FVC (or other VC) readings must be within 150ml of each other.

11. Ensure that the result is saved and printed. Dispose of mouthpiece. Discuss the results or arrange a follow-up with the relevant clinician to discuss further.

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