Respiratory
Division 
Diagnostic Products
Spirometry
Spirometry made Simple
Health Screening
Spirometry is the measurement of choice for diagnosing and evaluating the severity of COPD. It is also the most accurate, simple method for screening lung function. Peak flow measurements may supplement spirometry, but will only detect abnormalities in airflow obstruction and not any restrictive defects.
New patient screening and smokers over the age of 40 years
The most effective time to prevent COPD is before and symptoms appear – when FEV1 per cent predicted is between 70-90% of normal values. By screening smokers over the age of 40 years, or younger if desired, early changes in airflow obstruction may be detected and special emphasis should be made on smoking cessation. Using the Graphs of Fletcher and Peto, it can be explained that the lung function in these patients is likely to deteriorate more rapidly if they continue to smoke. This may result in severe disability in the future. Smoking cessation will lead only to the very slow decline seen in non-smokers and symptoms may never appear.
The routine screening of new patients will, detect any significant abnormality (below 80% predicted) of lung function and focus further investigations to determine the cause and any necessary treatment. In this way a spectrum of lung disorders may be detected at an early stage and subsequent morbidity minimised.
Screening patients with breathlessness
Many patients present to the doctor with shortness of breath or dyspnoea. There can be many causes, but predominantly they are of respiratory or cardiac origins; although anemia, metabolic disorders and psychogenic factors may need to be excluded. Normal spirometry results point to a non-respiratory cause of breathlessness. Conversely, a patient with pulmonary congestion from cardiac failure is likely to have a restrictive lung defect until the cardiac failure is treated.
Patients with previous poliomyelitis or multiple sclerosis may be breathless due to weakness of the respiratory muscles or the diaphragm. Annual spirometric screening is a useful way to detect when difficulty with breathing may be becoming a problem. Patients with diaphragm paralysis are likely to be more affected when in supine position and a large difference between the FVC in the seated and lying position may help to diagnose this condition.
Medicals for employees and occupational screening
Increasingly, spirometry is a requirement for new employees entering a variety of workplaces where fumes or other potentially damaging may be encountered. Once employed. Staff will require annual assessment of lung function to detect and earl developments of an range of occupation lung diseases from asthma to allergic alveolitis.
Healthcare insurance
More comprehensive medical examinations for insurance or health screening will often include measurements of FEV1 and FVC.
Medicals for scuba diving and commercial diving will require assessments of spirometry.
Reference – Fletcher C, Peto J. The natural history of chronic airflow obstruction BMJ 1977, 1645-48
