Port Moresby Medical Laboratories (POMMEDLAB)

Spirometry/Lung Function Testing

What is Spirometry

Spirometry is a quick and simple test of lung function. It is widely used in assessing respiratory function in specialist clinics, emergency departments, occupational safety assessment and sports medicines.

For example, Spirometry is advocated for pre-assignment examination, screening and surveillance of employees for effects of exposure, evaluation of impairment/disability, for relocation in the workplace and for compensation.

What is the Basis of Spirometry?

Spirometry is the measurement of volume and/or flow rate of gas breathed in and/or out of the lungs under the specific condition of maximal effort, according to established criteria and standards. Spirometry apparatuses include volume measuring devices and flow measuring devices.

Who Performs Spirometry?

The person performing Spirometry is usually a medical practitioner, a nurse working in industry, a physiotherapist, a specially trained clinical technologist or some other member of the health care profession.

When do I need Spirometry?

Spirometry provides information on the mechanical properties of the tracheobronchial tree, interstitium of the lung, pleura, chest wall and respiratory muscles. It is important to stress, however, that Spirometry is merely an adjunct that provides quantitative data which must be used in conjunction with other clinical methods. There are 5 general indications for Spirometry:

· identifying the presence of abnormal lung function (asthma/bronchitis/emphysema)

· determining the nature of abnormal lung function (obstructive verse restrictive)

· grading the extent of functional impairment; (mild/moderate/severe asthma)

· monitoring the onset and progression of dysfunction; and evaluating the response to interventions.

· Occupational Spirometry (exposure to inhaled gases/chemicals)

Certain work practices are well-recognized hazards for lung disease. If you work with the following you need pre-employment or regular Spirometry. These include mining, minerals processing, iron and steel founding, brick and ceramics manufacture, cotton and grain milling, plastics, paints and resins manufacture and use, and other occupations involving exposure to free silica, asbestos, isocyanides, anhydrides, animal products etc.

In addition, irritant dusts, fumes and gases produced in a variety of chemical and engineering processes, and jobs such as welding and spray-painting, extend considerably the list of possible respiratory hazards.

 

 

 

 

 

 

 

 

 

 

 

 

Flow-Volume loop showing successful FVC manoeuvre. Positive values represent expiration, negative values represent inspiration. The trace moves clockwise for expiration followed by inspiration. (Note the FEV₁, FEV_1/2 and FEV₃ values are arbitrary in this graph and just shown for illustrative purposes, they must be recorded as part of the experiment).

Objectives of Spirometry in the Workplace

Its main function in the workplace is that of medical surveillance of workers exposed to respiratory hazards.

A medical surveillance programme, using Spirometry, is a planned programme of periodic testing, including pre-placement of workers, in order to detect pre-existing disease, early disease or early deviation from normality. A finding of abnormality may lead to repeating the tests after suitable intervals or after withdrawal from exposure, or to medical referral, counseling or permanent re-deployment in another job. It is chiefly conditions involving airflow limitation that are detectable by such screening. Early signs of lung fibrosis as in pneumoconiosis should be sought by serial radiography.

Medical surveillance also entails the use of abnormal findings, together with exposure histories, to identify hazardous areas, and to assess the effectiveness of engineering controls and work practices. Good records linking results to job or exposure categories are indispensable for this purpose.

Spirometry will also find important use in the clinical setting of diagnosis, management and monitoring of common respiratory diseases, notably asthma and COPD. Tests performed before or after shift, working week or removal from exposure can serve to detect reversible airflow limitation caused by a workplace agent.

Progression of known fibrotic lung disease such as pneumoconiosis can also be monitored through its effect on vital capacity.

Lung function testing may be a key part of a smoking cessation programme, by drawing visible attention to the effects of smoking, and by identifying susceptible smokers on whom effort can be concentrated.

Who must be included in a Spirometry Programme

The only way to decide which employees must be included in the programme is to conduct a thorough, integrated health risk assessment (HRA). A HRA is a complete assessment of the occupational health risks to all employees in the workplace, based on actual and potential health and safety risks at the workplace. Ongoing HRA in the workplace should be conducted by a properly qualified person or group, ideally by an approved inspection authority (in terms of the Occupational Health and Safety Act). The HRA will elucidate the respiratory health risks, if any, faced by individuals and groups of workers. The degree of risk, the intrinsic nature of exposures and known health effects will help to determine the type of Spirometry programme.

Ongoing HRA determines who to include in the Spirometry programme. Workers who face no respiratory health risk arising from the workplace may still be included e.g. smokers and individuals with chronic respiratory disease.