What is Spirometry?
Spirometry measures the volume and speed of air being inhaled and exhaled. It is the most common pulmonary test. Spirometry provides important information vital for the diagnosis and treatment of lung conditions such as asthma, COPD, chronic bronchitis and emphysema.
During a spirometry test, patients will be asked to:
- Sit upright in a chair with legs uncrossed and feet flat on the ground
- Breathe in completely and rapidly
- Pause for less than 1 second
- Place the spirometer mouthpiece in mouth and close lips to form a tight seal
- Breathe out as fast and as hard as possible, until lungs are completely empty, or until unable to blow out any longer
- Breathe in completely and rapidly again
- Remove the mouthpiece
Patients typically need to repeat the test at least three times to get the best result.
- To diagnose or manage asthma
- To measure bronchial responsiveness in suspected asthma
- To diagnose and differentiate between obstructive lung disease and restrictive lung disease
- Unexplained, frequent, and/or persistent dyspnea (shortness of breath) or persistent cough
- Basic preoperative evaluation of lung function if indicated
- To identify those at risk from pulmonary barotrauma while scuba diving
- To diagnose vocal cord dysfunction
- To measure response to treatment of conditions which spirometry detects
- Known or suspected interstitial lung disease or tuberculosis
- Pneumothorax (collapsed lung)
- Haemoptysis (coughing up blood)
- Aneurysms (thoracic, abdominal, or cerebral)
- Cataracts or recent eye surgery
- Nausea, vomiting, or acute illness
- Unstable angina, myocardial infarction or pulmonary embolism in the last month
Asthma & COPD
- Asthma is a disease of the airways. Sometimes it is harder for a person with asthma to breathe in and out, but at other times their breathing is normal. Asthma is a long-term (chronic) disease. If you have asthma, your airways are always inflamed. They become even more swollen and the muscles around the airways can tighten when something triggers your symptoms. This makes it difficult for air to move in and out of the lungs.
- Who develops asthma?
- An estimated 300 million people worldwide suffer from asthma, with 250,000 annual deaths attributed to the disease.
- Asthma is more common in families with allergies or asthma, but not everyone with asthma has allergies.
- Adults of any age can develop asthma, even if they did not have asthma as a child.
- Indoor and outdoor pollution (including mould, gases, chemicals, particles and cigarette smoke) can increase the risk of developing asthma.
- Athletes can develop asthma after very intensive training over several years, especially while breathing air that is polluted, cold or dry.
- Symptoms include: wheezing, shortness of breath, tightness in the chest and coughing.
- Chronic obstructive pulmonary disease (COPD) is a serious, progressive and disabling condition that limits airflow in the lungs. It includes emphysema and chronic bronchitis. People with COPD are prone to severe episodes of shortness of breath, with fits of coughing. The condition mainly affects older people.
- The development of COPD occurs over many years and therefore mainly affects middle aged and older people while asthma affects people of all ages.
- The prevalence (the number of cases present in the population at a given time) of COPD is difficult to determine from routine health surveys. Since COPD is formally defined in terms of an abnormality of lung function, accurately estimating the prevalence of the disease requires clinical testing.
- The only intervention that has been shown to slow the long term deterioration in lung function associated with COPD is assisting smokers to quit. Three other interventions for COPD that can help maintain quality of life are medications, oxygen therapy and pulmonary rehabilitation.
(Sources: World Health Organisation, National Asthma Council Australia, Australian Institute of Health and Welfare)
Typical spirometry parameters include the following
||Forced vital capacity: the determination of the vital capacity from a maximally forced expiratory effort
||Forced expiratory volume : a generic term indicating the volume of air exhaled under forced conditions
||Inspiratory vital capacity: the maximum volume of air inhaled from the point of maximum expiration
||Peak expiratory flow: the highest forced expiratory flow
||Forced expiratory flow: related to some portion of the FVC curve
||Maximal expiratory flow
||Forced expiratory time : the length of the expiration in seconds
||Mean transit time: the area under the flow-volume curve divided by the forced vital capacity.
||Forced inspiratory vital capacity: the volume change of the lung between a maximal expiration to residual volume and a full inspiration to total lung capacity
||Forced inspiratory volume: the volume that can be forcefully inhaled in the first second during a forced inspiratory maneuver started from residual volume
||Peak inspiratory flow
||Forced inspiratory flow: specific measurement of the forced inspiratory curve is denoted by nomenclature analogous to that for the forced expiratory curve
||Vital capacity: the volume of air breathed out after the deepest inhalation
||Inspiratory reserve volume: the maximal volume that can be inhaled from the end-inspiratory level
||Expiratory reserve volume: the maximal volume of air that can be exhaled from the end-expiratory position
||Tidal volume: the amount of air inhaled and exhaled normally at rest
||Positive end-expiratory pressure
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