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The measurement, by a form of gas meter, of volumes of gas that can be moved in or out of the lungs. The classical spirometer is a hollow cylinder (bell) closed at its top. With its open end immersed in a larger cylinder filled with water, it is suspended by a chain running over a pulley and attached to a counterweight. The magnitude of a gas volume entering or leaving is proportional to the vertical excursion of the bell. Volume changes can also be determined from measurements of flow, or rate of volume change, that can be sensed and recorded continuously by a transducer that generates an electrical signal. The flow signal can be continuously integrated to yield a volume trace.

The volume of gas moved in or out with each breath is the tidal volume; the maximal possible value is the vital capacity. Even after the most complete expiration, a volume of gas that cannot be measured by the above methods, that is, the residual volume, remains in the lungs. It is usually measured by a gas dilution method or by an instrument that measures blood flow in the lungs. Lung volumes can also be estimated by radiological or optical methods.

At the end of an expiration during normal resting breathing, the muscles of breathing are minimally active. Passive (elastic and gravitational) forces of the lungs balance those of the chest wall. In this state the volume of gas in the lungs is the functional residual capacity or relaxation volume. Displacement from this volume requires energy from natural (breathing muscles) or artificial (mechanical) sources. See Respiration



the measurement of the breathing capacity of the lungs. Spirometry was introduced in 1846 by the English scientist J. Hutchison.

Breathing capacity comprises the resting tidal volume of air that moves in and out of the lungs with each breath (approximately 500 cc), the inspiratory reserve volume of air that enters the lungs with maximal inhalation (approximately 1,500 cc), and the expiratory reserve volume of air that emerges from the lungs with maximal exhalation after normal exhalation (approximately 1,600 cc).

The breathing capacity of the lungs is usually measured with a spirometer (see Figure 1), which consists of a water-filled cylindrical tank that contains a floating cylindrical bell (1). The bell is

Figure 1

open at the bottom end and balanced by two counterweights. A rubber connecting tube (2) passes beneath the bottom of the bell. When a person forcefully exhales into the tube after taking a deep breath, the exhaled air forces the interior cylinder to rise. The volume of exhaled air is measured in cm3 according to a calibrated scale (3). Air is released from the spirometer by turning a valve (4).

The spirometer is used in examining healthy persons and in diagnosing and treating diseases of the lungs and cardiovascular system. In recent years spirographs have also been used to measure breathing capacity. Respiratory movements are recorded on spirograms, and breathing capacity is calculated according to special tables.



The measurement, by a form of gas meter (spirometer), of volumes of air that can be moved in or out of the lungs.
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Influence of secular trends and sample size on reference equations for lung function tests. Eur Respir J 2011;37:658-64.
Brusasco et al., "Interpretative strategies for lung function tests," European Respiratory Journal, vol.
The two-year agreement will also allow 200 patients to get the latest lung function test measuring devices - also called pulmonary function tests (PFTs) - free of charge.
without airway obstruction as measured by lung function tests or
A Jaeger Masterscreen pneumotachometer system (Erich Jaeger, Germany), with daily volume calibration as per American Thoracic Society (ATS)/European Respiratory Society (ERS) protocol was used for lung function tests. [16] Ability to perform adequate lung function tests was determined by the child's ability to produce an acceptable flow volume loop according to ATS/ERS criteria.
An official American Thoracic Society workshop report: optimal lung function tests for monitoring cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheezing in children less than 6 years of age.
The Love Your Lungs campaign will offer a chance for those who have had a persistent cough for three weeks or more, or feel breathless or wheezy, to come along to one of sessions taking place in November and speak to respiratory nurses who will provide free advice, information and lung function tests.
Those who attend can speak to the respiratory nurses who will be on hand to provide free advice, information and lung function tests.
Table: Comparison of lung function tests in study and control goups (with and without exercise).
Report Working Party "Standardization of Lung Function Tests", European Community for Coal and Steel," European Respiratory Journal, vol.
Shoppers who have had a persistent cough for three weeks or more, or feel breathless or wheezy are encouraged to speak to the nurses who will provide free advice and lung function tests.