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Device for spirometry. The patient places his or her lips around the blue mouthpiece. The teeth go between the nubs and the shield, and the lips go over the shield. A nose clip guarantees that breath will flow only through the mouth. Screen for spirometry readouts at right. The chamber can also be used for body plethysmography.
A Wiggers diagram modified from [1]. A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century.
The interpretation of tests depends on comparing the patients values to published normals from previous studies. Deviation from guidelines can result in false-positive or false negative test results, even though only a small minority of pulmonary function laboratories followed published guidelines for spirometry, lung volumes and diffusing ...
Bear in mind, however, that this number does not apply to children, and that it can differ depending on the patient's native result; small patient's with pulmonary fibrosis, restrictive lung disease etc. will have a measurably lower FEV1 than healthy average-sized adults. This can give a false positive result of the test.
Lung function development is reduced in children who grow up near motorways [5] [6] although this seems at least in part reversible. [7] Air pollution exposure affects FEV 1 in asthmatics, but also affects FVC and FEV 1 in healthy adults even at low concentrations. [8] Specific changes in lung volumes also occur during pregnancy.
Output of a spirometer. Vital capacity (VC) is the maximum amount of air a person can expel from the lungs after a maximum inhalation.It is equal to the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume.
To interpret the significance of peak expiratory flow measurements, a comparison is made to reference (normal, predicted) values based on measurements taken from the general population. Various reference values have been published in the literature and vary by population, ethnic group, age, sex, height and weight of the patient.
Preconceived notions that 'white' people have greater pulmonary function are embedded in spirometer measurement interpretation and have only been reinforced through this medical stereotyping. In the United States, spirometers use correction factors of 10-15% for those identified as 'black' and 4-6% for those identified as 'Asian.' [ 6 ]