Welch Allyn PneumoCheck Operating Instructions Manual page 22

SPECIAL NOTES:
A normal spirometry test does not preclude the existence of
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lung cancer or the very early stages of many of the restrictive
lung disorders.
If both the FEVl and FEVl/FVC ratio are normal, some
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pulmonary specialists will examine the FEF 2575% (MMEF).
If it is low, the patient may have a 'slight obstruction.' There is
some controversy regarding this variable and its clinical
significance in indicating small airways dysfunction.'
It is risky to attempt the interpretation of results when
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acceptable and reproducible maneuvers were not obtained.
To do so may yield false positive results.
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