Thamir Al Khlaiwi, Syed Shahid Habib.
Utility of spirometry in assessment of upper airway obstructions: the neglected parameters.
Khyber Med Uni Med J Jan ;15(1):60-5.

Upper airway obstructions represent a huge burden to the health care system due to its high morbidity and cost to the economic systems. Therefore, it is important to understand the physiological parameters used in diagnosis and prognosis of these diseases. Various physiological lung parameters should be examined simultaneously to make the precise diagnosis of upper airway obstruction. Relying on only one parameter and neglecting others might lead to misdiagnosis and subsequent mismanagement. The shape of the flow-volume loop, Forced Expiratory Flow at 50% of vital capacity/Forced Inspiratory Flow at 50% of vital capacity ratio (FEF-50%/FIF-50%), Forced Expiratory Volume in 1 second /Forced Expiratory Volume after 0.5 seconds (FEV1/FEV0.5), Empey index, and the refined version of the Expiratory Disproportion Index (EDI) are of great value in the diagnosis of different types of upper airway obstructions. The shape of the flow-volume loop changes earlier than other spirometrical parameters and is very useful in detecting early changes in upper airway diseases. This review was aimed to explain and simplify the role of pulmonary function tests and flow volume curve not only for pulmonologists, but also for surgeons, anesthesiologists, and ENT specialists who can utilize and implement usefully these tests in their clinical practice.

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