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Average values for FEV1 in healthy people depend mainly on sex and age, according to the diagram. Values of between 80% and 120% of the average value are considered normal. [14] Predicted normal values for FEV1 can be calculated and depend on age, sex, height, mass and ethnicity as well as the research study that they are based on.
In obstructive lung disease, the FEV1 is reduced due to an obstruction of air escaping from the lungs. Thus, the FEV1/FVC ratio will be reduced. [4] More specifically, according to the National Institute for Clinical Excellence, the diagnosis of COPD is made when the FEV 1 /FVC ratio is less than 0.7 or [8] the FEV 1 is less than 75% of predicted; [9] however, other authoritative bodies have ...
Online calculators are available that can compute predicted lung volumes, and other spirometric parameters based on a patient's age, height, weight, and ethnic origin for many reference sources. British rower and three-time Olympic gold medalist Pete Reed is reported to hold the largest recorded lung capacity of 11.68 litres; [ 16 ] [ 17 ] [ 18 ...
The difference between the highest values of two FVCs need to be within 5% or 150 mL. When the FVC is less than 1.0 L, the difference between the highest two values must be within 100 mL. Lastly, the difference between the two highest values of FEV1 should also be within 150 mL. The highest FVC and FEV1 may be used from each different test.
For this reason, tables or charts are used to determine the normal value for a particular individual. More recently, medical calculators have been developed to calculate predicted values for peak expiratory flow. There are a number of non-equivalent scales used in the interpretation of peak expiratory flow.
The positive predictive value (PPV), or precision, is defined as = + = where a "true positive" is the event that the test makes a positive prediction, and the subject has a positive result under the gold standard, and a "false positive" is the event that the test makes a positive prediction, and the subject has a negative result under the gold standard.
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 ]
TLC: Total lung capacity: the volume in the lungs at maximal inflation, the sum of VC and RV. TV: Tidal volume: that volume of air moved into or out of the lungs in 1 breath (TV indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation, the symbol TV or V T is used.)