Forced expiratory volume in one second FEV

Single dose or short-term treatment with aerosolized steroids inhibits both the late asthmatic response and allergen-induced bronchial hyperresponsiveness (45,92). However it does not affect the early asthmatic response nor does it induce bronchodilation (45,92). Long-term treatment with steroids protects against both the early and late asthmatic responses and also reduces bronchial hyperresponsiveness (44,71,86,93). Over time, the airways relax (dilate) and measures of airway function, such as forced expiratory volume in one second (FEV ), gradually return to almost normal levels. 

If the effect of a given treatment for asthma is to increase forced expiratory volume in one second (FEV ) 12 hours after treatment by 300 ml above what it would have been without treatment, (whatever it would have been), then the treatment is additive on the FEVi scale. If it increases FEV by 15%, however, then while it increases a value which would have been 2000 ml by 300 ml, it only increases a value which would have been 1500 ml by 225 ml, and one which would have been 1000 ml is only increased by 150 ml, Thus, treatment is not additive on the FEV scale. However, if we take logarithms of the data then we can restore additivity, as is illustrated in Table 8.1. 

Consider an AB/BA cross-over trial in extremely stable asthmatic patients who in the absence of treatment will show no change over time. The trial is to compare a beta-agonist with placebo. Suppose that the outcome measure is forced expiratory volume in one second (FEV ) and suppose that the patients in the two groups are the same on average and that FEV under placebo is 2000 ml and that the treatment effect is 300 ml. In that case the results (mean FEVi) that we expect to see are given in Table 17.1, in which the results for the beta-agonist have been set at 2300 ml so that the difference from placebo, recorded in the final column, recovers the treatment effect of 300 ml, not only when averaged over both sequences, but individually in each sequence also. 

Forced expiratory volume in one second (FEV,) is that volume of air that can be expelled forcibly during the first second of expiration. 

COPD, chronic obstructive pulmonary disease FEV, forced expiratory volume in one second. 

FEV, forced expiratory volume in one second MMRC, modified Medical Research Council. From Celli BR, Cote CC, Marin JM, et al. The body-mass index, airflow obstruction, dyspnea, and exercise capacity index in chronic obstructive pulmonary disease. N Engl J Med 2004 350 1 005-1 01 2. Copyright 2004 Massachusetts Medical Society. All rights reserved. Used with permission. 

C) A physical examination directed to the pulmonary and gastrointestinal systems, including a chest roentgenogram to be administered at the discretion of the physician, and pulmonary function tests of forced vital capacity (FVC) and forced expiratory volume at one second (FEV(1)). Interpretation and classification of chest shall be conducted in accordance with Appendix E to this section. 

In clinical practice, pulmonary function testing is the primary measurement used to assess disease and monitor asthma pharmacotherapy. Pulmonary function testing methods vary. The two most common measures of lung function include forced expiratory volume exhaled in one second (FEVi) and peak expiratory flow rate (PEE). FEV], measured in milliliters, represents the amount of air that patients can forcibly blow out in 1 second. 

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