Forced expiratory volume in one

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. 

The onset of symptoms is variable but often does not occur until the forced expiratory volume in one second (I EV ) has fallen to approximately 50% of predicted.2... 

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. 

A spirometry test is a breathing test in which a person takes as deep a breath as possible and blows out quickly and completely into a tube cormected to a spirometry machine (Table 3.1). Lung measurements obtained from fhis fesf include forced expiratory volume in one second (FEVi), fhe amounf of air blown ouf in one second forced vifal capacify (FVC), fhe fofal amounf of air blown ouf fhe FEVi/FVC ratio and fhe... 

Desjardins A, Bergeron J-P, Ghezzo H, et al. 1994. Aluminum potroom asthma confirmed by monitoring of forced expiratory volume in one second. Am J Respir Crit Care Med 150 1714-1717. 

FVC, forced vital capacity FEVi, forced expiratory volume in one second RV, residual volume TLC, total lung capacity Tco, carbon monoxide transfer factor. 

Forced vital capacity (FVC) measures the maximum volume of air expelled from the lung in a single forced expiration there is no time limit. Forced expiratory volume in one second (FEVi) measures the volume of air which can be expelled from the lung in one second. In a normal individual 80% of the vital capacity can be expired in one second, but patients with obstructive disease have difficulty in emptying the lung and this value is significantly reduced. 

Figure 4 Determination of airway reactivity using an aerosolized broncho-constrictor. Incrementally increasing concentrations of bronchoconstrictor agonist aerosol are administered to a subject. The decrease in forced expiratory volume in one second (FEV1.0) is measured after each concentration. The dose of bronchoconstrictor that induces a 20% decrease in FEV10 is then interpolated from the dose-response curve obtained in the subject. This concentration provides an index of airway sensitivity or reactivity. Severe asthmatics are extremely sensitive to bronchoconstrictor stimuli (i.e., respond to a lower concentration of bronchoconstrictor), more so than mild asthmatics and nonasthmatic subjects.

The caliber of airways through which the aerosol has to pass to get to the more distal parts of the lungs is of utmost importance. In functional terms, the forced expiratory volume in one second, FEVi, is usually taken as a measure of the instantaneous resistance (and, hence, the caliber) of the airways. Therefore, it is customary to attempt to relate FEVi to the deposition pattern. Using such... 

To explore this scenario, five virtual patients were developed to explore the uncertainty surrounding the pathophysiology of moderate asthma, that is, the simulations were designed to plumb the space of how one became a moderate asthmatic in the first place. While the array of inflammatory mediators underlying the pathophysiology of asthma have been identified, for the most part, and are fairly well understood, the contribution of each to the disease process is not yet known in detail. Though all five virtual patients have similar clinical behaviors consistent with moderate asthma (i.e., a forced expiratory volume in one second [FEV1] between 65 and 80%), each virtual patient was created to explore a different combination of these mediators. 

Coal Tar Products. In an industrial health survey of employees in four wood preservative plants in which coal tar creosote and coal tar were the main treatments used, decreased pulmonary function was noted (TOMA 1979). Restrictive deficits in pulmonary function, as indicated by decreases in FVC, were noted in 44 of 257 employees (10 of 47 nonsmokers). Obstructive deficits, as indicated by decreases in percentage forced expiratory volume in one second (FEV1) were noted in 19 of 257 employees (3 of 54 nonsmokers). Nevertheless, no clear relationship could be established because exposure routes in... 

Contrary to what is commonly supposed, it is not necessary for clinical trials to be balanced in order to produce a valid comparison between treatments. Consider Table 3.2, which shows the cross-classification of numbers of patients by sex and treatment for a clinical trial. (Suppose, for argument s sake that the trial is in asthma and that we shall be measuring forced expiratory volume in one second, FEVi.)... 

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. 

It is desired to run a placebo-controlled parallel group trial in asthma. The target variable is forced expiratory volume in one second (FEVi). The clinically relevant difference is presumed to be 200 ml and the standard deviation 450 ml. A two-sided significance level of 0.05 (or 5%) is to be used and the power should be 0.8 (or 80%). What should the sample size be. ... 

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. 

Observations of relief of bronchoconstriction without cardiovascular side effects suggest that prostaglandins have a potential clinical role in conditions such as asthma. Cuthbert [273] compared the effect of aerosol-administered PGEi on airways resistance in healthy and asthmatic volunteers with reversible airways obstruction. In the healthy subjects, the forced expiratory volume in one second (FEVi) was unaffected by the prostaglandin when administered as the free acid or as the triethanolamine salt. However, in the asthmatics, inhalation of 55 pg of the triethanolamine salt produced an increase in FEVi comparable in both degree and duration with that produced by an inhalation of 550 jig of isoprenaline sulphate. The triethanolamine salt was employed in the asthmatic trials since it was better tolerated, the free acid being irritant to the upper respiratory tract. Similar results were obtained with PGE2 [274]. 

Dockery DW, Berkey CS, Ware JH, Speizer FE, Ferris BG Jr. Distrihution of forced vital capacity and forced expiratory volume in one second in children 6 to 11 years of age Am Rev Respir Dis 1983 128 405 12. 

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

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