Forced expiratory volume in 1 second

FEV, forced expiratory volume in 1 second PEF, peak expiratory flow MDI, metered-dose inhaler DPI, dry powder inhaler. 

FIGURE 11-3. Emergency department and hospital-based management of asthma exacerbation. FEV-, forced expiratory volume in 1 second Pco2, partial arterial pressure of carbon dioxide PEF, peak expiratory flow 02, oxygen. (From Kelly HW, Sorkness CA. Asthma. In DiPiro JT, Talbert RL, Yee GC, et al, (eds.) Pharmacotherapy A Pathophysiologic Approach. 6th ed. New York McGraw-Hill 2005 517, with permission.)... 

Pulmonary function tests (PFTs) indicate decreased forced expiratory volume in 1 second (FEN/,), decreased forced vital capacity (FVC), and increased residual volume. Values are typically worse during acute pulmonary exacerbations. 

FEV Forced expiratory volume in 1 second Hib Hemophilus influenzae type b... 

Spirometry demonstrates obstruction (forced expiratory volume in 1 second [FEVJ/forced vital capacity less than 80%) with reversibility after inhaled P2-agonist administration (at least a 12% improvement in FEVj). Failure of pulmonary function to improve acutely does not necessarily rule out asthma. If baseline spirometry is normal, challenge testing with exercise, histamine, or methacholine can be used to elicit BHR. 

From U. S. Department of Health and Human Service, National Institutes of Health, National Heart, Lung and Blood Institute July 1997. FEVi, forced expiratory volume in 1 second (values < 100% indicate increased airway obstruction) PEF, peak expiratory flow (greater variability indicates less control of disease). 

E. Therapeutic response Improvement in labored breathing and sputum clearance are indicative of a therapeutic response to Pulmozyme. In a well-controlled trial, Pulmozyme, compared with placebo, resulted in signihcant reductions in the number of patients experiencing respiratory tract infections requiring use of parenteral antibiotics. Within 8 days of the start of treatment with Pulmozyme, mean forced expiratory volume in 1 second (FEVl)... 

Figure 10-7 Mean change in forced expiratory volume in 1 second (FEVi) after instillation of timolol, betaxolol, or placebo (vehicle). Timolol induced a significant decrease in airflow, whereas betaxolol produced values no different from those for the placebo. (Reprinted with permission from Am J Ophthalmol 1984 97 86-92. Copyright by the Ophthalmic Publishing Company.)...

In Figure 18.16, the Emax model is used to quantify the relationship between theophylline serum level and improvement in pulmonary function as measured by the increase in forced expiratory volume in 1 second (FEVi) in six patients who were treated with placebo and three incremental doses of theophylline (14). 

FIGURE 18.16 Theophylline pharmacodynamics in patients with asthma. Effect, which was measured as improvement in forced expiratory volume in 1 second (FEVI), is related to the serum drug level in six patients, who were studied after placebo and tliree incremental doses of theophylline. An Emax model is fit to the concentration-effect data. Based on this analysis, a therapeutic range of 10-20 pg/mL was proposed (shaded area). (Adapted from data published by Mitenko PA, Ogilvie RI. N Engl J Med 1973 289 600-3.)... 

The FVC, which represents the total amount of air than can be exhaled, can be expressed as a series of timed volumes. The forced expiratory volume in 1 second (FEVi) is the volume of air exhaled during the first second of the FVC maneuver. Although the FEVi is a volume, it conveys information on obstruction because it is measured over a known time interval. The EEVj depends on the volume of air within the lung and the effort during exhalation therefore, it can be diminished by a decrease in TLC or by a lack of effort. A more sensitive way to measure obstruction is to express the FEVi as a ratio of FVC. This ratio is independent of the patient s size or the TLC therefore, the FEVi/FVC is a specific measure of airway obstruction with or without restriction. Normally, this ratio is 75% or greater, and any value below 70% to 75% suggests obstruction. 

Patients with AAT deficiency develop COPD at an early age (20 to 50 years) primarily owing to an accelerated decline in lung function. Compared with an average annual decline in forced expiratory volume in 1 second (FE Vi) of 25 mL/year in healthy nonsmokers, patients with homozygous Z deficiency have been reported to have declines of 54 mL/year for nonsmokers and 108 mL/year for current smokers. Patients developing COPD at an early age or those with a strong family history of COPD should be screened for AAT deficiency. If the concentration is low, phenotype testing (DNA) should be performed. 

COPD chronic obstructive pulmonary disease Dlco diffusion capacity for carbon monoxide DPI dry powder inhaler FEVi forced expiratory volume in 1 second FVC forced vital capacity... 

Diagnosis of aspirin-induced asthma requires a detailed medical history. The definitive diagnosis is made by aspirin provocation tests, which may be done via different routes. An oral provocation test is used commonly where threshold doses of aspirin induce a positive reaction measured by a drop in forced expiratory volume in 1 second (FEVi) and/or the presence of symptoms. A nasal provocation test is done by the application of one dose of lysine-aspirin, and aspirin sensitivity is manifested with clinical symptoms of watery discharge and a significant fall in inspiratory nasal flow. When lysine-aspirin bronchoprovocation was compared with oral aspirin provocation, both methods were equally sensitive. ... 

ACE angiotensin-converting enzyme CNS central nervous system COPD chronic obstructive pulmonary disease DPIs dry-powder inhalers EDTA ethylenediamine tetraacetic acid EDA Eood and Drug Administration EEVi forced expiratory volume in 1 second HIV human immunodeficiency virus IPS idiopathic pneumonia syndrome NSAIDs nonsteroidal anti-inflammatory drugs... 

Figure 3.1 A dual-phase response in a polyurethane foam worker after bronchial provocation with toluene diisocyanate (TDI). Early-phase bronchospasm is followed by spontaneous recovery, which in turn is followed by late-phase bronchospasm. The concentration of methacholine required to reduce the forced expiratory volume in 1 second (FEV,) by 20 per cent (PC20) fell from a baseline normal of 25 mg. ml 1 to 10 mg. ml 1 the day after TDI challenge (with permission from Bernstein, JA et ai., 1996).

The best way to determine the caliber of the intrathoracic airways is to utilize pulmonary tests measured at maximal flow rates such as forced expiratory volume in 1 second (FEVj) and maximal expiratory flow-volume curves. The forced expiratory volume maneuver requires a subject to inspire maximally and then exhale as hard as possible into a spirometer. The typieal... 

Clinical Trials In controlled clinical trials in patients with asthma, the onset of improvement in pulmonary function, as measured by maximum midexpiratory flow rate (MMEF), was within 30 minutes after a dose of albuterol tablets, with peak improvement occurring between 2 and 3 hours. In controlled clinical trials in which measurements were conducted for 6 hours, clinically significant improvement (defined as maintaining a 15% or more increase in forced expiratory volume in 1 second [FEVj] and a 20% or more increase in MMEF over baseline values) was observed in 60% of patients at 4 hours and in 40% at 6 hours. In other single-dose, controlled clinical trials, clinically significant improvement was observed in at least 40% of the patients at 8 hours. No decrease in the effectiveness of albuterol tablets was reported in patients who received long-term treatment with the drug in uncontrolled studies for periods up to 6 months. 

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