Forced expiratory volume FEVJ

FIGURE 17.2 The measurement of timed forced expiratory volume (FEVj) and forced vital capacity (FVC). 

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. 

Assessment of airflow limitation through spirometry is the standard for diagnosing and monitoring COPD. The forced expiratory volume after 1 second (FEVj) is generally reduced except in very mild disease. The forced vital capacity (FVC) may also be decreased. The hallmark of COPD is a reduced FEVpFVC ratio to less than 70%. A postbronchodilator LEV, that is less than 80% of predicted confirms the presence of airflow limitation that is not fully reversible. 

In one study, the various P2-AR haplotypic combinations (see Section 2. for description and ref. 3 for nomenclature) were utilized to assess the acute response to a standard dose (two puffs) of albuterol, with the change in forced expiratory volume in 1 s (FEVj) as the outcome measure. As shown in Fig. 12, there was a relationship between haplotype pair and FEVj response (p = 0.007 by analysis of covariance). The two homozygous haplotype pairs (2 and 4) were further studied in transient transfected cells, with P2-AR mRNA and protein as measures of expression. Haplotype 4 had approx 50% decreased expression compared to haplotype 2. This was entirely consistent with the physiological data for the asthmatics in that those with the 4/4 haplotype had a lower FEV) response to albuterol compared to those with the 2/2 haplotype. Those with the 4/4 haplotype, then, may be the least responsive to acute administration of P-agonist, and either alternative dosing or different agents might be considered for these individuals. 

Until recently, there has only been indirect evidence that SEs could possibly also impact lower airway disease, especially in poorly controlled asthma. By studying the TCR Vp repertoire of bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMCs) from subjects with poorly controlled asthma [forced expiratory volume in 1 s (FEVj) <75%], subjects with well-controlled asthma and control subjects, Leung and coworkers [51] found a significantly higher expression of Vp8+ T cells in BAL fluid of poorly controlled asthmatics compared to the other groups. Increased Vp8+ BAL T cells were present in the CD4+ and CD8+ subsets, suggesting activation by SEs. 

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. 

Metoprolol in asthmatic patients at rest with isoprenaline infusion " In contrast, another study found that the increase in forced expiratory volume (FEV) with a terbutaUne inhalation and infusion was reduced by about 300 mL by atenolol and metoprolol. The authors considered that this would be clinically relevant in severe asthma." Another study in 12 patients with mild asthma found that single doses of ceUprolol 200 mg or nebivolol 5 mg reduced the FEVj by 272 mL and 193 mL, respectively, when compared with placebo. Inereasing inhalation of salbutamol to a total dose of 800 mierograms reversed these reduetions but did not restore the FEVj baek to its initial value. None of these ehanges was considered to be clinieally signifieant by the authors. ... 

Forced expiratory volume in t seconds (FEV,) is shown in Figure 17.2, which identifies FEV, 5 and FEV, q, and Table 17.1 presents normal values for FEVj q. 

Aimual spirometric evaluations will be conducted by the Safety Division on all employees filling job classifications requiring the use of respirators in the performance of their duties. Spirometry testing will be used to measure forced vital capacity (FVC) and forced expiratory volume-1 second (FEVi). If FVC is less than 75% and/or FEVj is less than 70%, the employee will not be allowed to wear a respirator unless a written waiver is obtained from a medical... 

The rate of decline in the forced expiratory volume in one second (FEVj) of BMT recipients is widely variable. Despite treatment with bronchodilators, corticosteroids, and immunosuppression, improvement in lung function is noted in only 8% to 20%. The reported case fatality rates of BO in BMT recipients range from 10% to 100%, with overall mean case fatality rate of 61% (1,5,8). 

Asthma is a common chronic inflammatory disorder that affects the airway passages of the lungs. Primarily, asthma is characterized by reversible, episodic narrowing of the airway s smooth muscle secondary to hypersecretion of mucus, hyper-reactivity, and mucosal edema. The narrowing may be of sudden or prolonged onset, which accounts for the varying degrees of airway obstruction seen in this disease. The hallmark of airway obstruction is a reduction in the forced expiratory volume in 1 second (FEV and the ratio of FEVj to the forced vital capacity (FVC). 

A less controversial method of monitoring allograft function is patient-administered home spirometry. Once postoperative function has been stabilized, the forced expiratory volume in one second (FEVj) and forced vital capacity (FVC) should vary less than 5% from the baseline FEVj and FVC right after transplantation (Bjortuft et al. 1993 Morlion et al. 2002). A decline of 10% or more in spirometric values that persists for more than 2 days has been reported to indicate either rejection or infection. 

Respiratory problems are diagnosed using a spirometer. The patient exhales as hard and as fast as possible into the device. The spirometer measures (1) the total volume exhaled, called the forced vital capacity (FVC), with units in liters (2) the forced expired volume measured at 1 second (FEV,), with units in liters per second (3) forced expiratory flow in the middle range of the vital capacity (FEV 25-75%), measured in liters per second and (4) the ratio of the observed FEVj to FVC X 100 (FEVj/FVC%). 

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