Forced expiratory time--its reliability as a lung function test.

Abstract

. (1975). Thorax, 30, The time taken for a forced expiration can be measured easily with stopwatch and stethoscope. Over the last 30 years many observers have been attracted by this simplicity and have proposed a number of uses for forced expiratory time (FET) as a lung function test. Recently, McFadden and Linden (1972) and Cochrane et al. (1974a) have drawn attention to FET as a possible measurement of obstruction to airways of less than 2 mm internal diameter. Both groups suggest a good correlation between FET and other tests of small airways obstruction. Since smokers appear to develop small airways obstruction before standard spirometry becomes abnormal (McFadden and Linden, 1972), a simple small airways test might show which smokers are most likely to develop chronic airways obstruction (Cochrane et al., 1974b) and be of use in epidemiological surveys. Previous tests of small airways disease-frequency dependence of compliance (Macklem, 1972), closing volume (McCarthy et al., 1972), and maximal expiratory flow at 50% of forced vital capacity (McFadden and Linden, 1972)

Computer Evaluation of Tracheal Forced Expiratory Noise Time for Bronchial Obstruction Diagnostics

“…We also found a significant correlation between FET a and FEV 1 /FVC, and FEV 1 and FEV 1 % in BA patients. Along with studies [12,13] , we revealed a significant correlation between FET a and FET s but only in asthma patients. A substantially weaker correlation in healthy subjects was found.…”

“…In the study of [4] the mean FET s in healthy non-smokers was 9.8 (9.2-10.4) s with shorter exhalation time commonly seen in young adults. [13] reported that both FET as and FET s have a high intrasubject variability (CV of FET as was 25%; CV of FET s was 21.4%). At the same time Kern and Patel (1991) [9] believed that performing the FE maneuver can be standardized, thereby decreasing the intrasubject variability of FET as .…”

“…However contradictory results are reported. According to MacDonald, et al [13] , a high variability in both FET as and FET s were observed. According to [26] longer FET s were associated with better spirometric performance.…”

Small Airways in Idiopathic Pulmonary Fibrosis

“…The lower limit of lung volumes was considered to be -20% of the predicted value. The lower limit for FEV,% was considered to be equal to the predicted FEV,%-5% (25).…”

Does Dyspnoea during dipyridamole cardiac stress testing indicate bronchospasm and is the pretest clinical history predictive of this side-effect?

“…The dipyridamole stress protocol of our institution used a higher dipyridamole dose (0.7 mg/kg body weight) than is currently recommended and low-level (25 W) bicycle stress to enhance image quality [5]; both factors have to be considered, yet seem unlikely to have seriously affected our results. Reproducibility is crucial for pulmonary function testing [6], and is indicated by invariable expiratory efforts and global volume parameters. However, regional pulmonary function parameters reflecting obstruction in smaller airways [7] indicated peripheral bronchospasm.…”