The mean forced expiratory flow during the middle half of the forced vital capacity (FEF25-75%) is the simplest test currently in use for detection of early, reversible airway obstruction. However, FEF25-75% often decreases paradoxically following bronchodilator challenge, while other tests of airflow improve. Review of spirometric tracings from 30 patients revealed a 67% reduction in FEF25-75% with more than 80% increase in the 1-second forced expiratory volume (FEV1). When FEF was recalculated with correction for changes in the forced vital capacity (isovolume forced expiratory flow), there was a 90% improvement following administration of bronchodilator. These findings suggest that FEF25-75% should be volume-corrected for determining response to bronchodilators.
Get full access to this article
View all access options for this article.
References
1.
LeuallenEC, FowlerWS. Maximal midexpiratory flow. Am Rev Tuberc1955;72:783–800.
2.
McFaddenERJr, LindenDA. A reduction in maximum midexpiratory flow rate. A spirographic manifestation of small airway disease. Am J Med1972;52:725–737.
3.
SniderGL, ShapiroDA. Patterns of response of spirometric indices to bronchodilator drugs in patients with obstructive lung disease. Am J Med Sci1965;250:367–373.
4.
ACCP-ATS Joint Committee on Pulmonary Nomenclature. Pulmonary terms and symbols. Chest1975;67:583–593.
5.
ACCP Committee on Clinic and Office Pulmonary Function Testing. Office spirometry in clinical practice. Chest1978;74:298.
6.
KoryRC, CallahanR, BorenHG, SynerJC. The Veterans Administration/Army cooperative study of pulmonary func-tion. I. Spirometry in normal men. Am J Med1961;30:243–258.
7.
OlsenCR, HaleFC. A method for interpreting acute re-sponse to bronchodilators from the spirogram. Am Rev Respir Dis1968;98:301–302.
8.
BancroftH.Introduction to biostatistics. New York: Harper and Row Publishers, 1965:178–179.
9.
SobolBJ, EmirgilC.Pulmonary function in ambulatory asthmatics. J Chron Dis1976;29:233–242.
10.
BousheySF. The use of expiratory forced flows for de-termining response to bronchodilator therapy. Chest1972;62:534–541.
11.
LevineER. Mechanisms of improvement in bronchopul-monary disease. Dis Chest1966;49:610–624.
12.
BouhuysA, van de WoestijneK.Mechanical consequences of airway smooth muscle relaxation. J Appl Physiol1971;30:670–676.
13.
PopaVT, WernerP.Dose-related dilation of airways after inhalation of metaproterenol sulfate. Chest1976;70:205–211.
14.
McFaddenERJr, LyonsHA. Airway resistance and uneven ventilation in bronchial asthma. J Appl Physiol1968;25:365–370.
15.
DasheCK, PontoRA, GanapesCM, DrageCW, Kronen-bergRS. The distribution of nebulized isoproterenol and its effect on regional ventilation and perfusion. Am Rev Respir Dis1974;110:293–300.
16.
WilliamsMHJr, KaneC.Dose response of patients with asthma to inhaled isoproterenol. Am Rev Respir Dis1975;111:321–324.
17.
PaviaD, ThomsonM, ShannonHS. Aerosol inhalation and depth of deposition in the human lung. Arch Environ Health1977;32:131–137.
18.
StevensPM, OrmanBF, GravesGJr. Contribution of lung recoil and airway resistance to forced expiratory flow limita-tion. Am Rev Respir Dis1969;100:54–62.
19.
McFaddenER, Newton-HowesJ, PrideNB. Acute effects of inhaled isoproterenol on the mechanical characteristics of the lungs in normal man. J Clin Invest1970;49:779–790.
20.
KeighleyJF. Response to sympathomimetic aerosols of differing particle size in subjects with chronic bronchitis. Am Rev Respir Dis1968;98:879–882.
21.
BachusBF, SniderGL. The bronchodilator effects of aero-solized terbutaline. JAMA1977;238:2277.
22.
SherterCB, ConnollyJJ, SchilderDP. The significance of volume/adjusting the maximal midexpiratory flow in assessing the response to a bronchodilator drug. Chest1978;73:568–571.
23.
LightRW, ConradSA, GeorgeRB. The one best test for evaluating the effects of bronchodilator therapy. Chest1977;72:512–516.
