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THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY
Citation:
McDonnell, W F. THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. Presented at American Thoracic Society Annual Meeting, Atlanta, GA, May 17-22, 2002.
Description:
THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. William F. McDonnell Human Studies Division, NHEERL, U.S. Environmental Protection Agency, RTP, NC 27711.
Short-term exposure to ozone results in a neurally-mediated decrease in the ability to inhale to total lung capacity without a change in residual volume. Ozone-induced airway obstruction cannot be directly assessed using routine measures derived from the forced expiratory spirogram (e.g. FEV1) because of the dependence of these measures upon maximal inspiratory position. The purpose of this study is to describe the effects of voluntary reduction in inspiratory position (reflected by a reduced forced expiratory volume (RFEV)) on spirometric measures. To date, 13 of 14 healthy volunteers (ages 18-30 yr) each successfully completed 17 forced expiratory maneuvers with inspiratory position varying from just above FRC to TLC. FEV1, FEV1/RFEV, FEF25-75, and PEF were calculated as if the measured RFEV were the FVC, and were regressed against the RFEV for each of the 13 volunteers. The graphs of FEV1, FEF25-75, and PEF vs. RFEV for individual participants were generally either linear or slightly concave upward. The graphs of FEV1/RFEV vs RFEV were more variable in shape. For linear models, individual differences in slopes and intercepts were evident and could not be fully explained by other characteristics. For quadratic models the minimum, mean, and maximum R2 were 0.979, 0.992, and 0.998 for FEV1; 0.616, 0.935, and 0.989 for FEF25-75; 0.928, 0.971and 0.993 for PEF; and 0.073, 0.692, and 0.942 for FEV1/RFEV. We concluded that for FEV1, FEF25-75, and PEF the effects of a reduced inspiratory position during forced expiratory spirometry can be accurately and precisely estimated for most individuals by having each perform several forced expiratory maneuvers from varying inspiratory positions. This research was supported by the U.S. EPA and does not necessarily reflect Agency policy.