EFFECT OF DIFFERENT INSPIRATORY MANEUVERS ON FEV(1) IN PATIENTS WITH CYSTIC-FIBROSIS

The time course of inspiration has been shown to have a significant in fluence on the subsequent maximal expiratory flows and timed forced ex piratory volumes in healthy adults and those with COPD, The purpose of this study was to evaluate the effect of two different inspiratory ma neuvers on the spirogram in 15 patients with cystic fibrosis, aged 13 to 35 years, who had mild to moderate airway obstruction. Patients per formed a forced expiratory maneuver either after a rapid inspiration w ithout an end-inspiratory pause or after a slow inspiration with a 4-s end-inspiratory pause. Flow-time and volume-time curves were measured by a pneumotachograph. The mean values of FVC, FEV(1), and peak expir atory flow were significantly larger by 11%, 13%, and 26%, respectivel y, after the rapid inspiration without an end-inspiratory pause compar ed to the slow inspiration with the end-inspiratory pause. This discre pancy probably reflects differences in effective elastic recoil pressu re between the two maneuvers. Although the nature of this phenomenon i s not fully understood, our results show that for spirometry in patien ts with cystic fibrosis, the preceding inspiratory maneuver influences the results, An important corollary is that this inspiratory maneuver should be standardized.