Single-Breath DLCO

We have observed in some patients with pulmonary disease and normal subjects that the difference between two successive measurements for single-breath OLeo amounted to 10%. Byscrutinizing data from these subjects, we observed that they spontaneously changed their preinspiratory maneuver just before inhaling the test gas mixture. The purpose of the present work is to assess the influence of five different preinspiratory maneuvers on OLeo. Nine healthy males were investigated. They performed at random the five following maneuvers: (A) rapid exhalation from functional residual capacity (FRC) to residual volume (RV), (B) rapid exhalation from FRC to RV and long apnea at RV, (C) rapid exhala­ tion from FRC to RV and short apnea at RV, (0) slow exhalation at a constant speed from FRC to RV, and (E) curvilinear exhalation from FRC to RV. The Oleo values after maneuver B were higher than those after the four other maneuvers; there was a significant relationship between OLeo and the du­ ration of the preinspiratory maneuver. The data are best explained by an alteration in the distribution of the inspired gas mixture to areas with different diffusing capacities. In conclusion, the preinspira­ tory maneuvers must be standardized in order to improve the reproducibility of the single-breath Oleo measurements. Lebecque P, Mwepu A, Nemery B, Verlter C, Frans A. Effed of prelnsplratory ma­ neuver on the single-breath DLCO. AM J RESPIR CRIT CARE MED 1995;152:804-7.