The Use of a Helium-Oxygen Mixture during Maximum Expiratory Flow to Demonstrate Obstruction in Small Airways in Smokers

摘要: We measured the response to breathing a mixture of 80% helium and 20% oxygen (He) during maximum expiratory flow-volume (MEFV) maneuver in 66 nonsmokers 48 smokers, aged 17-67. All subjects studied had (forced volume 1 s/forced vital capacity [FEV(1.0)/FVC]) x 100 greater than 70%. While flow rates smokers were within +/-2 SD those at 50% VC (Vmax(50)), both groups showed reduction with age (nonsmokers: r=-0.34, P<0.01; r=-0.52, P<0.001). Nonsmokers no significant He, while marked (r=-0.63, P<0.001 Vmax(50)). also lung which (Vmax) subject was He became equal Vmax he air, expressed it as percent VC. This most sensitive method separating from nonsmokers. These results indicate that use an MEFV affords sufficient sensitivity enable detection functional abnormalities stage when they are air is normal.