the changes in maximum expiratory flow rates after washing out lung air with a helium/oxygen mixture ( he/o2 , 80 : 20 ) were measured in 24 patients with chronic irreversible airflow obstruction ( fev1 1.77 +/- sd 0.39 litres ; fvc 3.62 +/- 0.59 litres ) , and in six normal subjects .
C1875235
helium/oxygen
C0030054
o2