Helium-oxygen flow volume curves in young healthy adults

Helium-oxygen (HeO2) flow volume curves were done in young, healthy, nonsmoking adults. This paper discusses the theoretical design of the test, the nomenclature, and the results in this population. Our study shows that HeO2 and air curves crossed around 15% of vital capacity; one point of identical flow occurs more frequently than has been appreciated; and fully developed laminar flow occurs infrequently at low lung volumes in young adults.