title: The history and physics of heliox.
abstract: Since the discovery of helium in 1868, it has found numerous applications in industry and medicine. Its low density makes helium potentially valuable in respiratory care applications, to reduce work of breathing, improve distribution of ventilation, reduce minute volume requirement, and improve aerosol delivery. This review includes a brief history of the use of heliox (a mixture of helium and oxygen) and addresses issues related to the physics of gas flow when heliox is used. Specifically covered are the Hagen-Poiseuille equation, laminar versus turbulent flow, the Reynolds number, orifice flow, Bernoulli's principle, Graham's law, wave speed, and thermal conductivity.
authors.affiliation: Department of Respiratory Care, Massachusetts General Hospital, Boston, MA 02114, USA. dhess@partners.org
authors.forename: Dean R
authors.initials: DR
authors.lastname: Hess
authors.forename: James B
authors.initials: JB
authors.lastname: Fink
authors.forename: Shekhar T
authors.initials: ST
authors.lastname: Venkataraman
authors.forename: In K
authors.initials: IK
authors.lastname: Kim
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Myers
authors.forename: Benoit D
authors.initials: BD
authors.lastname: Tano
mesh_terms: D000818:Animals; D001703:Biophysics; D006371:Helium / Q000266:history / Q000494:pharmacology / Q000627:therapeutic use; D049672:History, 19th Century; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D010100:Oxygen / Q000266:history / Q000494:pharmacology / Q000627:therapeutic use; D012140:Respiratory Tract Diseases / Q000188:drug therapy; D012212:Rheology; D013814:Thermal Conductivity; D014783:Viscosity; D014831:Voice / Q000187:drug effects
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen