helium /he·li·um/ (He) (hēl´e-um) chemical element, at. no. 2. It is obtained from natural gas. Used as a diluent for other gases, particularly with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics.
helium (He)
helium (He) (hē´lēum),
he·li·um (h  l- m)n. Symbol He An inert gaseous element used in liquid form as a cryogen and as a substitute for nitrogen in artificial breathing mixtures for deep-sea diving and workers in high-pressure conditions. Atomic number 2. |
helium (He)
[hē′lē·əm]
Etymology: Gk, helios, sun
a colorless, odorless gaseous element; the second lightest element. Its atomic number is 2; its atomic mass is 4.00. Helium is one of the rare or inert gases and does not combine with other elements. It occurs in the atmosphere at concentrations of five parts per million. Because of its lightness and lack of flammability, it is also used to lift airships and balloons. In the liquid state it is used for low-temperature activities. The main physiologic and medical uses of helium are in respiratory therapy and testing and the prevention of nitrogen narcosis and decompression sickness in hyperbaric environments. Helium is one third as soluble in lipids as is nitrogen. That characteristic accounts for its preferred use in hyperbaric atmospheres, such as those associated with deep-sea diving. A mixture of 80% helium and 20% oxygen is commonly breathed by deep-sea divers to prevent gas emboli and by patients undergoing treatment to clear obstruction of the respiratory tract. Problems associated with such uses involve the high velocity of acoustic transmission in helium and the high thermal conductivity of the gas. These characteristics produce voice distortions and hypothermia in persons who inhale it. The low density of helium reduces the effort of breathing any gas mixture of which it is a component. Helium is used in pulmonary function testing to calculate the diffusion and residual capacities of the lungs.
helium (He) (hē´lēum),
n a colorless, odorless, tasteless gas; one of the inert gaseous elements. Atomic number, 2; atomic weight, 4.003. Used in medicine as a diluent for other gases.
helium
a chemical element, atomic number 2, atomic weight 4.003, symbol He. See Table 6.
Helium is a chemically inert element that is odorless, tasteless and noncombustible. Because of its low density it is easily moved through the air passages and therefore requires little effort in breathing on the part of the patient who is in respiratory distress. Although helium itself has no chemical therapeutic value, when combined with oxygen it facilitates the delivery of this gas to the lungs (see helium-oxygen therapy).
How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content.
| ?Page tools | ||
|---|---|---|
|