HELIUM

Toxicity

Little evidence of toxic effects from helium therapy in clinical settings. Due to high thermal conductivity, may cause hypothermia in case of prolonged administration.

Description

Helium is a colorless, odorless, and tasteless monoatomic gas with an atomic weight of 4, a density of 1.78 g per 1 at 0°C and 1 atmosphere pressure, and an aqueous solubility of 0.97 mL per 100 mL at 50°C. The Bunsen solubility coefficient (the volume, in mL, of gas at standard conditions dissolved per mL of liquid).
of helium at 38°C is 0.0086 in water, and 0.015 in olive oil. After hydrogen, helium is the most abundant element in the universe; these elements are believed to represent 76 and 23 percent, respectively, of all matter in the universe. The earth’s atmosphere, however, contains only 5 ppm of helium. Mineral gases from wells contain higher concentrations and serve as the principal source for industrial production. Helium is chemically very inert; it has a weak tendency to combine with other elements such as fluorine. It is usually marketed as compressed gas, with the USP grade containing not less than 99 percent helium.
The largest biological use of helium is the replacement for nitrogen in synthetic breathing gas mixtures for divers and others working under high pressure conditions. The low solubility in body fluids compared to nitrogen decreases the danger of bends on depressurizing.

The Uses of HELIUM

Helium is used as an inert gas shield in arc welding, as a lifting gas for lighter-than-air aircraft, and as a gaseous cooling medium in nuclear reactors. It is also used to provide a protective atmosphere for growing germanium and silicon crystals for transistors, to provide a protective atmosphere in the production of such reactive metals as titanium and zirconium, to fill cold-weather fluorescent lamps, to trace leaks in refrigeration and other closed systems, and to fill neutron and gas thermometers. Its thermal conductivity makes it an important gas for lasers and fiber optic production. It is used extensively in chromatography due to its inertness and high thermal conductivity. It is used in cryogenic research such as for superconductivity. In mixtures with oxygen, it has medical and diving applications. Radioactive mixtures of helium with krypton are available to users licensed by the Nuclear Regulatory Commission. NASA uses helium for purging and pressurizing the liquid hydrogen tanks of spacecraft because it is the only element that remains a gas in the extreme cold necessary to maintain the liquid hydrogen fuel used in many rockets and the Space Shuttle. Liquid helium is used for cooling superconductive magnets, used in magnetic resonance imaging, and in magnetic separation.

Indications

For use in patients who are not getting enough oxygen into their blood due to blockages in the lungs from pathological conditions or injuries. Suggested potential benefit in upper airway obstruction, in severe asthma, and in exacerbations of COPD/COLD. Helium may be used in place of carbon monoxide during laparoscopic surgeries as it lowers the risk of developing respiratory acidosis in selected patients.

Background

Helium is a second most abundant chemical element in the universe with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas located at the top of the noble gases on the periodic table. Its boiling and melting points are the lowest among all the elements. Its clinical benefit in inhalation therapy arises from its advantageous physical properties than ambient air. Helium has lower density than air and generates less resistance than to provide improved lung ventilation. It is also used as an analytical reagent in diagnostic/imaging tests to detect respiratory function of the patient.

Pharmacokinetics

Helium provides lung ventilation and prevents narrowing or collapse in respiratory units. It increases the tendency to laminar flow and reduces the resistance in turbulent flow, leading to more efficient penetration of gases to the distal alveoli, higher minute volumes and improved ventilation.

Metabolism

Not Available