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Heliox is a breathing gas mixture of helium (He) and oxygen (O 2).It is used as a medical treatment for patients with difficulty breathing because this mixture generates less resistance than atmospheric air when passing through the airways of the lungs, and thus requires less effort by a patient to breathe in and out of the lungs.
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas. Other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats such as scuba equipment, surface supplied diving equipment, recompression chambers, high-altitude mountaineering, high-flying aircraft, submarines ...
Trimix scuba cylinder label IMCA Trimix cylinder shoulder colour code alternative IMCA Trimix cylinder shoulder colour code. Trimix is a breathing gas consisting of oxygen, helium and nitrogen and is used in deep commercial diving, during the deep phase of dives carried out using technical diving techniques, [1] [2] and in advanced recreational diving.
Hydrox, a gas mixture of hydrogen and oxygen, is occasionally used as an experimental breathing gas in very deep diving. [ 1 ] [ 2 ] It allows divers to descend several hundred metres. [ 3 ] [ 4 ] [ 5 ] Hydrox has been used experimentally in surface supplied, saturation, and scuba diving, both on open circuit and with closed circuit rebreathers.
Helium (He) is colorless, odorless, tasteless, and inert noble gas. Helium is second lightest gas after hydrogen. [10] Heliox has a similar viscosity to air but a significantly lower density (0.5 g/L versus 1.2 5g/L at STP). Flow of gas through the airways comprises laminar flow, transitional flow and turbulent flow.
The patient is then asked to breathe (normal breaths) in the mixture starting from FRC (functional residual capacity), which is the gas volume in the lung after a normal breath out. The spirometer measures helium concentration. The helium spreads into the lungs of the patient, and settles at a new concentration (C2).
Helium is the least water-soluble monatomic gas, [96] and one of the least water-soluble of any gas (CF 4, SF 6, and C 4 F 8 have lower mole fraction solubilities: 0.3802, 0.4394, and 0.2372 x 2 /10 −5, respectively, versus helium's 0.70797 x 2 /10 −5), [97] and helium's index of refraction is closer to unity than that of any other gas. [98]
Analysing a trimix blend using a portable helium analyzer Two oxygen cells as used by oxygen anylysers for diving gas Oxygen and helium analyser for breathing gas for diving. Before a gas mix leaves the blending station and before the diver breathes from it, the fraction of oxygen in the mix should be checked.