In the atmosphere it is present in the concentration of 0.003%. It is stored as high pressure gas in the cylinders. There are several effects of helium Inhalation .
The medical diagnostic utility is secondary to its low density, insolubility and thermal conductivity.
• Molecular weight is 4.
• Specific gravity is 176.
• It can diffuse through rubber.
• It is non-inflammable and does not support combustion.
• The cylinder is brown in colour and kept at pressure of 1987 psi. Premixed with oxygen can be administered via facemask.
The other effects of helium Inhalation include:
• It is helpful in pulmonary function testing as it is highly diffusible gas carried away by the pulmonary circulation, and so dilution in lungs can be measured. Helium breathing is helpful in large airway obstruction, apart from the other effects of helium Inhalation .
• Helium/Oxygen mixture decreases the resistance of breathing and thus is helpful.
• It is used during Laser surgery on the airway. It is used as diluent inert gas as it lacks in narcotic effect. There is minimum chance of microembolism after decomposition due to minimal solubility in the body tissues. There is no specific gas toxicity but under hyperbaric conditions it produces hypothermia. This being one of the effects of helium Inhalation .