Medical Gases

Storage and Delivery of Medical Devices

  • Reference: Egan's Chapter 37

Medically Used Gases

  • Types of gases in medical usage:

    • Laboratory gases

    • Therapeutic gases

    • Anesthetic gases

Fire Classification

  • Categories of gases based on flammability:

    • Nonflammable: Does not ignite or support combustion.

    • Nonflammable, but supportive of combustion: Does not ignite itself but can enhance the fire.

    • Flammable (combustible): Can easily ignite and support combustion.

Medical Gases

  • Key medical gases include:

    • Oxygen (O2): Essential for respiration.

    • Air: A mixture important for various applications.

    • Carbon Dioxide (CO2): Used in medical diagnostics.

    • Helium (He): A nonflammable gas used in specific treatments.

    • Nitrous Oxide (N₂O): An anesthetic gas commonly known as laughing gas.

    • Nitric Oxide (NO): Used in medical treatments, especially for respiratory issues.

Oxygen (O2) Characteristics

  • Physical Properties:

    • Colorless, odorless, transparent, and tasteless.

    • Found in nature primarily in the form of water, making up about 50% of the earth’s crust.

    • While non-flammable, it accelerates combustion.

Oxygen Production Methods

  • Fractional Distillation:

    • Most common and least expensive method.

    • Involves liquefying air through compression and rapid expansion.

    • Results in liquid oxygen (O2) and nitrogen (N).

    • Produces oxygen with 99.5% purity, whereas FDA requires a minimum of 99% purity.

  • Physical Separation using Molecular Sieves:

    • Utilizes aluminum silicate pellets to absorb nitrogen.

    • Involves a vacuum method.

    • Oxygen concentrators often used in home care for patients.

Air Characteristics

  • Properties:

    • Colorless, odorless, and composed naturally of:

      • 20.95% O2

      • 78.1% N

      • 1% trace gases (e.g., argon)

    • Produced by compressor; must be dry and free of oil/debris.

    • Standard working pressure is 50 psig in hospitals.

Carbon Dioxide (CO2) Characteristics

  • Properties:

    • Colorless, odorless, with specific gravity 1.5 times heavier than air.

    • Does not support combustion.

    • FDA purity requirement is 99%.

    • Primarily used for diagnostic testing.

Helium (He) Characteristics

  • Properties:

    • Colorless, tasteless, nonflammable.

    • Lightest and least dense of all gases.

    • Produced from natural gas and cannot support life.

    • Used in diagnostics and special therapeutic treatments for airway obstruction.

Nitrous Oxide (N2O) Characteristics

  • Properties:

    • Colorless with a slightly sweet taste and odor.

    • Cannot support life.

    • Non-flammable, but supports combustion.

    • Commonly used as an anesthetic gas (laughing gas).

Nitric Oxide (NO) Characteristics

  • Properties:

    • Colorless, tasteless, with a slight metallic odor.

    • Cannot support life.

    • Non-flammable, but supports combustion.

    • Employed as a therapeutic treatment for neonates with immature lungs or adults with respiratory distress syndrome by reducing pulmonary vascular resistance.