Properties of Medical Gases

Properties of Medical Gases

• Air is a colorless, odorless gas mixture containing 21% Oxygen, 78% Nitrogen, and 1% other gases. It is nonflammable but supports combustion.
• Oxygen (O2) is a colorless, odorless, tasteless gas that makes up 20.9% of Earth's atmosphere. It is essential for life and supports combustion. Oxygen becomes a pale-blue liquid at -183°C (-300°F) and is slightly heavier than water.
• Carbon Dioxide (CO2) is a colorless, odorless gas at normal atmospheric temperature and pressure. It is 1.5 times heavier than air, nonflammable, and does not support combustion. CO2 mixtures with oxygen are used for various therapeutic purposes, like stimulation/depression of the central nervous system and calibration of medical equipment.
• Helium (He) is the lightest gas after hydrogen. It is colorless, odorless, and tasteless. It is nonflammable and does not support combustion. Helium is combined with oxygen (heliox) to deliver oxygen in case of severe airway obstruction.
• Nitric Oxide (NO) is a colorless gas with a slight metallic odor. It is a potent pulmonary vasodilator but is toxic in high concentrations.
• Nitrous Oxide (N2O), also known as laughing gas, is a colorless, odorless, tasteless at normal temperature and pressure. It is nonflammable and does not support combustion but is a powerful anesthetic.

Storage and Transport of Medical Gases

• Cylinders are the most common way to store and transport medical gases.
• Cylinder Markings include:
  • Department of Transportation (DOT) specifications
  • Service pressure
  • Hydrostatic testing dates
  • Manufacturer’s identification
  • Ownership mark
  • Serial number
  • Cylinder size
• Color Codes identify medical gas cylinders:
  • Oxygen (O2): Green
  • Helium (He): Brown
  • Nitrous Oxide (N2O): Blue
  • Carbon Dioxide (CO2): Gray
  • Medical Air: Yellow or Black (if painted before 1981)
• Cylinder Valves can be either direct-acting or diaphragm-type.
• ASA Indexing is a system of specifications for threaded low-pressure connections between station outlets, flowmeters, and other devices like nebulizers, ventilators, and anesthesia apparatus.
• Pin Index Safety System (PISS) is a safety system that prevents the wrong gas from being connected to a device.
• Diameter Index Safety System (DISS) is a newer, better safety system that uses different sized connecting threads to prevent the wrong gas from being connected.

Liquid Oxygen Systems

• Bulk Liquid Oxygen Systems are used to store and deliver large quantities of oxygen.
• Portable Liquid Oxygen Systems are used for home care settings and consist of a stationary base reservoir and a portable unit.

Medical Air Supply

• Medical Air Compressors are used to generate medical air. They can be piston, diaphragm, or rotary compressors.
• Bulk Air Supply Systems use two compressors that can operate together or independently to create high-pressure air.
• Central Supply Systems are a network of pipes that deliver medical air to different parts of a hospital.
• Station Outlets are locations in a hospital where medical gases are dispensed.

Oxygen Concentrators

• Oxygen Concentrators use a semipermeable membrane or molecular sieve to concentrate oxygen from atmospheric air. They can provide a flow rate of 1-10 L/min with an FiO2 around 93% at flow rates less than 6 L/min.

Explore the essential properties of various medical gases including air, oxygen, carbon dioxide, and helium. Understand their characteristics, uses, and significance in medical settings. This quiz will test your knowledge on the properties and applications of these gases.