Medical Gases Flashcards
Classifying gases: State of matter in cylinder
- Non liquified compressed gas
2. Liquified compressed (only N2O)
Classifying gases: Uses
- Anesthesia
- Therapeutic
- Laboratory
Classifying gases: Flammability
- Non-flammable
- Supports combustion
- Flammable
Compressed Gas NON-liquidified
- Remains a gas at ordinary temps and under pressure of 2000-2500 PSIG
- At very low temperatures becomes “cryogenic liquid”
- Service pressures of common gases at 70 F
- Oxygen= 1800-2400 PSIG
- Nitrogen= 1800-2200 PSIG
- Helium= 1600-2000 PSIG
- Air=1800 PSIG
Compressed Gas Liquified
- Becomes liquid in a container at ordinary temperatures and pressures from 25-2500 PSIG
- Liquid at temperature and service pressure at 70 PSIG:
- CO2: (<88 degrees)= 838 PSIG
- N2O: (<98 degrees)=745 PSIG
- Ethylene: (<50 degrees)=1200 PSIG
- Cycloprone (liquid)= 75 PSIG
Flammability
Non Flammable: will not burn, support, combustion, explode.
-some gases can extinguish flames (CO2)
Combustion supporting: increase the rate and intensity of anything that’s burning or could burn
- combustible material ignited in pure oxygen or nitrous oxide environment may be explosive
- minium of 15 feet from flame
Flammable: can be readily ignited
-explosive in the presence of oxygen
Common cylinder size and capacity of O2
E Cylinder: 660 L at 1900 PSIG (these are on back of anesthesia machine)
H Cylinder: 6900 L at 2200 PSIG
Anesthetic Gases
Air Oxygen N2O CO2 Helium Heliox
Anesthetic Gases: Air
- readily available
- can be compressed from the atmosphere, dried and purified by chemical and mechanical means
- may also be synthetically produced from the already purified major components nitrogen and oxygen
Anesthetic Gases: Helium
- less dense than air- reduces airway resistance and turbulence
- chemically inert, lighter than air, colorless, odorless, non flammable, will NOT support life
- main source is from natural gas wells
Anesthetic Gases: Oxygen
- gas in a cylinder b/c critical temperature is below room temp
- colorless, odorless, tasteless, supports life
- non-flammable, but supports combustion
- liquid at -300 F
- when combined with most elements produces ___ oxides
- most commercial O2 produced by liquefaction and separation
- With is our FIO2 right now? 21%
Anesthetic Gases: HeliOX
- Helium-oxygen mixture
- pre mixed 40% O2 or 20% O2
- reduces airway resistance
- reduces airway fires during laser surgery
Anesthetic Gases: Nitrous Oxide N2O
-Molecular weight: 44
BP: -88 degrees C
-vapor pressure: 39,000
-liquid at room temper because “critical temp” is above room temp
-room temp nitrous oxide condenses into liquid at 747 PSGI
-Full E cylinder contains 1590 L of gas and weighs 20.7 lbs
-cylinder gauge reads 747 PSIG, weighs, 14.2 lbs, contains 250 L and has NO Liquid remaining
-produced by thermally decomposing ammonium nitrate (NH4NO3), a common ingredient used in fertilizers and explosives
Anesthetic Gases: Carbon Dioxide CO2
- colorless, odorless, acidic taste, will NOT support life
- non-flammable and does NOT burn
- solid form (dry-ice) converts from solid to gas at atmospheric pressure and room temp without going liquid
- collected as waste gas from burning of other combustibles, purified and liquified
Regulation of Gas and Cylinders
US Department of Transportation***
Compressed Gas Association
-sets safe standards. no legal authority but compliance through JCAHO
National Fire Protection Association (NFPA)
- no legal authority but JCAHO
- bulk oxygen systems
American National Standards Institute (ANS)
-sets basic performance and safety standards for components of anesthesia machines, ETTs and connectors, pressure and vacuum, and gas pressure regulators
NIOSH and OSHA
-protects workers— ppm in ambient air
Must be less than 25 ppm of N2O in ambient air*