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Flashcards in Medical Gases Deck (48)
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1

Classifying gases: State of matter in cylinder

1. Non liquified compressed gas
2. Liquified compressed (only N2O)

2

Classifying gases: Uses

1. Anesthesia
2. Therapeutic
3. Laboratory

3

Classifying gases: Flammability

1. Non-flammable
2. Supports combustion
3. Flammable

4

Compressed Gas NON-liquidified

1. Remains a gas at ordinary temps and under pressure of 2000-2500 PSIG
2. At very low temperatures becomes "cryogenic liquid"
3. Service pressures of common gases at 70 F
-Oxygen= 1800-2400 PSIG
-Nitrogen= 1800-2200 PSIG
-Helium= 1600-2000 PSIG
-Air=1800 PSIG

5

Compressed Gas Liquified

1. Becomes liquid in a container at ordinary temperatures and pressures from 25-2500 PSIG
2. 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

6

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

7

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

8

Anesthetic Gases

Air
Oxygen
N2O
CO2
Helium
Heliox

9

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

10

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

11

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%

12

Anesthetic Gases: HeliOX

-Helium-oxygen mixture
-pre mixed 40% O2 or 20% O2
-reduces airway resistance
-reduces airway fires during laser surgery

13

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

14

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

15

Regulation of Gas and Cylinders

US Department of Transportation***

16

Compressed Gas Association

-sets safe standards. no legal authority but compliance through JCAHO

17

National Fire Protection Association (NFPA)

-no legal authority but JCAHO
-bulk oxygen systems

18

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

19

NIOSH and OSHA

-protects workers--- ppm in ambient air
Must be less than 25 ppm of N2O in ambient air*

20

FDA

-standards for medical gases

21

American Society for Testing and Manufacturing

-technology standards

22

JCAHO or TJC

-voluntary accreditation

23

US Pharmacopeia and National Formulary

-purity of medical gases

24

US Department of Transportation

-regulates the construction and handling of all medical compressed gas cylinders including: design, construction, testing, marking, labeling, filling, storage, handling, maintenance, transportation
-Requires periodic visual inspection, especially for fire or thermal damage: internal illuminati
-Every 5 years cylinders are inspected for: dents, gouges, arc burns, physical signs of stress
-Damaged cylinders may be removed from circulation or deemed unsafe for medical use

25

Gas Cylinders

-usually chrome molybdenum alloy (alluminum in MRI scanner)
-sized A-J (A and H NOT in medicine)
-E most common in healthcare: 660L at 1900 PSIG
-cylinders tested to 166% service pressure
-tested every 10 years
-stamped with: cylinder specs, individual serial number, manufacturer, date of manufacture, date of retesting
-color coded and labeled

26

& required DOT Cylinder markings

1. DOT type and material
2. Serial number
3. Purchaser, user, and manufacture "Praxair"
4. Manufacturer's mark
5. Manufacturer's identifying symbol
6. Retest data, retester, ID symbol, 110% filling, 10 year test interval
7. Neck ring owner's ID

27

PSI
PSIG
PSIA

PSI= pounds per square inch

PSIG= pounds per square inch gauge (different between pressure measured and surrounding atmosphere, most gauges will read zero at atmospheric pressure)

PSIA= pounds per square inch absolute
psia= psig + local atmospheric pressure

28

1 ATM=
____ kPa
____ mbar
____ Hg
____ cmH2O
____ Psi

100 kPa (kilopascal)
1000 mbar (milibar)
760 mm Hg (millimeters of mercury)
1030 cm H2O (centimeters of water)
14.7 Psi (pounds pre square inch)

29

Cylinder pressure gauge: Bourdon Pressure Gauge

-measures pressure of GAS remaining in cylinder
-made of small hollow metal tube, soldered at one end, bent into a curve, and linked to a clockwork
-increase in pressure cause tube to straight, decrease to regain its curve. Movement transmitted to clock mechanism and accompanying scale
-gauges calibrated in kPa but PSI also used

30

The E cylinder with the highest pressure will_____________

-supply gas to the machine