Medical Gases Flashcards
(48 cards)
1
Q
Classifying gases: State of matter in cylinder
A
- Non liquified compressed gas
2. Liquified compressed (only N2O)
2
Q
Classifying gases: Uses
A
- Anesthesia
- Therapeutic
- Laboratory
3
Q
Classifying gases: Flammability
A
- Non-flammable
- Supports combustion
- Flammable
4
Q
Compressed Gas NON-liquidified
A
- 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
5
Q
Compressed Gas Liquified
A
- 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
6
Q
Flammability
A
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
Q
Common cylinder size and capacity of O2
A
E Cylinder: 660 L at 1900 PSIG (these are on back of anesthesia machine)
H Cylinder: 6900 L at 2200 PSIG
8
Q
Anesthetic Gases
A
Air Oxygen N2O CO2 Helium Heliox
9
Q
Anesthetic Gases: Air
A
- 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
Q
Anesthetic Gases: Helium
A
- 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
Q
Anesthetic Gases: Oxygen
A
- 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
Q
Anesthetic Gases: HeliOX
A
- Helium-oxygen mixture
- pre mixed 40% O2 or 20% O2
- reduces airway resistance
- reduces airway fires during laser surgery
13
Q
Anesthetic Gases: Nitrous Oxide N2O
A
-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
Q
Anesthetic Gases: Carbon Dioxide CO2
A
- 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
Q
Regulation of Gas and Cylinders
A
US Department of Transportation***
16
Q
Compressed Gas Association
A
-sets safe standards. no legal authority but compliance through JCAHO
17
Q
National Fire Protection Association (NFPA)
A
- no legal authority but JCAHO
- bulk oxygen systems
18
Q
American National Standards Institute (ANS)
A
-sets basic performance and safety standards for components of anesthesia machines, ETTs and connectors, pressure and vacuum, and gas pressure regulators
19
Q
NIOSH and OSHA
A
-protects workers— ppm in ambient air
Must be less than 25 ppm of N2O in ambient air*
20
Q
FDA
A
-standards for medical gases
21
Q
American Society for Testing and Manufacturing
A
-technology standards
22
Q
JCAHO or TJC
A
-voluntary accreditation
23
Q
US Pharmacopeia and National Formulary
A
-purity of medical gases
24
Q
US Department of Transportation
A
- 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
31
Cylinder content and pressure
- cylinder pressure will be an indicator of content volume only if the contents are all in the gaseous state (NOT liquid)
- if the contents are partially liquid (like N2O) the pressure will remain constant until the last of the liquid is evaporated, then the pressure will fall rapidly
32
N2O content
Full: 20.7 lbs, 1590 L, 745 PSIG
No liquid remaining: 14.2lbs, 250 L, 745 PSIG
Nearly empty: 14.1 lbs, 125 L, 350 PSIG
33
The PISS System
Pin Index Safety System
- Each gas cylinder has it's own unique PIN system
- 2 PINS in anesthesia machine, 2 holes in cylinder valve
- PINS should NOT allow wrong cylinder to be mounted
- not failsafe though*
34
FYI: Oxygen Index Pins
N2O Index Pins
Air Index Pins
2,5
3,5
1, 5
35
Cylinder Safety (10 points)
1. only handled by trained personnel
2. no oil, grease, lubricants on valves, pressure regulators, gauges, or fittings
3. 20F (-7C) < Temp < 130 F (54 C)
4. Tight connections to prevent leaks
5. Do NOT obstruct pressure relief device
6. Do NOT cross use regulators, hoses, etc
7. Do NOT use reducer adapters--- defeats PISS
8. Keep valves closed when not in use
9. Valve is the most easily damaged part of cylinder
10. DONT CARRY CYLINDER BY ITS VALVE
36
Open cylinder slowly--- why?
-adiabatic heat of compression: open too fast= fire
37
Pressure Relief Device
rupture disc: under a safety cap and bursts at specific pressures
fusible plug: safety device that melts between 170F and 212 F (constructed of woods metal= bismuth, lead, tin, cadmium)
combo of both
pressure relief valve: spring loaded device that closes when pressure returns to limit
38
cylinder Yoke
- the cylinder Yoke is where it attaches
- labeled, color coded, PIN indexed
- pressure gauge; check valve to prevent empty cylinder filling from full cylinder, filter for particulates, plug when not in use
39
Free floating valve
- Oxygen valve opens with pressure and closes with pressure
- this prevents the cross filling of cylinder to cylinder and pipeline O2 from pressurizing cylinders
- the cylinder with the highest pressure will supply O2 to the machine
- if cylinder valve doesn't open- no gas flows to machine
40
All machines have at least 1 yoke for:
O2
N2O
Air
41
First stage regulator
- decrease cylinder pressure to 45 PSIG (intermediate)
- lower than pipeline pressure (prevents cylinder from emptying into pipeline)
- diaphragm valve that covers both yokes
42
Second stage regulator
- reduces from 45-50 PSIG to 16 PSIG (from intermediate to LOW pressure)
- diaphragm valve only reduces pressure
43
Oxygen flush valve
- be careful, VERY careful
- only pure O2 @ 35-75L/min flow rate
- pressurized at 40-50 PSIG
- ball and spring valve
- can cause barotrauma
44
Advantages of central/wall/pipeline oxygen
- large capacity
- economies of sale
- stable, continuous supply
- safety
* Bulk N2O is from a bank of H cylinders in the basement stored in liquid form
45
Liquid Oxygen supply-safety
```
NFPA requires:
Oxygen cryogenic vessel:
-25-50 ft from hospital
-25-50 ft from flammable gas storage
-50 ft from wooden structures
-on asphalt of concrete
-fenced
-posted "no smoking/open flame"
```
46
Diameter Indexed Safety System
DISS:
- located on machine
- quick connect for wall hoses
- each connection is sized "indexed" for a specific gas and will not allow another hose to be hooked up to it
- a check valve in the DISS prevents cylinder gas from escaping the machine through the pipeline hoses
47
Pipeline Gas Supply to OR
- oxygen and N2o arrives from hospital reservoir at 50 PSIG
| - hoses are DISS and color coded (quick connects with pin-like extrusion but NOT PISS)
48
```
Colors associated with gases:
Oxygen
Air
N2O
Scavenger
Suction
```
oxygen: green
air: yellow
n2o: blue
scavenger: purple/black
suction: white
