1. Medical Gas Systems
210a

2. Medical Gases
Oxygen – O2
Air
Carbon dioxide – CO2

3. Medical Gases
Helium – He
Nitrous oxide – N2O
Nitric oxide - NO

4. Chemical and Physical Properties of Therapeutic Gases
Oxygen and air are life supportive because these gases supports the metabolic production of energy in the carbon-based organisms found on earth.
Atmospheric concentrations are given in percentage values (%), which represent the relative quantities of gases as they are present in the earth’s atmosphere.

5. Oxygen – O2 (Green tank) Characteristics
Colorless, odorless, tasteless
Non-flammable
Supports combustion

6. Oxygen – O2 Characteristics Critical temperature
°C (-181 °F)
Makes up approximately 21% of air

7. Oxygen – O2 Commercially produced through fractional distillation
Physical separation
Used in oxygen concentrators

8. Fractional Distillation
Atmospheric air is filtered of pollutants, carbon dioxide and water
Air is compressed and cooled to a liquid
Then it is slowly heated and the nitrogen boils off.
Liquid oxygen remains
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9. Molecular Sieve Composed of inorganic sodium aluminum silicate pellets
These pellets absorb the nitrogen and water vapor from the air
Produces up to 90% mixture
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10. Semipermeable Membrane
Pulls air through membrane
Oxygen passes through faster than nitrogen
Can produce 40% mixture
Good for long-term low flow oxygen
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11. Physical Separators
Will produce concentrations for nasal cannula but only at low flows
Used in oxygen concentrators IN THE HOME
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12. Air (yellow cylinder) Characteristics Colorless, odorless, tasteless
Non-flammable
Supports combustion

13. Therapeutic Gases in Respiratory Care
At normal atmospheric conditions, air is an odorless, colorless, transparent, tasteless mixture of gases and water vapor that is nonflammable and supports combustion.
Air is composed of about 78% nitrogen and 21% oxygen by volume.
Compressed air may be referred to in medical settings as room air or ambient air.

14. Therapeutic Gases in Respiratory Care
Compressed air is supplied in cylinders that are color coded yellow.
Piped compressed air is commonly provided in hospital medical gas systems for use in areas such as the operating room and intensive care units.
Smaller, portable air compressors are available for hospital or home use.

15. Air Produced by filtering and compressing atmospheric air Must be dry
Must be free of oil

16. Therapeutic Gases in Respiratory Care
Carbon dioxide (CO2) is a colorless, transparent, odorless to pungent, and tasteless or slightly acid-tasting gas with a specific gravity of 1.522, making it heavier than air.
CO2 is nonflammable and does not support combustion or animal life.
CO2 is a by-product of animal metabolism and the burning of carbonaceous fuels.

17. Carbon Dioxide – CO2 Characteristics Colorless, odorless
Does not support combustion
Cannot support life
Grey cylinder

18. Carbon Dioxide – CO2
Produced by heating limestone in contact with water
Critical temperature above room temperature; stored as liquid in cylinder

19. Carbon Dioxide – CO2
Used in the past in mixtures with oxygen (90% O2 with 10% CO2, 95% O2 with 5% CO2); current use is limited

20. Carbon Dioxide – CO2
Current CO2 mixtures used primarily in membrane oxygenators and for calibration of analyzers

21. Helium – He Characteristics Second lightest of gases
Odorless, tasteless
Non-flammable
Brown cylinder

22. Helium – He Characteristics
Good conductor of heat, sound, and electricity
Inert
Cannot support life

23. http://www.youtube.com /watch?v=nripiMQt0ls
Helium – He
Produced through liquefaction
When used therapeutically, must be mixed with at least 20% O2 (Heliox)
/watch?v=nripiMQt0ls

24. Helium – He
Used to manage severe airway obstruction to decrease work of breathing

25. Therapeutic Gases in Respiratory Care
Nitric oxide (NO) is a colorless, tasteless gas with a slight metallic odor. This nonflammable and non-life-supporting gas supports combustion and is toxic.
Nitrogen (N2) is the major component of the atmosphere, 78% by volume.
Nitrogen gas is responsible for the blue color of the sky on earth.

26. Nitrous Oxide – N2O Characteristics Colorless
Slightly sweet odor and taste
Supports combustion
Cannot support life

27. Nitrous Oxide – N2O
Produced by thermal decomposition of ammonium nitrate

28. Nitrous Oxide – N2O
Critical temperature above room temperature; stored as liquid in cylinder
Used as an anesthetic agent

29. Nitric Oxide - NO Characteristics Colorless Non-flammable
Supports combustion

31. Nitric Oxide - NO
Produced by oxidation of ammonia at high temperature in the presence of a catalyst

32. Nitric Oxide - NO
Respiratory irritant capable of causing chemical pneumonia and pulmonary edema

33. Nitric Oxide - NO High concentrations can cause methemoglobin to form
Used in term and near-term infants for the treatment of persistent pulmonary hypertension

34. Cylinders Markings Sizes/oxygen contents D – 12.6 cu.ft./356 L
E – 22 cu.ft./636 L
G – 186 cu.ft./5260 L
H/K – 244 cu.ft./6900 L

35. H Cylinders 2200 psi A.S.S.S safety system Threaded connection
Need to be safety chained and in a secured dolly for moving
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36. E Cylinders Small and lightweight (15 pounds) PISS – Pin Index
Yoke connection
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37. Types and colors of cylinders
Air - Yellow
Oxygen - Green – Int’l (White)
Helium - Brown
CO2 - Grey
Nitrogen - Black
Nitrous Oxide-Blue
Do NOT trust the color of the tank as sole indicator of it’s contents
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38. Other Oxygen Tank Markings
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39. Bulk Oxygen Systems Large capacity Small system (or back up)
Liquid oxygen
Small system (or back up)
Nitrous Oxide
Bank of H cylinders
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40. Large Oxygen Supply System
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41. Small Bank of Cylinders
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42. Liquid vs Gas Insulated – Liquid Solid metal - Gas
Large continuous demand – Liquid
Small portable – Liquid or tank
Tanks act differently if they contain gas or liquid
No accurate gauge on liquid tank content
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43. Go figure
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44. Liquid Oxygen Constantly losing oxygen despite insulation
Needs pressure and insulation for cold temperature (-118oC)
Low pressure (200 psi)
Large system has vaporizers fins to help with heat transfer when liquid turns to gas (frozen year round)
Small system is great for mall shopping
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45. Wall (low pressure) systems
D.I.S.S.
50 P.S.I
The MJC lab has these
Quick connect
A newer “better system”
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46. DISS
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47. DISS Wall Outlet
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48. Flowmeters
Thorpe Tube is most common
Can use Bourdon Gauge
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49. RsCr 220

50. Zone Valves
RsCr 220

51. Regulators
They decrease internal tank pressure down to a working pressure (50psi)
They read and display the internal tank pressure
They meter out the precise flow for patient use.
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52. Cylinder connections A.S.S.S. (American Standard) P.I.S.S. (Pin Index)
H cylinders
High pressure, large tanks
P.I.S.S. (Pin Index)
E cylinders
High pressure, small tanks
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53. Pin Index System
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54. Pin Index System
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55. Pin Index Numbering
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56. Cylinder Duration Calculations
You can memorize size of tank then calculate how long it will last
Or use:
Conversion factors
3.14 for H cylinders
0.28 for E cylinders
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57. Liquid Oxygen Duration
Convert pounds to liters
Multiply by 860 to get volume of gaseous oxygen (Liters)
Divide by the liter flow (L/min)
Convert minutes to hours and minutes
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58. Storage and Distribution of Medical Gases
Steel cylinders are used to store compressed oxygen and other gases.
Medical gases can be stored and transported in the gaseous state or as liquefied gas in various-sized cylinders and cryogenic bulk containers.

59. Cylinders Filling cylinders
Compressed gas cylinders filled to service pressure plus 10%

60. Cylinders Measuring contents Compressed gas cylinders
Contents directly proportional to pressure
Liquid gas cylinders
Contents determined by weight of cylinder

61. Cylinders
Duration of flow
Duration of flow = Contents
Flow

62. Cylinders Factors for determination of duration “E” cylinder = 0.28
“H/K” cylinder = 3.14
 Duration of flow = Pressure x Cylinder factor
Flow

63. Cylinder Storage Cylinder cap in place when not in use
Segregate full and empty cylinders

64. Cylinders Factors for determination of duration Liquid system = 860
Amount of gas in liquid = Weight of liquid x 860
2.5

65. Cylinder Storage Must be in racks or chained to wall
No combustible material in the vicinity

66. Cylinder Storage
Flammable gases stored separately from gases that support combustion

67. Cylinder Storage
Always use “No Smoking” signs when oxidizing gas is present
Liquid oxygen containers must be in a cool, well-vented area

68. Cylinder Transport Use approved carts for transporting cylinders
Keep protective cap in place during transport

69. Cylinder Use
Cylinders must always be secured either with a chain to the wall, or an approved cart or stand

70. Cylinder Use Cylinders must be uncovered
“Crack” a cylinder valve before use
Storing cylinders:
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71. Cylinder Use Do not position cylinders near sources of heat
Do not alter the safety system for the cylinder

72. Bulk Systems Defined as containing at least 20,000 cubic feet of gas
May be in either gaseous or liquid form

73. Bulk Systems - Advantages
More economical over the long term
More dependable; less prone to interruption

74. Bulk Systems - Advantages
Eliminates need to transport large numbers of cylinders
Delivery pressure uniform
Operating pressure is lower (50 psig)

75. Bulk Systems - Disadvantages
Expensive to construct
Failure may affect large numbers of patients

76. Bulk Systems Supply systems Cylinder manifold system
Cylinder supply system with reserve supply

77. Bulk Systems Supply systems Shut-off valves, zone valves
Bulk gas system with reserve
Shut-off valves, zone valves

78. Regulation of Medical gases
Food And Drug Administration (FDA)
Oversees purity of gases produced

79. Regulation of Medical gases
Department of Transportation (DOT)
Oversees construction of cylinders and transportation of medical gases

80. Regulation of Medical Gases
National Fire Prevention Association (NFPA)
Oversees construction of bulk systems and sets standards for storage of medical gases

81. Regulation of Medical Gases
Compressed Gas Association (CGA)
Regulates handling, storage, fittings, and markings

82. Safety Indexed Systems
American Standard Safety System (ASSS)
Standardizes threaded high-pressure connections for cylinder sizes “F” to “H/K”
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83. American Standard Safety System (ASSS)
26 connections total within the system
Thread diameter
Threads per inch

84. American Standard Safety System
26 connections total within the system
Right-handed vs. left-handed
External vs. internal

85. Pin-Index Safety System (PISS)
Sub-system of ASSS
Applies only to cylinders up to size “E”

86. Pin-Index Safety System (PISS)
System of two pins aligning with holes in cylinder valve face; six possible positions

87. Pin-Index Safety System (PISS)
Pin Positions
Oxygen – 2-5
Oxygen/Carbon dioxide – 2-6
Helium/Oxygen – 2-4
Nitrous oxide – 3-5
Air – 1-5

88. Pin-Index Safety System (PISS)

89. Diameter-index Safety System (DISS)
Used For low pressure (<200 psig) medical gas connectors
Consists of an externally threaded body and mated nipple with a nut
Twelve standardized connections

90. Quick-connect systems
Made by various manufacturers
Each connector has distinct shape so it cannot be used with a different gas

91. Regulators Two types of high pressure reducing regulators
Single stage – Reduces cylinder pressure to working pressure in one stage

92. Regulators Two types of high pressure reducing regulators
Multiple stage – reduces cylinder pressure to working pressure in two or more stages

93. Regulators Pre-Set pressure reducing regulator
Delivers fixed, pre- set outlet pressure
Adjustable reducing regulator
Delivers outlet pressure adjusted to specific need

94. Flowmeters
Used to set and control the flow of gas to the patient from a 50 psig source

95. Flowmeters
Three types
Bourdon gauge
Thorpe tube
Flow restrictor

96. Bourdon Gauge
Measures pressure within the flowmeter; calibrated to read as flow
Unaffected by gravity; can be used in any position

97. Bourdon Gauge
Inaccurate when pressure distal to the orifice increases, causing back pressure to increase; causes flowmeter to read high

98. Bourdon Gauge

99. Figure 15-15: DISS safety systems: flow meter and 50-psig outlet.
Courtesy of Western/Scott Fetzer Company

100. Thorpe Tube Measures true flow Must be used in the upright position
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101. Figure 15-11A: ASSS, PISS, and DISS connections.
Courtesy of Western/Scott Fetzer Company

102. Thorpe Tube Pressure compensated
Flow control valve distal to the meter; Prevents changes in downstream resistance from affecting accuracy of reading

103. Thorpe Tube Uncompensated
Flow control valve proximal to the meter; records less than actual flow

104. Thorpe Tube
Compensated

105. Flow Restrictor
Has a fixed orifice capable of delivering one specific flow
Need variety of restrictors in the event of patient needs changing

106. Flow Restrictor Cannot be used during resuscitation
Unable to increase flow for CPR