Medical Gases Week 2

Therapeutic gases are used to relieve symptoms and improve oxygenation of patients with hypoxemia (O2, O2-NO,O2-He)

Anesthetic gases are combined with oxygen to provide anesthesia during surgery (N2O)

NO=nitric oxide

N2O=nitrous oxide

All medical gases can be classified either as nonflammable or flammable or inflammable

  • Nonflammable gases do not burn but some support combustion

    • Nitrogen

    • Oxygen -supports combustion, burns faster and hotter

    • Helium

    • Air

    • Carbon dioxide

Characteristics of Oxygen~

  • Colorless, orderless, transparent, tasteless

  • Not very soluble n water

  • Not flammable but accelerates combustion

  • Compressed oxygen is supplied in cylinders that are green

Characteristics of Medical Gases~

Oxygen production is done by 2 methods [fractional distillation is most common and least expensive]

  1. Most large quantities of O2 are produced by one fractional distillation of atmospheric air

*distillation- evaporation and subsequent condensation of liquid to extract purified concentration of a substance

*STPD= standard temp, pressure, and dry

  1. Physical separation- this method utilizes low flow concentrators in homecare settings

[Both methods produce 99.5% pure oxygen which FDA requires 99% purity]

H.P.I- behind ear, nose,

Non-rebreather is a high flow concentrators

Air~ colorless, orderless, naturally occurring gas mixture containing 20% o2 and 78% nitrogen has a density of 1.29g/L

Air is utilized in a medical sense and blended wit O2 to change FiO2 delivery

Compressed air is supplied in cylinders and colored yellow

Small portable air compressors that can be used at home CPAP, nebulizer

Compressed air~

-Dilute 100% O2 to provide 22-99% mixtures

-COPD patient should have their breathing treatments given via air flow meter or compressed air gas source

Carbon Dioxide~ colorless, orderless gas, heavier than air, does not support combustion, can be used to treat hiccups (singulitis)

Helium (He)~ colorless, transparent, orderless, tasteless, and nonflammable

-doesn’t support combustion or life, therefore must be delivered with at least 20% O2 [helium and oxygen mixtures referred to Heliox

-Heliox can be given to the patient with severe asthma to reduce the work of breathing by reducing turbulent flow

RAW=airway resistance

Reduces SOB by delivering low density gas to bypass around obstructions

-increased raw

-edema

-foreign object obstruction

-vocal cord paralysis

80% He + 20% O2

70% He + 30% O2

*Helium must be delivered with at least 20% O2

Heliox must be given wth a non rebreather through a ventilator or HFNC

1.8x greater than L/min with 80/20mix

1.6x greater than L/min with 70/30 mix

Giving 80/20 with a flow of 10LPM the actual flow is 18LPM (10× 1.8)

Total flow = flow rate X factor

Nitric Oxide (NO)~ improves blood flow to alveoli which improves oxygen transport, relaxes smooth muscles, improves ventilation/perfusion mismatch

NO is FDA approved for use in infants with hypoxia respiratory failure

Compressed gas cylinders are manufactured form seamless steel

Steel cylinders are used to store compressed oxygen and other gases

H Tank factor= 3.14 E Tank factor= 0.28 a full tank is 2200 psig

Cylinder markings~

  1. Color-coding

  2. Labeling- you will be able to positively indentify what gas is in a tank by label

  3. Connection indexing systems- these safety systems make misconnection between pieces of equipment nearly impossible

Oxygen-O2-99% purity-Green

Air-99% purity-Yellow

Helium-He-99% purity- Brown

Helium/oygen (Heliox)-He/O2-99% purity-Brown & Green

Nitric Oxide/nitrogen-NO/N2-99% purity-Teal & Black

Cylinder Use- to clean cylinder quickly open then close the cylinder valve slightly to remove dust. Ensure valve closed before attaching a regulator known as “cracking” the cylinder

Post NO SMOKING signs where O2 is

Duration of flow (min) = PSIG x Cylinder factor/flow (L/MIN)

Usual method of monitoring remaining contents in a gas filled cylinder is by reading the pressure gauge

The point in the piping system where a collection of valves can be found is the zone valves

Zone Valves~

Zone valves are located throughout the system and accessible to RTs

-terminate O2 delivery in case of fire

-turn off one section of the system for maintenance without turning off the whole system

  • Each gas distribution system must have automated continuous-monitoring & alarm system to alert personnel to changes

  • Station outlet is the working end of gas distribution piping system

  • Compressed medical grade air is commonly used as source gas to aerosolize medications, activate large volume nebulizers. And mix w oxygen in vents

A ful gas cylinder tank contains greater than 2,200 psig

This pressure is too high and must be reduced to a working pressure of 50 psig

When a flow meter is attached to a reducing valve it is called a regulator

Rule of thumb: use the bourdon gauge when the Thorpe tube can’t be in an upright position

3 types of flow meters used in resp care~ flow restrictor, bourdon gauge, and Thorpe tube

  • Bourdon gauge would be best if there was a need to make complex changes to flow and pressure

Thorpe tube- pressure compensated (used most often)

  • All Thorpe tube flow meters are calibrated at a fixed 50 psi with the gas source. Different gases or pressures will cause inaccurate readings

  • Most commonly seen at the outlets for bedside care

  • A limiting factor to the Thorpe tube is limited by gravity it is only accurate in an upright position

Three indexed safety systems~~

  • American Standard Safety System (ASSS)

    • For high pressure threaded connections on LARGE cylinders (H)

  • Pin Index Safety System (PISS)

    • For high pressure, yoke type connections on SMALL cylinders (E)

  • Diameter Index Safety System (DISS)

    • Quick connects/wall attachments

The DISS connectors are found at [outlets of pressure reducing valves attached to cylinders, at station outlets of central piping systems, and at the inlets of our pneumatic equipment (blenders, flow meters, and vents)}

  • If your intention is to deliver oxygen therapy via a compressed gas cylinder you must affix a regulator correctly

  • Before attaching regulator quickly open then close the cylinder valve to help clear dust/debris

  • Known as cracking the tank valve which prevents debris from entering he regulator