Egan’s Chapter 40 Storage and Delivery of Medical Gases – Flashcards
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Non flammable
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Unable to support combustion
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Oxidizing
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Not flammable but supports combustion
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Bourdon gauge
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A fixed orifice comma variable pressure flow meter
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Thorpe tube
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A variable orifice, constant pressure flow meter
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Reducing valve
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A valve that reduces gas pressure
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Regulator
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A device that controls both pressure and Flow
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Flow meter
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A device operated by a needle valve that controls or measures gas flow according to viscosity and density
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Zone valve
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On and off piping valve that controls medical Gas Distribution to pre-specified zones of the hospital
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List three gases that are categorized as non flammable
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Nitrogen, helium, and carbon dioxide
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Most therapeutic gases will oxidize or support combustion. List three gases in this category.
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Air, oxygen, and nitric oxide
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Describe the four basic steps of the fractional distillation process
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Atmospheric air is filtered to remove pollutants, water, and carbon dioxide. Purified air is liquefied by compression and cooled by rapid expansion. The remaining mixture of liquid oxygen and nitrogen is heated slowly in the distillation tower and repeated twice. The remaining liquid oxygen is transferred to specifically insulated cryogenic storage cylinders.
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What Purity level is required for medical-grade oxygen?
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99%
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Describe the two methods used to separate oxygen from Air. What concentration is produced by each method?
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A. Inorganic sodium aluminum silicate pellets absorb nitrogen and water vapor producing 90% oxygen. B. Pulling of ambient air through a membrane and allows oxygen and water to pass at a faster rate than nitrogen in ambient air.
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What is the most common use of CO2 mixtures?
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It is used for the calibration of blood gas analyzers and for Diagnostic purposes in Clinical Laboratory settings
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What is heliox? What is it used for in the clinical setting?
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Heliox is a gas mixture of oxygen and helium and may be used clinically to manage severe cases of Airway obstruction. Example: life threatening asthma
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What is the primary medical use for nitrous oxide? What are some of the hazards of nitrous oxide Administration?
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Nitrous oxide is clinically used as an anesthetic agent. Hazards consist of the president of the central nervous system, increased risk for fetal disorders, and spontaneous abortion.
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Describe two possible hazards for using nitric oxide
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A. Exposure to high concentration of NO can cause methmoglobinemia which could lead to tissue hypoxia B. Use of inhaled NO in treatment of premature neonates with hypoxic respiratory failure does not improve outcomes and may increase the risk for intracranial hemorrhage
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Give the chemical symbol for each of the following medical gases
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Oxygen- O2 Air- AIR Carbon Dioxide- CO2 Helium- He Nitrous Oxide- N2O Nitric Oxide- NO
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What do the symbols * and + mean when stamped on a cylinder
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* next to the test date indicates DOT approval for 10-year testing + indicates the cylinder is approved for filling up to 10% greater than its service pressure
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Identify the proper color for these gas cylinders
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Oxygen - green Carbon dioxide - gray Nitrous Oxide - blue Helium - brown Nitrogen - black Air - yellow
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Because cylinder color is only a guideline, how do you actually determine which gas is in a cylinder?
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Contents must be identified through careful inspection of the label and analyzing the gas.
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List two gases that can be stored in the liquid state at room temperature
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Carbon dioxide and nitrous oxide
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Explain why the pressure in a gas-filled cylinder is different from that of a liquid-filled cylinder
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Pressure in a cylinder depends on its contents. In a gas-filled cylinder, the pressure represents the force required to compress the gas into its smaller volume whereas the pressure and a liquid-filled cylinder is the vapor pressure needed to keep the gas liquefied at current temperature.
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Describe the methods for using the contents of a gas-filled cylinder and a liquid-filled cylinder
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A. Gas filled: the volume of gas is directly proportional to pressure at constant temperature B. Liquid filled: the measured pressure is the vapor pressure above the liquid
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What are the cylinder factors for the E, G, and H gas field oxygen cylinders?
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E- 0.28 G- 2.41 H- 3.14
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Write the formula for calculating duration of flow in minutes of gas filled cylinders.
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Duration of flow (min) = (pressure x cylinder factor) / (flow rate)
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Describe a gaseous bulk systems. Be sure to discuss the manifold, the primary, and Reserve Banks.
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Oxygen is stored in a large tank at low pressure, as the liquid flows through, it is heated up. The liquid is then converted back to gas pressure. It is then decreased by Regulators to 50 psi which is then sent to the hospital.
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Why do most hospitals use a liquid bulk oxygen system?
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A small volume of liquid O2 provides a very large amount of gas in 02 and minimizes space requirements
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Where are small liquid oxygen cylinders usually used?
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Used for home 02 Supply
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what is the normal working pressure for a hospital oxygen piping system?
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50 psi
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What are zone valves?
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zone valves are valves that shut off O2 to the sections of the hospital and are needed in case of a fire or maintenance.
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If a cylinder overheats, the pressure will rise. Describe the type of pressure release valve usually found in these cylinder stems.
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Small cylinder - fusible plug relief valve Large cylinder - spring loaded relief valve
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List the three basic indexed safety systems for medical gases. Both names.
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ASSS - American Standard safety system DISS- diameter index safety system PISS - pin index safety system
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what type of cylinder typically uses pins and holes for the safety connection system?
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small cylinders up to size E
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LWhat system was established to prevent accidental interchange of low pressure medical gas connectors? What is meant by low pressure?
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Diameter index safety system ; less than 200 PSIG
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Describe the action of the following devices. Reducing valve, flow meter, and regulator
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Reducing valve - reduction of gas pressure Flow meter - controlled gas flow to the patient Regulator - control pressure and flow of gas
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Describe the normal way each of the following is used in Respiratory Care. Preset reducing valve, adjustable reducing valve, and multiple stage reducing valve
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A. Preset reducing valve - is used only to give out the amount of pressure set by manifold. B. Adjustable reducing valve - is used on the high pressure system to the regulator from high to low pressure to the system C. Multiple stage reducing valve- used in reducing high pressure in multiple stages
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What two hazards can be created when you open a cylinder attached to a high pressure reducing valve?
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The gas undergoes rapid decompression followed by recompression
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What are two advantages and two disadvantages of flow restrictors?
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Advantages - can be low-cost, reliable and used in any position Disadvantages - accuracy varies and it can't be used with high resistance equipment
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Describe the board bourdon flow meter flow meter
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Indicated flow will be higher than actual flow when there is significant Downstream resistance
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What is the chief advantage of the bourdon type flow meter
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It operates under variable pressures
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What do board on gauges actually measure? Thorpe tubes?
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A. Bourdon: pressure B. Thorpe: flow
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Compare indicated flow and actual flow in a compensated Thorpe flow meter when Downstream resistance occurs
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Compensated Thorpe flow meters deliver the same flow that indicated. Uncompensated flow meters delivering more fun than indicated where there is Downstream resistance.
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What happens to the float in a compensated Thorpe to you but when you connect it to a 50 psi gas source?
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It jumps and returns to zero as the Thorpe tube is pressurized
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a patient is to be transported from the ICU to the imaging department for a CT scan. The patient requires continuous supplemental oxygen at 2 liters per minute by mask. You will need to provide portable oxygen for the transport. An E cylinder is available.
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What type of regulator is most appropriate for transport? Bourdon gauge How long will the cylinder last at the given flow rate if the pressure is 1000 PSI? 28 minutes
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when you turn on the cylinder valve, a hissing noise is heard from the regulator. The flow meter is off, so there must be a leak. What should you check to try to correct the leak?
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A. Tighten the hand screw B. Check the washer
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Calculate duration of an e cylinder with 1500 PSI running at 2 liters per minute
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(1500 x 0.28) / 2 = 210 min or 3 1/2 hours
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Calculate the duration of an H cylinder with 1500 PSI running at 2 liters per minute
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(1500 x 3.14) / 2 = 2355 min or 39 1/4 hours
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An H cylinder of oxygen is being used to deliver oxygen to a patient in a sub-acute care facility where no piped-in oxygen is available. The cylinder gauge shows a pressure of 1000 PSI. The patient is receiving oxygen at 5 liters per minute by cannula. Approximately how long will the cylinder gas last at this flow rate?
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10 hours
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a respiratory therapist notices that a flow meter plug into the wall outlet continues to read 1 liter per minute even though it is not turned on. What is the most appropriate action at this time?
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Replace the flow meter
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A respiratory therapist has to transport a patient via air from the island of Maui to Honolulu. The patient is being manually ventilated with an oxygen flow set at 10 liters per minute using an e cylinder of gas. This cylinder gauge reads 2000 PSI. How long will the cylinder last?
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56 minutes
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When a respiratory therapist unplug a Thorpe type flow meter a huge leak occurs from the wall outlet. What action should the RT take at this time?
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plug the flow meter back into the outlet
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a fire breaks out in the Pediatrics unit because of a faulty electrical cord. One respiratory therapist has ensured that patients with oxygen are safe. Your responsibility in this situation would be to
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prepare to shut off the zone valves to the unit
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What would happen if nitrous oxide leaked into the room in the emergency department or operating room setting?
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nitrous could have harmful effects on any pregnant Personnel or patient. In a relatively close space, Personnel could become intoxicated
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Your text describes the catastrophic consequences of both system failures.
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Total failures are reported in major problems occur with up to one-third of all bulk systems. A protocol should be established to identify and prioritize all affected patients. Backup systems should be used such as portable cylinders and bag and valve mask resuscitators. The system should then be bypassed an alternate supplies established while bulk system is repaired.
