Medical and Compressed Gases PDF

MEDICAL AND COMPRESSED GASES OBJECTIVES Describe the chemical and physical properties of the medical gases most often encountered in respiratory care. Identify the following cylinder markings: Department of Transportation (DOT) specifications, service pressure, hydrostatic testing dates...

MEDICAL AND COMPRESSED GASES OBJECTIVES Describe the chemical and physical properties of the medical gases most often encountered in respiratory care. Identify the following cylinder markings: Department of Transportation (DOT) specifications, service pressure, hydrostatic testing dates, manufacturer’s identification, ownership mark, serial number, and cylinder size. List the color codes used to identify medical gas cylinders. Compare the operation of direct-acting cylinder valves with that of diaphragm-type cylinder valves. Explain the American Standards Association (ASA) indexing, the Pin Index Safety System (PISS), and the Diameter Index Safety System (DISS). OBJECTIVES Identify and correct a problem with cylinder valve assembly. Calculate the gas volume remaining in a compressed-gas cylinder and estimate the duration of gas flow based on the cylinder’s gauge pressure. Describe the components of a bulk liquid oxygen system and use of liquid oxygen in bulk systems. Discuss the operation of a portable liquid oxygen system. Calculate the duration of a portable liquid oxygen supply. Identify three types of medical air compressors and describe the operational theory of each. Identify a DISS station outlet and a quick-connect station outlet. OUTLINES Properties of Medical Gases Storage and Transport of Medical Gases !Air ! Cylinders !Oxygen (O2) !Liquid Oxygen Systems !Carbon Dioxide (CO2) !Medical Air Supply !Helium (He) !Central Supply Systems !Nitric Oxide (NO) !Piping Systems !Nitrous Oxide (N2O) !Station Outlets OUTLINES !Oxygen Concentrators  PROPERTIES OF MEDICAL GASES AIR Colorless, odorless, gas mixture that contains varying amount of water vapor Nonflammable but it supports combustion Composition: 21% Oxygen, 78 % Nitrogen, other gases about 1% Produced by filtering it from pollutants, then it compressed by compressors Compressed air prepared synthetically from nitrogen and oxygen Compressors give pressures of 50 psi & Liquid air can be obtained through a process called liquefaction  OXYGEN (O2) It is colorless , odorless , tasteless gas at normal temp. and pressure It makes up 20.9% of earth atmosphere At temperature less than – 183 C (- 300°F), it becomes pale bluish liquid that is slightly heavier than water It supports combustion but it's not flammable It is considered as a drug ! It can be toxic MANUFACTURE OF O2 Fractional Purification distillation Liquefaction Distillation (of liquid air) https://www.youtube.com/watch?v=J6J47XX55CU Physical separation Molecular sieves (of atmospheric air) Semi permeable membrane concentrators CARBON DIOXIDE (CO2) It is colorless and odorless gas at normal atmospheric temp. and pressure 1.5 times heavier than air Not flammable and does not support combustion or maintain life CO2 can exist as solid, liquid, and gas Mixtures of O2 & CO2 , e.g., (95%/5%), (90%/10%) are used for various therapeutic purposes including: Hiccups Stimulation/depression of central nervous system Calibration of blood gas machines, transcutaneous electrodes and capnographs CARBON DIOXIDE (CO2) Solid Liquid To refrigerate fragile materials Fire extinguishing agent in portable while in transport and stationary fire-extinguishing systems Gas Used in food processing and as a growth stimulant for plants  HELIUM It is the lightest gas after hydrogen It is colorless, odorless, and tasteless gas Nonflammable gas that will not support combustion Breathing 100% helium can lead to severe hypoxemia Because of its low density, helium is combined with oxygen (heliox) to deliver oxygen in case of severe airway obstruction 80%– 20 % He - O2 (flow is multiplied by 1.8) 70%– 30 % He - O2 (flow is multiplied by 1.6) 60%– 40 % He - O2 (flow is multiplied by 1.4) NITRIC OXIDE (NO) Is a colorless, has slight metallic odor and very toxic gas Nonflammable gas but will support combustion In the presence of air, nitric oxide combines with oxygen to form brown fumes of nitrogen dioxide (NO2) The higher the oxygen available , the greater the potential for developing toxic levels of NO2 The monitoring of NO/NO2 is very important  NITRIC OXIDE (NO) Nitric oxide and nitrogen dioxide combined form a potent irritant that can cause chemical pneumonitis and pulmonary edema Although nitric oxide is toxic in high concentrations, low doses are a powerful pulmonary vasodilator Dose of nitric oxide to improve oxygen ranges from 2-80 ppm , higher values may be used but toxicity should be considered Another critical value to monitor is the formation of methemoglobin CONT. B. Nitroprusside (NTP) causes non- C. Inhaled nitric oxide (NO) dilates selective vasodilation of all only ventilated alveoli, an outcome pulmonary arteries, which may that improves V/Q worsen ventilation-perfusion (V/Q)  NITROUS OXIDE (N2O) Laughing gas Colorless, tasteless, odorless at normal temp. and pressure Nonflammable but support combustion Oxidizing agent Used as an analgesic/anesthetic agent (CNS depressant) Should be used with O2 or it will lead to brain damage or death STORAGE AND TRANSPORT OF MEDICAL GASES  Construction and Maintenance of Filling of Medical Cylinder Sizes and Compressed Gas Cylinders Capacities Cylinders CYLINDERS Cylinder Identification Cylinder Valves Pressure-Relief Valves Setting Up and Determining the Volume Troubleshooting of Gas Remaining in a Safety Systems Compressed-Gas Cylinder and the Cylinders Duration of Cylinder Gas Flow CYLINDERS Metal cylinders used for compressed gas Department of Transportation (DOT) requires all cylinders used to store and transport compressed gases confirm to well defined specifications CONSTRUCTION AND MAINTENANCE OF COMPRESSED GAS CYLINDERS Compressed-gas cylinders should be capable of holding up to 10% more than the maximum service pressure as marked All cylinders should contain a pressure-relief mechanism to prevent explosion Cylinders must be reexamined every period of time as recommended FILLING OF MEDICAL CYLINDERS 1 2 3 4 Cylinder prefill Cylinder filling Post-fill Appropriate inspection procedures documentation CYLINDERS’ SIZES CYLINDER SIZES AND CAPACITIES E- cylinders Crash carts Used in transporting patients Anesthetic gases Calibration gases for portable diagnostic equipment D- Cylinders Nitric Oxide CYLINDER SIZES AND CAPACITIES G and H cylinders The primary source of oxygen & other gases in small hospitals As a secondary or reserve system Home-care for long-term oxygen therapy Store calibration gases that are required in the blood-gas and pulmonary function lab  CYLINDER IDENTIFICATION Size Cylinder color Labels and Tags Cylinder markings COLOR CODING OF CYLINDERS Air: Yellow or black and white Oxygen: Green or white Helium: Brown CO2: Gray Nitrogen: Black Nitrous Oxide: Light Blue 26 LABELS AND TAGS 27 CYLINDER MARKINGS 28 CYLINDER VALVES Valves are control devices that seal the contents of a compressed cylinder Valves composed of: A chrome-plated, brass body A threaded inlet connector for attachment to the cylinder turned by a hand wheel or handle A stem that opens and closes the cylinder An outlet connection that allows for attachment of regulators and pressure-reducing valves A pressure-relief valve CYLINDER VALVES Direct acting  CYLINDER VALVES Diaphragm Diaphragm PRESSURE RELIEF VALVES Rupture disk (Frangible disk) Fusible plugs Spring loaded SAFETY SYSTEMS American Standard indexing Thread Index for large cylinders as H/K Pin Index Safety System (PISS) For small cylinders as E PIN INDEX SYSTEM 35  SETTING UP AND TROUBLESHOOTING COMPRESSED- GAS CYLINDERS The cylinder’s contents should be clearly labeled.. Full and empty cylinders should be appropriately labeled and kept separate. Cylinder valves should be fully opened when in use and always closed when the gas contained in the cylinder is not being used. Cylinder valves should be closed if the cylinder is empty. Box 3-4 SETTING UP AND TROUBLESHOOTING COMPRESSED- GAS CYLINDERS Large cylinders have a protective cap that fits over the valve stem. This cap should be kept on the cylinders when they are moved or stored. Small cylinders.with PISS valve stems do not have protective caps but have an outlet seal that must be removed before the appropriate regulator is attached. Regulators and other appliances intended for use with a specific gas should not be used with other gases. Cylinders should be properly secured at all times, either in a stand, chained to a wall, or in a cart, to prevent them from tipping over. Box 3-4 RECOMMENDATIONS FOR COMPRESSED-GAS CYLINDERS HANDLING AND TRANSPORTATION STORAGE AND TRANSPORT OF CYLINDERS SETTING UP AND TROUBLESHOOTING COMPRESSED- GAS CYLINDERS Gas leakage at the valve stem or in the regulator. Failure to achieve adequate gas flow at the cylinder regulator outlet Box 3-4  DETERMINING THE VOLUME OF GAS REMAINING IN A CYLINDER AND THE DURATION OF CYLINDER GAS FLOW ! When full: ! “H” cylinder contains 250 cubic feet of oxygen ! “E” cylinder contains 24 cubic feet of oxygen ! One cubic foot of oxygen equals 28.3 liters ! Full cylinders contain 2200 psi pressure EXAMPLE Patient is receiving Cylinder pressure = Calculate the 4L/m NC 1800 psi duration  Bulk liquid oxygen system BULK OXYGEN SYSTEM Portable liquid oxygen system BULK LIQUID OXYGEN 1 cubic foot of liquid O2 = 860 cubic foot of gaseous O2 Liquid gas is cheaper and occupy less space Bulk is more than 20000 Cubic Feet of gas at atm. Temp. and pressure  PORTABLE LIQUID O2 SYSTEMS For the home care setting Home liquid oxygen system consists of two components: A stationary base reservoir 12 to 60 L of liquid O2 Portable unit 0.5 to 1.2 L of liquid O2 Can provide 8- to 10 hours supply of O2 Can last 4-6 weeks PORTABLE LIQUID O2 SYSTEMS Calculate duration Duration of supply (minutes) = Gas supply remaining (in liters) ÷ Flow (L/min) 1 L of liquid O2 weighs 2.5 lb ! If we divide the weight of liquid oxygen by 2.5, we will know how many L of O2 is remaining 1 L of liquid O2 = 860 L of gaseous O2 ! we multiply the answer by 860 Finally divide the volume by the flow rate (L/min)  Liquid tank weigh 4.5 kg Patient on 2 l/min EXAMPLE NC How long it will last? Portable Air Compressors MEDICAL AIR SUPPLY Bulk Air Supply Systems BULK AIR SUPPLY SYSTEMS Use two compressors that can operate together or independently Usually piston or rotary compressors working pressure of 50 psi and to prevent unnecessary high pressures. PORTABLE AIR COMPRESSORS Piston Diaphragm Rotary CENTRAL Continues supply system SUPPLY SYSTEMS Alternating supply system Pressure relief valves* Organized in zones PIPING SYSTEM Shutoff valves Testing and inspecting the piping system Alarm CENTRAL Continues supply system SUPPLY SYSTEMS Alternating supply system Pressure relief valves* Organized in zones PIPING SYSTEM Shutoff valves Testing and inspecting the piping system Alarm PIPING SYSTEMS CLINICAL SCENARIO A fire breaks out on the north wing of the fifth floor of the hospital where you work. How should you respond to this emergency?  A system of specifications for threaded low- pressure connections between station outlets, flowmeters, and other devices such as nebulizers, ventilators, and anesthesia apparatus. Wall (low pressure) safety systems: STATION Quick Connect. Newer OUTLET D.I.S.S. “better system” Color coded  Semipermeable membrane 1 – 10 L/min OXYGEN CONCENTRATOR Molecular sieve Concentration of O2 depends on the flow rate With flow less than 6 L/min (FiO2 around 93%) ANY QUESTIONS ? THANK YOU ! REFERENCE CHAPTER 3