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anesthesia machine.pptx

  1. Institute of Technology Department of Biomedical Engineering BIOMEDICAL INSTRUMENTATION LAB-II BMEG 3154 LECTURE ON – ANESTHESIA MACHINE 21/03/2023 1
  2. Content Introduction Basic components Anesthesia Machine Standards 21/03/2023 2
  3. Objective After the end of this lecture the student will able to:- Know the definition of an Anesthesia Machine Know the different parts of an Anesthesia Machine and their use. Set up and use of anesthetic machine Demonstrate anesthesia machine at lab 21/03/2023 3
  4. Introduction Anesthesia Machine is a device used to provide an accurate and continuous supply of medical gases (such as medical air, Oxygen and nitrous oxide), mixed with an accurate concentration of anesthetic vapor (such as isoflurane), and deliver this to the patient at a safe pressure and flow.
  5. What is Anesthetic Gas?  Gas used to temporarily keep the patient in total unconsciousness. (General anesthesia)  2 types of anesthetic gases are common: Ether Halogenated (most common):e.g. ISOFLURANE, SEVOFLURANE Non-Ether Halogenated hydrocarbons: e.g. HALOTHANE, HOLOROFORM  Non-Ether Halogenated hydrocarbons are no longer used in developed countries because they are toxic, but are very common in Third World. E.g. HALOTHANE is very common in Rwanda.  21/03/2023 5
  6. Cont.…  Other types of anesthetic gases: XENON (costly)  The Anesthetic gases are stored in liquid state at room temperature but are very volatile.  A vaporizer is used to administer the anesthetic gases to patients 21/03/2023 6
  7. 7 International Color code GAS COLOUR Oxygen White Nitrous Oxide Blue Medical Air Yellow Carbon dioxide Grey
  8. vaporizer bellow Corrugated tube Soda lime Flow meter ventilator APL valve Scavenging system
  9. Basic Components Pressure Reducing Valve Regulates the pressure of the gas leaving the tank and going into the anesthesia machine. Reduces the pressure of oxygen that leaves the tank at 2200 psi to a safer 50 psi.
  10. Vaporizer Converts the liquid anesthetic agent (usually isoflurane or sevoflurane) into a vapor. Adds controlled amount of these vapors to the carrier gas. The mixture of the anesthetic gas and carrier gas is known as FRESH GAS. Once mixed, fresh gas cannot return to the vaporizer.
  11. Safety Features of Vaporizers • Pin safety system to prevent filling up with wrong agent. • Interlock mechanism to prevent using two agents simultaneously.
  12. Reservoir Bag  Fills as gases enter the circuit or patient exhales, deflates as patient inhales for manual ventilation FUNCTIONS 1) Stores gas 2) Allows assessment of respiratory rate and depth
  13. Oxygen Flush Valve (O2+) This valve allows a high flow oxygen to go directly to the breathing system without going through a flowmeter and vaporizer. Machine standard requires that the flow be between 35 and 75 L/min. The ability to provide jet ventilation.
  14. Carbon dioxide Absorber  Sodalime (CaOH2 + NaOH + KOH + silica) or Baralyme (Ba[OH] 2 + Ca[OH]2) contained in the absorber combines with carbon dioxide, forming CaCO2 and liberating heat and moisture (H2O).  The canister should be changed when 25% to 50% of the contents has changed color.  Soda lime is the most common absorbent and is capable of absorbing up to 23L of CO2 per 100g of absorbent. It´s main component is calcium hydroxide (80%).
  15. Adjustable Pressure Limiting (APL) Valve The APL valve is used to control the pressure in the breathing system and allows excess gas to escape. APL Valve limits the amount of pressure buildup that can occur only during manual ventilation. Manual Ventilation: Valve is usually left partially open. During inspiration the bag is squeezed pushing gas into the inspiratory limb until the pressure relief is reached.
  16. Cont.… APL Valve is also called pop-off valve. When the user adjusts the APL valve to trap more gas inside the breathing circuit, a spring inside the APL valve is compressed according to how much the user turns the APL valve. The degree of spring compression exerts a proportional force on a sealing diaphragm in the APL valve. The pressure inside the breathing circuit must generate a force that exceeds the spring compression force for the APL valve to open.
  17. APL valve Protects the breathing circuit or ventilator from excessive positive or negative pressure.
  18. Anesthesia Ventilators The bellows is compressed intermittently when oxygen or air is directed into the chamber, thereby pressurizing it. Most ventilators allow direct adjustment of tidal volume, with I : E ratio.
  19. Scavenging Systems  A scavenging system channels waste gases away from the operating room to a location outside the hospital building. Specific anesthetic gas-scavenging systems should be used routinely. These systems consist of a collecting system, a transfer system, a receiving system, and a disposal system.
  20. Scavenging Systems
  21. Common Gas Outlet  The common gas outlet is the port where gases exit the machine and is connected to the breathing system via the fresh gas hose.
  22. Breathing System 23 1 Absorber canister 2 Inspiratory port 3 Inspiratory valve 4 Expiratory port 5 Expiratory valve 6 Bellows 7 Airway pressure gauge 8 Handle 9 Bag Arm 10 APL valve
  23. Anesthesia Machine Standards Compromise of 3 different pressure system. High Pressure System: From Cylinder to pressure reducing valves Intermediate Pressure System: From Pressure reducing valve to flowmeter. Low Pressure System: From flowmeter to common gas outlet.
  24. The Anesthesia Machine High Intermediate Low Pressure Circuit
  25. High Pressure System Gas from the high pressure cylinders or from a compressor and an O2 plant is supply via the back of the anesthesia machine (2200 psig for O2) The high pressure side consists of: Hanger Yolk (reserve gas cylinder holder) Check valve (prevent reverse flow of gas) Cylinder Pressure Indicator (Gauge) Pressure Reducing Device (Regulator) Cylinders are not used if there is wall-mounted gas supply.
  26. Intermediate Pressure System  Gets gas from the cylinder regulator or the hospital pipeline at pressures of 40-55 psig  Consists of:  Pipeline inlet connections  Pressure gauges  Pipes  Gas power outlet  Master switch  Oxygen pressure failure devices  Oxygen flush  Additional reducing devices  Flow control valves
  27. 3.The low-pressure circuit: includes components distal to the flowmeter needle: Valves Flowmeter tubes Vaporizers Common gas outlet.
  28. 21/03/2023 31