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Anaesthesia machine

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Anaesthesia machine

  1. 1. The Anesthesia Machine<br />Dr. Smriti Gupta<br />
  2. 2. Introduction<br />The anesthesia gas machine is a device which delivers a precisely-known but variable gas mixture, including anesthetizing and life-sustaining gases.<br />Original Boyle was made by the firm COXTERS.<br />There are several differences between newer and older anesthesia machines.<br />Advanced ventilators are the biggest difference between newer and older gas machines.<br />
  3. 3. The differences between older gas machines -such as the Ohmeda modulus, Excel, or Aestiva and the DrägerNarkomed GS, Mobile, MRI, 2B, 2C, 3 or 4- are less than their similarities. <br />While the differences between new models from GE Healthcare (ADU, Aisys, Aespire, Avance) and Dräger (Fabius GS, Narkomed 6000/6400, Apollo) are more than their similarities. <br />
  4. 4. Types of anesthesia machine<br />Intermittent-Gas flows only during inspiration<br />Egs: Entonox apparatus ,Mackessons apparatus<br />Continuous-Gas flows both during inspiration and expiration. Egs :<br /> Boyle Machine<br />Forregar<br />Dragger <br />
  5. 5. History<br />
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  7. 7. Anesthesia work station<br />Integrates most of the components necessary for administration of anesthesia into single unit.<br />Standard guidelines have been given to manufacturers for minimum performance, design, characteristics and safety requirements of machine.<br /> The current standard for anesthesia workstation as( promulgated by American society for testing and materials) (ASTM) is F1850. European standard is EN740<br />
  8. 8. Components of anesthesia machine<br />
  9. 9. Pressure units to remember<br />1 atm pressure = 1 bar = 760 mm Hg =<br />14.7 psi = 100 kilopascals<br />
  10. 10. Components of pressure systems<br />
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  16. 16. Limitations of check valve assembly<br />The check valves are not designed to act as permanent seals for empty yokes.<br />Small amounts of gases can escape if the yoke is empty or an empty cylinder (or cylinder with low pressure) and valve open is present in the yoke.<br />
  17. 17. In order to minimize such losses –<br />Yokes should not be left vacant for extended periods<br />An empty cylinder should be replaced as soon as possible , if not then,<br />An yoke plug can be used to prevent gas leak or<br />An empty cylinder can be left behind after closing the valve<br />
  18. 18. Yoke Block(Dummy Cylinder plug)<br />Yoke block is a solid piece of metal that has a conical depression on one side to fit into the retaining screw and a hollow area on the other side to fit over the nipple.<br />They are pin indexed.<br />Uses <br />Prevents gas leak from the machine when placed in an empty yoke.<br />Connect cylinders larger than size E to the machine.<br />Connect pipeline supply to the machine that does not have pipeline inlet connections.<br />
  19. 19. Limitations of yoke block<br />Can be responsible for crossover of gases in the machine.<br />Pressure regulators in the machine are designed to accept gases at cylinder pressure may not function properly when supplied with gases at reduced pressure(pipeline supply through yoke block)<br />
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  21. 21. Limitations of pin index safety system<br />A wrong cylinder can be placed in yoke if-<br />2 washers are placed on the port.<br />Pins on the yoke are broken.<br />Holes on the cylinder valve are too deep.<br />
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  24. 24. Pin index safety system<br />
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  26. 26. Bourdon pressure gauge<br />
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  28. 28. Safety features in cylinder pressure indicator<br />Gauge is usually color coded.<br />Name and symbol of gas are written over dial.<br />If bourdon tube ruptures gas is vented from back side <br />Gauges are angled and placed in such a way that it can be easily read by anesthetist.<br />Instructions like “use no oil’’ “open the valve slowly’’ are written on the gauge.<br />
  29. 29. Electronic cylinder pressure indicator<br />Light emitting diodes(LED’S)in electronic pressure gauge indicate<br />Cylinder valve is close –Dark color<br />Cylinder valve is open –<br /> Pressure adequate –Green<br /> Pressure inadequate-Red<br />
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  32. 32. Types of pressure regulators<br />Adam’s pressure regulatorvalve-<br />Used in past<br />Working principle is same differs in internal structure from newer valves(toggle levers instead of push rod)<br />Fins on Adam’s regulator for N2O which are not present in newer regulators.<br />Mackesson’sregulator<br />Medishieldvalve<br />Endurancevalve<br />Modernpresettypeofreducingvalve-DirectandIndirect.<br />
  33. 33. Safety features on pressure regulator<br />Pressure regulators have safety relief valves<br />If due to any reason there is build up of pressure in pressure regulator then the safety valve blow off at a set pressure of 525 k pa(70psi)<br />
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  40. 40. Oxygen failure safety valve<br />Pressure sensor shut off valve<br />Based on threshold principle<br />Cuts off N2O supply when O2 pressure falls below 25 psi.<br />MOA-O2 pressurises and holds open shut off valve that interrupts the supply of N2O and other gases if O2 pressure<threshold setting.<br />oxygen failure protection device<br />Based on proportioning principle<br />Gas loaded regulator<br />When O2 pressure decreases there is a proportional decrease in N2O supply and complete cut off seen at<12psi.<br />MOA-O2 pressure regulator(primary regulator) controls secondary(slave) regulator located in N2O line<br />
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  47. 47. Master switch<br />Turning the master switch to the ‘on’ position activates both pneumatic and electrical functions of the machine as well as certain alarms and safety devices.<br />
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  61. 61. Electronic flow meter<br />Prefer digital system<br />Solenoid valves<br />Control flow on or off valves <br />Computer controlled<br />.<br />
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  69. 69. Link-25<br />.<br />
  70. 70. Oxygen ratio monitor controllerSensitive oxygen ratio controller<br />Linear resistors [3:1 ratio for N2O & O2)between O2 andN2O flow control valves.<br />Ensure 25% O2 by limiting N2O flow.<br />ORMC shuts off N2O if ratio of O2 flow falls below 30%<br />S-ORC-newest hypoxic guard . installed in Fabius-GS by Drager.ensures aFiO2 of 23%.O2 flow <200ml/min.<br />.<br />
  71. 71. Limitations of proportioning system<br />Anti hypoxic device may also deliver hypoxic mixture under following conditions-<br />Wrong supply of gas.<br />Defective pneumatics/mechanics.<br />Inert gas administration(3rd gas-He,N2,CO2).<br />Leaks downstream.<br />
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  84. 84. Thank You<br />

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