Anaesthesia machine 2014 spmc


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Anaesthesia machine 2014 spmc

  1. 1. Guidance- Presented By- Dr.Sadhana Jain Prof. & Head Dept. of Anaesthesiology, Dr. Deepak Kumar Post Graduate student Dept. of Anaesthesiology S.P. Medical College , Bikaner 1
  2. 2. ANAESTHESIA MACHINE  Anaesthesia machine is a device which delivers precisely known but variable gas mixture, including anaesthetizing and life sustaining gases ANAESTHESIA MACHINE- 2 types 1. Intermittent gas flow type 2. Continuous gas flow type
  3. 3. Intermittent gas flow type      1. 2. – They provide oxygen and nitrous oxide. They operate on demand. Gas flow are drawn by inhalation. They are useful for short surgical procedures . Example – Walton V machine Modified Walton V machine(Lucy Baldwin’s apparatus) 3
  4. 4. 3. Entonox apparatus :Intermittent gas flow machine by Rovenstein. It has premixed cylinder of oxygen (50%) with nitrous oxide (50%). - Cylinder has body of French blue with top white with pin index of 7. - Pressure regulator. - Pressure gauge (2000 psi). - Demand valve. - Key to open the cylinder. - Circuit provided with facemask, expiratory valve, corrugated tube & metal hand piece to hold mask. 4
  5. 5. - Oxygen & nitrous oxide mixture available in gas form due to Poynting effect. (At 2000 psi pressure & at room temperature, oxygen has solvent action, keeps nitrous oxide in gaseous form) - The mixture separates into component parts, at -7 degree celsius known as pseudocritical temperature, carries risk of hypoxia due to nitrous oxide . - This is prevented by:  proper storing,  avoiding excessive cooling  rewarming of cylinder,  shaking ,  inverting several times before use. 5
  6. 6. - Used very effectively as analgesic for : . Dressing of surgical wounds. . Dressing of burns. . Labour analgesia. . Dentistry. . Pain relief for trauma pts. . Post-operative pain relief . In ophthalmological examination. . During cardiac catheterization. 6
  7. 7. - Other intermittent gas flow machines : 1) EMOTRIL – E.M.O. apparatus with trilene. Grey in colour. Draw-over giving air+trilene (0.3 to 0.5 %). 2) TECOTA – Temperature compensated trilene apparatus giving air+trilene . 3) CYPRANE INHALER - Giving air+ methoxyflurane(0.35 %) for labour analgesia. 4) CARDIFF INHALER - Giving air+ methoxyflurane(0.35 %) for labour analgesia. ( inhaled during painful uterine contractions in first stage of delivery. 7
  8. 8. Continuous gas flow type-Gas flows both during inspiration and expiration. Egs : • Boyle Machine • Forregar • Dragger
  9. 9. History  INVENTOR ? Henry Edmund Gaskin Boyle 1917 Modified machine manufactured by James Tayloe Gwathmy
  10. 10.  ORIGINAL BOYLE’S MACHINE Sight-feed water bottle and controls mounted on a vertical rod 4 N2O cylinders Reducing valves with spirit lamps 1 O2 cylinder Rebreathing bag Face piece/mask
  11. 11. MODIFICATIONS  1920 : Addition of ether bottle  1926 : Addition of chloroform bottle  1927 : Back bar added  1930 : Addition of plungers and cowls in ether and chloroform bottles  1933 : Dry bobbin flow meters replaced water sight feed bottles  1937 : Rotameter displaced dry bobbin flowmeters  1979 : Standards for anaesthesia machines
  12. 12. MODELS AVAILABLE IN INDIA  Porta Boyle  King Porta Boyle  Boyle Cadet  Boyle F  Boyle major  Boyle mark III (Boyle Basic)  Boyle mark IIIS  Boyle mark IV
  13. 13. “ the traditional pneumatic anesthesia machine has evolved into a complex electrical, mechanical and pneumatic multi component workstation”
  14. 14. Functions of a WORKSTATION  Safe provision, selection and delivery of anesthetics  Provision of back up supplies of gases  Respiratory support  Monitoring of machine function  Monitoring of patient  Record Keeping  Anesthetic Gas Scavenging System (AGSS)  Suction regulator  Supplemental oxygen  Work surface and storage facility for “everyday items”  Electricity sockets
  16. 16. Electrical Components  Master Switch:  Activates both electrical and pneumatic function  Standby mode: Quicker power up
  17. 17. Electrical Components  Power failure indicator:  Visual or Audible indicator to alert provider of power failure.
  18. 18. Reserve power: Electricity is crucial – Backup necessary Back up with Single power source UPS may be added Amount of charge left is displayed
  19. 19. Electrical Components  Electrical outlets  Convenience electrical outlets on the back of the anesthesia machine. These should be used only for anesthesia monitors and not for general operating room use.  Circuit breakers to protect from overload
  20. 20. Data communication ports : Communication between anaesthesia machine, monitors and data management system. View Figure
  22. 22. 100 kPa = 1000 mbar = 760 mm Hg = 1030 cm H2O = 14.7 psi = 1 atm 1 psi = 6.8 kpa Psig = pounds per square inch gauge
  23. 23. Pneumatic system High Pressure system Intermediate Pressure system Low pressure system
  24. 24. O2 = 2000 psig N2O = 750 psig Cylinder = 45- 50 psig Pipeline= 50- 60 psig just above atmospheric pressure and variable (5-8 psig)
  25. 25. BRIEF NOTE ON CYLINDERS  Components:  Body  Valve – Port, stem  Handle  Pressure relief device  Conical depression  Pin index safety system
  26. 26.  BODY Alloy of molybdenum and steel MRI – ALUMINIUM  VALVE Filled and discharge through valve Port : Point of exit Stem : stem against seat arrangement to close valve  HANDLE body
  27. 27.  CONICAL DEPRESSION Receives retaining screw of the yoke  PRESSURE RELIEF DEVICE Venting of contents at dangerously high pressures TYPES :  Rupture disc – copper  Fusible Plug (Woods alloy) – bismuth, lead tin, Cadmium (Melts at 150-170 deg F)  Combination of both  Pressure relief valve (spring loaded)
  28. 28. SIZE OF CYLINDERS Cylinder classified using a letter code A type cylinders are smallest However AA (smaller than A) also available. SIZE D & E is the cylinder most commonly used
  29. 29. TYPICAL MEDICAL GAS CYLINDRES, VOLUMES, WEIGHT cylinde r size Cylinder Dimensions (O.D. × Length in Inches) wt .(lb) A B 3X7 0.23 3 1/2 x 13 5 D 4 1/2 x 17 11 E 41/4 x 26 M 7 EMPTY oxygn (litres) NITROUSO XIDE 76 Air CO2 (litres) (litre s) 189 (litres) 370 200 375 940 400 14 625 1590 660 1590 x 43 63 2850 7570 3450 7570 G 8 1/2 x 51 97 5050 1230 0 13800 H 91/4 X 51 119 6550 6900 940 15800
  30. 30. COLOUR OF CYLINDER GAS USA INTERNATIONAL oxygen Green White Shoulder& Black Body Gray Carbon dioxide Gray Nitrous oxide helium Blue Blue Brown Brown Nitrogen Black Black Air Yellow Gray Body ,Shoulder black/white quartered
  31. 31. CONTENT AND PRESURE FIG:A nonliquefied gas such as oxygen will show a steady decline in pressure until the cylinder is evacuated. Each cylinder, however, will show a steady decline in weight as gas is discharged.
  32. 32. CONTENTS AND PRESSURE FIG:The relationship between cylinder weight, pressure, and contents. A gas stored partially in liquid form, such as nitrous oxide, will show a constant pressure (assuming constant temperature) until all the liquid has evaporated, at which time the pressure will drop in direct proportion to the rate at which gas is withdrawn.
  33. 33. Cylinder marking1.Name of manufacturer and name of institute 2.Specific number 3.Name of the gas 4.Year of testing and name of the test like BT-bending test 5.Weight in kg 6.Capacity in liters Name of tests1.BT-Bending test 2.Tensile test 3.Impact or flattening test 4.Pressure or Hydraulic test(Every 5 year) 35
  34. 34.  Critical Temperature is the temperature above which any gas cannot be liquefied no matter how much pressure is applied ( O2=-119° C, N2O= 36.5 ° C)  Critical pressure is the minimum pressure that is required to liquefy a gas at critical temperature.  Service pressure is the maximum pressure to which cylinder may be filled at 21.1 ° C  Filling ratio (for liquefied gases) is the percent ratio of the weight of the gas in the cylinder to the weight of water a cylinder can hold at 60 ° F. (N2O = o.68 in tropical, 0.75 in temperate)
  35. 35. Components of pressure systems
  36. 36. High Pressure System  HIGH, VARIABLE LOW, CONSTANT  Components Hanger yoke assembly Cylinder Pressure Indicator Pressure Regulators
  37. 37. HANGER YOKE  Orients and supports the cylinder  Gas tight seal, unidirectional flow
  38. 38.  BODY BODY  Threaded into frame of machine  Supports cylinder  Hinged Swinging gate Swinging gate
  39. 39.  RETAINING SCREW:  Threaded into the distal end of yoke  Tightening the screw – gas tight seal  Conical point fits into conical depression on cylinder  NIPPLE:  Projects from yoke and fits into cylinder port  Entry of gas NIPPLE RETAINING SCREW
  40. 40.  INDEX PINS  Component of pin index safety system  4mm in diameter and 6mm long (except pin 7 which is slightly thicker) .  Pinhole are 4.8mm in diameter . Diameter of valve outlet is 7mm  Fit into the corresponding holes on the cylinder  Holes are on the circumference of a circle of 9/16th inch radius centered on the port of a cylinder
  41. 41.  1, 3  1, 4  1, 5  1, 6  2, 4  2, 5  2, 6  3, 5  3, 6  4, 6 7 Ethylene Nitrogen Air CO2 or O2 (CO2 >7%) Helium & O2 (He <80%) Oxygen CO2 or O2 (CO2 <7%) Nitrous oxide Cyclopropane He & O2 (He >80%) Entonox
  42. 42.  Swinging gate–type Placing cylinder in yoke. The cylinder is supported by the foot and guided into place manually yoke. Note the washer around the nipple and the index pins below.
  43. 43.  FAILURE OF PIN INDEX SAFETY SYSTEM? Breakage of pins Double washer Pushing in of pins
  44. 44.  WASHER (BODOK SEAL)  Seal between cylinder valve & yoke  Fits over the nipple  FILTER  Between cylinder and check valve  Particulate matter
  45. 45.  CHECK VALVE ASSEMBLY  Plunger slides away from the side where pressure is greater  Unidirectional flow  Prevents transfilling  Prevents loss of gas when changing cylinders
  46. 46.  YOKE PLUG  Check valve not designed to function as seals  Place yoke plug when no cylinder present  If cylinder present keep valve closed
  47. 47. Pressure gauge2 common type- 1) Bourdon gauge 2) Aneroid gauge Bourdon pressure gauge Bourdon gauge1.It is robust 2.Inexpensive 3.Able to withstand high pressure 4.Low precision 5.Used to indicate cylinders and pipeline pressure Aneroid gauge1.Delicate and sensitive 2.Comparatively expensive 3.Able to indicate low pressure 4.Used for airway & blood pressure measurement 49
  48. 48. Pressure gauge 1. The gauge is usually colour coded and name and symbol of gas are written over the dial. Blue colour for nitrous oxide and white for oxygen. 2. Cyclopropane and nitrous oxide does not need to carry pressure gauge as weight is the only reliable guide to detect the exact amount in the cylinder as they are in liquid form. 3. The scale must be at least 33% greater than the maximum filling pressure of the cylinders or the full indication position. 4. Gauge is calibrated in (kilopascal)kPa or (pound per square inch)psi or Kg/cm2 . 50
  49. 49. Digital pressure indicator LEDs(light –emitting diodes ) indicate cylinder or pipeline pressure.  Green light- Pressure is adequate.  Red light- Pressure is inadequate.  Dark light- Either valve is not open or the cylinder or pipeline are disconnected.  The pipeline pressure indicator should be towards pipeline side of check valve, not towards machine. 7 December 2009 Presented by Dr.Mukesh Kumar 52
  50. 50. PRESSURE REGULATORS  3 main reasons:  Pressure delivered is too high to be used safely  Fine and accurate control of gas difficult at high Pr.  As contents of cylinder exhausted Pr falls necessitating continual adjustment to maintain flow rate Reduced PRESSURE Constant
  51. 51.  BASIC PRINCIPLE A larger pressure acting over a small area is balanced by a smaller pressure acting over a large area. a1XP1=A2Xp2
  52. 52.  SIMPLE PRESSURE REGULATOR diaphragm Adj. screw Spring Low pr chamber Valve seating
  53. 53.  SIMPLE PRESSURE REGULATOR  Diaphragm – rubber, neoprene, metal  2000 psi to 60 psi
  54. 54.  ADAMS REGULATOR  Lazy tongs toggle arrangement
  55. 55.  Adjustments to alter regulated pressure – only by service engineers  Modern pressure regulators are “universal”  Required to withstand 30 mega pascals(4410 psig)  Output should not vary more than 10% across wide flow range (100 ml/min to 12L/min)  Relief valves on Regulators: Safety blow off valves on downstream side Relief valve set at 70 psig-100psig
  56. 56. INTERMEDIATE PRESSURE SYSTEM  COMPONENTS  Pneumatic part of the master switch  Pipeline inlet connections  Pipeline pressure indicators  Piping  Gas power outlet  Oxygen pressure failure devices  Oxygen flush  Additional pressure regulators  Flow control valves
  57. 57.  Pneumatic part of the master switch  Located downstream of the inlets for cylinder and pipeline supply  Oxygen flush usually independent  Pipeline inlet connections  Entry point for gases (O2, N2O, air)  Unidirectional check valve  Filter with pore size < 100 µm  Threaded non interchangeable DISS  Body, Nipple, Nut combinations  Diameters on each part varies so that only properly mated parts will fit together
  58. 58.  DISS
  59. 59.  Pipeline pressure indicators Indicates pipeline pressure of each gas 50 – 60 psig Pipeline side of check valve    Will monitor pipeline pressure only If on machine side, would monitor machine pressure If pipe line fails, cylinder open – no indication
  60. 60.  Piping  Previously copper now high density nylon  Connects individual components  Withstand 4 times the intended service pressure  Leak between inlet and flowmeter not more than 25 ml/min  If yoke and pressure regulator are included leak not more than 150 ml/min
  61. 61.  Gas power outlet (Auxiliary Gas)  Driving gas for ventilator, gas for jet ventilator  O2 or air
  62. 62. Oxygen Pressure Failure devices These includes-  1.Oxygen Failure safety devices- (Oxygen Failure safety valve,low pressure guardian system, Oxygen Failure protection devices, pressure sensor shutoff system,fail safe,nitrous oxide shutoff valve)  This valve shuts off or proportionally decreases and ultimately interrupts the supply of nitrous oxide if the oxygen supply pressure decreases.  The anaesthesia workstation standard requires that whenever the oxygen supply pressure reduced below the manufacturer-specified minimum,the delivered oxygen concentration shall not decrease below 19% at the common gas outlet.
  63. 63. SPRING LOADED VALVE  O2 Failure Safety Device (Valve)  Located in the intermediate pressure system upstream of the flow control valves of all gases except O2  Shuts off or proportionally decreases N2O
  65. 65. 2.Oxygen Supply Failure AlarmThe anaesthesia workstation standard specifies that whenever the oxygen supply pressure falls below the manufacturer-specified threshold {usually 30psi (205kP)}. - Alarm shall be enunciated within 5 sec. - Alarm shall be of at least 7 sec. duration and shall have a noise level of at least 60dB measured at 1m from the front of the anaesthetic machine. - They add in preventing hypoxia caused by problems occurring in the machine circuit. - Equipment problems(leaks) or operators error (closed or partially closed flow control valve) occur downstream are not prevented by these devices. 68
  66. 66.  O2 Supply Failure Alarm  The Ritchie whistle : Normal operation
  67. 67.  The Ritchie whistle : During O2 failure
  68. 68.  Secondary Pressure Regulators:  Machine working pressure may fluctuate. Eg: At times of Peak demand.  Parallel fluctuations in flowmeter performance  Pressure regulator set below the anticipated pressure drop smoothes out the supply.  Mechanically linked anti hypoxia device assume oxygen pressure to be constant  26 psig for N2O  14 psig for O2
  69. 69. Flow Adjustment Control  The flow adjustment controls regulate the flow of oxygen, air, and other gases to the flow indicators.  There are two types of flow adjustment controls: mechanical and electronic.  The anesthesia workstation standard requires that there be only one flow control for each gas. It must be adjacent to or identifiable with its associated flowmeter.
  70. 70. Mechanical flow control valve  The mechanical flow control valve (needle valve, pin valve, fine adjustment valve) controls the rate of gas flow through its associated flowmeter  Some also have an ON-OFF function. On some machines, the ON-OFF function is controlled by the master switch.  Mechanical flow control valves are used with both mechanical and electronic flowmeters
  71. 71. Mechanical Flow Control Valve  COMPONENTS  Body. The flow control valve body screws into the anesthesia machine.  Stem and Seat.  The stem and seat have fine threads so that the stem moves only a short distance when a complete turn is made.  When the valve is closed, the pin at the end of the stem fits into the seat, occluding the orifice so that no gas can pass through the valve. When the stem is turned outward, an opening between the pin and the seat is created, allowing gas to flow through the valve. The greater the space between the pin and the seat, the greater the volume of gas that can flow.
  72. 72.  To eliminate any looseness in the threads, the valve may be spring loaded. This also minimizes flow fluctuations from lateral or axial pressure applied to the flow control knob.
  73. 73. Contd  It is advantageous to have stops for the OFF and MAXIMUM flow positions. A stop for the OFF position avoids damage to the valve seat. A stop for the MAXIMUM flow position prevents the stem from becoming disengaged from the body.  Control Knob : The control knob is joined to the stem. If it is a rotary style knob, the oxygen flow control knob must have a fluted profile and be as large as or larger than that for any other gas. All other flow control knobs must be round. The knob is turned counterclockwise to increase flow. If Other types of flow control valves are present, the oxygen control must look and feel different from the other controls.
  74. 74. Flow Control Knobs
  75. 75. Contd…..  When a machine is not being used, the gas source (cylinder or pipeline) should be closed or disconnected.  The flow control valves should be opened until the gas pressure is reduced to zero and then closed.  If the gas source is not disconnected, the flow control valve should be turned OFF to avoid the fresh gas desiccating the carbon dioxide absorbent and to conserve gas.  Before machine use is resumed, the control valves should be checked to make certain that they are closed.  Sometimes, a flow control valve remains open after the gas is bled out or opened when the machine is cleaned or moved.  If the gas supply to an open flow control valve is restored and the associated flow indicator is not observed, the indicator may rise to the top of the tube where its presence may not be noticed.  Even if no harm to the patient results, the sudden rise may damage it and impair the flow meter accuracy.
  76. 76. LOW PRESSURE SYSTEM  Downstream of flow control device  Pressure only slightly above atmospheric, variable COMPONENTS :  Flowmeters  Anti Hypoxia Devices  Unidirectional valves  Pressure relief devices  Vaporisers – (another class not today)  CGO (Common Gas Outlet)
  77. 77.  Flowmeters  Mechanical flowmeter  Thorpe tube : Transparent tapered with float  Variable orifice  Smallest diameter at bottom  Gas enters from below  Float moves with the flow of gas  Rests at seat when no flow
  78. 78.  Flowmeters  Rate of flow depends on Pressure drop across constriction Size of annular opening Physical properties of the gas
  79. 79.  Flowmeters  Pressure drop across constriction Friction b/w indicator and tube wall Loss of energy Pressure drop constant Weight / cross sectional area
  80. 80.  Flowmeters  Size of annular opening Increase in flow causes an increase in the size of the opening
  81. 81.  Flowmeters  Physical characteristics of the gas:  Low flow :Longer & narrow constriction Laminar flow Viscosity (Hagen Poiseulle law)  High flow: Shorter and wider constriction Turbulent flow Density(Graham’s law)
  82. 82.  Flowmeters Temperature and pressure effects  Calibrated at 760 mmHg, 20 C  Temp, pressure affect viscosity & density  Accuracy of flow can be affected  Temperature changes are minor  Insignificant change in flow  Low barometric pressure, high altitude  Low flow setting, laminar flow, depends on viscosity    Independent of altitude High flow setting, turbulent flow, depends on density ↓ density due to high altitude – flow more than indicated
  83. 83.  Flowmeter Assembly  Tube, indicator, stop, scale,  Empties into a common manifold
  84. 84.  Tube  Glass (pyrex)  Single / Double taper  Rib guides for ball indicator SINGLE TAPER DUAL TAPER
  85. 85.  Indicator  Free moving device  Made of aluminium  Nonrotating  Rotating – grooves, colored dot.  Ball – rib guides, rotates.
  86. 86.  Scale  Marked on/adjacent to tube  Calibrated at in L/min  Flow < 1L – ml/min, decimal fraction  Lights
  87. 87.  Flowmeter tube arrangement SAFE
  88. 88.  An oxygen leak from the flow tube can produce a hypoxic mixture, regardless of the arrangement of the flow tubes
  89. 89.  PROBLEMS WITH FLOWMETERS Inaccuracy  Improper assembly  May occur after service  Improper calibration  Dirt   Bobbin can get stuck, may not rotate, even if afloat Flow meter indicates higher than actual flow  Back pressure  Standards require back pressure compensation  Improper alignment  If not vertical, annular opening asymmetrical, inaccurate  Static electricity  If bobbin rotates normally, no inaccuracy
  90. 90.  PROBLEMS WITH FLOWMETERS  Float damage  Float hitting the top when cylinder opened  Bobbin stuck at the top  Blocked outflow of the tube  Flow control knob loose  Inadvertent change of set flow
  91. 91.  ANTI HYPOXIA DEVICES  “The anesthesia workstation standard requires that an anesthesia machine be provided with a device to protect against an operator -selected delivery of a mixture of oxygen and nitrous oxide having an oxygen concentration below 21% oxygen(V/V) in the fresh gas or the inspiratory gas”
  92. 92.  ANTI HYPOXIA DEVICES  Mechanical device : Link 25 system  Pneumatic device : Oxygen Ratio Monitor Controller (ORMC)  Electronically controlled : Penlon Ltd
  93. 93.  Mechanical device : Link 25 system 28 gears 14 gears
  94. 94. Mechanical device : Link 25 system  N2O and O2 flow control valves are identical. A 14-tooth sprocket is attached to the N2O flow control valve, and a 28-tooth sprocket is attached to the O2 flow control valve. A chain links the sprockets. The combination of the mechanical and pneumatic aspects of the system yields the final oxygen concentration.
  95. 95.  Mechanical device : Link 25 system  Not possible to deliver less than 25% O2  Further safety feature : 25-250 ml/min basal flow of O2  Limitations:  Takes no account of gases other than nitrous (eg: air, He)  Variations in gas supply pressure  Low flow anesthesia– 25% may not be enough.
  96. 96.  Pneumatic devices  Oxygen Ratio Monitor Controller (ORMC) (Drager)  Depend on the balance of pressure exerted by O2 & N2O on a coupled diaphragm  Nitrous oxide slave control valve
  97. 97.  ORMC An O2 chamber, a N2O chamber, and a N2Oslave control valve. mobile horizontal shaft The pneumatic input into the device is from the O2 and the N2O flow meters Resistorbackpressure Movement of the shaft regulates the N2O slave control valve
  98. 98.  Electronically controlled anti hypoxia device  Paramagnetic O2 Analyzer  N2O cut off when O2 < 25%
  99. 99.  BACK BAR “describes the horizontal part of the frame of the machine, which supports the flowmeter block, the vaporizers and some other components”  Flowmeter outflow to pop off valve  Vaporiser heads are mounted  Selectatec arrangement  Common gas outflow  Ends in non-return pop-off valve (30 -40 kPa=345 cm H2O)
  101. 101.  Uni directional check valve  Positive pressure from breathing system transmitted of back  Affects flowmeter readings and vaporizer delivery  Check valves incorporated upstream of where O2 flush joins FGF  Great importance when checking for leaks in machine
  102. 102.  COMMON GAS OUTLET (CGO)  FGF into breathing system  15 mm female slip in  Coaxail 22 mm male connector  Pressure delivered at outlet is 5-8 psig  Not to be used to administer supplemental oxygen- “inadvertant anesthesia”
  103. 103. PATHWAYS OF O2 Auxiliary
  104. 104. SAFETY FEATURES Antistatic large castor wheels: 360 rotation Front wheel locking bar Small floor space 83 cm X 67 cm Colour coded cylinders Provision to accommodate 2 type E cylinders High pressure gas conduit tubing
  105. 105. SAFETY FEATURES Pin index system Pressure gauges Pressure reducing valves Oxygen fail safe device Low pressure alarms 2 auxillary oxygen outlets
  106. 106. SAFETY FEATURES  Flow meters:         Flow control valves, colour and touch coded Oxygen knob; large, stands out Minimium distance between knobs 25 mm Recessed, guarded, bar protected knobs Minimum 90 rotation required to change setting Base rest for the bobbin Rotating bobbin (slanted grooves/cuts at the top) Long tubes, easy and accurate setting of flow
  107. 107. SAFETY FEATURES  Flow meters:        Gas specific colour coded bobbin Flouroscent dot on the bobbin Position of the tubing Top stop spring loaded Arrangement of flowmeters, O2 flowmeter downstream Antistatic lumen of the tubes (tin oxide coating) Back plate flouroscent
  108. 108. SAFETY FEATURES  Non-return pop-off valve  Trilene lock (Boyle F)  Antistatic tubing, bag and mask  Oxygen flush device  Vaporiser arrangement (boiling pt, potency)  Colour coded vaporisers  Keyed filling ports of vaporisers
  109. 109. Places at which static electricity charges can develop :1.At the wheels(eliminated with antistatic rubber). 2.At the yoke(use nonexplosive grease,Castro-sphirol). 3.At the flow meter (eliminated with antistatic spray like Croxtene or Sphirol H). 4.At the junction of metal & rubber (use antistatic black rubber). 5.At the red rubber & it’s connector(eliminated by exhaled moisture) 6.At the sodalime canister(eliminated by exhaled moisture). 7.At the chain of cork in vaporizing bottle.(If the chain breaks, a touch by someone carrying static charge can cause spark). 115
  110. 110. PRE-ANESTHESIA CHECKLIST First checklist – 1987 Revised in 1993. Latest revision in 2008 Principle based as no one checklist applies to all modern machine models
  111. 111. 1. Verify backup ventilation equipment is available & functioning.  Contaminated oxygen supply, Loss of oxygen supply pressure Obstruction of the breathing system   So check for that Ambu!
  112. 112. 2. Check oxygen cylinder supply  1 cylinder atleast half full (1000 psi)  Not necessary to check N2O  Close cylinder after checking
  113. 113. 3. Check central pipeline supplies.  Check for proper connection at wall  Check the pipeline pressure gauge- should read approximately 50 psi.
  114. 114. 4. Check initial status of low pressure system.  Check liquid level and fill vaporizers if necessary  Fill ports tightly capped.  Check vaporizer interlock.
  115. 115. 5. Perform leak check of low pressure system.  Leaks as low as 100 mL/min may lead to critical decrease in the concentration of volatile anesthetic (creating a risk for intraoperative awareness), or permit hypoxic mixtures under certain circumstances.  Negative pressure leak test (10 sec.) is recommended.  Repeat for each vaporizer.
  116. 116. 6. Turn master switch on. 7. Test flowmeters.  Damage  Full range  Hypoxic guard.
  117. 117. 8. Calibrate oxygen monitor  Final line of defense against hypoxic mixtures.  Calibrate/daily check: Expose to room air and allow to equilibrate (2 min). Then expose to oxygen source and ensure it reads near 100%
  118. 118. 9. Check initial status of breathing system  Set the selector switch to Bag mode  Check that the breathing circuit is complete, undamaged, and unobstructed.  Verify that the carbon dioxide absorbent is adequate  Install the breathing circuit accessory equipment (e.g., humidifier, PEEP valve) to be used during the case
  119. 119. 10. Test Ventilation systems and unidirectional valves  Test ventilator – Bag on Y piece- look for adequate tidal volume, filling of bellows at minimal flows.  Check proper action of unidirectional valves.
  120. 120. 11. Perform leak test of breathing system  High pressure leak test : Pressurise breathing system to 30 cm H2O  10 seconds  Open APL  pressure must decrease  Bains : Inspection Inner tube occlusion test O2 flush test – Venturi effect
  121. 121. 12. Adjust and check scavenging system.  Ensure proper connections between the scavenging     system and both the adjustable pressure limiting APL pop-off valve and the ventilator's relief valve Adjust the waste gas vacuum (if possible). Fully open the APL valve and occlude the Y-piece With minimum O2 flow, allow the scavenger reservoir bag to collapse completely, and verify that the absorber pressure gauge reads about zero. With the O flush activated, allow the scavenger reservoir bag to distend fully, and then verify that absorber pressure gauge reads <10 cm H O
  122. 122. 13. Check, calibrate, set alarm limits of all monitors  Capnometer  Oxygen analyzer  Pressure monitor with alarms for high and low airway pressure  Pulse oximeter  Respiratory volume monitor i e , spirometer
  123. 123. 14. Check final status of machine  Vaporizers off  Bag/Vent switch to "bag" mode  APL open  Zero flows on flowmeters  Suction adequate  Breathing system ready
  124. 124. 15. “Anesthesia Time Out” – To be checked immediately before induction :  All monitors attached, functional?  Capnogram, SpO2 waveforms?  Flowmeter, vent settings proper?  Manual/vent switch to manual and APL open?  Vaporizers filled?
  125. 125. Repeat Check before each patient: Suction  Absorbent  Vaporizers  Breathing circuit Monitors/alarms Anesthesia time out
  126. 126.  Minimum test under life-threatening conditions 1. High pressure test of the breathing circuit 2. Check patient suction 3. Observe and/or palpate breathing bag during preoxygenation.  This ensures adequate flow of oxygen  Good mask fit (very important)  The patient is breathing  The Bag/Vent switch is on "Bag" not "Vent" Checklist can be bypassed only a limited number of times
  127. 127. Thanks for your attention