Vaporizer part 2 - Copy.pptx by anaesthesia

vaporisers are imp part of anaesthesia machine

1. Vaporizer part 2 PRESENTED BY : DR.NEHA SHUKLA MODERATOR : DR.NAMRATA SADAPHULE

2. FLAGG’S CAN Invented by PALUEL J.FLAGG. Flagg’s can consist of tin can later replaced by plastic. The lid had a hole through which a rubber tube was used to connect the can to the endotracheal tube. Side holes allows entry of air and could be partially closed to adjust the concentration of ether .

3. Area of the holes was equal to the area of the trachea,to minimize resistence of breathing . Oxygen can be supplemented by inserting a catheter connected to oxygen source via holes. The tip of the catheter should be kept above the level of the liquid ether to prevent bubbling of ether leading to high concentration which can be dangerous. The KEM bottle is a modification of Flagg’s cann . HAZARDS T ipping:lead direct entry of ether into the tube and respiratory tract. If side holes are obstructed hypoxic mixture will be delivered to patient.

4. SCHIMMELBUSCH MASK and YANKAUER’S MASK USES OPEN DROP METHOD ETHER The liquid dropped evenly over the whole surface. 16 layers of gauze is used. High rate of vaporization require, high latent heat so that the mask becomes cool which l ead to formation of water vapor from exaled air may condense on it and freeze. This cause increase in resistence of flow of air through gauze,to minimize this fresh gauze or second mask is needed. CHLOROFORM The liquid is restricted to one half of it to ensure that air is freely drawn and concentration of vapor is not to high. 12 layer of gauze or 1 layer of lint.

5. In schimmelbusch mask ,the patient’s face is covered with Gamgee with a hole to expose mouth and nose . This prevents entering of liquid in patient’s eye. It also reduces the amount of air drawn in by the patient between the mask and his face.

6. OGSTON’S INHALER Uses semi drop method. It consist of a mask surmounted by wire frame around which a napkin or gauze could be erected to keep the vapor trapped.

7. BOYLE’S BOTTLE CLASSIFICATION Variable by pass , flow over without wick or bubble though ,out of system. No temperature compensation. Not caliberated AGENTS USED Ether Methoxyflurane Trilene Chloroform Halothane

8. FUNCTION When the lever in OFF position gas flows via bypass entirely. As the lever is turned towards ON gases starts to flow through the bottle. In full on position all gases pass through the bottle . When the cowl is up , gases flows directly from U-TUBE to the outlet of the vaporizer. By lowering the cowl over the end of U-TUBE gases may be diverted, as gases are forced to impinge on surface of ether. When cowl is fully down , gas bubbles up through liquid to produce maximum vaporization. The position of the cowl is adjusted by plunger.

9. The control drum rotates inside the body of the vaporizer ,its position is maintained by locking rings which are present laterally. Grease is used to maintain a seal and yet allows rotation. With the time as gases and vapors pass through the vaporizer , the grease tends to be washed away slowly which cause stiffness . If the plunger become loose it tend to fall ,which can be corrected by tightening the gland. The site of filling orifice is blocked by cork stopper, which is retained by small chain. The stopper should have a tight seal to prevent leak of gases. If the chain is broken , the metal core of the cork can act as a spark plug . Therefore it is important that the chain is intact. Copper in ether bottle act as an anti-catalyst preventing decomposition of ether. Colored bottles are used to prevent decomposition of volatile gases,eg;Trilene .

10. EVALUATION The concentration of vapor depends on the temperature, the level of the liquid anesthetic agent and the rate of gas flow. Temperature is maintained by wiping bottle from outside or by wrapping the bottle with warm Gamgee. For ETHER vaporizer broad bottle is used as higher concentration of ether is required in the early phases of inhalational anesthesia due to its high blood gas solubility . Volatile agents must be removed in the vaporizer after use and be discarded in order to prevent a risk of being used in other bottle. Minimum concentration of Ether with 10oz ether filled with 8 lit gas flow is 4.5%. Maximum is 14.5% with cowl at highest position. Maximum concentration with cowl fully depressed for maximum bubbling is 40%. For Chloroform and Trichloroethylene ,sufficient concentration is produced by turning the knob fully on,depressing the plunger may lead to dangerously high concentration.

11. HAZRADS Lever gets stuck due to thymol ,which is used as a preservative. Plunger may get stuck. As ether is a volatile agent and there may be a build-up of the vapor in the bottle ,more so in warm environment It leads to a surge of high concentration ether vapor when vaporizer is turned on It can be prevented by running a small quantity of gases through the vaporizer prior to commencement of anesthesia or by removing the cork from the filler orifice. As bottles are not color coded the residual agent in the BOYLE’S bottle may be poured back into the wrong bottle.

12. TRILENE INTERLOCK Trilene interlock is present on the back of bar of some machines which does not allow the operator to switch on trilene vaporizer when machine is on CIRCLE SYSTEM and vice versa. This ensure that trilene cannot flow on the soda lime canister (as trilene forms phosgene gas with soda lime).

13. EMO INHALER CLASSIFICATION Concentration calibrated , variable bypass. Flow over with wicks. Draw over ( low internal resistance ). Agent specific. Temperature compensated by specific heat and by altered flow. Vaporizer in and out of system.

14. CONSTRUCTION It is 23cm in diameter,24cm in height and weighs 6.5kg with the water compartment full. It has annular ether vaporizing chamber (V). It is lined with wicks. Surrounding this is a water compartment (W). Automatic thermocompensating valve (T). Air inlet communicates with a large chamber with two outlet. One gives access to the main ether chamber via closing mechanism (L). It seals of the entry to ether chamber when control indicator is in ‘transit’ position. Inlet relief valves-it allows air to enter the inhaler if main inlet is blocked. Outlet port leads into small chamber in the center of the control rotor which is fully open in the ‘transit’ position ,but as the concentration indicator (C) is moved around towards the 20% position ,it closes progressively, so directing a greater proportion of air into the ether chamber.

15. The central chamber has a second inlet port leading from the ether vaporizing chamber via the thermocompensating valve (T). This port is fully closed in transit position but opens progressively as the indicator is moved towards 20% position , permitting extra air to leave the vaporizing chamber. Therefore the control mechanisms directs larger proportion of the air to the ether chamber without altering the total flow through the inhaler. It also seals the ether chamber when the inhaler is not in use. The temperature compensating mechanism is a bellow shaped capsule containing liquid ether which allows more air to pass through the vaporizing chamber,when the temperature in the vaporizing chamber drops thereby, maintaining the volatile agent output concentration constant between 15° a nd 30 °C. The indicator on the compensating unit,shows red if the temperature is more than 32°. Black band if the temperature is between 20-25°C.

16. PRECAUTIONS When supplied ,water jacket is dry and must be filled uptill 1200ml of cold distilled water via filler (F). Water must be checked every 3 months because chemical action may lead to generation of gases which can damage inhaler parts. While filling , the control must be in zero position so that air escape from the vaporizing chamber. The inhaler must not be overfilled otherwise the wicks will be covered and vaporization of ether will be decreased. The control pointer may get stuck if inhaler is not used for long with completely filled with ether, so drainage of ether is required if inhaler is not in use. Also open the control fully to allow the vapor to escape or oxidation of ether will occur.

17. CHECKING OF EMO The level indicator is checked by inverting the inhaler ( with concentration control in transit),when it should fall freely to the FULL position. Connect the bellows to the inlet and block the outlet. The control knob is turned to the transit position, the filler held open, the bellows are compressed and no air should escape. The filler is released, the control pointer turned to 10%,and this is repeated o check the leakage in filler. Bellows is then attached to outlet,inlet is closed ,control knob is set at 2 to suck air in though the safety release valve. If valve is working correctly sound of hissing is heard.

18. OXFORD MINIATURE VAPORIZER AGENTS Halothane,MethoxyfluraneTrichloroethylene It is used with EMO , when used it is plugged with outlet of EMO. Never fitted with inlet , otherwise halothane will be drawn in causing corrosion. When combined with inflating device can be used as draw over anesthetic apparatus. Low resistance system. Not temperature compensated. Flow over with steel wicks.

19. CONSTRUCTION It is 13.5cm high ,weigh 1060gms(with water jacket full). It has a scale which gives volumetric % concentration at 25°C. The base contain a water jacket which act as heat source. When used with EMO the flow of the gases is from right to left. Another versions are for gas machines in which the flow of gases is from left to right. The OMV has special filler designed to limit the volume of anesthestic used . The lever of OMV must be fully pressed down to open the filling port. The built in funnel surrounding the filler contains about 10ml. It covers about 1/8 th of the level indicator. The indicator is designed such that some liquid remains in the chamber even when it can no longer be seen in window. It consist of heat sink with is made up of glycol which act as a heat reservoir.

20. OXFORD INFLATING BELLOWS(OIB) CONSTRUCTION 25 cm long ,23 cm high ,18cm wide ,weight -3.5 g, spring loaded concertina bellows with 2 non –return flap valves. Has two unidirectional valves , one at the inlet and other at the outlet. The valve consist of a disc of metal that lifts by air flow and falls by gravity. There is also oxygen inlet connection. It is mainly used for spontaneous respiration.

21. FUNCTION The bellows was first designed to use with a simple spring loaded expiratory valve. For artificial respiration a non-rebreathing valve or inflating is used. During artificial respiration(inspiration) ,compression of the bellows produce full deflection of the flap valves. In order to draw the flap valve back and permit the patient to expire a small amount of gas must pass through the corrugated tube towards the bellows. If the outlet flap valve is not immobilize air will unable to pass back and non rebreathing valve will stick in inspiratory position,magnet is provided for immobilizing of distal flap. So a magnet must be fitted if a non rebreathing valve is used. The bellows have internal spring,press studs inside the concertinas keep them closed during storage and transport. It can delive a volume of 1300ml A 10cm stroke will deliver about 800ml.

22. THE PENLON BELLOWS UNIT(PBU) This has a single flap valve designed specifically for use with a non-rebreathing valve. Pediatric bellows has capacity of 400ml.

23. USE OF EMO WITH ANESTHESIA MACHINE Flow meter is connected directly into the air inlet of the EMO. This arrangement can allow the EMO to work as a plenum vaporizer, allowing a lower than indicated concentration of ether to be delivered if fresh gas flow is less than 10 lit/min. If the fresh gas flow is less than patient’s minute volume,air will be drawn through the inhaler. It can cause overfilling of the bellows.

24. ARRANGEMENT OF EMO If the vaporizers are palced in series, the vaporizer for the more volatile agent should be placed upstream from the vaporizer for the less volatile agents. The bellows or inflating bag should placed between the patient and the vaporizer. Oxygen and nitrous when used should always be in upstream side of the vaporizer. When using the OIB the magnet must be used to immobilize the downstream flap valve ,when an automatic non rebreathing valve is used. Before using the apparatus the bags and bellows must be operated in order to ensure the flow is in correct direction.

25. Emo for children Dead space of the non rebreathing valves and connections are too high for children. The inspiratory flow rates generated by children is too low to use EMO as a draw over vaporizer. So EMO must be used as CONSTANT FLOW OVER VAPORIZER.. Pediatric entrainer was designed to provide flow of oxygen enriched air through the EMO. Gas flow of 10L/min is needed to deliver correct concentrations. The pediatric entrainer is connected to a oxygen cylinder preferably via a regulator. On side arm of entrainer a manometer is attached. Flow from the cylinder is increased until manometer reads 100mmhg. This will deliver the correct flow of 10l/min.

26. With oxygen as the driving gas an inspired oxygen of about 35% is given. When compressed gas is used as the driving gas,the ether remains flammable but not detonable. Oxygen and ether mixture is explosive so it is better to test them with an empty vaporizer or at the very least in a well ventilated spot. If the outlet of the unit is blocked ,the high pressure gas escapes from the air inlet port and maximum pressure in the system will be 15cm H2O. This act as a safety valve preventing the patient from getting high pressure. The consumption of driving gas is 2L/min. The entrainment ratio is 1.5:1 .

27. The pediatric entrainer is inserted at the inlet of EMO with OIB and OMV. The anesthetic mixture is delivered to the patient via a Ayer T PIECE or endotracheal tube. One end leads to patient via facemask or ETT ,the other end has reservoir which has volume greater than the tidal volume. When penlon is used ,the OMV or BSIU remains on the downstream side of the vaporizer. MINUTE VOLUMES: 1.5 L - One year 2 L - Three year 3 L – Five year A FGF of 2.5 to 3 times the minute volume should be used with Ayre’s T piece to prevent rebreathing.

28. GOLDMAN VAPORIZER CLASSIFICATION Variable by pass , draw over or flow over vaporizer Can be used with or with out wick. In or out of system. No temperature compensation. Multiple agents. MODELS Mark Ⅰ Self –locking in off position. Three divisons between off and on position .

29. Mark Ⅱ Click stops at each settings Three divisions between on and off positions. Size and shape port differs from Mark Ⅰ. Mark Ⅲ Two divisions between on and off positions. Click at each setting.

30. CONSTRUCTION A small bowl which holds 20cc liquid. Bowl is attached to head which receives gas and divides gas between vaporizing and bypass chamber. A control lever which is present on the top controls the vaporizer output, works while turning in counterclockwise direction. MANUFACTURER-1959 ,adapted from Leyland fuel pump.

31. EVALUATION AND USE Low resistance vaporizer. Easy to operate and does not deliver high concentration. When vaporizing chamber is full ,output concentration is 3%. When used inside breathing circle,maintain high concentration of halothane. CAPACITY: 30 ML It should be drained periodically. Vaporizer chamber should be cleaned out and allowed to dry. Output can be increased by wiping away water of condensation from the surface.

32. HAZARDS Agitation or tilting will increase the vapor output Tipping . ADVANTAGE Small ,simple , inexpensive , portable and user friendly. OUTPUT CAN BE INCREASED BY: Fill the bottle to max. Wipe the bottle . Attach two goldmann in series.

33. ROWBOTHAM VAPORIZER Modification of GOLDMAN VAPORIZER. Flow over vaporizer. Not temperature compensated. CAPACITY 35 ML. Maximum concentration upto 3.1 % with 4L/min rate. Vapor strength is controlled by means of lever stopcock.

34. COPPER KETTLE CLASSIFICATION Measured flow Bubble through. Non-temperature compensated but has heat sink. Out of system. Multiple agent.( chloroform,ether,halothane and isoflurane). MANUFACTURER –Dr. Lucien E Morris in 1952

35. PRINCIPLE A small precise volume of carrier gas is completely saturated with the anesthetic agent and predetermined amount is added to the fresh gas flow. Every time the fresh gas flow is changed the vaporizer setting has to be changed manually. GAS FLOW Gas enter the vaporizer from the inlet and passes upward through the central tube into the surge chamber. It then passes downward around the central tube and enter diffuser at the base of the vaporizer. Bronze disk is present at the top of the diffuser,it conducts the heat to the gas-liquid interface and prevents cooling.

36. As the carrier gas permeates through the disk,it is broken down in bubbles,which rise through the anesthetic liquid. Gas saturated with vapor rises to he top of the kettle and passes out through the discharge tube. Level indicator window is present. Filling port at top in older model and at back in newer ones. Newer model have a back pressure check valve. CAPACITY : 160 ml and 400ml

37. CONSTRUCTION Separate flow meter for flow to the kettle. Vaporizer circuit control valve is present. Copper is used because of its high heat capacity and thermal conductivity. HAZARDS Calculations are required to determine the flow of gases through the vaporizer for a particular output. Failure to turn on the main gas result in undiluted vapor delivery to patient. Overfilling in older model.

38. Tec vaporizers CLASSIFICATION Variable bypass Flow over with wick. Out of system. Temperature compensation by automatic floe alteration. Concentration calibrated. Agent specific.

39. FUNCTIONING OF TEC VAPORIZERS (2,3,4,5AND 7) The gases passes through the vaporizer by 2 channels . One leading through a bypass chamber and other through the vaporization chamber. Proportion of gases passing through the bypass chamber is determined by calibrated control knob ,which is attached to a spindle. On off position the ,vaporizing chamber is isolated from the bypass ,all gages pass through the bypass to the fresh gas outlet. When the spindle is pulled towards the operator and rotated in countercloxkwise direction,inlet and outlet portion of vaporizing chamber opens. A bimetallic thermostatic valve determines the fraction of gas passing through the vaporizing chamber

40. This valve is in the vaporizing chamber in TEC 2, and in other vaporizer it is present in by pass chamber. When the temperature in the vaporizing chamber falls, thermostatically operated valves opens wider and increase proportion of gases pass through the chamber. This keeps the vapor output constant. Wicks in vaporizing chamber increase the surface area. Which ensures that gases are saturated with vapor.

41. TEC Ⅰ MANUFACTURER-CYPRANE COMPANY IN 1956 AS FLUOTEC Ⅰ. It has design flaw which could cause the proportioning valve to stick thus posing a risk of over dosage to the patient. Therefore all MARK Ⅰ are recalled , remodified and re-released as MARK Ⅱ.

42. TEC Ⅱ Halothane – Fluotec –MARK Ⅱ. Methoxyflurane – Pentec – Mark Ⅰ. CONSTRUCTION Filling tap at side. Draining at bottom. Level indicator on side.

43. Round vapor chamber ,wicks are concentric and in series. External calibrated knob is attached to spindle . Temperature compensation by bi metallic strip. EVALUATION With flow of 2 lit/min, at dial setting less than 2%,output is less than the setting. With dial setting more than 2% output is more than the setting. With nitrous oxide it give greater output at lower setting and vice versa. Pumping effect at low flow and pressurizing effect at high flow. There can be leak in off position.

44. CARE AND CLEANING Yearly servicing. Halothane – thymol as preservative which accumulates. Vaporizer should be drained every two weeks. HAZARDS Thymol cause operating spindle to stick. High concentration low flows.

45. Tec Ⅲ MODELS Flutech Mark 3 Pentec mark 2 Enfluratec fortec

46. CONSTRUCTION Lower vaporizing chamber Upper duct and valves. SINGLE CONTROL DIAL Co ntrols the concentration delivered. M ovement of dial , open and close appropriate parts and regulates the proportion of gas passing through the vaporizing chamber. Larger bypass chamber The tube to the vaporizing chamber is long with an expansion area. Wicks are excluded ,which helps in reducing the back pressure on vaporizer output. Concentration dial on top.

47. Window for liquid level on left. Filling and draining at the bottom. EVALUATION Accurate with lower dial setting. At higher setting higher than expected concentration and at lower setting lower than expected concentration. Nitrous oxide has little effect on output. Tipping upto 90°dose not affect output more than this cause increase in output. Small amount of leak in bypass in off position.

48. Care and cleaning Annual maintenance . Halothane drained every two weeks. HAZARDS Can be rotated beyond off position. Leak from dial setting

49. TEC Ⅳ MODELS Fluotec 4 Enfluratec 4 Fortec 4 CLASSIFICATION: plenum,variable bypass, Flow over with wicks,temperature compensated CONSTRUCTION Modified version of TEC - Ⅲ. Attached to the back bar of anesthesia machine by means of Select-a-Tec manifold.

50. PARTS Control dial on top,turned counterclock wise direction to increase the concentration. Release button located to the left of the dial,should be depressed before the vaporizer is turned on. Locking lever is connected to the control dial,so it not turned on unless it is locked to the manifold. When vaporizer is turned on-two plunger operate with in the vaporizer to open the valve into the fresh gas stream. Two extension rods prevents attachment of other vaporizer in on position. Filling mechanism: screw cap or keyed filling system

51. GAS FLOW OFF POSITION – incoming gas flows from inlet through bypass to the oulet . ON POSITION- incoming gas is split into two stream by a rotatory valve which is attached to the concentration dial. One stream is directed to the vaporizing The remaining fresh gas flows to the c hamber ,after this it is directed over two bypass chamber ,which contain c oncentric wicks,which enclose a copper helix. Temperature sensitive element. Wicks ensure maximum contact between gas a nd agent. The vapor laden gas leaves via second chamber Surrounding the bypass chamber to outlet.

52. EVALUATION Fluctuating back pressure can increase the concentration by altering the flow distribution with in the vaporizer. Maximum effects with-low flow rates, low dial setting. Output when nitrous used as carrier gas. Vaporizer filled and used in upright position. No spillage after tilting or inversion till 180° CLEANING AND CARE Yearly service Every two weeks, drain the vaporizer.

53. Tec Ⅴ MODELS Isotec 5 Fluotec 5 Enfluratec 5 Sevotec 5 CLASSIFICATION Plenum,variable bypass,flow Over with wicks,temperature compensated

54. CONSTRUCTION At the top control dial Release button at the rear of dial ,pushed in for turning on the vaporizer. At the Rear end is a locking lever connected to the dial,so that the vaporizer can’t be turned ON until it is locked to manifold. At the bottom right is a glass that shows liquid level. Filling devices – keyed filling and screw cap. A locking lever to secure the filling block is located on the left of vaporizer. Internal baffle system system is designed to keep liquid from reaching the outlet if the vaporizer is tipped.

55. fUNCTION When the concentration dial is in the zero position all the gases from the flowmeters bypasses the vaporizer through Select-a-Tec bar. When the dial is turned pass ZERO , inflowing gas is split into two streams by rotatory valve. One stream to the vaporizing chamber. Other through the bypass. In the bypass chamber gases flows down through one side of the vaporizer and past the THERMOSTAT . THERMOSTAT- bimetallic strip in the base.

56. As the temperature in the vaporizer decreases , the thermostat permits less gas flow to the bypass , so that more gas pass through the vaporizing chamber. From the thermostat ,gas flows up the other side of the vaporizer and near the outlet joins the gas that has passed through the vaporizing chamber. The gas flowing through the vaporizing chamber first passes through the central part of the rotatory valve. After this gas is directed though a helical channel ,then it past a spiral wick that is in contact with the wick skirt , which dips into the liquid agent. Gas with vapor leaves the vaporizing chamber via a channel in the concentration dial and flows to the outlet.

57. EVALUATION Greatest accuracy: FGF less than 5L/min and dial setting of 3%. Temperature between 15° and 30°C. Thermostat doesn’t respond to temperature below 15°C. If temperature more than 35°C ,high output will be high. CAPACITY-300ML MAINATENCE V aporizer is wiped with damp cloth. Vaporizer should be drained every 2 weeks. Service every 3 years.

58. HAZARDS Gas leak if filling port is open or partially loose. Loss of liquid agent if vaporizer is fully filled. Tilting the vaporizer results in over filling. Can be over filled if the adaptor is loose or dial is in ON position.

59. TEC Ⅵ Concentration calibrated. Thermocompensated by electrical heat. Agent specific Out of circuit. Plenum. Gas vapor blender.

60. Need for different vaporizer Desflurane has higher vapor pressure of 669mmhg , therefore much higher concentration of FGF is required to dilute this vapor to be used in clinically. Boiling point of DESFLURANE is 22.8°C , so room temperature more than 22.8°C ,the amount of vapor formed would be limited only by heat available from the vaporizer. Latent heat of vaporization-amount of energy required to convert liquid into vapor form ,more vaporization means more loss of heat and faster cooling,so external heat source is required to maintain constant vapor output.

61. CONSTRUCTION The concentration dial at the top is calibrated from 1% to 18%. A dial release at the back of the dial must be depressed to turn the dial from standby position. Filler port at the front. It has LED panel display: Amber warm up LED-warm up period after the vaporizer is connected to power. Green LED- vaporizer is operational. Red LED – no output , level less than 20 ml. Amber low agent LED-less than 50ml agent in vaporizer. Amber battery low LED.

62. The liquid level indicator has a liquid crystal display , which indicates the amount f liquid between 50 and 425 ml. There are 20 bars a single bar corresponds to volume of 20ml. Internal construction: Two heater present at the base. Sump assembly holds-filling port, drain,agent level Sensor,heaters . Concentration dial and rotatory valve. Shut off valve which opens when above two are turned. It also consist of a fixed resistor and variable resistor. Pressure transducer.

63. T he vaporizer have two independent circuit arranged in parallel. The diaphragm in the pressure transducer seperates the FGF from vaporizing chamber with the help of FLOW RESISTOR. It senses the amount of FGF through the differential pressure transducer. Liquid desflurane heater present at the base heats the DESFLURANE to 39°C. This much temperature is required to build vapor prseeure of 1300mmhg . This pressure is regulated through flow control valve which in turn is regulated by pressure transducer. Second flow control valve is control by vaporizer dial.

64. Two atmospheric pressure is needed to act as d driving pressure ,so tat the vapor joins the FGF. EVALUATION The vaporizer is calibrated for flows from .2L to 10L/min. The output is almost linear at the 3% ,7% and 12 % settings , with slightly lower output at flows less than 5L/min and vice versa. Nitrous oxide as carrier gas decrease the output. The battery must be replaced annually. Service annually. HAZARDS Vapor can leak into the fresh gas flow with vaporizer turned off. The bottle may be dropped when released under pressure.

65. Aladin vaporizer Designed for-sevoflurane , isoflurane desflurane , halothane and enflurane . This vaporizer regulates anesthetic vapor concentration with electro pneumatic proportional flow valves , controlled by microprocessors. CLASSIFICATION Plenum,variable bypass,flow over with wicks, Agent specific,color coded,

66. CONSTRUCTION Vaporizer consist of two parts. The electronic control device in the anesthesia machine. The agent is the portable cassette , inserted into a slot in machine, alongside the concentration dial. On the display screen agent is identified by name and color code also magnetically coded so that the machine can automatically identify the cassette. Handle on the side to carry it and release on inside of the handle which when squeezed release the cassette from the machine. The back of the cassette has two ball valves, which act as inflow and outflow port. Key Filled or Easy fill – halothane, enflurane and isoflurane.

67. Keyed filled or Quik fill-sevoflurane , saf -T-fil for desflurane . CAPACITY-225ML When the ball in the side tube is at the bottom cassette 80ml or less.

68. The FGF enters the vaporizer and split into bypass and vaporizing chamber. Amount of in each is managed by sensors. Wicks are present in vaporizing chamber which increase the surface area.. Check valve at the inlet of vaporizing chamber prevent back flow of agent in bypass. The flow at the outlet of vaporizing chamber is controlled by CPU. CPU-has information regarding the FGF , dial setting,temperature in the rear of cassette and flow. All this is used to determine the ratio of gas flow through the bypass and vaporizing chamber. Inside the vaporizing chamber metal plates increase the heat conductivity and capacity,this improves temperature stability and vaporization. When cassette is removed two spring loaded valves automatically closes the channel.

69. EVALUATION Accuracy for all agents is +/-10% of the setting or +/-3% of max.dial setting with FGF from 200ml/min – 8L/min. Temperature less than 15° and FGF more than 8L/ min,vaporizer may be unable to produce high concentration and message of insufficient agent or decreased flow will show on machine. The vaporizer can be tilted in any direction. HAZARDS The cassette is fitted with an overfill protection mechanism ,if air is allowed into the agent this mechanism fails.,which can result in overfilling. Turning the vaporizer ON while filling ,pressurize the cassette and results in liquid leak .

70. FILLING SYSTEMS DRAW OVER VAPORIZER- The chamber can be unscrewed from the back or gas channel and liquid poured in unit. Draining is recommended after use and transport. SCREW FILL- Early plenum vaporizer had filling port at the bottom. The screw threaded stopper is unscrewed ,agent filled and stopper replaced. Hazards of both of them is overfilling , wrong agent and environment pollution.

71. KEY FILL SYSTEMS It has three parts : -The bottle with neck collar -The adaptor. -The vaporizing filling port. The vaporizer filler receptable (filler socket,vaporizer fill unit etc.) permits only the intented bottle adaptor to be inserted . One end of the adaptor has a connector with a screw thread to match the thread on the bottle. Bottle has color coded collar :red – halothane , orange- enflurane ,violet-isoflurane, yellow-sevoflurane, and blue – desflurane . The filling port has a ledge which corresponds to the adaptor and is agent specific.

72. EASY-FIL The port on the vaporizer is modified along with modification of distal end of adaptor. The filler channel and the bottle adaptor have groove and ridges which align with each other. BOTH THE SYSTEM CAN LEAD TO MISFILLING IF THE WRONG AGENT IS DECANTED INTO THE AGENT SPECIFIC BOTTLE . QUIK-FIL Abbott lab produces sevoflurane bottle and the agent specific filling device is fitted on the neck. The bottle is opened and inverted onto the filling port.

73. SAF-T-FIL For desflurane TEC 6. It has a filler nozzle which fits into the filler port of TEC6. The nozzle is pushed onto the spring loaded aperture of the and the bottle is inverted . The vaporizr can be filled while in use. Shut off valve present which liquid from leaving the sump.