Vaporizers types and its working mechanisms
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This document discusses different types of vaporizers used to deliver anesthetic gases to patients. It describes six classifications of vaporizers: 1) method of regulating output, 2) method of vaporization, 3) temperature compensation, 4) specificity, 5) resistance, and 6) location. Common vaporizers are then explained in more detail, including how they work, advantages, and disadvantages. Safety mechanisms are also reviewed to minimize risks from incorrect concentrations or agent delivery.
Vaporizers types and its working mechanisms
- 2. VAPORIZERS Instrument designed to facilitate change of liquid anaesthetic agent into its vapor and add a controlled amount of this vapor to the flow of gases going to the patient 2
- 4. 4 I-METHOD OF REGULATING OUTPUT a. variable bypass b. measured flow II-METHOD OF VAPORIZATION a . flow over b. bubble through c . injection
- 5. 5 III-TEMPRATURE COMPENSATION a . Thermo compensated b . Non compensated IV-SPECIFICITY a . Agent specific b . multi agent V-RESISTANCE a . Plenum b . Draw over VI-LOCATION a . In circuit b . Out of circuit
- 6. VARIABLE BYPASS • Accept total gas flow from anaesthesia machine and deliver it with a predictable concentration of vapor to common gas outlet e.g. TEC vaporizer , ether bottle 6
- 7. MEASURED FLOW • Utilize a measured flow of carrier gas usually oxygen to pick up anaesthetic vapor 7
- 8. FLOW OVER VAPORIZER • Carrier gas over surface of a liquid e.g TEC vaporizer. 8
- 10. INJECTION VAPORIZER • Known amount of agent is injected to deliver a desired concentration of agent e.g. TEC 6 10
- 11. THERMO COMPENSATION •To maintain a constant output a . alteration in splitting ratio-bimetallic strip b . computer control-electronic vaporizer c . supplied heat-TEC 6 11
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- 13. RESISTANCE •PLENUM High resistance eg-boyle’s , TEC •DRAW OVER Low resistance eg- Goldman bottle , EMO 13
- 14. LOCATION IN SYSTEM- patient’s inspiratory and expiratory gases go through the vaporizer OUT OF SYSTEM- located out of breathing system and have a dedicated flow meter 14
- 15. FACTORS AFFECTING VAPORIZER OUTPUT • Flow through vaporizing chamber • Surface area of liquid gas interface • Temperature • Time • Gas flow rate • Carrier gas composition • Ambient temperature 15
- 16. How much liquid agent does a vaporizer use per hour? • Ehrenwerth and Eisenkraft gives the formula • 3 X Fresh gas flow(L/min) X Volume % = ml liquid used /hr • This formula is based on the fact that typically 1 ml of liquid volatile agent yields about 200ml of vapor
- 17. EFFECT OF LOW ATMOSPHERIC PRESSURE Concentration calibrated -slight increase in vapor output - concentration increase If expressed in volume percent but deliver same amount of partial pressure Measured flow -delivered partial pressure and volume percent increases 17
- 18. EFFECT OF HIGH ATMOSPHERIC PRESSURE •Decrease output in both concentration calibrated and measured flow 18
- 19. EFFECT OF INTERMITTENT BACK PRESSURE •Transmission of positive pressure from breathing system to machine and vaporizer •Also seen with oxygen flush • PUMPING EFFECT • PRESURIZING EFFECT 19
- 20. PUMPING EFFECT •Increase in vaporizer output •Especially seen when -carrier gas flow is low -agent in chamber is low -dial setting is low pressure fluctuations are high and frequent 20
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- 23. MODIFICATIONS TO MINIMIZE PUMPING EFECT •Keep the vaporizing chamber small or increase the size of bypass chamber 23
- 24. 24 •Add spiral or large diameter tube to lead into vaporizing chamber
- 25. 25 •Increase resistance to gas flow
- 26. Check valve to prevent backward flow of gas 26
- 27. PRESSURIZING EFFECT •Seen when -high flow -large pressure fluctuations -low dial setting 27
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- 29. HAZARDS I. Incorrect agent II . Tipping -high concentration of vapor delivered III . Overfilling -high concentration delivered -decrease in surface area for vaporization 29
- 30. 30 IV . Incorrect concentration delivered V . Reversal of flow VI . Leaks -wastage -wrong concentration OT pollution
- 31. SAFETY MECHANISM • AGENT SPECIFIC FILLING SYSTEM 31
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- 33. 33 • Cap of bottle removed • Adapter screwed to bottle
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- 35. 35 •Low filling port-minimize overfilling •Secured vaporizers-minimize tipping •Interlock prevent administration of more than one agent at a time -SELECTATEC system
- 36. ORDER OF VAPORIZERS • Upstream-low vapor pressure , less potent • Downstream-high vapor pressure , more potent , explosive , easy to clean 36
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- 40. BOYLES BOTTLE •Concentration calibrated •Flow over or bubble through •Non temperature compensated •Multiple agent •Out of circuit vaporizer 40
- 41. OXFORD MINIATURE VAPORISER •Variable bypass •Flow over • temperature compensated •Multiple agent •Out of circuit 41
- 42. -Concentration calibrated -flow over -temp compensated -draw over -in circuit EPSTEIN MACINTOSH OXFORD (EMO) VAPORISER 42
- 43. GOLDMAN VAPORIZER • Concentration calibrated • Flow over • Temp compensated • Multi agent • Draw over • In circuit 43
- 44. TEC VAPORIZER (I-V) •Variable by pass •Concentration calibrated •Flow over with wick •Out of circuit •Temperature compensated •Agent specific 44
- 45. TEC -6 VAPORIZER •For Desflurane •Concentration calibrated •Thermo compensated •Agent specific •Out of circuit •Plenum •Gas vapor blender 45
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- 47. WHY DESFLURANE HAS A SEPARATE VAPORIZER •Its vapor pressure is higher than other agents •Desflurane boils at 22.8 degree Celsius •MAC is higher than that of other modern volatile anaesthetics 47
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- 49. TEC 7 VAPORISER •Similar to TEC 5 •Easy fill mechanism •Non spill •Prismatic sight glass •Smaller graduation for accuracy •Accurate through clinical flow range 49
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- 51. ALADIN CASSETTE •Concentration calibrated • flow over •Automatic thermo compensation •2 parts #cassette-agent specific magnetic code # anaesthesia delivery unit-contain software to recognize agent , part of workstation 51
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- 53. VAPOR 2000/3000 •Concentration calibrated •Flow over •Automatic temperature calibration •Variable bypass •Agent specific •Out of circuit •Vapor 3000 is only for Isoflurane & Sevoflurane and 2000 is also for Halothane & Enflurane 53
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- 55. SIEMENS KION •Concentration calibrated injector •No thermal compensation 55
- 56. THANK YOU 56