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Inhaled anesthetic Delivery Systems

Inhaled anesthetic Delivery Systems. Sahmeddini MD Department of Anesthesia Shiraz medical university. Inhaled anesthetic Delivery Systems. Safety Standards. ANSI - (American National Standards Institute ) 1979 -- Standards set for all machines sold in the U.S .

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Inhaled anesthetic Delivery Systems

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  1. Inhaled anesthetic Delivery Systems Sahmeddini MD Department of Anesthesia Shiraz medical university

  2. Inhaled anesthetic Delivery Systems

  3. Safety Standards • ANSI - (American National Standards Institute) • 1979 -- Standards set for all machines sold in the U.S. • ASTM -- (American Society for Testing and Materials 1988 • 1994: ASTM F1161-94 • 2000: ASTM F1850-00

  4. To comply with the 2000 ASTM F1850-00 standard • Continuous breathing system pressure • Exhaled tidal volume • Ventilatory carbon dioxide concentration • Anestheticvapor concentration • Inspired oxygen concentration • Oxygen supply pressure • Arterial oxygen saturation of hemoglobin • Arterial blood pressure • Continuous electrocardiogram.

  5. Functions of anesthesiamachine • Convert supply gases from high pressure to low pressure • Convert liquid agent to gas • Deliver in a controlled manner • Provide positive pressure for ventilation • Alert the provider to malfunction • Prevent delivery of a hypoxic mixture

  6. Testing Specific Components of the Anesthesia Delivery System 1)Calibration of the oxygen analyzer 2) The low-pressure circuit leak test 3) The circle system tests.

  7. High Pressure System Receives gasses from the high pressure E cylinders attached to the back of the anesthesia machine. (2200 psig for O2, 745psig for N2O)

  8. High Pressure System • Receives gasses from the high pressure E cylinders attached to the back of the anesthesiamachine • 2200 psig for O2 • 745 psig for N2O • Usually not used, unless pipeline gas supply is off

  9. High Pressure System

  10. Hanger Yoke • Hanger Yoke: orients and supports the cylinder • Providing a gas-tight seal • Ensuring a unidirectional gas flow into the machine

  11. Pin Index Safety System(PISS) Prevents tank swaps Pin positions Air 1-5 Oxygen 2-5 Nitrous oxide 3-5

  12. Pin Index Safety System(PISS)

  13. Two sources of gas: • Pipeline 50 psig • Tanks • »Oxygen: 2200 psig • »Nitrous oxide: 745 psig • »Both reduced to 45 psig upon entering the machine

  14. Tank H Tank E Tank

  15. E Size Compressed Gas Cylinders

  16. Approximate remaining time# Oxygen cylinder pressure(psig) 200 .oxygen flow rate(L/min)

  17. Intermediate Pressure System

  18. Intermediate Pressure System • Receives gasses from the regulator or the hospital pipeline at pressures of 40-55 psig

  19. Pipeline Inlet Connections • Mandatory N2O and O2,usually have air and suction too • Inlets are non interchangeable due to specific threading as per the Diameter Index Safety System (DISS)

  20. Diameter Index Safety System (DISS)

  21. Oxygen Pressure Failure Devices Machine standard requires that an anesthesiamachine be designed so that whenever the oxygen supply pressure is reduced below normal, the oxygen concentration at the common gas outlet does not fall below 19%

  22. Oxygen Pressure Failure Devices A Fail-Safe valve is present in the gas line supplying each of the flow meters except O2. This valve is controlled by the O2 supply pressure and shuts off or proportionately decreases the supply pressure of all other gasses as the O2 supply pressure decreases

  23. Oxygen Pressure Failure Devices Historically there are 2 kinds of fail-safe valves • Pressure sensor shut-off valve (Ohmeda) • Oxygenfailure protection device (Drager)

  24. Pressure Sensor Shut-Off Valve • Oxygen supply pressure opens the valve as long as it is above a pre-set minimum value (e.g.20 psig). • If the oxygen supply pressure falls below the threshold value the valve closes and the gas in that limb (e.g..N2O), does not advance to its flow control

  25. Pressure sensor shut-off valve

  26. Oxygen Failure Protection Device (OFPD) • Based on a proportioning principle rather than a shut-off principle. • The pressure of all gases controlled by the OFPD will decrease proportionately with the

  27. Oxygenfailure protection device

  28. Oxygen Supply Failure Alarm • The machine standard specifies that whenever the oxygen supply pressure falls below a manufacturer specified threshold (usually 30 psig) alarm shall blow within 5 seconds.

  29. Limitations of Fail-Safe Devices/Alarms • Fail-safe valves do not prevent administration of a hypoxic mixture because they depend on pressure and not flow. • Do not prevent hypoxia from accidents such as pipeline crossovers or a cylinder containing the wrong gas.

  30. OXYGEN FLUSH VALVE • By passes vaporizer • Delivers large volumes of oxygen to breathing circuit • Is under high(er) pressure caution!!!

  31. OXYGEN FLUSH VALVE • Receives O2 from pipeline inlet or cylinder reducing device and directs high, unmetered flow directly to the common gas outlet (downstream of the vaporizer) Machine standard requires that the flow be between • 35 and 75 L/min • The ability to provide jet ventilation • Hazards: • May cause barotraumas • Dilution of inhaled anesthetic

  32. Second-Stage ReducingDevice • Located just upstream of the flow control valves • Receives gas from the pipeline inlet or the cylinder reducing device and reduces it further to • 26 psig for N2O and • 14 psig for O2 • Purpose is to eliminate fluctuations in pressure supplied to the flow indicators caused by fluctuations in pipeline pressure

  33. Low Pressure System • Extends from the flow control valves to • the common gas outlet • Consists of: • Flow meters • Vaporizer mounting device • Check valve • Common gas outlet

  34. Flow Meter Assembly

  35. Flow Meter • When the flow control valve is opened the gas enters at the bottom and flows up the tube elevating the indicator • The indicator floats freely at a point where the downward force on it (gravity) equals the upward force caused by gas molecules hitting

  36. Flow Meter Standards • Oxygen flow control knob Physically different • Larger and projects further • Different shape • All knobs are colour coded • Knobs are protected

  37. Electronic flow sensors • Some newer anaesthesia workstations have now replaced the conventional glass flow tubes with electronic flow sensors that measure the flow of the individual gases. • These flow rate data are then presented to the anaesthesia care provider in either numerical format, graphic format, or a combination of the two.

  38. Cracked tubes • In the presence of a flow meter leak (either at the “O” ring or the glass of the flow tube) a hypoxic mixture is less likely to occur if the O2 flow meter is downstream of all other flow meters

  39. Proportioning Systems • Mechanical integration of the • N2O and O2 flow control valves • Maintain a minimum 25% concentration of oxygen with a maximum N2O:O2 ratio of 3:1

  40. Proportioning Systems

  41. Proportioning Systems

  42. Proportioning Systems

  43. Vaporizers • A vaporizer is an instrument designed to change a liquid anesthetic agent into its vapor and add a controlled amount of this vapor to the fresh gas flow

  44. Vaporizers

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