The document summarizes the key components and functions of an anesthetic machine. It describes the high pressure and low pressure systems, including gas supplies, cylinders, manifolds, regulators and flow meters. It explains the purpose and mechanisms of vaporizers and breathing circuits. Safety features like oxygen failure alarms and leak tests are also summarized.

1. ANESTHETIC MACHINES AND RELATED EQUIPMENT PROF. AMIR B. CHANNA FFARCS ,DA (ENG)

2. ANESTHESIA MACHINES

6. Anesthesia Machine

10. Vaporizers

12. Gas supply Pipeline Cylinder

14. Gas Management Systems

18. Medical gas pipeline diagram

27. Pipeline

29. Medical gas cylinders with plastic wrapping intact

30. Oxygen cylinder valve and pin index

31. Nitrous cylinder valve and pin index

32. Carbon dioxide cylinder valve and pin index

33. Anesthetic machine cylinder yoke

34. Color coding of medical gas cylinders and their pressure when full Body color Shoulder color Pressure,kPa (at room temp) Oxygen Black White 13 700 Nitrous oxide Blue Blue 4400 Carbon dioxide Grey Grey 5000 Air Grey White/black quarters 13 700 Entonox Blue White/blue quarters 13 700 Oxygen/helium Black White/brown quarters 13 700

35. Diagram showing the index positions of a cylinder valve. Oxygen: 2 & 5 Nitrous oxide: 3 & 5 Air: 1 & 5 CO 2 : 1 & 6

36. A cylinder yoke and pin index system. Note that a Bodok seal is in position

37. New cylinder valve which allows manual opening and closing

38. A Bodok seal

39. Inserting a remote probe into its matching wall- mounted outlet socket

40. Outlet sockets mounted in a retractable ceiling unit

41. Color-coded hoses with NIST fittings attached to an anesthetic machine

42. A oxygen cylinder manifold

43. A vacuum-insulated evaporator

44. Schematic diagram of a liquid oxygen supply system

46. Pressure Relief Valves – Heidbrink valve An anesthetic machine may contain a pressure valve operating at 35 kPa, situated on the back bar of the machine between the vaporizers and the breathing system. Modern ventilators may contain a pressure relief valve set at 7 kPa Anesthetic scavenging systems operate at pressures of 0.2 – 0.3 kPa

47. A pressure relief valve

49. A simple pressure-reducing valve p a P A =

52. Needle valve

54. Mechanism of action of a flowmeter

55. As the bobbin rises from A to B, the clearance increases (from X to Y)

56. Different types of bobbins 1. ball, 2. non-rotating, 3. skirted, 4. non-shirted

59. Pressure sensor's shut - off valve A, The valve is open because the oxygen supply pressure is greater than the threshold value of 20 psig. B, The valve is closed because of inadequate oxygen pressure

60. The oxygen failure protection device ( OFPD ) OFPD responds proportionally to changes in oxygen supply pressure

61. Flow Meter Assemblies

64. Flowmeter Patient VARIABLE BYPASS

65. Flowmeter Patient

66. Flowmeter Patient

68. Principle of the draw-over vaporizer

69. Oxford miniature vaporizer (OMV)

70. The Goldman drawer vaporizer

71. The EMO (Epstein and Macintosh of Oxford) drawover ether vaporizer

72. Principle of the plenum vaporizer

73. The Boyle’s bottle

74. Halothane vaporizer at 20 0 C illustrating principle of action

76. Relationship between vapor pressure and temperature for different anesthetic agents

77. A simple type of vaporizer

78. Generic variable bypass vaporizer

79. Simplified schematic of the Ohmeda Tec 4 vaporizer

80. North American Drager Vapor 19.1 vaporizer

81. Tec Mk 5 vaporizers mounted on the back of an anesthetic machine

82. Agent-specific, color coded, keyed filling devices

83. The Tec Mk 6 vaporizer

84. Tec 6 desflurane vaporizer

87. Techniques to achieve full saturation of the gas in the vaporizer chamber. (A) use of wicks, (B) use of small bubbles from sintered glass or metal (A) (B)

88. Partial control of the temperature in the vaporizer by the use of a metal casing and a heat reservoir

90. The effect of a hyperbaric pressure of a 200 kPa on the performance of a halothane vaporizer

91. Negative Pressure Leak Test

92. Negative Pressure Bulb is in Drawer If not, Page your Anes Tech

93. Anesthesia Apparatus Checkout Recommendations

106. Physical Principles of Conventional Flow Meters The clearance between the head of the float and the flow tube is known as the annular space . It can be considered an equivalent to a circular channel of the same cross - sectional area .

107. Physical Principles of Conventional Flow Meters viscosity (laminar flow) density ( turbulent flow )

109. The flow meter sequence is a potential cause of hypoxia A and B, In the event of a flow meter leak, a potentially dangerous arrangement exists when nitrous oxide is located in the downstream position . C and D, The safest configuration exists when oxygen is located in the downstream position

110. An oxygen leak from the flow tube can produce a hypoxic mixture, regardless of the arrangement of the flow tubes

112. N 2 O and O 2 flow control valves are identical. A 14-tooth sprocket is attached to the N 2 O flow control valve, and a 28-tooth sprocket is attached to the O 2 flow control valve. A chain links the sprockets. The combination of the mechanical and pneumatic aspects of the system yields the final oxygen concentration. The Datex-Ohmeda Link-25 proportioning system can be thought of as a system that increases oxygen flow when necessary to prevent delivery of a fresh gas mixture with an oxygen concentration of less than 25%

113. Oxygen Flush Valve

121. PIPELINES

124. PIPELINE CONNECTION

125. PRESSURE GAUGE

127. PRESSURE REGULATOR

131. Vapor pressure versus temperature curves for desflurane, isoflurane, halothane, enflurane, and sevoflurane The vapor pressure curve for desflurane is steeper and shifted to higher vapor pressures compared with the curves for other contemporary inhaled anesthetics.

132. Variable - bypass vaporizer

133. Ohmeda Tec-type vaporizer. At high temperatures , the vapor pressure inside the vaporizing chamber is high. To compensate for the increased vapor pressure, the bimetallic strip of the temperature-compensating valve leans to the right, allowing more flow through the bypass chamber and less flow through the vaporizing chamber. The net effect is a constant vaporizer output. In a cold operating room environment , the vapor pressure inside the vaporizing chamber decreases. To compensate for the decreased vapor pressure, the bimetallic strip swings to the left, causing more flow through the vaporizing chamber and less through the bypass chamber. The net effect is a constant vaporizer output

134. North American Dräger Vapor 19.1 vaporizer. Automatic temperature-compensating mechanisms in bypass chambers maintain a constant vaporizer output with varying temperatures. An expansion element directs a greater proportion of gas flow through the bypass chamber as temperature increases.

135. Tec 6 desflurane vaporizer. The vaporizer has two independent gas circuits arranged in parallel. The fresh gas circuit is shown in red, and the vapor circuit is shown in white. The fresh gas from the flow meters enters at the fresh gas inlet, passes through a fixed restrictor (R1), and exits at the vaporizer gas outlet. The vapor circuit originates at the desflurane sump, which is electrically heated and thermostatically controlled to 39°C, a temperature well above desflurane's boiling point. The heated sump assembly serves as a reservoir of desflurane vapor. Downstream from the sump is the shut-off valve. After the vaporizer warms up, the shut-off valve fully opens when the concentration control valve is turned to the on position. A pressure-regulating valve located downstream from the shut-off valve downregulates the pressure. The operator controls desflurane output by adjusting the concentration control valve (R2), which is a variable restrictor

136. MEASURED FLOW

137. PRECISION VS. NON-PRECISION

138. PRECISION VAPORIZER

140. NON-PRECISION VAPORIZER

143. FLOWMETERS

145. FRESH GAS PORT

149. OXYGEN FLUSH VALVE

150. OXYGEN FLUSH VALVE

153. Condensed water vapor Makes Ventilators fail Makes Gas Monitors fail Use a H eat and M oisture E xchanger

154. Wet dome valve - Ohmeda Mod 2

155. Wet dome valve - Aestiva

156. Fabius flow sensor gets wet, too

157. Wet ET tube, dry circuit

158. Datex-Ohmeda Edith ® is BWH present HME product

159. Gas Line Filters sometimes crack Save them if they do crack Page Anes Technician who will bring it to ORCSS Materials Management” to return to Manufacturer For analysis

160. Inhaled Anesthetic Delivery Systems

162. Mapleson Systems

167. Components of the C ircle system APL, adjustable pressure limiting; B, reservoir bag; V, ventilator

183. Inspiratory (A) and expiratory (B) phases of gas flow in a traditional circle system with an ascending bellows anesthesia ventilator. The bellows physically separates the driving-gas circuit from the patient's gas circuit. The driving-gas circuit is located outside the bellows, and the patient's gas circuit is inside the bellows. During the inspiratory phase (A), the driving gas enters the bellows chamber, causing the pressure within it to increase. This causes the ventilator's relief valve to close, preventing anesthetic gas from escaping into the scavenging system, and the bellows to compress, delivering the anesthetic gas within the bellows to the patient's lungs. During the expiratory phase (B), the driving gas exits the bellows chamber. The pressure within the bellows chamber and the pilot line declines to zero, causing the mushroom portion of the ventilator's relief valve to open. Gas exhaled by the patient fills the bellows before any scavenging occurs because a weighted ball is incorporated into the base of the ventilator's relief valve. Scavenging happens only during the expiratory phase, because the ventilator's relief valve is open only during expiration

184. Inspiratory (A) and expiratory (B) phases of gas flow in a Dräger-type circle system with a piston ventilator and fresh gas decoupling. NPR valve, negative-pressure relief valve.

186. Components of a scavenging system . APL valve, adjustable pressure limiting valve

187. Each of the two open scavenging interfaces requires an active disposal system. An open canister provides reservoir capacity. Gas enters the system at the top of the canister and travels through a narrow inner tube to the canister base. Gases are stored in the reservoir between breaths. Relief of positive and negative pressure is provided by holes in the top of the canister. A and B, The open interface shown in A differs somewhat from the one shown in B. The operator can regulate the vacuum by adjusting the vacuum control valve shown in B. APL, adjustable pressure limiting valve

188. Closed scavenging interfaces. Interface used with a passive disposal system (left). Interface used with an active system (right)

189. Avogadro’s Hypothesis Avogadro’s hypothesis states that the equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

190. Avogadro’s number is the number of molecules in 1 g molecular weight of a substance and is equal to 6.022 x10 23

191. Under conditions of standard temperature and pressure, 1 g molecular weight of any gas occupies a volume of 22.4 litres (L)

192. N 2 O mol. Wt. 44 i.e 44 gm of N 2 O occupy 22.4 lit. gas at STP If full cylinders wt. Of N 2 O is 3 kg then it will yield 3 x 1000 x 22.4 44 = 1524 Lit of N 2 O at STP When the last drop of liquid N 2 0 is vaporized- 400L of gas still in cylinder L

193. Critical Temperature The critical temperature of a substance is the temperature above which that substance cannot be liquefied by pressure, irrespective of its magnitude .

195. The term adiabatic implies a change in the state of a gas without exchange of heat energy with its surroundings

196. Filling Ratio The degree of filling of a nitrous oxide cylinder is expressed as the mass of nitrous oxide in a cylinder divided by the mass of water that the cylinder could hold.Normally, a cylinder of nitrous oxide is filled to a ratio of 0.67. This should not be confused with the volume of liquid nitrous oxide in a cylinder .

197. A full cylinder of nitrous oxide at room temperature is filled to the point at which approximately 90% of the interior of the cylinder is occupied by liquid, the remaining 10% being occupied by gaseous nitrous oxide .

199. The Entonox two-stage pressure demand regulator

200. Viscosity is defined as that property of a fluid that causes it to resist flow. The coefficient of viscosity (  ) is defined as : (  ) =force x velocity gradient area Flow Of Fluids

202. Laminar Flow Laminar flow through a tube is smooth flow The linear velocity of axial flow may be twice the average linear velocity of flow In a tube, the factors determining flow are given by the Hagen – Poiseuille formula: Q =  Pr 4 8  l The Hagen – Poiseuille formula applies only to Newtonian fluids R = 8  l  r 4

203. In turbulent flow fluid no longer moves in orderly planes but swirls and eddies around in a haphazardly manner. Turbulent flow is affected by changes in density Turbulent Flow

204. The relationship between pressure and flow in a fluid is linear up to the critical point, above which flow becomes turbulent

205. The critical point or critical velocity at which the characteristics of flow change from laminar to turbulent Reynolds’ number =  r /   - linear velocity r - radius of the tube   - density and  - viscosity If Reynolds’ number exceeds 2000 , flow is likely to be turbulent, whereas a Reynolds’ number of less than 2000 is usually associated with laminar flow

207. Resistance to gas flow through tracheal tubes of different internal diameter (ID)

210. The Injector The injector is frequently termed as Venturi , formulated by Bernoulli in 1778 some 60 years earlier than Venturi As fluid passes through a constriction, there is an increase in velocity of the fluid; beyond the constriction velocity decreases to the initial value.

211. The Bernoulli Principle

212. Fluid entrainment by a Venturi injector

213. A simple injector

214. Fixed performance mask with a range of Venturi devices

215. Color Delivered FiO 2 Fresh gas flow(l/min) Blue 24% 2 White 28% 4 Orange 31% 6 Yellow 35% 8 Red 40% 10 Green 60% 15 Entrainment ratio 100ax21b=30x required FiO 2 a+b=30

217. The Coanda effect