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.
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
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
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
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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
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
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90. The effect of a hyperbaric pressure of a 200 kPa on the performance of a halothane vaporizer
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 )
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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
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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%
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.
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
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
167. Components of the C ircle system APL, adjustable pressure limiting; B, reservoir bag; V, ventilator
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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.
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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 .
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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 .
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
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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
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207. Resistance to gas flow through tracheal tubes of different internal diameter (ID)
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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.
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
Morton was running late on the day in questions, waiting for a final modification to his inhaler. He arrived just as Warren was going to start the operation, and reportedly said, “Sir, your patient is ready”. Morton ignored him and went about getting Abbott to breath deeply. IN about five minutes, Morton turned to Warren and said, “Sir, your patient is ready”. The operation took about seven minutes, and at the end, Warren uttered his famous words.
Medical Gas Pipeline products are used in Hospitals, Universities and Research Labs, to process and monitor the delivery of medical gases from source systems to various operating and care areas of the facilities. Medical Gas Pipeline Products include, Air Compressors, Vacuum Systems, Medical Gas Outlets, Alarms, Manifolds, Zone Valves and Zone Valve Boxes. The Architectural Products include a variety of wall or floor mounted Headwall Systems designed and installed to continue the delivery of the medical gases and electrical services for delivery of these essential services in the high acuity areas of the facilities. These systems feature rail profiles which allow extremely effective equipment management concepts to better utilize floor space and provide flexibility in equipment movement. Since the ventilator is concerned to supply a mixture of air and oxygen, we will concentrate on oxygen supplies especially.