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43 Cards in this Set
- Front
- Back
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What is the most common single source of injury in the AM?
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The breathing circuit.
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What is an AM
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A pneumatic device that delivers a precisley known variable mixture of oxygen, gasses, and an anesthetic agent to a patient.
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What are the 2 major manufacturers of AM in the US
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Drager and GE Healthcare. Narkomed also mfg.
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Describe the high pressure circuit.
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Is solely the e-cylinders and their respective regulators.
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What are the starting and ending pressures of O2 and N2O in the high pressure circuit.
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O2 starts at 1900-2200 and is regulated to 45 psig. N2O starts at 745 and is regulated to 45 psig.
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Describe the intermediate pressure circuit.
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Starts at the regulated cylinder supply sources or the pipeline supply. Includes the 2nd stage O2 pressure regulator, the fail-safe valve, the oxygen supply failure alarm, and the O2 flush valve.
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What are the starting and ending pressures of O2 and N2O in the intermediate pressure circuit.
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Both start at 45-55 psig and end at 12-16.
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Describe the low pressure circuit.
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Starts at the flow control valves and ends at the CGO. Includes flowmeters, calibrated vaporizers, and the check valve
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What are the starting and ending pressures of O2 and N2O in the low pressure circuit.
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Pressures for both start at 12-16 and end at a decided upon lower pressure.
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What does the check valve do?
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It prevents back-flow into the vaporizer during positive pressure ventilation.
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What is the back-up for the pipeline supply in the AM?
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The e-cylinders.
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What are 2 steps that must be followed if a suspected crossover of gasses in the pipeline system occurs?
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First, turn on the e-cylinders. Second, turn off the pipeline supply or the AM will continue to use the supply with the higher pressure which is usually the pipeline.
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What system is used to prevent crossing-over of gas to the AM?
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The DISS system.
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True or false: Each DISS fitting has to have a backflow check valve.
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True. To prevent backflow of anesthetics and gasses into the pipeline.
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What is the purpose of the Bourdon pressure gauge on an AM?
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To measure cylinder pressure.
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What size filter does each pipe inlet have to contain?
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100 micrometers or less pore size.
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What is the most fragile part of a cylinder?
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The cylinder check valve.
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What is the purpose of the fragile valves in the cylinders?
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To break or open under extreme pressure to vent the gas, so the cylinder does not become an explosive.
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What type of metal is used as a fusible plug to cover the tank during transport?
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Woods metal.
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What are the functions of the dual yoke system?
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Orient cylinders, provide gas-tight seal, ensure a unidirectional flow, and facilitate changing of supply without stopping flow of gas.
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Why should you not open both cylinders in the yoke at the same time?
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Transfilling can occur, which generates heat and can cause fire.
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Explain the workings of the O2 regulator on the cylinders.
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Two diaphragms connected by a rod move together. As the user adjusts the wanted pressure a screw and spring lessen pressure on one of the diaphragms, thus raising the other up, opening the outlet valve to allow more gas to flow out.
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Why are regulated cylinder pressures less than pipeline pressures?
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This is to prevent the "silent leak" of the cylinders as the AM uses the gas source with a higher pressure. If the pipeline supply were to drop to less than cylinder pressure and the cylinders were open, the AM would use up the cylinder supply without warning.
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What is the purpose of the O2 flush valve?
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It rapidly fills the breathing circuit with O2.
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How should the O2 flush valve be used?
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It should be used in short bursts during expiratory phase only.
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What are some negative effects that can occur by misuse or over use of the O2 flush valve?
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Barotrauma and dilution of the anesthetics leading to a lessened depth of anesthesia.
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How does the fail-safe system work?
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It is in the N2O line. It is operated by pressure much like the diaphragm system in O2 regulators. As the O2 pressure drops the diaphragms move proportinally. The lower the O2 pressure the lower the amount of N2O is allowed through the line.
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What is the limitation of the fail-safe system?
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It reads only pressures. If the gasses are crossed the fail-safe will still allow the hypoxic mixture.
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What are the 5 tasks of O2 in the AM?
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Proceeds to the fresh gas flowmeter, powers the O2 flush valve, activates fail-safe mechanism, activates O2 low pressure alarms, compress the bellows of mechanical ventilators.
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What are the components of the flowmeter?
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Flow control knob, needle valve, valve stops, flow tube, indicator float.
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How do flowmeters for different gasses differ?
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The are color coded and labeled. The flow control knobs are uniquely shaped and touch coded.
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What can happen if the flowmeters are left open at the end of the case and what can prevent this?
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The float can shoot to the top of the tube and crack it. Flow tubes should be shut off at the end of the case or day and should be off when connecting pieline or cylinders. It can also dry out the CO2 scrubber.
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Where do you read on each of the different floats to determine flow rate?
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On the ball style float you read in the middle. On all other flat top style floats it is read at the top of the float.
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What is the most fragile part of the AM?
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The flow tube.
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What is the purpose of the manifold?
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It blends all the gasses together before leaving to the CGO.
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Why is O2 the last gas in sequence on the manifold?
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This ensures that if there is a crack O2 still enters the CGO. (Unless the leak is in the O2 flow tube)
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What would the low pressure alarm signify?
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Pressure has been lost in the O2 circuitry.
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What is the proportioning system/hypoxic guard and where is it present?
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It is designed to prevent the hypoxic delivery of breathing mixes by linking the flowmeter knobs of O2 and N2O thus ensuring the ration is not more than 3:1.
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What are the ways the proportioning system can permit hypoxic mixtures?
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Crossing of gasses, defective pneumatics or mechanics, leaks downstream of the flow control valves, or inert gas administration.
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What is the only way to ensure the gas mixture going to the pt is not hypoxic and what are the two types used today?
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An inspired O2 analyzer. Electrochemical and paramagnetic analyzer.
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What is the minimum O2 flow of anesthesia machines and at what rates does it flow.
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It is a flow of O2 that happens even if the provider forgets to turn on the O2. 50-200 mL/min.
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When do most problems with the gas systems occur?
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After initial installation of a new system and after any repairs. Systems should be tested before attempted use.
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What is the required flow rate of oxygen in the O2 flush valve?
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35-75 LPM
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