The Anesthesia Machine – Flashcards
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What are the four functions of the anesthesia machine?
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deliver oxygen, deliver anesthetic gas, dispose of CO2, remove waste anesthetic gas
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What color are the tanks and hoses associated with oxygen?
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green
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What pressure are oxygen tanks under?
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2000psi
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What does the tank pressure need to be reduced to in order for us to use the oxygen with a patient?
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50psi
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What are concerns with oxygen tanks?
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under high pressure, supports combustion, keep away from flames/grease/sparks
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What is required for proper storage of oxygen tanks?
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a chain, to ensure they do not fall or get knocked over
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What are the two O2 tank sizes typically seen in a vet clinic?
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Big (H) and small (E)
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At what psi do you typically change out the tanks to ensure you do not run out of O2 when needed?
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100-200psi for the E tanks, 300-500psi for the H tanks
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Why do the O2 tanks use a pin hole indexing system?
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to ensure another gas, like nitrous oxide, is not accidentally placed where the oxygen tank should go on the machine
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How do you turn the O2 tank on?
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just like a faucet, righty tighty (off), lefty loosey (on)
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After turning off O2, what can you do if the gauge on the machine still shows pressure?
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evacuate or "bleed off" the lines using the flowmeter or the O2 flush valve
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What is the function of the pressure regulator?
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to reduce the pressure down to the operating pressure of the anesthesia machine
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What is the function of the flowmeter?
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measures gas flow through the machine in L/min
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What can happen if you overtighten the flowmeter when turning it off?
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you can strip the needle valve
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At what point on the ball in a flowmeter do you read L/min rate?
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the center of the ball
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Where do you read the L/min rate on a flowmeter that has a bobbin?
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the top of the bobbin
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Does the flowmeter need to be off when you are not using oxygen?
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yes
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Does the flowmeter need to be on when you are using anesthesia?
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yes
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What is the function of the vaporizer?
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to convert volatile liquid into gas
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How is the anesthesia delivered to the patient?
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by oxygen
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What must you do to turn the vaporizer on?
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push down on the safety lock
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What is the unit used when recording the amount of anesthetic used with a vaporizer?
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%
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When is the best time to refill the vaporizer?
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the end of the work day
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What should you do if you spill the liquid when filling a vaporizer?
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airtight the room and go outside, wait for it to dissipate
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What are two things that can be used for filling the vaporizer?
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funnel filler and filler key
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When would you need to empty out the vaporizer?
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if there is a problem and it needs to be sent out for repair
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Where would you find the fresh or common gas outlet on the anesthesia machine?
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always after the vaporizer
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What runs through the fresh/common gas outlet?
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O2 and vaporized anesthetic
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When would there not be anesthetic in the common gas outlet?
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if the O2 flush valve is in use or we are only using oxygen
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What does fresh gas mean?
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gas that has not been exhaled by the patient
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What is the purpose of the oxygen flush valve?
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to allow 100% oxygen to bypass the vaporizer and go directly to the patient
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What is the rate typically in the oxygen flush valve?
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20-80 L/min
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Can you use the oxygen flush valve in a non-rebreathing system?
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no
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Why can you only use the oxygen flush valve with a rebreathing system?
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the resistance in the system keeps the pressure from entering the lungs
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What happens when you use the oxygen flush valve?
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dilutes anesthetic gas in breathing circuit
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What happens to the percent of anesthetic being delivered to the patient when it is diluted using the oxygen flush valve?
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the percent delivered decreases
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When would you want to use the oxygen flush to dilute the anesthetic?
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when the patient is too deep or when you are only using oxygen anyway (emergency)
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When should you not use the O2 flush valve?
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when filling up the bag at the beginning or middle of surgery
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What is the proper way to fill the bag before or during surgery?
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open the flowmeter more and once the bag is full turn it back down to where it needs to be
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What is the purpose of the scavenger system?
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to take away waste air from the anesthesia machine
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Which is heavier, inhalants or air?
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inhalants
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What are the two types of scavenger systems?
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active and passive
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What happens if you close the relief valve while a patient is hooked up and using the machine?
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pressure will build up in the lungs and could kill the patient
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What can the scavenger system empty into other than being dumped outside into the open air?
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a charcoal canister called an "f/air" canister
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What is the highest O2 flow rate you should use when using an f/air canister?
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2L/min
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Why should you not use more than 2L/min of O2 when using an f/air canister?
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they will expire sooner
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What are the two types of patient circuits for anesthetic machines?
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rebreathing or circle system and non-rebreathing
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What is the path of flow for gases in a circle system?
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fresh gas into circle, into patient, out of patient, into circle, through CO2 absorber, back to patient
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What is needed to ensure unidirectional flow in a circle system?
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one way valves and pop off valve
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What are two types of tubing used for circle systems?
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Y-piece and tubing or universal F circuit
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Why do some say they prefer the universal F-circuit?
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the air going into the patient is in a tube surrounded by a tube containing the air being exhaled, so the exhaled air warms the intake before it gets to the patient
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Are the inspiratory and expiratory valves one way?
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yes
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What is the purpose of having the inspiratory and expiratory valves be one way?
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so that the air must pass through the CO2 absorber before being breathed by the patient again
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What are the unidirectional valves called?
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flutter valves
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What is the pop-off valve?
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pressure relief valve
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What does the pressure relief valve do?
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allows gases to exit the circle system into the scavenge system
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When should the pressure relief valve be closed?
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only when bagging the patient, and immediately reopen
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What is the negative pressure relief valve?
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prevents a vacuum from developing inside the breathing circuit
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Where is the negative pressure relief valve located?
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on top of the inhalation flutter valve?
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Where is the pop off valve located?
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on top of the exhalation flutter valve
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How does the negative pressure relief valve work?
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opens up and lets room air in when vacuum is detected in the circle
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What would cause a vacuum in the circle system?
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overactive scavenger, empty oxygen tank, flowmeter off
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How can you tell there is a vacuum building up in the machine?
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the rebreathing bag will be empty
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What is the purpose of the rebreathing bag?
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a reservoir so you can use a lower flow rate, permits ventilatory assistance (IPPV) to prevent atelectasis, allows view of animal's breaths
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What does IPPV mean?
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intermittent positive pressure ventilation
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What is atelectasis?
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lung collapse
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How do you typically determine what size bag you need for a patient?
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usually 1 liter per 30lbs, minimum of 40-60ml/kg
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Some bags come with an exit hole, which system is this used for?
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non rebreathing
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What do you do if you need to change the anesthetic depth rapidly?
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empty the bag into the scavenge, use the flowmeter to refill using the new vaporizer setting
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Why do you not want to refill the bag with the O2 flush?
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it will dilute the inhalant
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What is the purpose of the manometer or circle pressure gauge?
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allows for monitoring of pressure within the circle system
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What units are used within the manometer?
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usually cm/H2O but some in mm/Hg
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What should the pressure be on the manometer?
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0 cm/H2O
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What are some problems that could cause the pressure on the manometer to rise?
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flowmeter too high, pop-off closed, scavenge occluded
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What should the pressure stay around when bagging?
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<15-20 cm/H2O
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What can overzealous ventilation cause in the patient?
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barotrauma
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What are some examples of barotrauma?
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pneumothorax, subcutaneous emphysema, air embolism
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What is the purpose of the CO2 absorber?
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allows the animal to breathe the same air again
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What product is usually used in the CO2 absorber?
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soda lime or barium hydroxide
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What is produced in the chemical reaction in the CO2 absorber?
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heat and water
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How can you tell the difference between old and new soda lime in the CO2 absorber?
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new crumbles easily, old is hard and won't crush, some have dyes that turn purple when spent
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How long can you usually use the soda lime in a CO2 absorber before it needs to be changed?
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about 10 hours
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The precautionary time to change the soda lime in the CO2 absorber is when how much of the soda lime has turned purple?
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1/3 to 1/2
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What are some precautions to take when changing the CO2 absorber?
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wear gloves and a mask
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Why should you wear gloves and a mask with the soda lime?
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caustic, eye and skin irritant, respiratory irritant
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How do you dispose of used absorber?
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throw in trash and take outside because it releases gases
