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71 Cards in this Set
- Front
- Back
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What does the flow meter depend on to function?
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Regulator
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Two portable gas sources
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- E cylinders
- H cylinders |
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Two pipeline gas options
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- Manifolds with H cylinders
- Liquid O2 tank systems |
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3 characteristics shared between O2 and N2O cylinders
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- Color coded (O2/Green, N2O/Blue)
- Label/Warning - Cylinder tags |
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Pressure of O2 tanks
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2,200 PSI
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Pressure of N2O tanks
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750 PSI
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Capacity of E O2 tanks
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700 L
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Capacity of H O2 tanks
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7,000 L
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Capacity of E N2O tanks
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1,600 L
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Capacity of H N2O tanks
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16,000 L
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State of O2 in tanks
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100% gaseous
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State of N2O in tanks
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Liquid and Gas
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Pin index safety system configuration for O2
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2 & 5
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Pin index safety system configuration for N2O
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3 & 5
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What pressure does the regulator have to decrease to for the flowmeter to work?
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50 PSI
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Consequence of using flush valves (2)
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- Can over inflate lungs and cause damage
- Can lighten depth of anesthesia of patient |
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2 systems that you should not use a flush valve for
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- Pediatric
- Pop-off |
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What determines maximum vaporizer output?
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Vapor pressure
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What controls vapor pressure?
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Temperature
- Liquid temperature must be controlled for constant vaporizer output |
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Three common metals used in construction of vaporizers
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- Cu
- Al - Brass |
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What quality of material is best for vaporizers to maintain constant temperature?
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High thermal conductivity
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What is the range of temperature of liquid anesthetic in a vaporizor?
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15 to 35 C
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Range of carrier gas flows through the vaporization chamber
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0.5 to 10 L/min
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What is the problem with back pressure in the vaporizer?
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Produces surges in output
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Back pressure amount during spontaneous breathing
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None
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Back pressure trend during artificial ventillation
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Increased
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Back pressure trend during flush valve usage
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Increased
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Vapor pressure of isoflurane
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240 mmHg
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Vapor pressure of sevoflurane
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160 mmHg
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What differs a measured flow output from a variable bypass output?
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All gasses enter the vaporizer during variable bypass
- In measured flow, one hose goes into the vaporizer while the other meets up downstream to dilute out vapor concentration |
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2 methods of output regulation
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- Measured flow
- Variable bypass |
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2 methods of vaporization and which do we use
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- Bubble-through
- Flow-over |
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What increases surface area in flow-over vaporizers?
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Wicks
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Which location of the vaporizer provides low resistance?
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VIC (Vaporizer in the System)
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Which location of the vaporizer provides highest safety?
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VOC (Vaporizer Outside System)
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Which vaporizer location allows for precision?
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VOC (Vaporizer Outside System)
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What alters flow in a modern vaporizer?
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Bimetallic strip valve
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What's the downside of multi-purpose vaporizers? (2)
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- Lethal doses possible
- Requires attention to flow rates |
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What's the main is the primary benefit of agent specific vaporizers?
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Increased safety
- Due to decreased variation in output and decreased probability of miscalculations |
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Formula for the calculation of anesthesia
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3 * fresh gas flow (L/min) * Vol (%) = ml agent / hr
ml agent / hr * cost = total cost |
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3 classifications of breathing systems
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- Rebreathing
- Non-rebreathing - Closed containers/masks |
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4 purposes of breathing systems
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- Deliver O2
- Remove CO2 - Deliver anesthetic - Artificial ventilation |
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What MUST a rebreathing system do?
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Allow for removal of CO2
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What does the amount of rebreathing depend on? (3)
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- Fresh gas flow into breathing system
- Amount of dead space - System design |
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2 effects of rebreathing
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- Retains heat (controls body temperature)
- Retains moisture (less respiratory drying) |
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What's the primary difference between the three circle breathing systems?
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Amount of fresh gas inflow rate
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Amount of Fresh Gas Flow in a closed system
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4 - 7 ml/kg/min
- FGF = Metabolic needs |
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What's the primary advantage of circle systems over nonrebreathing systems?
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Economy
- Decreased gas usage |
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Two limits on flow rate
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- Flow meter accuracy
- Vaporizer requirements |
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What is the maintenance O2 flow rate that the university uses?
What is the exception? |
33 ml/kg/min
During first 15 minutes of anesthesia, double the rate (66 ml/kg/min) |
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What's the minimum maintenance amount of O2 during anesthesia?
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500 ml/min
Use 1 L during 1st 15 minutes |
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Flow rate with a low-flow circle system
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7 - 22 ml/kg/min
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Flow rate in a semi-closed circle system
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22 - 33 ml/kg/min
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General guideline of O2 consumption with a semi-closed circle system
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3x metabolic need
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Two advantages of semi-closed circle systems
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- Stable anesthetic concentrations
- Safety while using N2O |
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What is the function of a rebreathing/reservoir bag in a circle system, and how much does it hold in small and large animals?
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Supplies peak inspiratory flow rate demands
- SA: 3-5x tidal volume - LA: 20 L |
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Two other names for a pop-off valve
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- Overflow valve
- Adjustable Pressure Limiting valve |
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Simplified chemical reaction for chemical absorption of CO2 in absorbent containers
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Ca(OH)2 --> CaCO3 + H2O + heat
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3 pieces of evidence for the depletion of sodalime
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- Color change from white to blue
- Hardening of granules - No heat production |
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What contributes to the resistance of a circle system? (5)
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- Valves
- Length of system - Diameter of hoses - Soda lime - Sharp bends |
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What is an emergency, optional component of a circle system that allows ambiant air flow should the O2 supply deplete?
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Negative pressure relief valve
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How long should pressure be maintained during a successful circle system check?
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At least 10 seconds
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What weight is used to determine usage of non-rebreathing systems?
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< 15 lbs (7.5 kg)
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3 advantages of non-rebreathing systems
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- Decreased resistance
- Decreased dead space - Reduced inspiratory effort |
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What contributes to the dead space of a closed circle system?
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Y-piece only
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2 disadvantages of a non-rebreathing system
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- Cost
- Greater need for scavenging of excess gases |
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Maximum flow rate with a non-rebreathing system
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3 L/min
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What flow rate insures no rebreathing in a non-rebreathing system?
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2 - 3x minute volume
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What flow rates in a non-rebreathing system have been deemed acceptable in practice?
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200 ml/kg/min
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What FGF rate is used in a closed container system?
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5 L/min
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What's a difficulty in usage of a closed container/mask?
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Scavenging excess gases
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