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128 Cards in this Set
- Front
- Back
When are higher levels of CO more likely to occur?
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after prolonged contact between absorbent and anesthetic
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What FGF rates are enough to cause critical drying of the absorbent material?
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5L/min or greater
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Excessive dry soda lime reacts with volatile agents to form what?
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CO
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CO reacts with hgb to form carboxyhgb, this shifts the O2-hgb curve to ? (which direction)
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the left
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Is CO produced with hydrated soda lime?
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No
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Maximum amount of CO2 that can be absorbed by soda lime is what?
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26L of CO2 per 100g of absorbent
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What is the maximum capacity of calcium hyroxide lime?
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10.2L per 100g of absorbent
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What reduces the absorptive capacity to 10-20L of CO2 per 100g absorbent?
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channeling
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What is the pH indicator added to both soda lime and calcium hyroxide lime to assess the functional integrity of the abosrbent?
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Ethyl violet
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What happens when ethyl violet changes from colorless to violet?
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pH of the absorbent decreases as a result of CO2 absorption
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What does the change in color of the absorbent material mean?
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absorptive capacity of the material has been consumed.
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What are the clinical manifestations of Hypercarbia?
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-increased rate and depth of respiration
-increased BP -ventricular irritability -flushing of face, neck, thorax -increased ICP |
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What are the other structures of the breathing system?
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-fresh gas hose
-fresh gas outlet -insp and exp unidirectional valves -breathing hoses -Y-piece -APL or pop-off valve -CO2 absorber housing and canister -airway pressure gauge -return tube -breathing bag -bag/ventilator switch -ventilator drive gas tube -ventilator hose -mech vent control unit -bellows -ventilator pressure relief "spill" valve |
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How does gas enter the circle system?
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via the CGO by way of fresh gas hose
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How does gas exit the circle system?
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via the APL valve to the scavenger
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What is used to prevent accidental detachment of the gas outlet hose that connects the AM to the circuit?
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An anti-disconnect device
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in induction phase the O2 flow rates vary from ___-___L/min?
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6-15
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C(D)=?
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percent deliverd(vaporizer on)
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C (I)=?
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percent inspired
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C(E)=?
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percent expired
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The actual composition of expired gas misture depends on what?
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FGF rate, volume of breathing system, and absorption by the machine.
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During maintenance phase total FGF ranges from ___-__L/min?
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1-3
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During emergence phase High FGF ranges from ___-___L/min?
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6-15
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What is the fresh gas inlet?
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point where FG hose enters the breathing circuit
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Valve leaflets(disk) are subject to damage how?
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-occulsion
-foreign body -contamination -sticking with collected moisture, or dust, particularily on expiratory valve |
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____ (what) enforces a pattern of gas flow by which exhalations are made to pass through the CO2 absorbent granules?
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Valves
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What are two reasons for increased inspired CO2?
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-abosrbent granules have been exhausted
-faulty unidirectional valves |
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Is it mandatory to check unidirectional valves before each use?
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YES
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What does incompetent inspiratory or expiratory valves do?
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turn entire corrugated limb into dead space, resulting in increased inspired and expired CO2.
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What does the inspirational unidirectional valve do?
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-promotes gas toward patient in one corrugated limb
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What can result from an incompetent inspirational unidirectional valve?
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reverese gas flow and rebreathing
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During inspiration, flow of gases lifts the __________ off seat, and gases flow ________?
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valve disc, to patient
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Exhaled gases lift discs ____ seat to open?
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off
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WHere does the first portion of exhaled gas go to?
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rebreathing bag
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Where does the remaining portion of exhaled gas go to?
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APL
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What do the breathing hoses do?
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carry gases to and from the patient
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Hoses or corrugated limbs range from ____inches in length and internal diameter is ____mm?
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34-80 in, 22mm
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T or F the length of hoses does affect dead space or rebreathing?
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False it does not affect dead space or rebreathing
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T or F some circuits have a port where a thermometer can be placed if heated humidifier is used.
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True
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Where is the sampling port connection for obtaining a gas analysis?
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near the Y-piece
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What is the APL valve also known as?
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pop-off valve
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WHen is the APL valve ususally open?
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during spontaneous ventilation
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If the APL valve is completely open and the bag is squeezed where does the gas exit?
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the scavenger system
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If the APL valve is completely closed where does the gas go?
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ventilates the lungs
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If gas cannot exit through teh APL or ventilator relief valve what happens?
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pressure builds within the system
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What will partially closing of the APL valve during Sp respiration do?
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will result in CPAP
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How is the APL valve left when doing manual or assisted ventilation?
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left partially open
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During inspiration the bag is squeezed adn pressure _________ until the relief pressure is reached.
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increases
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Once the APL valve opens teh additional volume that the patient receives is determined by what?
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-the relative resistances to flow exerted by the pt and the APL valve
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The valve is adujusted on what basis?
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-of chest mvts or exhaled volume or pressure measurements to achieve teh desired level of ventilation and to maintain adequate bag volume
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If the APL valve is fully closed teh progressive rise in pressure could result in what?
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pulmonary barotrauma and hemodynamic compromise.
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What is usally the upper limit of pressure?
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70-80cmH2O
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Other uses of APL valve?
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-chest auscultation
-assist with breathing(low volume during sp respiration) |
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What are the classification of modern ventilators?
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-gas-driven bellows
-Piston-Driven ventilator |
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What type of classification is the ventilator that uses force of compressed gas (air or O2) as the driving mechanism to compress the bellows?
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gas-driven bellows
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____ within the bellows may cause dilution of gas within the bellows by driving gas or loss of agent and O2 from within it?
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Leaks
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What does a Piston-Driven ventilator use to compress the gas in a rigid piston during inspiratory phase?
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electric motor
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T or F the piston-driven ventilator uses no driving gas and may be used without depleting the O2 cylinder in case of pipeline failure?
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True
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When does the positive pressure relief valve open in the piston driven ventilator?
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75 +or- 5cm H2O
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bellows standing is _________ and hanging is _______.
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ascending, descending
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Which type of bellows is thought to have an advantage because it will not fill in teh event of a disconnect?
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standing
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What does the Bag/Ventilator switch do?
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changes the flow of anesthetic gases from the CGO and exhaled gases from reservoir bag to the ventilator bellows
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How do you figure the Tidal volume?
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8-10ml/kg
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What is the normal respiratory rate on vent set at?
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8-12 breaths/min
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What is the normal I:E rato for adults on mechanical ventilator?
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1:1.5 or 1:2
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What is VCV?
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volume-controlled ventilation
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Inspiratoin is terminated when?
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the desired VT is delivered or if an excessive pressure is reached (60-100cm H2O).
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T or F because volume is controlled, alveolar ventilation and arterial CO2 can be maintained despite changes in pulmonary function.
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True
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Peak Inspiratory Pressure (PIP) is uncontrolled and varies according to what?
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patient's compliance and airway resistance
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VT is adjusted to prevent what?
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atelectasis
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Respiratory rate is adjusted for what?
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to keep ETCO2 at desired level.
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What is PCV?
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Pressure-controlled ventilation
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in a PCV ventilator what is controlled?
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inspiratory pressure rather than volume
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How does a PCV operate?
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as pressure is limited and time cycled, with decelerating flow pattern
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What kind of flow rate is need at first for PCV?
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high flow rate
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What is adjusted for the desired VT?
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target pressure
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Is RR adjusted to maintain reasonable ETCO2 in a PCV?
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Yes
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Is the VT adjusted in the PCV?
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no
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PCV may result in _________VT at a _________PIP.
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increased, lower PIP
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what are indications for PCV?
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-pts with high inspiratory pressures
-patients with low compliance -lower airway pressure |
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What are some types of patients that have high inspiratory pressures?
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emphysema
neonates/infants |
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what are some pts with low compliance issues?
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pregnant women
laparoscopic surgeries |
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What is an example of when you might have lower airway pressure?
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one lung ventilation
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What are the typical settings for the PCV?
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Pressure limit: 20cmH2O, RR=6-12, I:E ratio: 1:2
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What does SIMV stand for?
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synchronized intermittent mandatory ventilation
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When would SIMV be used during general anesthesia?
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use of LMA, short- ambulatory procedures
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What is the difficulty with SIMV mode?
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if pt is maintained in plane of anesthesia that is too deep, resp acidosis will occur, if too light bucking and awareness are risks
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What are the ventilation modes that support a spontaneously breathing patient?
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SIMV, PSV, CPAP
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Is CPAP available on the AM vents?
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NO
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typical settings for SIMV?
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mirrors that of PCV or VCV
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What is PSV?
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Pressure support ventilation
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When can you use PSV?
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only on pts that are breathing spontaneously
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What is the typical settings for PSV?
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pressure support=10cm H2O, no minimum VT
-trigger window, max inspiratory flow, and apnea backup may be set |
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When is PSV useful?
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to augment the VT of a spontaneously ventilating pt during maintenance or emergence
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What is another part of equipment of breathing system?
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humidifier
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What does a humidifier do?
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prevents heat loss
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What does the scavening system do?
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collects wast of anesthetic gasses from the breathing circuit and ventilator and their removal from the OR
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T or F the amt of gas used to anesthetize a pt for a given anesthetic far exceeds the minimum needed.
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True
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This system minimizes OR pollution by removing this excess of gases?
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Scavenging system
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What is the amt that OSHA directs no worker be exposed to for halogenated agents based on a time-weighted 8hr avg concentration?
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2ppm
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What does OSHA direct that no worker be exposed to no more than how much N2O on a time-weighted 8hr avg concentration?
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25ppm
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What are the two major causes of waste gas contamination in the OR?
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1-anesthetic technique
2-equipment issues |
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What are some factors causing OR contamination?
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-failure to turn off the gas flow control valves at end of case
-poorly fitted masks -flushing the circuit -filling anesthetic vaporizers -use of uncuffed ETT -use of breathing circuits that are difficult to scavenge such as Jackson-Rees |
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What is the most important part of the scavengin system?
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interface-it protects the pt from excessive buildup of positive pressure and from exposure to suction
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What are the components of the scavenging system?
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-gas collection assembly at APL valve and ventilator relief valve
-transfer tubing -interfaces -gas disposal tubing -gas disposal assembly |
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This part of the scavenging system captures excess anesthetic gas and delivers it to teh transfer tubing.
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Gas-collection assembly
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What does transfer mean?
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carries excess gas from teh gas-collection assembly to the scavenging interface
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What is the size of the transfer means tubing?
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either 19 or 33mm, and ridgid to prevent kinking and short to prevent occlusion
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Is the transfer means sometimes color coded?
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yes
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This protects the circuit or ventilator from excessive positive pressure?
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Scavenging interface (most important)
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What is an open interface component of scavenging system?
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contains no valves and is open to atmosphere allowing positive and negative pressure relief.
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What is the closed interface component of scavenging system?
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communicates with the atmosphere through valves. Must have positive pressure relief valve to vent excess system pressure if obstruction occurs downstream teh interface
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This conducts waste gas from teh scavenging interface to the gas disposal assembly?
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gas assembly tubing
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This eliminates excess waste gas?
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gas dispoal assembly
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What is the most common type of disposal system?
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active-uses central evacuation system
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what is the formulat to calculate for FiO2 with N2O/O2?
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total flow of O2 + N2O (LPM) x 100= % FiO2
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During the first minutes of gas administration a higher concentration of the gas than necessary for maintenance or a loading dose is delivered to speed initial uptake what is this called?
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overpressuring or the concentration effect
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What is the rate of N20 for induction and maintenance?
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50-70% same for maintenance
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What is the percent of Iso for induction and maintenance?
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1-4 and 0.5-2
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What is the percent of Des for induction and maint?
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3-9% and 2-6 %
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What is the percent of Sevo for induction and maint?
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4-8% and 1-4%
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The coadministration of a relativesly slow agent such as Iso and a faster agent such as N2O can speed the onset of the slower agent what is this called?
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the second-gas effect
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What are the main factors that influence the ability to anesthetize a pt?
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-technical/machine specific
-drug related -respiratory, circulatory, and tissue related |
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What are the primary factors that influence absorption of the inhalation agents?
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-ventilation
-uptake into the blood -CO -soluability of the anesthetic drug in the blood -alveolar-venous blood partial pressure difference |
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During emergence the anesthetic leaves the tissues via the _________ and exits the _________ with ventilation.
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blood, lungs
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Is it routine practice to administoer 100% O2 to assist recovery?
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Yes- if N20 was used 100% O2 prevents diffusion hypoxia
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The longer the anesthetic is given the ________the pt emerges.
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slower
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Differences among anesthetics are small but significant and are seen when?
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during the final 20% of the elimination process
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