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128 Cards in this Set

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