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83 Cards in this Set
- Front
- Back
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Name the 4 classifications of Breathing circuits
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Open, Semi Open, Semi-Closed, Closed
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Which Classificatin of breathing system(s) has no reservoir?
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Open system. Examples of an open system: open drop, insufflation, nasal cannula
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Which classification of breathing circuits have rebreathing?
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Semi-closed and closed.
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Pt's have access to atmosphere only in ______ breathing systems.
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open
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With circle at high FGF (>MV), will rebreathing be present
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no
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With circle at low FGF (<MV), will rebreathing be present?
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Yes (partial)
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In a closed system when there is complete rebreathing, what valve is closed?
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APL (adjustable Pressure limiting valve)
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Is the following rebreathing or nonrebreathing: Those in which the exhaled gases containing CO2 are removed from the system
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Nonrebreathing Systems
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Is the following a rebreathing or nonrebreathing system? Inhalation of previously respired gases from which CO2 may or may not have been removed
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Rebreathing
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Amount of rebreathing varies (directly or inversely) with the total FGF
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Inversely: the higher the flowrate of FGF, the lower the amount of rebreathing
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What is dead space?
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The volume in a breathing circuit occupied by gases that are rebreathed without any change in composition.
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What part of the breathing system makes up dead space?
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The ETT extending beyond the patient's incisors, monitor adaptors (End tidal CO2), the volume within a mask, humidification management exchangers, the y-piece
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How does nitrogen affect induction?
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Slows induction. Nitrogen that is not eliminated from the circuit delays the establishment of the desired agent concentration. Higher FGF is appropriate during induction.
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If there is an acute increase in dead space, what would you increase to prevent hypercarbia?
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Increase minute ventilation. Increase respiratory rate or tidal volume.
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In a breathing circuit, where does dead space end?
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Y piece. The y piece is where the expiratory streams and inspiratory streams diverge.
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Why does the AM use dry gases?
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To avoid internal corrosion and bacterial colonization
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Why is active humidification less common that passive humidification?
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Active humidification is less effective at preventing hypothermia and added moisture can clog gas-analysis lines and soda lime granules. It can obstruct unidirectional valves.
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When rebreathing is minimal or absent, what does the concentration of gas resemble?
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It resembles the gas that is delivered from the CGO
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What are common features of nonrebreathing circuits?
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All lack unidirectional valves, all lack soda lime CO2 absorption, amount of rebreathing is highly dependent on the FGF in all, Amount of resistance is low in all (no unidirectional valves)
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Name 5 components of the Mapleson system?
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Facemask, spring-loaded pop off valve, reservoir tubing, fresh gas inflow tubing, reservoir bag
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Why are Mapleson systems, or nonrebreathing circuits sometimes called washout circuits or flow controlled breathing systems?
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Because there is no CO2 absorbing device, and FGF must wash the CO2 out of the circuit; amount of rebreathing is highly dependent on the FGF
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Mapleson A is also known as ______ circuit
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Magill
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With spontaneous ventilation using the Mapleson A, the APL valve should be kept in the _____ position
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Open
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In controlled ventilation with the Mapleson A system, excess gas is vented throught the APL valve during inspiration or expiration?
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Inspiration
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Rank the systems from worst to best efficiency
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Worst to best efficiency: Mapleson A during controlled or assisted ventilation, bc, def, Mapleson A with spontaneous ventilation
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What FG inflow rate does the Mapleson A require during spontaneous ventilation?
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1 x the minute ventilation
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During controlled ventilation, how many liters per minute does the mapleson A require to prevent rebreathing?
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20LPM which is about 4x the minute ventilation
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In the Mapleson B & C, where is the spring-loaded POV located? Where is the FG inlet tubing located?
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POV is located near the facemask; inlet tubing located near patient (Basically, they are near eachother)
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Which systems are more efficient, BC or DEF?
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DEF
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Does BC require higher or lower Ve than DEF
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BC requires higher Ve
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In BC systems, during spontaneous ventilation, when is excess gas vented, during I or E?
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During exhalation (APL valve is left fully open to vent excess gas)
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In the Mapleson B & C systems, what rate of FGF is recommended during spontaneous and controlled ventilation respectively?
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2 x minute ventilation for spontaneous, 2-2.5x minute ventilation for controlled
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The t-piece group is part of what Mapleson functional group?
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DEF (the F group was added in 1975)
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How is rebreathing prevented in the Mapleson D nonrebreathing circuit?
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During expiration, FGF fills the limb, which forces the previously exhaled gas distally (toward the bag). FGF needs to be sufficient
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Which Mapleson system is particularly easy to perform IPPV
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Mapleson E
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What 13 factors affect CO2 rebreathing associated with Mapleson systems?
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FG flow rate
Minute ventilation Mode of ventilation tidal volume RR CO2 sample site I/E ratio Duration of Expiratory pause Peak inspiratory flow Volume of the reservoir tube Volume of breathing bag Ventilation by mask ventilation through an ett |
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Most popular representative from the DEF group
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Bain circuit
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What system has a hidden FG hose?
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Bain system
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What system is the Pethick's test used?
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Bain system
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Advantages of nonrebreathing systems: Mapelson/Bain
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Lightweight
Convenient Easily sterilized and scavenged exhaled gases in corrugated limb may give heat and humidity to inhaled gas (bain) |
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Disadvantages of nonrebreathing systems: Mapelson/bain
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Unrecognized disconnection or kinking of FG hose in the Bain circuit
Pollution, increased costs of agents and gases Need for higher flows Loss of heat from patient May require disconnectionof circle FG supply hose and scavenger connections for assembly can be reassembled improperly |
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Traditional circle breathing systems, "universal F" or "single limb circuit" advantages:
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Constant inspired concentrations
Conservation of respiratory tract heat and humidity, Minimal OR and environmental pollution Useful for closed system, low flow, and semi open configurations Low resistance |
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Traditional circle breathing systems, "universal F" or "single limb circuit" Disadvantages:
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Relatively complex,
Can misconnect or disconnect, Malfunctioning unidirectional valves can cause "bad outcomes" Open: Rebreathing Closed: Occlusion Less portable Increased Dead space |
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What are some causes of circle system obstruction
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Manufacturing defects
debris patient secretions Particulate obstruction from other sources, eg: albuterol neb |
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T/F: To prevent rebreathing of CO2 in a traditional circle, unidirectional valve must be located between the patient and the reservoir bag on both I/E limbs of circuit
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True
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The overflow (APL) valve cannot be located between the patient and what valve? Inspiratory or Expiratory?
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Inspiratory. To prevent CO2 rebreathing, the APL valve is located just downstream from the expiratory valve
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To prevent CO2 rebreathing, FG inflow cannot enter the circuit between the ____ valve and the patient. (exp or insp)
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Expiratory. FG inflow needs to enter upstream to inspiratory valve
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7 components of circle breathing system:
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FG inflow source
I/E unidirectional valves I/E corrugated tubes (limbs) Y piece connector APL valve Reservoir bag Cannister containing CO2 Absorbent |
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Which following sytem is the most commmonly used application in the US? Semi open, semi closed, closed?
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Semi closed.
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T/F: FGF above minute ventilation, like 5-8LPM, is associated with full reliance on absorbent granules to prevent rebreathing of CO2
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False. At FGF above minute ventilation, exhaled CO2 is rapidly diluted and sent to the scavenger with high FGF.
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Circle system with FGF of ___ to ___ LPM provides near total rebreathing and full reliance on absorbent for prevention of rebreathing of CO2
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0.3 to 0.5 L/min (300-500mL)
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T/F when faced with exhausted granules, one must increase minute ventilation (increase RR or TV)
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False
This is ineffective because the patient inspires more of a gas mixture containing CO2. |
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What would the CRNA do in response to hypercarbia associated with absorbent exhaustion
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Increase FGF, then change absorbent at end of case
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Free granules from bulk absorbent can create a leak if they lodge between the clear plastic cannister and the _____gasket of the absorber
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O-ring
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What is an example of how a CO2 cannister can become obstructed?
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Forgetting to remove the plastic shipping wrapper
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What are two commonly used absorbents
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Calcium hydroxide lime (Amsorb) and Soda lime (widely used)
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What compound is the activator in Soda lime?
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KOH, potassium hydroxide
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What is the composition of high moisture soda lime?
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80% calcium hydroxide, 15% water, 4% sodium hydroxide, and 1% KOH
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What is added to Soda lime to make a harder, more stable pellet, and reduced dust formation
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Silica is added to produce calcium and sodium silicate
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What chemical is the catalyst for the CO2 absorptive properties of soda lime
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Sodium hydroxide
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What CO2 absorbent is implicated as an agent that may produce fires in the breathing system when used with Sevo?
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Barylime, which is a mixture of 20% barium hydroxide and 80% calcium hydroxide
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What is the newest agent for CO2 absorption and what two agents serve to enhance the hardness of the agent
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Calcium hydroxide lime, agents are calcium sulfate and polyvinylpyrolidine
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What is the most significant advantage of Calcium hydroxide lime
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lack of strong bases (sodium and potassium hydroxide)...these strong basess can contribute to the production CO and the nephrotoxic substance"Compound A"
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T/F Calcium hydroxide lime may reduce the possiblilty of fire in the breathing system
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True
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2 disadvantages of calcum hydroxide lime
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Less absorptive
Higher cost |
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In regards to granules in the CO2 cannister, as particle size decreases, will the airflow resistance increase or decrease?
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Increase
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What mesh size of granules optimizes absorptive surface area and resistance to flow
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4-8 mesh
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What gas has been shown to produce degradation products when interacting with CO2 absorbents
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Sevo
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What animal has the highest blood pressure?
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Giraffe...it takes a lot of pressure to pump blood all the way up its neck
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What are factors that lead to an increase in the concentration of Compound A
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low flow or closed circuit anesthetic techniques
Use of Baralyme rather than soda lime higher absorbent temperatures fresh absorbent higher sevoflurane in anesthetic circuit |
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When using sevo, limit to ___ MAC hours at flow rates < ___L/min
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2, 2
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T/F: No CO is produced with hydrated soda lime
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True
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What is the maximum amount of CO2 in liters that can be absorbed by 100 grams of SODA LIME absorbent?
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26
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what is the maximum amount of CO2 in liters that can be absrobed by 100 grams of CALCIUM HYDROXIDE absorbent
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10.2
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When Co reacts with hgb to form carboxyhemoglobin, it shifts O2 to the ____on the hgb curve
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Left
a left shift prevents normal unloading of O2 in capillary bed; results in tissue hypoxia while blood partial pressure is high |
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How does channeling affect the absorptive capacity
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reduces absorptive capacity
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What is the name of the pH indicator added to CO2 absorbents?
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Ethyl violet
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Name some clinical manifestations of hypercarbia
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Increased rate, depth of respiration
Increased BP Ventricular irritability Flushing of face, neck and thorax Increased ICP |
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Gas enters the system from the ____ and exits the circle via the ____
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CGO, APL
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In Bain breathing system, is the APL and FGF located near the reservoir bag or patient
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reservoir bag
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Components/parts of the spring loaded disc type APL valve
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Disc, cap, gas trap, guide pin
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Components of the CO2 absorber
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Canister, gasket, drain port
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Where does FGF enter the Mapleson A circuit
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FGF enters the opposite end of the circuit near the reservoir bag
http://www.capnography.com/Circuits/maplesona.htm |
