Breathing Systems Pt. 1 (Exam II) Flashcards
This type of circuit is characterized by no reservoir bag and no rebreathing.
Open Circuit
This type of circuit is defined by a reservoir bag and complete rebreathing. This circuit is also dependent on fresh gas flow.
Closed Circuit
This type of circuit is characterized by a reservoir bag with no rebreathing.
Semi-open Circuit
This type of circuit is characterized by a reservoir bag and partial rebreathing.
Semi-closed Circuit
What component of the anesthesia machine is indicated by 1 on the figure below?
Common (Fresh) gas inlet
What component of the anesthesia machine is indicated by 2 on the figure below?
Pressure gauge
What characteristics are necessary for unidirectional valves?
- Must open widely w/ little pressure
- Must close rapidly w/ no backflow
- Metal disc w/ low resistance & high competence.
What anesthesia breathing system component directs respiratory gas flow in the correct direction?
Inspiratory/Expiratory valves
Which valve opens on inspiration, closes on exhalation, and prevents backflow of exhaled gas?
Inspiratory valve
Where is a mask supposed to fit on a patient’s face?
Inbetween the interpupillary line and the groove between the mental process and alveolar ridge.
What size is the connection that fits the mask to the Y-piece of the machine.
22mm female connector.
What are the general benefits of connectors/adapters on the airway portion of the anesthesia machine?
- extends distance between patient and breathing system
- change angle of connection
- allow flexibility
What are the general disadvantages of connectors/adapters on the airway portion of the anesthesia machine?
- increased resistance
- increased dead space
- additional points of failure/disconnection
How long is breathing tubing?
How much internal volume does it typically have?
- 1 meter long
- 400-500 mL/m of length
What type of flow is typically present in corrugated breathing tubing?
Turbulent due to corrugation
Does adding longer tubing increase dead space?
Interestingly no it does not
Only adds dead space if bidirectional air flow is occurring.
What adds dead space?
- Y-piece attached to patient due to unidirectional gas flow
At what pressure should a circuit pressure check be done?
30 cmH₂O
What is required for dead space?
Bidirectional gas flow
Includes anatomic dead space, ETT, and Y-piece.
A unidirectional valve is broken. Is the attached inspiratory limb considered dead space?
Yes, now bidirectional gas flow is occurring. If valve is fixed then the limb will not be considered dead space again.
Which valve opens on exhalation & prevents rebreathing?
Expiratory valve
What shape do breathing/reservoir bags have?
Ellipsoidal
What volume do breathing bags have?
3L for adults
(0.5 - 6L range)
What is the minimum pressure of a breathing bag?
30 cmH₂O
What is the max pressure of breathing bags?
40 - 60 cmH₂O
Plastic bags have ____ the distending pressure of rubber bags.
twice
What functions does the breathing/reservoir bag serve?
- Reservoir for gasses & O₂
- Manual ventilation
- Assistance w/ spontaneous ventilation
- Protection from excessive positive pressure
- Visual/tactile monitoring of ventilation
- Protection from excessive pressure
Where is the preferred location for the fresh gas inlet?
Between CO₂ absorbent and inspiratory valve
What is the purpose of the APL (adjustable pressure limiting) Valve?
- Permits gas to leave the circuit to the scavenging system
- Controls pressure in the breathing system
Turning the APL valve in a clockwise motion will ______ pressure.
increase
Turning the APL valve in a counterclockwise motion will ______ pressure.
decrease
How many turn are required to go from fully open to fully closed on the APL valve?
1-2 clockwise turns
What is the purpose of the side/center tube located in the absorbent cannister?
Returns gas to the patient
What is the chemical formula for soda lime?
Ca(OH)₂
What is the chemical reaction that occurs with soda lime in a CO₂ absorbent cannister?
CO₂ + Ca(OH)₂ → CaCO₃ + H₂O + heat
What are the components of soda lime?
- Calcium hydroxide (80%)
- Sodium & potassium hydroxide (5%)
- Water (15%)
When does soda lime become exhausted?
When all hydroxides become carbonates
How much CO₂ can soda lime absorb?
19% of its weight
100g can absorb 26L of CO₂
What absorbent has greater absorption capacity and is used in submarines and spacecraft?
Lithium Hydroxide
Which absorbent is responsible for compound A & CO formation?
Calcium Hydroxide Lime
What is Litholyme?
Lithium chloride
What are the benefits of Litholyme (Lithium chloride) ?
- No compound A formation
- No reaction with inhaled anesthetic agents
- Low exothermic reactivity, and low risk of fire
- Better for environment
What absorbent has no color indicator?
Spira-Lith (Anhydrous LiOH)
What are the benefits of Spira-Lith?
- Large reaction surface area
- ↓ temperature production
- Long duration
- Cheap
At what pH do absorbents undergo color change?
10.3
pH > 10.3 (absorbent is colorless & fresh)
pH < 10.3 (exhausted & purple absorbent)
What dyes are used in CO₂ absorbents?
- Ethyl Violet
- Ethyl orange
- Cresyl yellow
What is the purpose of the mesh located in CO₂ absorbents?
Maximize absorption and minimize resistance
What will excess liquid water do inside a CO₂ absorbent cannister?
- ↓ surface area
- ↓ absorbent efficiency
Approximately how much of a CO₂ absorbent cannister’s volume is gas?
½
What is channeling and its consequence?
- Small passage ways allowing gas to flow through a defined route
- Decreases functional absorptive capacity
How can channeling be minimized?
- Circular baffles
- Permanent mounting
- Prepackaged cylinders
- Avoiding over packing
Which gasses produced the most CO?
The least?
Desflurane ≥ Enflurane > Isoflurane > Halothane = Sevo
Why should sevoflurane use with dessicated strong base absorbents (baralyme, LiOH) be avoided?
High risk of fire
What component of the anesthesia machine is indicated by 3 on the figure below?
Inspiratory Unidirectional Valve
What component of the anesthesia machine is indicated by 4 on the figure below?
APL valve
What component of the anesthesia machine is indicated by 5 on the figure below?
Expiratory Unidirectional Valve
What component of the anesthesia machine is indicated by 7 on the figure below?
Reservoir Bag
What component of the anesthesia machine is indicated by 8 on the figure below?
Absorbent Cannisters
