Exam 2 (Breathing systems) Flashcards
What is an open cicuit?
No reservoir bag & no rebreathing
What is a semi-open circuit?
Reservoir bag but no rebreathing
what is a semi-closed circuit?
Reservoir bag & partial rebreathing
What is a closed circuit?
Reservoir bag & complete rebreathing
Where does the circuit mask fit on the face?
Between interpupillary line & groove between the mental process & alveolar ridge
What is the size of the Y-piece connector?
22mm
What are the benefits (3) of connectors/adapters?
- Extend distance between Pt & breathing system
- Change connection angle
- Allows more flexibility/less kinking
What are the disadvantages (3) of connectors/adapters?
- Increased resistance
- increased dead space (distal to the Y-piece)
- Additional locations for disconnects
What is the length of the breathing tubing & what is its internal volume?
- 1 meter
- 400 - 500mL/m
The breathing tubing has ___ resistance & is somewhat ___?
- low
- distensible
Circuit breathing tubing flow is ___ due to the ____?
- turbulent
- corrugation
Circuit pressure checks are done at ___ cm ____
- 30
- H₂O
In what case do unidirectional valves contribute to dead space?
When the valve does not close rapidly & all the way
Where are the unidirectional valves located?
Near the CO2 absorber, fresh gas inflow site & pop-off valve
What are the 5 requirements for unidirectional valves?
- Arrows or directional words
- Hydrophobic
- Must open & close appropriately
- Clear dome
- Must be placed between Pt & reservoir bag
Traditional adult reservoir bags hold how much air?
3L
What is the max pressure for rubber reservoir bags?
40 - 60 cm H₂O
Do plastic reservoir bags have a higher or lower distending pressure than rubber?
2x that if rubber bags
What are the reservoir bag functions (5)?
- Reservoir for anesthetic gases or O₂
- Means of manual ventilation
- Assistance with spontaneous ventilation
- Visual/tactile monitor of ventilation
- Protection from excessive positive pressure
What is the preferred location for the gas inflow site?
Between CO₂ absorbent & inspiratory valve
What does the APL valve control?
Pressure in the breathing system
The APL valve releases gases to the?
Scavenging system
What are the 3 APL valve requirements?
- Clockwise= increase pressure
- 1-2 clockwise turns from fully open to fully closed
- Arrow must indicate direction to close valve
What is the purpose of the side or center tube in the absorber canister?
Returns the gas to the Pt
When the absorbent canister is all purple the contents are?
All carbonates & NO hydroxides
What are the 2 fast reaction hydroxides?
- NaOH
- KOH
What is the full product after CO₂ reacts with Soda Lime?
CaCO₃ + H₂O + heat
What are the 3 strong bases used in absorbents?
- Ca(OH)₂
- NaOH
- KOH
100g of absorbent can absorb how much CO2?
~ 26L CO₂
What are the 3 advantages of Ensorb?
- Produces NO Compund A
- Reduced CO production
- ## Destruction of inhaled gases
- Ensorb is also called Calcium hydroxide lime
Which 2 absorbents do not contain NaOH?
- Spiralith
- Litholyme
- Sodasorb
Spiralith & Litholym
Which absorbent does not contain H₂O?
Spiralith
Which 2 absorbents do not contain LiCl?
- Spiralith
- Litholyme
- Sodasorb
Sodasorb & Spiralith
Spiralith is mostly made up of?
LiOH
Which 2 absorbents do not contain NaOH & KOH?
Litholyme & Spiralith
Which absorbent does not regenerate?
Litholyme
Which absorbent does not produce compound A & CO?
Litholyme
Which absorbents have lower exothermic reactions?
Litholyme & Spira-lith
Which absorbent does not change colors?
Spira-Lith
Which absorbent has a larger surface area for reactions?
Spira-Lith
What decreases surface area & CO₂ absorption efficiency?
- Excess liquid water within the canister
- Channeling
What 4 things can contribute to Compound A formation?
- Low FGF (1 - 2L)
- Increased absorbent temperature
- High Sevo Mac values
- Dehydrated absorbent
What 2 gases result in the highest CO production?
- Desflurane
- Enflurane
Sevoflurane combined with which absorbent can lead to high heat production & ultimately combustion.
Strong base absorbents like anhydrous LiOH (Spiralith)
What is missing with Mapleson circuits?
- CO₂ absorber
- Unidirectional valves
- separate inspiratory & expiratory limbs
Which Mapleson circuit is the best for spontaneous breathing?
Mapleson A (Magill’s system)
Which circuit is the worst for controlled ventilation?
Mapleson A (Magill’s system)
Which circuit does not contain corrugated tubing?
- Mapleson C
- C ya later corrugated tubing
Which circuit is the best for controlled ventilation?
Mapleson D
What does the FGF need to be with the Mapleson D circuit?
2 -2.5x minute ventilation
What makes the Bain circuit unique?
- It creates inspiratory & expiratory limbs
- Also, the FGF is moved away from the Pt
Which circuit does not have an APL valve?
Mapleson E & F
What is the Mapleson E used for?
In spontaneously breathing Pt’s to deliver O2
What is the Jackson Rees circuit?
Adding a Reservoir bag, with a hole at the end, to the Mapleson E circuit
Which Mapleson circuits have the APL valve close to the Pt’s mouth?
Mapleson A, B & C
Which Mapleson circuits waste a lot of FGF at the end of expiration?
- B & C
- A (if using for controlled ventilation)
Which 2 Mapleson circuits are least likely to be used for spontaneous ventilation?
B & C
How is the resistance to gas flow in Mapleson circuits?
Low resistance to gas flow
What are the disadvantages to Mapleson circuits?
- Need high FGF
- Do not conserve heat & humidity
- No scavenging system (Except D)
- Not suitable for MH Pt’s (as FGF might not go high enough to blow off CO₂)
How much expired gas is rebreathed with Low flow anesthesia?
~ 50% after CO₂ removal
What are the 3 advantages of Low-flow anesthesia?
- Decreased use of VA’s
- Improved temp & humidity control
- Reduced environmental pollution
What are the 3 disadvantages of Low-flow anesthesia?
- Difficult in rapidly adjusting anesthesia depth
- Possibility of accumulating unwanted exhaled gases
- VA degradation byproducts
What are advantages of Circle systems?
- Can use Low-flow anesthesia
- CO₂ elimination
- Stable inspired gas concentration
- Conservation of moisture, heat & gases
- Prevents OR pollution
What are the disadvantages of Circle systems?
- Complex design
- CO or Compound A
- May compromise Vt during controlled ventilation
- Increased law suits (D/t misconnections/disconnections)
What are the hazards for Ambu bags?
- Barotrauma due to Breath stacking
- Significant variation in Vt, PIP, PEEP
- Non-rebreathing valves generate resistance
What are the concerns with bacterial filters?
- Create high airflow resistance
- Prevent water penetration leading to increased resistance & efficiency
- Obstructions
- Leakage in housing of gas line filter
When is a Inspiratory filter placed?
When machine has previously been contaminated
What Pt’s need a Airway filter at the Y-piece?
- Covid Pt’s
- PUI Pt’s
What is relative humidity?
Percent saturation; amount of water at certain temperature
What is absolute humidity?
What is the value covered in class?
- Mass of water vapor in gas in mg H₂O/L
- 44 mg H₂O/L
Where is the isothermic saturation boundary?
Just below the carina
Cool inspired air can lead to what?
Bronchospasms
What can happen with underhumidification?
- Secretions thicken
- Ciliary function decreases
- Impairs surfactant activity
- Mucosa susceptible to injury
- Body heat loss
- ETT obstruction
- increased resistance & work of breathing
What can happen with overhumidification?
- Water intoxication
- inefficient mucociliary transport
- Obstruction to sensors
- Increased risk for pulmonary infection
- surfactant dilution
- atelectasis
What do Heat & moisture exchangers do?
Where are they placed?
- They conserve some exhaled heat & water & returns them to Pt
- They are placed between Y-piece & ETT
HME’s can cause what issues?
- Low EtCO₂ readings
- Increase resistance & dead space
- Reduced efficiency with large tidal volumes
Hygroscopic HME’s are most efficient for?
- Retaining heat & moisture
- H for heat
Hydrophobic HME’s are more efficient for?
Filtering of pathogens
What is the downside to Hygroscopic HME’s?
- Prone to becoming saturated
- Increased inspiratory & expiratory resistance
When are humidifiers used?
- Neonates
- Pt’s with difficult respiratory secretions
- hypothermic Pt’s
Condensation can lead to what?
Decreased tidal volumes
Where are humidifiers placed in a circle system?
On the inspiratory limb between the unidirectional valve and Y-piece
What devices has a higher chance for water aspiration?
Humidifiers
