IHS Breathing Systems
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1. How do breathing systems negatively effect breathing?
1. All breathing systems add resistance to flow. Especially bc of unidirectional valves and connectors
1. What are ways to minimize resistance to flow?
- 1. use the Largest lumen possible
- 2. Reduce circuit length
- 3. curved connectors
- 4. controlled ventilation
1. what is the primary purpose of breathing circ?
1. Deliver anesthetic Gases and O2 to pt and remove CO2
How do you calculate pt tidal volume?
1. What is different from ICU ventilators vs Anesthesia machine?
1. ICU vents. do re-breath gases
What are the four factors that affect rebreathing of gases?
- - design of circuit
- - FGF rate
- - ventilation mode
- - pt's respiratory pattern
What are the adv and disadvantages of rebreathing
- 1. Cost reduction
- 2. tracheal warmth and humidity
- 3. decreased exposure to OR ppl
- 1. CO2 accumulation
- 2. potential for O2 depletion
- 3. Increase system pressure.
1. where does mechanical dead space begin?
1. pt's incisors
1. Mechanical Dead space gas is the 1st gas inhaled at the beginning of each respiratory cycle.
2. Define Mechanical dead space
- 1. T
- 2. the volume of gas in a breathing system that are rebreathed without any change in composition.
FGF and rebreathed gas are inversely proportional?
Main components of breathing system.
- ! Deliver gases from machine to alveoli in the same concentration as set and in shortest possible time
- ! Effectively eliminate CO2
- ! Minimal apparatus dead-space
- ! Low resistance
1. How are breathing systems classified?
- 1. The presence or absence of reservoir bag
- 2. degree of rebreathing
- - means of neutralizing CO2
- - presence of unidirectional valves
1. When will there be rebreathing?
1. when the FGF is < pt minute ventilation
1. Mapleson breathing system
- - NO unidirectional valves
- - NO way to absorb CO2 - FGF washes out circ.
- - No inspiratory and exp limb - Rebreathing can occur when pt inspiratory flow > FGF
- - Vol of circ is = or > pt TV to minimize FGF
What are the 2 distinct functional mapleson groups?
- 1. Mapleson A
- 2. Mapleson D,E,F
1. Another name for Mapleson A circuit?
2. T/F - it is the most efficient circuit for spontAAAneous ventilation?
1. How do you calculate a normal VE?
2. In controlled ventilation how much FGF is needed to prevent rebreathing?
- 1. ~ 80ml/kg/min
- 2. 3x pt's minute volume
1. What is the Mapleson D,E, and F group called?
1. T-piece group
1. Mapleson D is the most efficient at controlleDDD ventilation
1. Mapleson E features?
- 1. No reservoir
- 2. NO Pop-off
- 3. requires 3x pt VE to prevent Rebreathing
- 4. unable to us vent
2. Ayre's T-Piece
1. Mapleson F - AKA?
2. T/F its a mapleson E with a reservoir bag and expiratory port but no valve
1. Jackson-Rees or Modified Ayres t-piece
1. Bain System - is like which mapleson?
What is the difference?
2. Great for controlleD vent. to preserve FGF
but uses 2.5-3x FGF for spontaneous breathing
- 1. Mapleson D
- 2. exhaled gas leaves outer tube. FGF enters through small internal tube
What are the advantages of Bain system?
- 1. Warming of Gas and improved humidification
- 2. ease of scavange
- 3. APL
- 4. disposable and sterile
Disadvantages of Bain
- 1. increased resistance
- 2. kinking of inner FGF tube
- 3. Unrecognized disconnection of FGF = Increased Rebreathing
What is the test that determines if the gas inlet tube is kinked?
What is the most commonly used breathing circ?
- what are its advantages?
- - Circle system
- - decrease rebreathing CO2 by unidirectional valves and absorber
- - reduces need for high FGF
- - Conserves heat and humidity
- - Reduces OR pollution
- - constant inspired concentrations
- - useful for all ages
- - low resistance
1. The FGF must be between the absorber and the inspiratory valve
What is normal dead space percent of TV?
1. T/F Soda lime and baralyme reaction is exothermic?
2. What are the bypoducts of this reaction?
- 1. T
- 2. Carbonates, Water, and Heat
What are the components of CO2 absorber?
What are the active components?
How much CO2 can be absorbed?
- 1. 94% CaOH
- 2. 5% NaOH
- 3. 1% KOH
- 23-26L/100g of absorbent
What happens if absorber bcomes too dry?
1. degradation of volatile anesthetics
1. What is the pH sensitive die that changes color when 50-70% of the die is exhausted?
2. T/F Regeneration of exhausted granules may revert color back to original if rested. But, absorbent is still exhausted
1. Ethyl violet - changes to violet in presence of carbonic acids
KOH is often not included or minimized in absorbers d/t its negative effects. What are they?
- - increased temp
- - Carbon Monoxide formation - Des,Enflurane, Isoflurane
- - Formaldehyde
- - Compound A formation - Sevoflurane
Baralyme consist of?
- 1. 80% CaOH
- 2. 20% BaOH2 (the activator)
- no longer available dt fire hazard
1. What is Amsorb and its composition?
2. Amsorb advantage?
- 1. CaHO
- 2. Less degredation of volatile anesthetics
- sevo -> compound A
- desflurane -> CO
- 3. alkaline free
- 4. Does not deteriorate as easily with dessication
1. Granule size for Amsorb is?
- 1. 4-8 mesh 4-8 openings/in2
- - lg the size < resistance, but < surface area
1. Optimal CO2 neutralization requires what about the pt TV?
1. the Pt's full TV accommodated within canister
What should you do to minimize absorber channeling?
1. shake before use.
What are the toxic reactions with volatile agents and CO2 absorbers
What increases the chance of toxins?
- Sevo - Compound A
- - baralyme
- - Temp
- - low flows
- - high gas conc.
- - fresh absorbent
- Recomended 2-5L/min flows
Des, Enfl, Iso have the risk of creating?
What increases this risk
- - CO build up
- - Carboxyhemaglobin may increase up to 30%
- - occurs with soda lime but > with baralyme
- - low flow
- - High anesthetic concentration ^ production
- - high temp
- - dessicated granules - turn off FGF at end of each day.
- - Flush with 100% 02 for 1min at start of Day
- - Soda lime dormant for > 24 should be changed and dated
1. CO2 + water -> carbonic acid (H2CO3)
- 2. H2CO3 + 2NaOH -> Na2CO3 + 2H2O + Heat
- - This is a fast reaction
- 3. Na2CO3 + Ca(OH)2 -> CaCO3 + 2NaOH + Heat
- - This is a slow reaction
- 4. H2CO3 + Ca(OH)2 -> CaCO3 + 2H2O + Heat
- - This is very slow reaction
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