Breathing systems (exam 2) Flashcards by Andrew Davis

where is the apparatus deadspace located within a breathing circuit? why?

Y piece to the patient
No gas exchange with bi-directional gas flow

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What volume of air is in 1 meter of circuit

400-500ml

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Flow in the breathing system is always turbulent due to

corrugation

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what pressure should ciruits be checked at?

30 cm H2O

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Which valve prevents rebreathing

expiratory valve

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Which valve prevents backflow of exhaled gas

Inspiratory valve

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Where are the valves located?

Near CO2 absorber, FGF site, and the pop-off valve

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What does proper valve placement help ensure?

It helps prevent any part of the circle system from contributing to apparatus dead space

deadspace= bi-directional flow in the system

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Requirements for valves

arrows/directional labels
hydrophobic
open/close appropriately
clear dome
must be placed between patien tand reservoir bag

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What’s the normal volume for a reservoir bag?

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What range can a reservoir bag contain?

0.5-6L

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What size connector must be on the end of a reservoir bag?

22mm female connector

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What are the minimum and maxiumum pressure for a reservoir bag? What if it is plastic instead of rubber?

Rubber min: 30 cmH20
Rubber max: 40-60 cmH20
Plastic: 2x as distensible

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Reservoir bag function

hold anesthetic gas
manual ventilation
assistance with spontaneous ventilation
visual/tactile monitor of ventilation (volume estimation)
protection from excessive positive pressure

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What is the preferred locaiton for the gas inflow site?

between CO2 absorbent and the inspiratory valve

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APL clockwise motion will do what to the pressure

Increase pressure

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APL counterclockwise will do what to the pressure?

reduce the pressure

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What makes up the bulk of soda lime?

calcium hydroxide (80%)

What percentage of soda lime is water?

15 %

What is the net reaction with soda lime and CO2?

CO2 + Ca(OH)2 –> CaCO3 +H20 + heat

List the sequential reaction for soda lime and carbon dioxide

CO2 + H20 –> H2CO3
H2CO3 + 2NaOH (or KOH) –> Na2CO3 (or K2CO3) + 2H2O + Heat
Na2CO3 (or K2CO3) + Ca(OH)2 –> CaCO3 + 2NaOH(or KOH) + heat

H2CO3 = carbonic acid

Does CO2 reaction with LiOH endothermic or exothermic?

Endothermic

absorbs heat

Regeneration is typically due to what elements in the soda lime?

Na or K

Soda lime can absorb ____% of its weight in CO2. This means 100g could absorb ____ L of CO2

19%
26L

when is an absorbant exhausted?

When all hydroxides become carbonates

calcium hydroxide lime containts what

* Ca(OH)2 70% * CaCl 0.7% * CaSO4 0.7 % * Polyvinyl 0.7% * Water 14.5%

Calcium hydroxide lime benefits

* Decreased Compound A * Decreased CO * Decreased degredation of inhaled VAs

Benefits of Litholyme

* reduced exothermic activity * reduced risk of fire * lower economic/environmental effect * No compound A or CO

Does Litholyme regenerate?

Does spira-lith have a color indicator

Whats the ideal mesh size

4-6

At least half the volume of each absorbent cannister is

gas

Excessive condensation in the cannister can caue

reduced surface area, reduced efficiency of CO2 absorption

Channeling is a result of

passage ways of gas going through a low-resistance area

What can minimize channeling?

* circular baffles * placement allowing vertical flow * permanent mounting * pre-packaged cylinders * avoiding overly tight packing

What contributes to compound A formation?

* low FGF * increased absorbant temperature * higher MAC of Sevo * dehydrated absorbent

Which VAs create the most CO from greatest to least

DEIS ("diez" lolllll) Des > Enf > Iso > sevo

What contributes to CO formation?

* Increased temp * Increased concentration of anesthetic gas * low FGF * smaller patient (absorbent dehydrates) * strong base absorbents (KOH or NaOH) * dry absorbents

What dessicated strong base absorbents reportedly created fires with sevoflurane?

Baralyme, anhydrous LiOH

what are the flammable degradation byproducts

methanol, formaldehyde, formic acid

APSF Recommendations for absorbent

* ALL gas flows off after each case * turn off vaporizers * change when color indicates exhaustion * change all absorbent (2 canisters..change BOTH) * change absorbent when unsure about hydration * if using compact canisters change more frequently

What are the compenents of an ideal breathing system

* Receives gas mixture from the machine * Delivers gas to the patient * Removes CO2 * Provides heating and humidification of the gas mixture * Allows spontaneous, assisted, or controlled respiration * Provides gas sampling, measures airway pressure, and monitors volume

Components of a mapelson (general)

* reservoir bag * corrugated tubing * APL valve * Fresh gas inlet * patient connection

Discuss the efficiencies of the mapelsons during spontaneous vs. manual ventilation

Sppontaneous: A > DFE > CB Controlled: DFE > BC > A