Anesthesia Breathing Systems Flashcards
Links patient to anesthesia machine, delivers oxygen
and anesthetic gases, eliminates carbon dioxide
breathing system
what DECREASES resistance of breathing system?
Decreased circuit length Increased circuit diameter Avoiding sharp bends Eliminating valves Maintaining laminar flow
increased fresh gas flow causes a decrease of …
rebreathing and time equilibration
You should have __ flows for induction, ___ flows for maintenance and ___ flows for emergence
high, low, high
Blowing gas across the face
More a technique than a circuit
insufflation
Patient inhales → air passing through → vaporizes the liquid agent → mask gets cold → condensation and decreased vapor pressure (proportionate to temperature) no longer in use bc ether and chloroform are highly ..
open drop anesthesia
flammable
Ambient air is inhaled over liquid agent, flow DEPENDENT
simple, portable, no need for compressed gases
draw over anesthesia
Portable, self filling with O2 or ambient air, valve to allow for pos pressure, must have high flows
resuscitation, ambu bag
What is the nonrebreathing system we need to be familiar with called?
Mapleson (bain)
What components create a mapleson system?
Breathing tube, fresh gas inlet, adjustable pressurelimiting valve (APL), reservoir bag
long tubes and/or high compliance result in ?
larger gradient between gas delivery to circuit and to patient
large in diameter (22 mm), rubber/corrugated
mapleson breathing tube component
High flow required to prevent significant rebreathing and during spontaneous ventilation fresh gas flow must at least equal minute ventilation
maplesons
with mapleson during controlled (pos) pressure ventilation, what minute ventilation is required?
2-3 x minute ventilation
Anesthesia gases (volatiles, N2O) + O2 + air from anesthesia machine enter the Mapleson through
fresh gas inlet
Controls pressure build-up in the circuit (vents or pops off when a set pressure is reached
APL valve
2 functions of the reservoir bag
anesthetic gas reservoir and pos pressure ventilation
components of circle system
CO2 absorber, FGI, unidirectional limbs
and valves (I & E), Y-connector, APL valve,
reservoir bag
what keeps flow moving forward
check valves
what causes valve incompetency?
Warped disk
“Stuck” in up position
Condensation
Malfunction of either side can lead to CO2 rebreathing and hypercapnia
best circle set up
-Valves near patient (prevents backflow when circuit leaks)
-FGI between absorber and inspiratory valve (less wasted fresh gas)
-APL between absorber and expiratory valve (conserves absorbent and less venting of
fresh gas)
-Reservoir bag in expiratory limb
(decreases resistance to exhalation and conserves
absorbent)
allows for rebreathing of all gases with disposal of CO2
circle system
with absorber, CO2 rebreathing is __ even at low flows
prevented
the gradient increases between delivered and expired with
low flows
Tidal volume that does not move into alveoli
dead space
where is dead space?
distal to y piece
disadvantages of circle system
Less portable, increased risk of malfunction, problems with absorber, less predictability with low flows
what are the 2 methods for CO2 elimination
CO2 absorber
high fresh gas flow
rebreathing conserves:
heat, humidity, volatiles
neutralize H2CO3 to water and
energy (heat)
Soda lime or Ca2+ lime (salts)
when should absorbent be replaced
50-70% color change
dry absorbent
dessication
breakdown of volatile gases
degredation
when is degredation highest?
desflurane
CO2 absorbent
resulting in less degradation
amsorb
what is the worst degredation?
KOH
By-product of sevoflurane degradation by
absorbent
-Nephrotoxic at 25-50 ppm (easily created in
extreme low flows)
compound A
what increases risk of compound A
- High concentration
- Long anesthesia time (>2 MAC hours)
- Low-flow technique (< 2 L/min)
Alveolar concentration that prevents movement in 50%
of patients in response to surgical stimuli (incision)
MAC - mean alveolar concentration
Absorbent exhaustion in areas where gas enters the absorber and along the canister walls
channeling
what is places in cannister to prevent channeling
baffles
avoid absorbents with ___
KOH
What does a circle system have that the maplesons does not?
Co2 absorber, unidirectional limbs and valves, y connector
