Anesthesia Machine II Flashcards
name the 4 vaporizer styles:
variable bypass, flow over wick design
copper kettle
desflurane design
aladin
what is the purpose of the vaporizer?
to add anesthetic gas into the path of fresh gas flow that is directed to the common gas outlet and delivered to the patient via the circuit
historically, vaporizers were inaccurate at __ flows but good for ___ flows
low flows
flow rates greater than 5L.min
contemporary: vaporizers are very accurate at ___ dial settings over a wide range of flow rates
ALL
very consistent now
MAC and vapor pressure of Halothane:
0.75%
243 mmHg
MAC and Vapor pressure of enflurane:
1.78%
175 mmHg
MAC and vapor pressure of Isoflurane:
1.19%
238 mmHg
MAC and Vapor pressure of desflurane:
6%
664 mmHg
MAC and vapor pressure of sevoflurane:
2%
160 mmHg
vapor pressure is typically at ___ degrees celsius
20
current anesthetic agents exist as a __ @ temps below 20 C
liquid
explain the variable bypass, flow over wick design
a stream of gas passes over the surface of a volatile liquid and picks up the vapor
vapor pressure ___ with varying temperature
changes
what happens to vapor pressure with application of heat vs cold
heat causes equilibrium to shift so that more molecules enter the vapor phase
lowering temp causes a shift toward the liquid phase and a decrease in pressure
what are the temperature compensation devices inside variable bypass vaporizers?
bimetallic strip design
temp compensation cone
what is the Tec 6 Soprano gas/vapor blender?
electrically heated
pressureized
vapor injection device
gas blender
small changes in temperature causes ___ changes in desflurane vapor pressure
large
what temp is desflurane heated to?
39-40C
why is desflurane heated so high?
it is above any reasonable physiologic temperature
it provides a controlled constant temperature within the vaporizer
what is the vapor pressure of desflurane
1300mmHg
which vaporizer has to be a digital readout?
the desflurane vaporizer start up
what vaporizers does tipping not apply to?
aladdin cassette and draeger 2000
what are the problems with tipping a vaporizer?
liquid agent can enter the control assembly and obstruct valves
can cause unpredictable vaporizer output
what to do if there is a tipped vaporizer:
drain vaporizer sump
flush for 20-30 min at high flow rates with high concentration set on dial
call Biomed
what is a way to prevent tipping the vaporizer
put that shit in transport mode
what guidelines that were published in 1999 and revised in 2000 apply to all liquid inhalational anesthetic agents
occupational safety and health administrations anesthetic gases guidelines for workplace exposures
what is the preferred method for rapid removal of large volumes of a liquid anesthetic spill?
suctioning in the operating room
how much can the puddle vac hold?
700mL/min used for large spills
manufacturer recommendations for a liquid anesthetic spill: (3)
collect the liquid spilled and absorbent materials used to contain a spill in a glass or plastic container
tightly cap ans eal container and remove it
transfer sealed containers to waste disposal compnay
what is the formula for how much liquid agent a vaporizer uses per hour?
3x fresh gas flow x vol%=mL liquid used per hour
what are the 3 breathing system classifications:
open
circle
transport
what are the characteristcs of an open breathing circuit:
anesthetic gases and oxygen blown directly across the face
no direct connection
no valves, resevoir bag, or Co2 absorber
no dead space
name examples of an open system breathing circuit:
blow by oxygen
mask held over patient face without touching face
assembly of components connecting the patient’s airway to the anesthesia machine
creates an artificial atmosphere into which the patient breaths
circle circuit
examples of breathing circle circuits
LMA, ETT, trach
what is the most popular breathing circuit system?
circle system
name the components of the circle system breathing circuit:
fresh gas inflow source
unidirectional valves
corrugated tubing
y connector
overflow/pop off valve
resevoir bag
CO2 cannister
granules
what is the purpose of teh circle system breathing circuit?
cleanses CO2 chemically
allows rebreathing of all other exhales gases
allows gas flow in a circular pathway thru separate inspiratory and expiratory channels
the direction of flow is determined by 2 unidirectional valves
what are the sizes for:
scavenger
ETT or common gas outlet
breathing circuit
19-30mm
15 mm
22 mm
what are the 5 advantages of the circle system
constant inspired concentrations
conserve respiratory heat and humidity
useful for all gases
useful for closed system or low-flow
low resistance
4 disadvantages of the circle system:
increased dead space
malfunction of unidirectinal valves
bulky
exhaustion of soda lime
the 3 ways the circle system can be:
closed
semi-closed
semi-open
fresh gas inflow exactly equal to patient uptake, complete rebreathing after carbon dioxide absorbed, and pop off valve closed
closed circle system
some rebreathing occurs, fresh gas flow and pop off valves at intermediate values
semi-closed circle system
no rebreathing, high fresh gas flow
semi-open circle system
what are the 3 valves present and necessary in the circle system?
inspiratory valve
expiratory valve
APL or pop off valve
valves are utilized in the circle system to assure _____ flow:
unidirectional
what is the main nonrebreathing system?
BAIN or a modified mapleson D
Bain needs ____ ml/kg of fresh gas flow for controlled ventilation and _______ ml/kg for spontaneous ventilation
70
100-300
elimination of CO2 from the Bain system is dependent on what 3 thihngs?
fresh gas flow
tidal volume
and to some extent the pattern of breathing
what breathing system has NO unidirectional valves and NO soda lime carbon dioxide absorption?
the Bain Nonrebreathing system
what is the purpose of the Pethick Test for the nonrebreathing system?
to assure patency of inner inspiratory tube
if occlusion occurs, the entire limb becomes dead space
how do you perform the Pethick test?
occlude the patient end of the circuit at the elbow
close the APL valve
fill the circuit using the oxygen flush valve
release the occlusion at the elbow and flush
what effect causes the resevoir bag to flatten if the inner tube is patent during the Pethick test?
the Venturi effect
incompetence or frature of the disc or ceramic valve may lead to jamming and predisopose the machine to resistance in gas flow leading to a :
respiratory emergency
cannot ventilate
back up oxygen supply tank and Ambu bag
do the valves have to be labeled?
YESSSS
what requires that the direction of intended gas flow is
permanently marked on the valve housing or near its
associated hose terminal with a directional arrow or
inspiration or expiration marking and fitting with a 22 mm
male connector?
the ASTM
name like 3 other names for the APL valve?
(there’s a shit ton)
Pressure relief valve, venting port, relief valve,
overspill valve, pop off valve, dump valve, blow off valve, safety relief valve, excess valve, heidbrink valve, adjustable pressure limiter, excess gas venting valve, spill valve, exhaust valve, expiratory valve, excess gas valve, pressure release valve, and release valve
what does the APL valve control in the breathing system?
the PRESSURE
how is pressure measured in the circle system?
a pressure gauge
what holds a volume of anesthetic gas that the patient can draw from during the beginning of inspiration, when minute volume far exceeds the fresh gas inflow?
the resevoir bag (rebreathing bag)
what serves as a shock absorber or pressure limiting device and as a means to provide positive pressure during ventilation?
the resevoir bag (rebreathing bag)
if the FGF is 0.3-0.5 LPM, what happens to the CO2 absorption flow rates?
Near total rebreathing and full
reliance on absorbent for prevention of rebreathing of CO2
if the FGF is 5-8 LPM, what happens to the CO2 absorption flow rates?
Almost no reliance on absorbent for
carbon dioxide absorption
name the 3 step reaction of carbon dioxide with soda lime
- CO2 = H2O — H2CO3
- H2CO3 + NaOH — Na2CO3+h2O + heat
- Na2CO3 + Ca(OH)2 — Ca2CO3 down arrow + NaOH
what are the 3 phases of CO2 absorption?
gaseous phase
liquid phase
solid phase
soda lime absorbs most efficienty when the moisture content is between ____ and ____ %
10 and 22%
The overall exothermic carbon dioxide absorption
reaction releases approximately _____kcal for
every______of carbon dioxide
absorbed
13,700 kcal
22.2L (1 mole)
temperatures within the soda lime can reach ____
45-50C
100 Grams of soda lime absorbs how many Liters of CO2
26L
what is the average CO2 production?
200mL/min OR 12-18L/hr
how do you calculate how long a 500 Gram mini cannister of soda lime will last?
100 G=26 L
26 x 5= 130 L CO2
130/ anywhere from 12-18 = range is 10.8-7.2 hours
what is the appropriate mesh size that has been accepted through trial and error of the CO2 absorbent?
4-8 mesh
whats larger? a size 4 or 8 mesh?
4
the higher the mesh number =
the smaller the absorbent particle
airspace occupies _____% of the volume of the CO2 absorbent cannister and is divided into two spaces:
48-55%
void space and pore space
absorbers have the highest efficiency when the space between the granules is _____ than the tidal volume of the patient:
equal to or greater than
what are 6 tips on handling soda lime canisters?
avoid open absorbents
handle it gently
hold it over a suitable receptacle
avoid pyramiding
avoid compression
remove the protective or plastic wrapper
____ is a n acid or a base that is added to the absorbent to signifity absorbent exhaustion
indicator dye
what is indicator dye?
ethyl violet
true/false: absorbent can regenerate even after color change is present?
false- there is no true regeneration
occurs ina loosely packed cannister or when the cannister design allows the gses to pass along the sides:
channeling or the wall effect
gas takes the path of ___ resistance
least
what are the 3 reactivity converns with CO2
fire risk
compound A
carbon monoxide
compound A concentrations of ____ PPM are achievable in clinical practice
25-50 ppm
when do the levels of Compound A concentrations increase:
increased absorber temp
low flow rates
high Sevo concentrations
long durations
dessication
compound A is lethal at ___ ppm and produces renal injury in rates at ___ ppm
130-340 ppm
25-50
___ is formed when desflurane, enflurane, or isoflurane passes thru dry alkaline rich absorbents
carbon monoxide CO
how does Desiccation occur?
retrograde flow of fresh gas through the absorber
Open:
is there a resevoir bag?
rebreathing?
give example
no
no
open drop or simple mask
Semi- open:
is there a resevoir bag?
rebreathing?
give example
yes
no
nonrebreathing circuit, or circle at high FGF
semi-closed
is there a resevoir bag?
rebreathing?
give example
yes
yes, partial
circle at low FGF
closed:
is there a resevoir bag?
rebreathing?
give example
yes
yes, complete
circle (with APL closed)
100% of a gas is ____ ppm
1% of gas is ____ ppm
1,000,000 ppm
10,000 ppm
what is the standard trace level of gas for halogenated agent with 100% O2?
Standard is less than 2
ppm in an 8 hour time
weighted sample
what is the standard trace level of gas for halogenated agent with N20
Standard is less than 0.5 ppm in an 8 hour time weighted
sample
what is the standard trace level of gas for nitrous oxide?
unscavenged room?
dentist office?
standard: 25 ppm in 8 hour weighted sample
7,000 ppm
50ppm in dentist office
if you can smell the agent, what is the PPM approx?
50-100 ppm already
name the 5 components of the scavenging system:
gas collecting assembly
transfer menas
interface
gas disposal tubing
gas disposal assembly
___ is the most complex device in the gas scavenging unit. It serves to prevent pressure increases or decreases in the scavenging system from being transmitted to the circuit or ventilator.
the interface
name the 4 types of interfaces of a scavenger:
active
passive
open
closed
true or false: active =suction
true
true or false= passive = no suction
true
true or false: open systems have to be active
true
The open reservoir scavenger system relies on open relief ports for ____ & ______
positive and negative pressure relief
