Ventilator Flashcards
(148 cards)
1
Q
the first ventilators used ____ pressure. They were called _____
A
negative
the iron lung
2
Q
The iron lung was developed to save victims of respiratory failure due to
A
polio
3
Q
in positive pressure ventilation, the only connection between the patient and the machine is the _____
A
endotracheal tube
4
Q
why we call them “agents” and not “gasses?”
A
administered as vapor, not gas
5
Q
Vapor
A
a solution in liquid form dissipates or evaporates and releases molecules into the air around it
6
Q
Vapor pressure
A
pressure exerted by a gas above a liquid in a sealed container
7
Q
Strong intramolecular forces = _____ vapor pressure
A
lower
8
Q
Weak intramolecular forces = ____ vapor pressure
A
higher
9
Q
Water has ___ vapor pressure
A
lower
10
Q
We can smell liquids that have (lower/higher) vapor pressure
A
higher
ie: acetone
11
Q
(low/high) vapor pressure liquids easily give up their molecules to evaporation
A
high
12
Q
Anesthetic agents have (lo/hi) vapor pressure.
A
high
13
Q
Highest vapor pressure amongst anes. agents
A
Desflurane
14
Q
We pressurize the agent ____ to ___ atm and heat it to ____ C
A
Des
2
40C (Barash: 39C)
15
Q
principle of fluid dynamics that pulls the vapor molecules off the canisters and into the circuit
A
Bernoulli’s
16
Q
Venturi Effect
A
The entrainment of fluid (gas or liquid) due to the drop in pressure
17
Q
Bernoulli’s principle states that…
A
An increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid’s potential energy
18
Q
Venturi effect in the machine
A
(a drop in pressure will entrain gas/liquid)
-fresh gas flows over the top of the canister
-creates a - pressure grdnt
-pulls vapor up and out
19
Q
why do we reach MAC faster if you turn your flows up at the beginning of the case?
A
Venturi effect
neg. pressure in vaporizer pulls vapor up and out of canisters
19
Q
MAC of Desflurane
A
6.6%
20
Q
most lipid insoluble of all the agents
A
Desflurane
21
Q
lipid insoluble volatile agents
A
-body trying to push it back out through the lungs
-force it in by high inspired %
(why Desflurane the quickest on and quickest off)
22
Q
quickest on and quickest off volatile agent
A
Des
23
Q
populations is Desflurane good for
A
Quick cases
obese
24
Which patients is Desflurane bad for?
Long cases
reactive airways (asthma, smokers)
tachycardia
25
Desflurane settings
flows max: 1L/min
inspired percentage high: 12%+
will reach MAC in same time as Higher % and flows, minus the SEs
26
Sevoflurane MAC
1.8%
27
Most to least lipid sol
Iso
sevo
Des
28
least pungent of the agents
Sevo
"Sevo smells bessst"
"smell the sevo, it's great!"
Sevo, sweetie
29
agent of choice for inhalational inductions
Sevo
b/c she smell gewd
30
Flow requirements for ____ are 2L/min due to risk of forming _____
Sevo
Compound A
"sevo serving us compound A"
31
populations is Sevoflurane good for?
Reactive airways
case that requires high flows (bronchs)
LMA (not paralyzed = higher risk of bronchospasm)
32
most lipid soluble of the agents
Isoflurane
33
(soluble/insoluble) agents take the longest to go on and to come off
soluble
Higher b:g = slower
Iso (highest b:g) is slowest
(remember, when talking about agents, "in/soluble" means *water/blood* solubility)
34
What happens to insoluble agents in the body?
body sequesters it in the fat and then rereleases it into the plasma
35
MAC of Isoflurane
1.17%
36
What cases is Isoflurane most suited for
remain intubated and ICU admit
lasts longer = anesthesia “for the road”
37
most neuroprotective of the agents
Iso
I so save your brain
38
All agents reduce ___, which is good for the brain, but reduce ___ , which is bad for the brain
cerebral metabolic rate
cerebral blood flow
39
What makes Iso more neuroprotective?
reduces Cereb metab rate more & blood flow less
(all agents:
reduce CMR= good
reduce CBF = bad)
40
When to use Iso
hemorrhagic stroke
head trauma w/ crani for hematoma evac
and other pts that always go direct to ICU on vent
41
basic components of air
21% oxygen
78% nitrogen
and other stuff we dc about rn
42
inspiring 75% oxygen & four 4.5 % Desflurane
where’s the rest?
We're giving air (78% Nitrogen)
remaining % = nitrogen
43
inspired and expired gasses here are measured in
%s
44
Flows are measured in
L/min
45
Six percent of 0.5 liters is the same DOSE as ___ percent of 2 liters
six
same percentage, just takes less amount
46
low-flow anesthesia allows us to use less agent at ____
steady state
47
Which is more expensive?
TIVA
inhaled agents
TIVA
48
Which is worse for the environment?
low flow anesthesia
TIVA
low flow anesthesia
49
primary benefit to low-flow delivery
economic
(earth, you're second I guess lol)
50
primary downside of low flow anesthesia
changing dose takes longer
51
How to best change dose in low-flow anesthesia
temporarily raise your flows
or
inspired % really high or really low
after desired MAC is reached, put settings back how they were
52
etCO2 capnography
normal range
30-40
NOT 35-45; thats PCO2 (PaCO2) on ABGs
53
capnography is measured in
pressure mmHg
54
_____ is about 5 points higher than ____
PaCO2 (listed as PCO2 on ABG)
>
etCO2
55
T/F
The gap in PCO2 (PaCO2) and etCO2 is due to dead space, especially from the vent circuit.
False
gap exits b/c gases use differences in *partial pressures* to diffuse (gas exchange)
etCO2 sensor on circuit so close to mouth that dead space is not a significant contributor
56
T/F
the vent circuit contributes greatly to dead space, which increases the gap between PCO2 and etCO2
False
etCO2 sensor on circuit so close to mouth that dead space is not a significant contributor
57
T/F
PACO2 measures CO2 in the arteries
False
PACO2 = Alveoli
PaCO2 = arteries
("Al" both tall; "ar" both short)
58
PCO2 NR
35-45
(etCO2 30-40)
59
T/F
PCO2 and etCO2 are interchangeable.
FALSE
PCO2 = PaCO2 =arterial CO2
etCO2 = expired CO2
60
Our etCO2 is 32. What would we expect the PCO2 to be?
37
etCO2 is usually 5 points lower than PCO2
61
T/F
PCO2 = PACO2
False
PCO2 a.k.a. PaCO2 = arterial
PACO2 = alveolar
62
respiratory alkalosis in a long case
kidneys compensate: excrete bicarb
in PACU: metabolic acidosis
compensate by hyperventilating
(hard to do with opioids they've been sedated with)
63
T/F
Dead space can increase gap between PaCO2 and etCO2.
True
but
not the reason it exists
64
When speaking on gas diffusion, we describe it in terms of _____
partial pressures!!!
65
The partial pressure gradient is
~5 mmHg
66
T/F
CO2 crosses alv. Mem using active transport.
False
passive transport/diffusion
67
How thick is the alv. memb?
0.3 micrometers
68
Passive transport is also called
diffusion
69
T/F
Gas exchange occurs when there is an equilibrium.
False
without a sloping gradient, molecules don't move
70
Gases move from areas of higher to lower _____
partial pressures
*not concentration* thats for solids dissolved in liquids
71
Fick’s Law of Diffusion
72
directly controls pH
CO2
73
In pH management, what parameter is easiest for us to control?
CO2
74
T/F
CO2 is a base.
False
its an acid
75
Abnormal pHs mostly result in
acidosis
76
T/F
Pts lose more blood at an acidic pH than at normal pH.
True
clotting cascade slows down
77
In acidosis, K moves (into/out of) the cell.
acidosis:
K out
H in
78
How does acidosis lead to hypovolemic shock?
flaccid peripheral vasculature
SVR drops
BP drops
79
How do shock and acidosis work together to make things 100x worse? lol
Acidosis: flaccid vasculature, SVR & BP drop
shock!
Shock: anaerob. respir8n = lactic acid
worsened acidosis
80
Normal etcO2 but pt is still trying to breathe
respiratorily compensate for metabolic acidosis
maybe d/t
early hypovol shock (blood loss/inadequate fluid resuscitation)
81
inspired CO2 should always be
zero
82
inspired CO2 above 0 means...
CO2 absorbent needs to be changed
83
T/F
Using low-flow anesthesia will require more frequent changing of CO2 absorbent
True
slower air is more likely to go thru channels in the crystals & wont absorb as well
84
Channeling
-preferential passage through absorber via pathways of low resistance.
-decreased efficacy
-bypass absorbent granules
85
Total flows should never be less than....
volume of inspiratory limb
86
Volume is measured in
mL
87
Volume waveform measures (inspired/expired) tidal volume.
expired
88
delta VT
difference between VT and VT-INSP
89
delta VT is also known as
your leak
90
T/F
O2 absorbed = CO2 expelled
O2 absorbed > CO2 expelled
91
troubleshooting a leak (delta VT)
check:
cuff pressure
circuit connections (CO2 sampling line)
92
An ETT cuff must be ____ to protect against aspiration.
patent
93
calculation for minute ventilation
RR x Vt = total volume/minute
94
Minute ventilation
definition
95
Minute ventilation is measured in
volume/min
L/min
96
circuit disconnects or vent failures can present early as...
a big leak
97
Circuit disconnect
break in the system that delivers ventilation and drugs to the patient
98
accidental extubation can present as a
Circuit disconnect
99
ETT occlusion will show a _____ alarm
A disconnect will be a ____ alarm
high pressure
leak
100
You are manually ventilating your pt as you had to disconnect them d/t a leak. Help is on the way. During this time you should administer ____.
propofol
(pt is not receiving any IA at this time)
101
new to anesthesia, who dis?
pressure waveform
102
pressure waveform measures ...(3)
3 pressures:
peak, plateau, and PEEP
103
pressure waveform measures in which units?
cm H20
104
2 modes of ventilation
volume and pressure
105
Volume mode
choose volume (mL) & rate
delivers volume regardless of pressure
can set a max pressure
106
normal PEEP (healthy lungs)
0
lungs return to atmospheric pressure on end expiration
107
pressure mode
set a pressure (cm H2O) & rate
delivers pressure regardless of volume
**no max volume setting!**
must monitor the pressure yourself
"pressure mode increases the pressure on the CRNA"
108
Which mode does not allow a max limit for the other parameter?
Volume
pressure
pressure
cannot set max volume
"pressure mode increases the pressure on the CRNA"
109
volume auto flow
type of volume mode
machine calculates pressure needed to deliver the set volume (for each breath)
accounts for pt's compliance
consistent vol w/ minimal peak prsr
110
(volume autoflow mode)
On the pressure waveform, __ & __ are the same.
peak and plateau
111
T/F
the same pressure can deliver variable volumes
True
(ie before and after insufflating belly)
112
if a small amount of pressure results in a large change in volume
high/good compliance
113
lot of pressure to result in just a small expansion of lung volume
low /poor compliance
114
Which is more common?
obstructive
restrictive
obstructive
115
pure obstructive
✅ compliance
❌how fast the gases can move through the airways
116
always worse on expiration
obstructive
117
examples of obstructive problems
Dz: COPD, OSA, asthma
Fxnl: bronchospasm, laryngospasm, obstruction
118
How obstructive issues change breathing?
slower, deeper breaths
reduced RR
reduces air lost to dead space
119
Dead space calc
2cc/kg/breath
or 150 cc/breath for adults
120
When do we see this?
obstructive capnography ("shark fin")
asthma, COPD
**breathing too fast and your VT is too low**
121
T/F
Obstructive patients need PEEP from the ventilator.
False
have pathologically high auto PEEP
don't add more
122
we usually add _____ of PEEP on the vent to prevent atelectasis
2-3
do not add any PEEP to obstructive Dz (ie: COPD)
123
restrictive processes call for (higher/low/no) PEEP
higher
124
Restrictive disease is anything that reduces
compliance
no obstruction to slow gases
125
examples of restrictive disorders
PnA
ARDS
MV w/ pulmonary failure
126
DO NOT hand-ventilate these patients during transport
restrictive Dz
keeps tighter control of their settings
127
Changing vent on pt with high PEEP & restrictive Dz
(PEEP 10-15)
when disconnecting,
inflate & clamp
unclamp when on new vent
prevents fluid buildup in RHF and pulm edema pts
128
Abdominal insufflation
Pregnancy
Trendelenburg position
are examples of...
functionally restrictive
Extrinsic Pulmonary Disease
129
restrictive Dz treatment
✅ air flow --> increase RR
✅ no significant dead space
reduce Vt (don't force volume)
PEEP! (so alveoli dont shut --> atelectasis)
130
do not use auto flow for pts with...
severe restrictive (ARDS, Pna)
use pressure mode for this instead
131
T/F
emphysema is both restrictive and obstructive.
True
what fun lol
132
what's happening?
Patient trying to breathe over the vent
133
What's happening?
obstruction
134
What do you do when this appears?
elevated baseline = change CO2 absorber
135
Whats happening?
136
whats happening?
137
You noticed this waveform, and recognize it as _______. The first step is to _____ and then ____.
esophageal intubation
pull ETT & intubate trachea
decompress stomach w/ OGT
138
You notice this waveform. Your first step is to _____. If that is working normally, you must ____.
check the CO2 sampling line
replace water trap
139
A defective water trap can also give you a false low ____.
etCO2
140
how long do water traps last?
4 weeks
141
We would to increase expiratory time for _____ diseases, but decrease it for ____ diseases.
increase E time = obstructive (COPD)
decrease E time = restrictive (ARDS, PnA)
142
compliance equation
change in lung volume
----------------------------------------
change in pleural pressure
143
We should use ______ mode in pts with restrictive processes
pressure mode (keep their alveoli open; need PEEP)
DO NOT USE volume autoflow
144
Volume autoflow is indicated for ____ processes
obstructive
obstructive: use slower, deeper breaths (volume; NO extra peep)
145
T/F
Volume autoflow is good for normal, healthy lungs.
True
146
Volume autoflow can be seen as...
a gentler version of normal volume mode
147
(restrictive mode)
What to do and what NOT to do
needs: pressure! (PEEP to keep alveoli open)
do not give: volume
