Anesthesia Circuits Flashcards
1
Q
dead space
A
any portion of the airway that doesn’t participate in gas exchange
2
Q
breathing normally do we rebreathe CO2?
A
yes b/c of dead space
3
Q
if you increase someones dead space do you increase or decrease the amount of CO2 rebreathed?
A
increase
4
Q
what is the amount of anatomic deadspace in patients in upright position?
A
2mL/kg
~ 1/3 of patients Vt
5
Q
Physiologic dead space
A
alveolar spaces that receive air but no blood flow
6
Q
What patients have more physiologic dead space?
A
smokers, elderly
7
Q
What is special about the physiology of smokers (airway)?
A
1- alveolar sacs fuse into blebs
2- excess mucus in bronchioles
3- pulmonary capillaries destroyed
8
Q
Mechanical dead space
A
circuit tubing
humidifiers
ETT
etc
9
Q
normal extrathoracic anatomic deadspace adults
A
70-75mL
10
Q
ETT dead space
A
12.6mL
~60mL less than a non intubated pt
11
Q
LMA dead space
A
90mL of dead space
12
Q
Face mask dead space
A
162mL
13
Q
Y piece dead space
A
8mL (peds= 4mL)
14
Q
Is dead space fixed?
A
yes
15
Q
pulmonary shunt
A
some blood vessels bypass alveoli and doesn’t pick up alveoli
16
Q
What is the normal healthy person % of shunting?
A
up to 3%
17
Q
Could we increase pulmonary shunting?
A
yes by ventilating only one
18
Q
Capital V
A
normal ventilation
19
Q
Lowercase v
A
less ventilation
20
Q
Capital Q
A
normal alveolar perfusion
21
Q
Lowercase q
A
less alveolar perfusion
22
Q
ventilation
A
alveolar capillary gas exchange
23
Q
perfusion
A
delivery of blood and oxygen to the organs of the body
24
Q
V/Q mismatch
A
decreased alveolar capillary exchange and some degree of hypoxia
25
V/q
dead space
| ventilation without perfusion
26
v/Q
pulmonary shunt
| perfusion without ventilation
27
lateral decubitus position
upper lung= more ventilation
| lower lung= more perfusion
28
3 types of circuits used in anesthesia
1. open circuit
2. partial rebreathing circuit
3. "non-rebreathing" circuit
29
3 examples of open circuit
nasal cannula
insufflation "blow by"
open drop anesthesia
30
example of partial rebreathing circuits
semi-open mapleson
semi closed machine
simple face mask
self inflating ambu bag
31
example non rebreathing circuit
t piece
| non rebreather
32
what is the caution of using an open circuit in facial/head/eye surgery?
if using cautery then chance for fire
33
equation to estimate FiO2 with a nasal cannula
21% + 4% per 1L/min flow
34
what is the max FiO2 with nasal cannula?
44% with 6L/min
35
what is the top flow rate you want to use to make the patient comfortable?
4L/min
36
insufflation blow by
people who do not want mask around face or children
37
EGD
esophagogastroduodenoscopy
38
oxygen options for EGD
NC and blow by
| special mask with hole for the scopes
39
how to manage a MAC case with a bovie and facial drapes
turn on air and place it under the drape
40
insufflation via bronchoscope
oxygen source hooked up and insufflated for brief apnea
41
what is the advantage for rebreathing circuits?
conserves heat and humidity
42
disadvantages to rebreathing
slower wake up
| CO2 retention and hypercarbia
43
how to prevent rebreathing in partial rebreathing circuit
turn up FGF rate
| adjust APL valve if has one
44
two common mistakes with oxygen
forgetting to turn on when transport or when preoxygenating
45
sedation outside OR
IV only medication
spontaneous breathing and oxygen
ambu bag on deck
46
limitation to NC and Facemask
not able to provide positive pressure ventilation
47
2 options for general outside the OR
1. bring machine
| 2. use mapleson circuit
48
if the room had oxygen wall supply but no wall scavenging then could you supply volatile agent?
no, TIVA only
49
mapleson A
best for spontaneous
| worst for control ventilation
50
mapleson d
best for cv
| worst for sv
51
mapleson E
ayre's T piece
52
mapleson F
jackson rees modification
53
advantage to mapleson circuit
ability to hook to ETT
| provide positive pressure ventilation
54
disadvantage of mapleson circuit
1. 1 tube for inhale exhale so increase deadspace
2. no CO2 absorber
3. no inspir. and expir. valves
55
how to minimize rebreathing in mapleson circuit
higher FGF (greater than minute ventilation)
2. open APL
2. shorten circuit volume
56
which maplesons are commonly used?
D,E,F
57
bain circuit
```
modification of mapleson D
co-axial design
inspired gas (inner)
expired gas (outer)
```
58
ayre's t piece
mapleson E
spontaneous only
close to 0 added rebreathing
59
advantage of t piece
no rebreathing
60
disadvantage of t piece
no positive pressure ventilation
61
when do we clinically use t piece?
when the pt is SV but not responding to commands to transport to PACU
62
jackson rees' modification
mapleson F
t piece that allows PPV
popular in peds transport
63
what are the components of the semi closed circuit
```
circuit tubing
elbow adapter
inspir. and expir. unidirectional valves
co2 absorber
breathing bag
humidifier
```
64
proximal to y piece
separate inspir and expir tubes
65
distal to y piece
inspir and expir share tubing
66
2 options for circuit tubing
inhalation and exhalation tubing
| coaxial circuit
67
advantage of coaxial circuit
conserves heat and humidity
68
disadvantage of coaxial circuit
disconnection or breaking/kinking of inner tube lead to rebreathing/hypercarbia/hypoxia
69
elbow adapter
attaches y piece to ett
70
when is the inspiration valve open?
during inspiration
71
when is the expiratory valve open?
during expiration
72
what does the CO2 absorber convert CO2 into?
water and heat
73
what color is an old(non usable) CO2 absorber?
purple
| change when 50-70% changed color
74
what are the CO2 absorber granules made of?
soda lime
| silica added
75
large grannules
lower resistance
| less absorptive capacity
76
small grannules
increases resistance
| better absorptive capacity
77
what are the two things that dried out CO2 grannules will do?
degrade volatile agents to carbon monoxide (Des is most)
| accelerate sevo into compound A
78
is the CO2 absorber a double or single canister?
double canister to decrease circuit resistance
79
when is the CO2 absorber unnecessary?
when FGF > 5L/min
80
which is more compliant lungs or breathing bag?
breathing bag
81
what is the humidity in the OR?
30-60%
82
humidifier
humidifies gases
filter to trap bacteria
adds 10mL-60mL deadspace
83
what is the lower weight limit for humidifiers?
2.5kg
84
what is the lower weight limit for filters?
3kg
85
what are the locations for the humidifier?
distal to elbow piece
| expiratory limb
86
simple face mask FiO2 at 5L/min
40%
87
simple face mask fiO2 at 10L/min
60%
88
venturi/venti mask
range 24-60% fiO2
| choose color for specific one
89
nonrebreathing mask at 10L/min and 15L/min
80% fiO2
| 90%
90
what are the two main reasons for supplemental oxygen?
compensate for:
hypoventilation
atelectasis
91
When are the supplemental devices usually used?
sedation
transport
pacu
92
two clinical uses of ambu bag?
emergency to ventilate
| transport patient that is not going to be extubated
93
what are the four steps to take when transporting with ambu bag?
call resp therapy to get ventilator in pacu
ventilate during transport
place patient on ventilator
administer a propofol drip if paralyzed
94
airway resistance
you can decrease resistance by a larger diameter and shorter length equipment
