Anesthesia Circuits Flashcards
1
Q
any portion of the airway that does not participate in gas exchange (pharynx, trachea, bronchi) or any portion of the airway that causes us to rebreathe CO2
A
dead space
2
Q
What is absent in dead space?
A
alveolar blood flow
3
Q
3 structures included in dead space
A
trachea, bronchi, pharynx
4
Q
anatomic dead space is approximately how many mL/kg in the upright position
A
2 mL/kg (also 1/3 of patient’s tidal volume)
5
Q
refers to alveolar spaces that receive air but no blood flow
A
physiologic dead space
6
Q
how does physiologic dead space occur?
A
when pulmonary capillaries are destroyed (smokers, elderly pts, etc); damaged alveolar spaces become more and more like the trachea
7
Q
3 aspects of physiology of smokers
A
1.) alveolar sacs fuse into blebs (bullae) 2. excess mucus forms in the bronchioles 3. pulmonary capillaries get destroyed
8
Q
what is included in mechanical dead space
A
airway equipment, circuit tubing, humidifiers, endotracheal tubes
9
Q
Normal EXTRATHORACIC anatomic dead space in adults (nose and pharynx only)
A
70-75 mL
10
Q
An 8.0 ETT tube has a dead space volume of ?
A
12.6 mL
11
Q
total dead space in an intubated adult?
A
up to 60 mL
12
Q
dead space with LMA
A
90 mL
13
Q
True/ False: LMAs have larger dead space but less resistance than ETTs.
A
TRUE
14
Q
adult Y piece dead space
A
8 mL
15
Q
pediatric Y piece dead space
A
4 mL
16
Q
humidifier dead space
A
10-60 mL
17
Q
True/ False: dead space volume is FIXED.
A
TRUE
18
Q
when pt takes a larger breath, ____ percentage of that breath will be dead space
A
lower
19
Q
when pt takes a smaller breath, a ___ percentage of that breath will be dead space.
A
higher
20
Q
what kinds of patients are most affected by mechanical dead space?
A
pediatric patients
21
Q
what kind of patient’s have the most dead space? (mask ventilated, ventilated w/LMAs, ventilated w/ ETT)
A
mask ventilated pts
22
Q
normal TOTAL anatomic dead space of a 70 kg adult
A
140 ml (2 ml/kg)
23
Q
when SOME of the blood in our body bypasses the alveoli and doesn’t pick up oxygen
A
pulmonary shunt
24
Q
what percentage of blood or cardiac output passes the alveoli and doesn’t participate in gas exchange?
A
3%
25
portions of the airway that don't participate in gas exchange due to shunting are said to be ____ but not \_\_\_\_
perfused but not ventilated
26
what does Q stand for in the V/Q ratio?
alveolar blood flow; alveolar perfusion
27
most common cause of hypoxemia in the recovery room
V/Q mismatch
28
v/Q mismatch is most likely due to
atelectasis
29
meaning of V/q; does it represent dead space or pulmonary shunt?
ventilation without perfusion (there is reduced or absent alveolar blood flow) ; dead space
30
meaning of v/Q; does it represent airway dead space or a pulmonary shunt?
perfusion without ventilation ; normal alveolar blood flow but less or absent ventilation (air flow); pulmonary shunt
31
collapsed lung/pneumothorax is an example of dead space or pulmonary shunt?
pulmonary shunt
32
pulmonary embolism is an example of dead space or pulmonary shunt?
dead space
33
pulmonary edema is an example of dead space or pulmonary shunt?
pulmonary shunt
34
atelectasis is an example of dead space or pulmonary shunt?
pulmonary shunt
35
pt experiences an increase in pulmonary vascular resistance this will lead to an increase in dead space or pulmonary shunt?
increase in DEAD SPACE
36
right mainstem intubation will lead to increase in dead space or pulmonary shunt?
pulmonary shunt
37
in the lateral decubitus position, does the upper lung have dead space or shunt?
dead space
38
in the lateral decubitus position, does the lower lung have dead space or shunt?
shunt
39
emphysema is an example of dead space or pulmonary shunt?
BOTH
40
spontaneous ventilation under GA is an example of dead space or pulmonary shunt?
pulmonary shunt
41
pt receives a bolus of nitroglycerin which dilates pulmonary vasculature and increases pulmonary blood flow will this cause more dead space or pulmonary shunt?
pulmonary shunting
42
pt has a profound drop in cardiac output from internal hemorrhage will this cause more dead space or pulmonary shunting?
dead space
43
types of circuits used in anesthesia (3)
1. open circuit 2. partial re-breathing circuit 3. non rebreathing circuit
44
types of OPEN circuits (3)
1. nasal cannula 2. insufflation "blow by" 3. open drop anesthesia
45
types of rebreathing circuits (3)
1. semi-closed partial rebreathing circuits (anesthesia machine circuits)
2. semi open (Mapleson circuits) partial rebreathing circuit
3. partial rebreathing oxygen masks (simple face mask, nonrebreather mask, Venturi mask, self inflating Ambu bag)
46
types of nonrebreathing circuits (2)
1. T piece 2. a nonrebreather mask
47
type of circuit used for oxygen delivery
open circuits
48
what should you be cautious about with open circuits?
higher risk for surgical FIRES with open circuits especially if the surgery is around the face!!!
49
most common flow rate used in pts w/ nasal cannula
4 L/min
50
what should be communicated to the pt in facial surgery where facial drapes and cautery will be used?
b/c they will not be able to use O2 that they won't be able to give as much sedation
51
if pt is NOT ok with minimal sedation.. .what can be done?
intubation or have an LMA placed
52
what should you do for anxious pts?
insufflate (O2 blow by) near the face until the pt is sedated
53
what procedures might require insufflation when an O2 mask can't be placed?
EGD or TEE ; pt can wear NC but not mask
54
without oxygen under the drapes how do we prevent accumulation of CO2 under the drapes?
place breathing circuit under the drape, turn on AIR up to 15 L/min, insufflate the air around the patient's face and create a path under the drape for the air (and Co2) to escape
55
what is used during bronchoscopy
insufflation via a bronchoscope
56
refers to provider soaking gauze in volatile anesthetic and placing it over the patient's face
open drop anesthesia
57
kind of circuit in our anesthesia machine; also referred as circle system breathing circuits
semi closed partial rebreathing circuit
58
primarily used outside the OR and are used to deliver oxygen (not anesthetic gases)
semi open/mapleson partial rebreathing circuit
59
what do semi open mapleson partial rebreathing circuits NOT have? (2)
1. inspiratory and expiratory unidirectional valves 2. a CO2 absorber
60
True/False: some exhaled gas is rebreathed whether it be in a full on circuit or in an oxygen mask
TRUE
61
advantage of rebreathing ?
conserved heat and humidity
62
disadvantage of rebreathing?
1. slower wake up on emergence 2. there is a potential for CO2 retention and hypercarbia
63
How to adjust rebreathing is partial rebreathing circuits?
1. APL valve 2. fresh gas flow
64
True/False: the higher the fresh gas flow, the less rebreathing
TRUE
65
two common method of supplemental oxygen delivery during transport or during sedation outside the OR
nasal cannula and oxygen face mask
66
if you want to provide general anesthesia with an ETT or LMA outside the OR what are the two options?
1. transport machine to the remote location 2. use a mapleson circuit
67
Identify type of mapleson circuit and what its best and worst for
Mapleson A; best for SV worst for CV
68
Identify type of mapleson circuit and what its best and worst for
Mapleson D; best for CV worst for SV
69
Identify type of mapleson circuit and what its best and worst for
Mapleson E; Ayre's T piece
70
Identify type of mapleson circuit and what its best and worst for
Mapleson F; Jackson Rees' Modification
71
advantages of mapleson circuit for supplemental O2 delivery instead of nasal cannula or oxygen facemask (2)
1. ability to be hooked up to ETT or LMA which can allow general anesthesia (with TIVA) in these locations outside the OR without an anesthesia machine
2. deliver positive pressure ventilation
72
disadvantage of mapleson circuit
lot more dead space and there is much greater potential to rebreathe CO2 b/c:
1. only one tube for inhalation and exhalation CO2 does into inspiratory tubing
2. there is no CO2 absorber
3. there are no inspiratory and expiratory valves
73
how do you minimize rebreathing in Mapleson circuits? (3)
1. using a higher fresh gas flow
2. opening the APL valve
3. shortening the circuit volume
74
which mapleson circuits are commonly used today?
D,E, and F
75
the bain circuit is what kind of mapleson circuit and where is fresh gas flow ?
D; fresh gas flow INSIDE the breathing limb
76
a T piece adds how much rebreathing?
minimal or 0% rebreathing of CO2
77
disadvantage of T piece
positive pressure ventilation is not possible; it can only be used in pts who are spontaneously ventilating
78
most common use for T piece
for pt breathing on own but not yet ready to be extubated ; have good tidal volume but not responding to verbal commands
79
t piece that can allow postive pressure ventilation because it has a breathing bag
mapleson F
80
Components of semi closed circuit (6)
1. circuit tubing
2. elbow adapter
3. inspiratory and expiratory unidirectional valves
4. CO2 absorber
5. breathing bag
6. humidifier
81
anesthesia circuit tubing options
1. circuit with inhalation and exhalation tubing
2. coaxial circuit
82
what's important before the Y piece (proximal to the Y piece) ?
separate tubes for inspiration and expiration in this portion of the circuit
83
what's important after the Y piece (distal to the Y piece) ?
expiratory and inspiratory gases share the same tube (expiratory CO2 mixed with the inspired gas) in this portion of the circuit
84
used to connect the anesthesia circuit with pt's airway device
elbow adapter
85
inspiratory valve is ___ during inhalation and ____ during expiration ; function?
open; closed; prevents exhaled gases from going into the inspiratory limb
86
the expiratory valve is ____ during inspiration and ____ during expiration. function?
closed; open; prevents the pt from inhaling gases from the expiratory limb
87
eliminates rebreathing of CO2 from the circuit (proximal to the Y piece) even with low fresh gas flows
unidirectional valves
88
does the dead space of a circuit increase if an anesthetist increases the length of the circuit DISTAL to the Y piece (like w/ elbow adapter, humidifier, ETT etc) ?
YES; increases the amount of CO2 that pt rebreathes they are considered DEAD space
89
where is air humidified in non-anesthetized pts?
upper airway
90
intubated pts have dry gases that absorb moisture /heat from the upper airway causing what? (2)
1. a decrease in body temp
2. dehydration of the airway , mucus plugging, and atelectasis
91
a relative humidity (%) inhibits bacterial growth and decreases the potential for static electricity?
50-60%
92
what is the recommended humidity range for the OR
30 to 60%
93
Functions of humidifier on anesthesia circuits (3)
1. humidifies dry operating room gases
2. a filter is also added to it in order to trap bacteria and virsues
3. can add 10-60 mL dead space to circuit
94
Possible locations for humidifier? (2)
1. distal to the Y piece/ elbow (best humidification here)
2. on the expiratory limb of the circuit (less effective humidification)
95
When do you give supplemental O2? (3)
1. during transport
2. in the recovery/PACU
3. sedation/MAC anesthesia cases
96
FiO2 with simple face mask at 5L/min
40%
97
FiO2 on simple face mask at 10L/min
60%
98
maximum FiO2 with Venturi mask
up to 60%
99
main purpose of supplemental oxygen is to compensate for what? (2)
1. anesthetic induced hypoventilation
2. atelectasis
100
what does the Hagen Poiseuille equation tell us? (2)
1. ) adding dead space (length) to a circuit increases airway resistance
2. ) resistance can be minimized if diameter of equipment is bigger and length of equipment is shorter
101
The compliance of pt's breathing circuit is 12 mL/cmH20. An anesthetist is providing positive pressure ventilation to their pt on the ventilator. Vent settings are:
PIP- 30 cmH20
Respiratory rate =6
minute ventilation= 7.2 L
what is the compliance loss (in mL) in the breating circuit?
360 mL
| (12 x 30)
