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PMI > Anesthesia Circuits > Flashcards

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

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2
Q

What is absent in dead space?

A

alveolar blood flow

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3
Q

3 structures included in dead space

A

trachea, bronchi, pharynx

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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)

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5
Q

refers to alveolar spaces that receive air but no blood flow

A

physiologic dead space

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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

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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

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8
Q

what is included in mechanical dead space

A

airway equipment, circuit tubing, humidifiers, endotracheal tubes

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9
Q

Normal EXTRATHORACIC anatomic dead space in adults (nose and pharynx only)

A

70-75 mL

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10
Q

An 8.0 ETT tube has a dead space volume of ?

A

12.6 mL

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11
Q

total dead space in an intubated adult?

A

up to 60 mL

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12
Q

dead space with LMA

A

90 mL

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13
Q

True/ False: LMAs have larger dead space but less resistance than ETTs.

A

TRUE

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14
Q

adult Y piece dead space

A

8 mL

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15
Q

pediatric Y piece dead space

A

4 mL

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16
Q

humidifier dead space

A

10-60 mL

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17
Q

True/ False: dead space volume is FIXED.

A

TRUE

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18
Q

when pt takes a larger breath, ____ percentage of that breath will be dead space

A

lower

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19
Q

when pt takes a smaller breath, a ___ percentage of that breath will be dead space.

A

higher

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20
Q

what kinds of patients are most affected by mechanical dead space?

A

pediatric patients

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21
Q

what kind of patient’s have the most dead space? (mask ventilated, ventilated w/LMAs, ventilated w/ ETT)

A

mask ventilated pts

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22
Q

normal TOTAL anatomic dead space of a 70 kg adult

A

140 ml (2 ml/kg)

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23
Q

when SOME of the blood in our body bypasses the alveoli and doesn’t pick up oxygen

A

pulmonary shunt

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24
Q

what percentage of blood or cardiac output passes the alveoli and doesn’t participate in gas exchange?

A

3%

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25
Q

portions of the airway that don’t participate in gas exchange due to shunting are said to be ____ but not ____

A

perfused but not ventilated

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26
Q

what does Q stand for in the V/Q ratio?

A

alveolar blood flow; alveolar perfusion

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27
Q

most common cause of hypoxemia in the recovery room

A

V/Q mismatch

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28
Q

v/Q mismatch is most likely due to

A

atelectasis

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29
Q

meaning of V/q; does it represent dead space or pulmonary shunt?

A

ventilation without perfusion (there is reduced or absent alveolar blood flow) ; dead space

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30
Q

meaning of v/Q; does it represent airway dead space or a pulmonary shunt?

A

perfusion without ventilation ; normal alveolar blood flow but less or absent ventilation (air flow); pulmonary shunt

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31
Q

collapsed lung/pneumothorax is an example of dead space or pulmonary shunt?

A

pulmonary shunt

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32
Q

pulmonary embolism is an example of dead space or pulmonary shunt?

A

dead space

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33
Q

pulmonary edema is an example of dead space or pulmonary shunt?

A

pulmonary shunt

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34
Q

atelectasis is an example of dead space or pulmonary shunt?

A

pulmonary shunt

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35
Q

pt experiences an increase in pulmonary vascular resistance this will lead to an increase in dead space or pulmonary shunt?

A

increase in DEAD SPACE

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36
Q

right mainstem intubation will lead to increase in dead space or pulmonary shunt?

A

pulmonary shunt

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37
Q

in the lateral decubitus position, does the upper lung have dead space or shunt?

A

dead space

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38
Q

in the lateral decubitus position, does the lower lung have dead space or shunt?

A

shunt

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39
Q

emphysema is an example of dead space or pulmonary shunt?

A

BOTH

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40
Q

spontaneous ventilation under GA is an example of dead space or pulmonary shunt?

A

pulmonary shunt

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41
Q

pt receives a bolus of nitroglycerin which dilates pulmonary vasculature and increases pulmonary blood flow will this cause more dead space or pulmonary shunt?

A

pulmonary shunting

42
Q

pt has a profound drop in cardiac output from internal hemorrhage will this cause more dead space or pulmonary shunting?

A

dead space

43
Q

types of circuits used in anesthesia (3)

A
  1. open circuit 2. partial re-breathing circuit 3. non rebreathing circuit
44
Q

types of OPEN circuits (3)

A
  1. nasal cannula 2. insufflation “blow by” 3. open drop anesthesia
45
Q

types of rebreathing circuits (3)

A
  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
Q

types of nonrebreathing circuits (2)

A
  1. T piece 2. a nonrebreather mask
47
Q

type of circuit used for oxygen delivery

A

open circuits

48
Q

what should you be cautious about with open circuits?

A

higher risk for surgical FIRES with open circuits especially if the surgery is around the face!!!

49
Q

most common flow rate used in pts w/ nasal cannula

A

4 L/min

50
Q

what should be communicated to the pt in facial surgery where facial drapes and cautery will be used?

A

b/c they will not be able to use O2 that they won’t be able to give as much sedation

51
Q

if pt is NOT ok with minimal sedation.. .what can be done?

A

intubation or have an LMA placed

52
Q

what should you do for anxious pts?

A

insufflate (O2 blow by) near the face until the pt is sedated

53
Q

what procedures might require insufflation when an O2 mask can’t be placed?

A

EGD or TEE ; pt can wear NC but not mask

54
Q

without oxygen under the drapes how do we prevent accumulation of CO2 under the drapes?

A

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
Q

what is used during bronchoscopy

A

insufflation via a bronchoscope

56
Q

refers to provider soaking gauze in volatile anesthetic and placing it over the patient’s face

A

open drop anesthesia

57
Q

kind of circuit in our anesthesia machine; also referred as circle system breathing circuits

A

semi closed partial rebreathing circuit

58
Q

primarily used outside the OR and are used to deliver oxygen (not anesthetic gases)

A

semi open/mapleson partial rebreathing circuit

59
Q

what do semi open mapleson partial rebreathing circuits NOT have? (2)

A
  1. inspiratory and expiratory unidirectional valves 2. a CO2 absorber
60
Q

True/False: some exhaled gas is rebreathed whether it be in a full on circuit or in an oxygen mask

A

TRUE

61
Q

advantage of rebreathing ?

A

conserved heat and humidity

62
Q

disadvantage of rebreathing?

A
  1. slower wake up on emergence 2. there is a potential for CO2 retention and hypercarbia
63
Q

How to adjust rebreathing is partial rebreathing circuits?

A
  1. APL valve 2. fresh gas flow
64
Q

True/False: the higher the fresh gas flow, the less rebreathing

A

TRUE

65
Q

two common method of supplemental oxygen delivery during transport or during sedation outside the OR

A

nasal cannula and oxygen face mask

66
Q

if you want to provide general anesthesia with an ETT or LMA outside the OR what are the two options?

A
  1. transport machine to the remote location 2. use a mapleson circuit
67
Q

Identify type of mapleson circuit and what its best and worst for

A

Mapleson A; best for SV worst for CV

68
Q

Identify type of mapleson circuit and what its best and worst for

A

Mapleson D; best for CV worst for SV

69
Q

Identify type of mapleson circuit and what its best and worst for

A

Mapleson E; Ayre’s T piece

70
Q

Identify type of mapleson circuit and what its best and worst for

A

Mapleson F; Jackson Rees’ Modification

71
Q

advantages of mapleson circuit for supplemental O2 delivery instead of nasal cannula or oxygen facemask (2)

A
  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
Q

disadvantage of mapleson circuit

A

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
Q

how do you minimize rebreathing in Mapleson circuits? (3)

A
  1. using a higher fresh gas flow
  2. opening the APL valve
  3. shortening the circuit volume
74
Q

which mapleson circuits are commonly used today?

A

D,E, and F

75
Q

the bain circuit is what kind of mapleson circuit and where is fresh gas flow ?

A

D; fresh gas flow INSIDE the breathing limb

76
Q

a T piece adds how much rebreathing?

A

minimal or 0% rebreathing of CO2

77
Q

disadvantage of T piece

A

positive pressure ventilation is not possible; it can only be used in pts who are spontaneously ventilating

78
Q

most common use for T piece

A

for pt breathing on own but not yet ready to be extubated ; have good tidal volume but not responding to verbal commands

79
Q

t piece that can allow postive pressure ventilation because it has a breathing bag

A

mapleson F

80
Q

Components of semi closed circuit (6)

A
  1. circuit tubing
  2. elbow adapter
  3. inspiratory and expiratory unidirectional valves
  4. CO2 absorber
  5. breathing bag
  6. humidifier
81
Q

anesthesia circuit tubing options

A
  1. circuit with inhalation and exhalation tubing
  2. coaxial circuit
82
Q

what’s important before the Y piece (proximal to the Y piece) ?

A

separate tubes for inspiration and expiration in this portion of the circuit

83
Q

what’s important after the Y piece (distal to the Y piece) ?

A

expiratory and inspiratory gases share the same tube (expiratory CO2 mixed with the inspired gas) in this portion of the circuit

84
Q

used to connect the anesthesia circuit with pt’s airway device

A

elbow adapter

85
Q

inspiratory valve is ___ during inhalation and ____ during expiration ; function?

A

open; closed; prevents exhaled gases from going into the inspiratory limb

86
Q

the expiratory valve is ____ during inspiration and ____ during expiration. function?

A

closed; open; prevents the pt from inhaling gases from the expiratory limb

87
Q

eliminates rebreathing of CO2 from the circuit (proximal to the Y piece) even with low fresh gas flows

A

unidirectional valves

88
Q

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) ?

A

YES; increases the amount of CO2 that pt rebreathes they are considered DEAD space

89
Q

where is air humidified in non-anesthetized pts?

A

upper airway

90
Q

intubated pts have dry gases that absorb moisture /heat from the upper airway causing what? (2)

A
  1. a decrease in body temp
  2. dehydration of the airway , mucus plugging, and atelectasis
91
Q

a relative humidity (%) inhibits bacterial growth and decreases the potential for static electricity?

A

50-60%

92
Q

what is the recommended humidity range for the OR

A

30 to 60%

93
Q

Functions of humidifier on anesthesia circuits (3)

A
  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
Q

Possible locations for humidifier? (2)

A
  1. distal to the Y piece/ elbow (best humidification here)
  2. on the expiratory limb of the circuit (less effective humidification)
95
Q

When do you give supplemental O2? (3)

A
  1. during transport
  2. in the recovery/PACU
  3. sedation/MAC anesthesia cases
96
Q

FiO2 with simple face mask at 5L/min

A

40%

97
Q

FiO2 on simple face mask at 10L/min

A

60%

98
Q

maximum FiO2 with Venturi mask

A

up to 60%

99
Q

main purpose of supplemental oxygen is to compensate for what? (2)

A
  1. anesthetic induced hypoventilation
  2. atelectasis
100
Q

what does the Hagen Poiseuille equation tell us? (2)

A
  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
Q

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?

A

360 mL

(12 x 30)

PMI (21 decks)

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