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1
Q

all anesthesia breathing systems have 2 purposes. what are they?

A

delivery of O2/anesthestic gases

eliminatin of CO2

2
Q

ALL breathing circuits create some degree of _______ to flow

A

resistance

3
Q

Resistance to flow can be minimized by what 5 things

A

reducing the circuit’s length

increasing the diameter

avoiding the use of sharp bends (turbulent flow)

eliminating unnecessary valves

Maintaining laminar flow

4
Q

who law describes that increasing the diameter can reduce resistance?

A

poiseuille

5
Q

resistance is ___________ proportional to flow rate with laminar flow?

A

indirectly

resistance increases and flow decreases

6
Q

for turbulent flow what is more important in relation to resistance and flow. density or viscosity?

A

density

(my rational the more dense = more turbulent)

7
Q

resistance is proportional to __________ of flow rate (turbulent flow)

A

square

8
Q

what type of flow is orderly movement of gas inside a “hose”

A

laminar flow

9
Q

with laminar flow where does the gas move the fastest at?

A
10
Q

what type of flow is seen with sudden narrowing or with branching of a tube?

A

turbulent flow

11
Q

what is increased with turbulent flow??

A

resistance

12
Q

Lmainar flow becomes turbulent when reynolds number is what

A

> 2000

13
Q

Poiseuille’s Law follows what type of flow?

A

Laminar

14
Q

formula for resistance

A

R= 8 n l / r4

R= resistance

n= viscsity

l=length

r=radius

15
Q

an ex of resistance is: when you double the radius of the tube, it will decrease the resistance by how much

A

16 times

22= 16

16
Q

Traditional attempts to classify breathing circuits combine ______ aspects with _______ characteristics

A

functional aspects (eg, extent of rebreathing)

Physical characteristics (eg, presence of valves)

17
Q

Classifications of breathing systems are based on the presence or absence of what 4 things

A
  1. A gas reservoir bag
  2. rebreathing of exhaled gases
  3. Means to chemically neutralize CO2
  4. Unidirectional valves
18
Q

what does the gas reservoir bag do?

A

provides gas for the moment during inspiratin where flow in the trachea is greater than fresh gas flow (FGF)

19
Q

4 diferent classifications of breathing systems

A
  1. OPen
  2. Semiopen
  3. semiclosed
  4. Closed
20
Q

what is the fuctions (2) of any breathing circuit?

A

deliver O2 and gases

Eliminate CO2

21
Q

what are the 2 ways that the breathing circuit can eliminate CO2

A

washout with adequate FGF

or

by soda lime absorption

22
Q

for the following tyes of breathing circuits, tell if they have a reservoir, if they allow rebreathing and give and example of each

Open

semiopen

Semiclosed

Closed

A

type Reservoir Rebreathing EX

_Open _ NO No Open gtt, insufflation, NC

Semiopen Yes No Non rebreathing circuit; circle @ high gas flow

Semiclosed Yes Yes (partial) Circle @ fresh gas flow less than MV

_Closed _ Yes Yes (complete) Circle @ extremly low FGF, with APL valve closed

23
Q

an open gtt, insufflation, and nasal cannula are ex of wha type of breathing circuit?

A

Open

24
Q

with the open breathing curcuits is there a reservoir? what abot rebreathing?

A

nope

and

nope

25
Q

a non rebreathing circuit and a circle at high FGF is an ex of what type of breathing curcuit?

A

semiopen

26
Q

with the semiopen curcuits is there a reservoir? what about rebreathing?

A

yes

and

no

27
Q

A circle system at FGF less than MV is an example of what type of breathing circuit?

A

semiclosed

28
Q

Does the semi closed circuits have a reservoir? what about rebreathing?

A

yes

and

yes (partial)

29
Q

what type of breathing circuit is a circle at extremly low FGF, with APL valve closed?

A

Closed

30
Q

with a closed breathing circuit is there a reservoir? what about rebreathing?

A

yes

and

yes (complete)

31
Q

breathing systems classifications Open

reservior?

rebreathing?

neutralization of CO2?

Unidirectional Valves?

and give 2 ex?

A

reservior? NO

rebreathing? NO

neutralization of CO2? NO

Unidirectional Valves? NO

Ex

Nasal cannula

Open gtt ether

32
Q

a way to remember open breathing circuits?

A

Think of it as anything where there is NO REBREATHING and NO SCAVENGING

33
Q

Breathing system classification

Semiopen

reservior?

rebreathing?

neutralization of CO2?

Unidirectional Valves?

what is important about FGF?

three examples?

A

reservior? YES

rebreathing? NO

neutralization of CO2? NO

Unidirectional Valves? NO

what is important about FGF? the FGF needs to EXCEED MV (2-3 times MN to prevent rebreathing) MINIMUM FGF 5Lpm

Examples

  1. Mapleson A,B,C,D
  2. Bain
  3. Jackson-Rees
34
Q

Breathing system classifications

Semiclosed

A type of what system?

reservior?

rebreathing?

neutralization of CO2?

Unidirectional Valves (if so how many and what are they)?

what is important about FGF?

Example?

A

A type of what system?“CIRCLE SYSTEM”

reservior? YES (ALWAYS)

rebreathing? PARTIAL (EXHALED GASES)

neutralization of CO2? YES (ALWAYS)

Unidirectional Valves (if so how many and what are they)? YES; 3, (INSPIRATORY, EXPIRATORY, APL)

what is important about FGF? FGF IS LESS THAN MV

Example?

  1. THE MACHINE WE USE EVERYDAY
35
Q

Classification of breathing systems

CLOSED

reservior?

rebreathing?

neutralization of CO2?

Unidirectional Valves ?

Example/ SIDE NOTE?

A

reservior? YES (ALWAYS)

rebreathing? YES (TOTAL)

neutralization of CO2? YES (ALWAYS)

Unidirectional Valves ? YES (ALWAYS)

Example/SIDE NOTE?

WE DON’T USE THESE…. SUFFICE TO SAY YOU CAN DO THIS WITH THE MACHINES WE HAVE IF YOU KEEP THE FGF TO METABOLIC REQUIREMENT AROUNG 150ML/MIN (supply of O2, N2O, and VAA just matches pt’s requirement) IF PT SPONTANEOUSLY VENTILATING, APL VALVCE SHOULD BE CLOSED (no scavenging since no waste ⇒ total rebreathing)

36
Q

All the retarded info you’ll need about nonrebreathing circuits!!!

(Just look at I don’t think it’s important and its alot of shit)

A

Mapleson classification-1954

  • Mapleson D sill commonly used
    • the modified Mapleson D is also called the bain. Arrangement of components are similar in both. The main difference is that the bain has the fresh gas hose inside the expiratory corrugated limb. unregnized kinking of the inner inspiratory hose will convert the expiratory outer hose into dead space.
  • Mapleson F- better known as Jackson-Rees modificatin of Ayre’sT-piece
  • used almost extensivly in children
    • Very low resistance to breathing
    • The degree of rebreathing is influenced by method of ventilation
    • Adjustable overflow valve
    • Delivery of FGF should be at least 2 x’s Minute volume
37
Q

All non-rebreathing (NRB) circuits lack what 2 things?

A
  1. Unidirectional valves (insp and exp)
  2. soda lime CO2 absorption
38
Q

with the NRB circuit (semiopen)the amount of rebreathing is highly dependent on what?

A

FGF (need high FGF to llow nonrebreathing)

39
Q

with nonrebreathing circuits (simiopen) what makes the work of breathing low?

A

no unidiredctional valves or sodalime granules to create resistance

40
Q

how do non-rebreathing circuits work?

A
  • During EXPIRATION, FGF pushes exhaled gas down the expiratory limb, where it collects in the reservoir (breathing) bag and opens the pop off (APL) valve
  • the next inspiration draws on the gas in the expiratory limb. The exp limb will have less CO2 (less rebreathing0 if FGF is high, TV is low, and the duration of the exp pause is long
  • all NRB circuits are convenient, lightweight, easily scavenged( if using appropriate FGF)
41
Q

Advantages of nonrebreathing circuits (Mapleson)

A

used during transport of children

Minimal dead space, low resistance to breathing

Scavenging

42
Q

Disdvantages of nonrebreathing circuits (Mapleson)

A

Scavenging (variable ability dependent on FGF)

High flows required (cools child, costly)

Lack of humidification (except for Bain)

Possibility of high airway prssures (barotrauma)

Unreconized kink of inner hose in Bain

Pollution and higher cost

Difficult to assemble

43
Q

Pic of Mapleson

to see what you just learned

A
44
Q

with the Mapleson what will determine the performance and classification?

A

the fresh gas inlet (refer to pic again and notice the FGF inlets)

45
Q

how does the APL valve work witht he mapleson?

(a nonrebreathing simiopen system)

how is it positioned during spont ventilation?

how is it positioned for assisted ventilation?

A
  • if gas inflow > pt’s uptake and circuit uptake = preesure buildup and opens APL (gas out via scavenger)
  • fully open
  • partial closure ehile squeezing breathing bag
46
Q

with the mapleson A*** why is it a bad choice for mechanical ventilation? and why is it a good choice for spont_A_***neous ventilation

A
  • mechanical bad- since no gas is vented during expiration, high unpredictable FGF (> 3 times MV) needed to prevent rebreathing
  • SpontAneous good- since a FGF = MV will be enough to prevent rebreathing

notice the A

47
Q

name the types of Mapleson

A
48
Q

which version of the mapleson uses FGF to force alveolar gas away from the pt toward the APL valve?

it is very effecient during contraolled ventilation

A

Mapleson D

efficient controlleD ventilation

49
Q

The mapleson D is also called what

A

Bain system

50
Q

what is the tubing like with the bain (mapleson D) system for FGF and exhaled gas

A

fresh gas enters through a norrow inner tube

exhaled gas exits through a currugated outer tube

51
Q

what are the FGF rates that are required for the Mapleson D (Bain) system?

spontaneous

Controlled ventilation

A

200-300ml/kg/min (2times Ve) spont

70 ml/kg.min controlled

52
Q

with the Bain system in the spontaneous mode what must you remember to do first, before connecting to the pt to it?

A

fill the breathing system with FG

53
Q

with the bain system it has been mathmatically calculated and clinically proven that the FGF shold be a least what times the pt’s MV in order to minimize rebreathing (high flows)

A

1.5 - 2 times

54
Q

Advantages of the Bain ( maplesin D)

A

Warming of FG inflow by surrounding exhales gases

Improved humidification with partial rebreathing

Ease of scavenging waste gases

Overflow/presure valve (APL)

disposable/sterile

55
Q

Disadvantages of the Bain (modified mapleson D system)

A

Unrecognized disconnection

kinking of the inner FGF tubing

Needs high flows

Not easily converted to portable when commercialy used in anesthesia machine

56
Q

what makes the Bain different from the standard mapleson D

A

APL valve addition

57
Q

what ia a way to test the unique hazard of the bain circuit to have an occult disconnection or kinking of the inner hose (FG delivery hose)

A

Pethicks test

58
Q

How do you perform the Pethicks’s test

A
  1. occulde the pt’s end of the cicuit (at the elbow)
  2. close the APL valve
  3. fill the circuit, using the O2 flush valve (like pressurizing the circuit when you are doing a leak test)
  4. Release the occlusion at the elbow and flush. a venturi effect flattens the reservoir bag if the inner tube is patent.
59
Q

what is included in the circular system?

A
  1. FGF
  2. Ins limp
  3. exp limp
  4. unidirectional valves
  5. spill valve
  6. Reservoir bag
  7. CO2 absorber
  8. Bellows (per book)
60
Q

what part of the circular system is placed in close proximity to the pt to prevent backflow into inspiratory limb if circuit leak develops?

A

Unidirectional valves

61
Q

what is placed b/t the absorber and inspiratory valve in the circle system.

A

Fresh gas outlet

Side note - of placed down stream from insp valve it would allow FG to bypass pt during exhalation and be wasted. If FG were placed b/t expiration valve and absorber FG would be diluted by recirculating gas

62
Q

where are the unidirectional valves located in the circle system

A

in clos proximity to the pt

63
Q

where is the fresh gas inlet placed in the circle system

A

b/t the absorber an the insp valve

64
Q

what is placed immediately before the absorber to conserve absorption capacity and to minimize venting of FG

A

APL valve (spill valve)

65
Q

in the circulatory system what is placed in the expiratory limb to decrease the resistance to exhalation.

A

Breathing bag

66
Q

where is the APL (spill) valve located in the circular system?

what does it do?

A

immediatly before the absorber

to conserve absorption capacity and to minimize venting FG

67
Q

where is the breathing bag placed in the circulatory system?

what does it do?

A

in the exp limb

to decrease resistance to exhalation

68
Q

the Breathing bag compression during controlled ventilation will do what

A

vent alveolar gas through APL valve, conserving absorbant.