Anesthesia Delivery System

Question 1

How can CO2 be eliminated?

Answer 1

1. washout with high flows of fresh gas

2. CO2 absorber

Question 2

What are essential requirements in a breathing system. regarding

1. gas delivery
2. CO2
3. dead space
4. resistance

Answer 2

1. deliver gases to alveoli in same concentration as set in shortest time
2. eliminate CO2
3. minimal dead space
4. low resistance

Question 3

What is the advantages to rebreathing of exhaled gases? What is a concern of rebreathing?

Answer 3

cheaper, adds humidification to gases but do not want to rebreathe CO2 - high FGF

Question 4

What effect does dead space have on CO2?

Answer 4

dead space increases chance of rebreathing

Question 5

How is gas delivered in an open system? What does this system not have? (3)

Answer 5

pt gets anesthetic gas plus gas in environment

no reservoir bag, no valves, no rebreathing

Question 6

What are the 2 types of open systems? Give examples.

Answer 6

1. insufflation - blow-by, tent, nasal cannula, steal induction
2. open drop - ether mask (schimmelbusch) - historical, wire mask with cloth where anesthetic is dripped onto cloth and patient inhales

Question 7

What are disadvantages of open systems?

Answer 7

no assist in ventilation
CO2/O2 accumulation under drapes
no control of anesthetic depth/FiO2
pollution

Question 8

What is the “Steal” induction and is it a form of insufflation or open drop open system?

Answer 8

• approach pt with gas mask slowly as they inhale gas and environment
• insufflation system -

Question 9

What are the 5 components of a semi-open system?

Answer 9

1. facemask or ETT
2. pop-off valve
3. reservoir tubing
4. fresh gas inlet
5. reservoir bag

Question 10

How do you prevent CO2 rebreathing in semi-open systems?

Answer 10

-with high fresh gas flows

Question 11

How do you set the APL valve with spontaneous vs controlled ventilation?

Answer 11

• open with spontaneous breathing

- partially closed with controlled ventilation

Question 12

What are examples of semi-open system?

Answer 12

Mapleson (A-F) - various configurations
Bain
Circle

Question 13

What does CO2 rebreathing depend on?

Answer 13

• FG inflow rate
• minute ventilation
• spontaneous or controlled ventilation

Question 14

What is the most efficient Mapleson model during controlled ventilation?
Where does FGF enter?
Where is the APL valve located?
What model is opposite of this?

Answer 14

• Mapleson D
• near facemask/patient
• opposite end
• Mapleson A

Question 15

What should be the FGF for a Mapleson D with

1. spontaneous respiration
2. controlled ventilation

Answer 15

1. FGF = 2-3 x MV
2. FGF = 1-2 x MV
   (MV = RR x TV, normal = 5L x 2 = 10 L of FGF)

Question 16

Which model is a T-Piece?
What does it NOT have? (2)
What would be the FGF for spontaneous?

Answer 16

• Mapleson E
• no reservoir bag, no APL valve (no manual ventilation?)
• 2-3 x MV

Question 17

Which Mapleson is popular in pediatrics?

Answer 17

• Mapleson F

- like Mapleson E (T-Piece) but has APL with reservoir bag

Question 18

Which Mapleson is the Bain Circuit a modification of?
What is FGF for the Bain Circuit?
Is it used in spontaneous or controlled or both?

Answer 18

-Mapleson D
-same as Mapleson D
1. FGF = 2-3 x MV - spontaenous
2. FGF = 1-2 x MV - controlled
Both

Question 19

What is a special feature in the Bain circuit FGF tubing?
What is the advantage to this?
What is the disadvantage of the Bain Circuit?

Answer 19

• FGF tubing is within corrugated/breathing tubing
• provide heat and humidity from exhaled gas to inspired gas
• potential for inner tube leaks, kinking, disconnect

Question 20

Which Maples is the ambu bag a modified version of?
Can it deliver high FiO2?
Does it require FGF?
How do you refill the reservoir bag?

Answer 20

-Mapleson A with a non-rebreathing valve (only one with NR valve)
-yes.
-yes, dependent on MV
it is self-filling

Question 21

What are 6 advantages of the Mapleson System?

Answer 21

1. simple
2. light
3. provides positive pressure ventilation
4. low resistance
5. portable
6. more predictable anesthetic concentration than open system and decreased pollution

Question 22

What are disadvantages of Mapleson system?

Answer 22

• calculate FGF which varies per circuit and mode of ventilation
• anesthetic depth is variable
• possible CO2 buildup with rebreathing, low FGF
• FGF costly
• Special assembly

Question 23

Which system does the anesthesia machine use?
What type of delivery system can it be used as?
What 2 things can adjust it into different systems?

Answer 23

• semi-closed Circle system
• semi-open, semi-closed, closed
• APL valve adjustment, FGF rates per system

Question 24

What are 7 components of the circle system?

Answer 24

1. FGF source
2. insp/exp valves (unidirectional)
3. insp/exp limbs/corrugated tubing
4. y-piece connector
5. adjustable APL
6. reservoir bag
7. CO2 absorber

Question 25

What is the size of the reservoir bag neck?

Answer 25

22 mm (female connection to )

Question 26

What is the reservoir bag made of?

Answer 26

neoprene or rubber

Question 27

What is the function of the reservoir bag?

Answer 27

- accumulates expired gas - assist/contrl ventilation - visual/tactile monitor for observing spontaneous respiration - protects from excessive pressure

Question 28

What is the size/diameter of a T-Piece and an ETT?

Answer 28

T-piece = 22 mm male connection | patient end of ETT = 15 mm female connection

Question 29

What is the purpose of an APL valve?

Answer 29

- releases gas to scavenge or atmosphere | - controls pressure in system

Question 30

How should the APL be positioned with 1. spontaneous resp 2. assisted vent 3. mechanical vent

Answer 30

1. open or partially closed only if reservoir bag is able to collapse 2. partially open 3. closed (if machine does not have mode switch)

Question 31

If unidirectional valves are working, where is dead space in the circle system?

Answer 31

between y piece and patient

Question 32

What are 3 rules for a circle system arrangement?

Answer 32

1. unidirectional valves must be between patient and reservoir bag on ins/exp limbs 2. FGF cannot enter between exp valve and patient 3. APL valve cannot be between patient and insp valve

Question 33

When is a semi-open circle system used?

Answer 33

Not often, sometimes for sedation (with mask placed over face to increase FiO2)

Question 34

In a semi-open circle system is there rebreathing? How? What position is APL valve? Does it conserve heat/gas?

Answer 34

No. High FGF (10-15 L/min) open no

Question 35

``` What is the most commonly used circle system? What flow rates does it use? Does it conserve heat/gas? Is there rebreathing? How is APL valve position? ```

Answer 35

- Semi-closed circle system - Low FGF (1-3 L/min) - conserves some heat/gas - some re-breathing (minus Co2) - partially closed and adjust as needed

Question 36

When is closed circle system used? How are flow rates? Is there rebreathing? What position is APL?

Answer 36

- third world countries - FGF at minimal to match metabolic O2 needs (i. e. 200 ml/min - O2 consumption calculation) - total rebreathing and conservation of all gases - APL is closed

Question 37

What is the formula for O2 consumption? (VO2)

Answer 37

10 x kg^(3/4)

Question 38

What are advantages of the circle system?

Answer 38

- stability of inspired gas - conserve moisture - prevent pollution - can be used for closed-system anesthesia - can use low flows and no rebreathing of CO2 - scavenge wastes

Question 39

What are disadvantages of circle system?

Answer 39

- complex, 10 connections (risk for leaks, obstr, disc) - malpractice due to disconnects etc - increased resistance - less portable/convenient