Breathing System and Endotracheal Tubes

Question 1

What are the two types of patient breathing systems?

Answer 1

Re-breathing

Non-rebreathing

Question 2

What are the two tubes for the rebreathing system?

Answer 2

Circle

Universal F

Question 3

What are the tubes in the non-rebreathing system?

Answer 3

Mapleson A-F
Bain (Modified Mapleson D)
Mapleson F

Question 4

Anatomic dead space

Answer 4

Airway structures that do not participate in gas exchange

Question 5

Mechanical dead space

Answer 5

the portion of the anesthesia circuit where bidirectional flow is occurring (rebreathing of exhaled gases).
If excessive, this may cause an unsafe increase in inspired CO2

Question 6

Capnograph adapter

Answer 6

the end of the endotracheal tube to sample gases

Question 7

What are the components of a re-breathing system?

Answer 7

Fresh gas input and O2 flush 
Unidirectional valves
Breathing hoses
CO2 absorber 
Adjustable pressure limiting valve
Reservoir bag

Question 8

What are the advantages of the re-breathing system?

Answer 8

Lowe fresh gas flow rate required
Patient breathes warm, humidified gases
saves money
decreases environmental pollution

Question 9

What are the disadvantages of the re-breathing system?

Answer 9

High resistance to breathing due to valves
Changes in anesthetic gas concentration occur slowly d/t lower fresh gas flow
More compnenets –> more potential for leaks

Question 10

O2 Flush Valve

Answer 10

Bypasses vaporizer
Dilutes anesthetic gas in breathing system and reservoir bag
Delivers O2 directly to the breathing system at high pressure and flow

Question 11

Adjustable pressure-limiting (APL)/pop-off valve

Answer 11

Limits pressure build up in breathing system

Pops off at 3-5 cmH2O

Question 12

Carbon Dioxide absorber

Answer 12

Soda Lime

contains ethyl violet which changes color from white to purple when granules are exhausted

Question 13

What are the signs of CO2 absorbent exhaustion?

Answer 13

Inspired CO2 is grater than 1-2mmHg on capnograph

Increased PaCO2 on blood gas

Question 14

Calculation of bag size for small animals

Answer 14

15mL/kg x 6

Question 15

What is the typical O2 flow rate for small animals (less than 50kg)?

Answer 15

Induction and recovery: 50-100mL/kg/min

Maintenance 20-50mL/kg/min

Question 16

What is the typical O2 flow rate for large animals?

Answer 16

Induction and recovery = 20-50mL/kg/min

Maintenance = 10-20mL/kg/min

Question 17

What are the components of the non-rebreathing system?

Answer 17

Fresh gas
Non-rebreathing tubes
APL valve (Bain) or open/close valve (Mapleson F)
Reservoir bag

Question 18

What is not present in the non-rebreathing system?

Answer 18

Soda Lime canister

Unidirectional valves

Question 19

What are the advantages of the non-rebreathing system?

Answer 19

Light, minimal dead space, minimal resistance to ventilation (use for small patients Less than 3 kg)
Concentration of anesthetic gas changes rapidly due to high fresh gas flow and small circuit volume

Question 20

What are the disadvantages of the non-rebreathing system?

Answer 20

Patient breathes cold and dry gas due to lack of rebreathing
More expensive
Increases environmental pollution

Question 21

What is important about Oxygen Flow rates in non-rebreathing systems?

Answer 21

Must be high as this is the mechanism for preventing rebreathing of CO2
Should be 2-3x tidal volume

Question 22

Which monitor would help determine if the O2 flow rate was too low and patient was rebreathing CO2?

Answer 22

Capnograph

Question 23

What is the advantage of Endotracheal tubes and intubation?

Answer 23

maintain patient airway 
Administer O2, deliver inhalant anesthetics 
Provide positive pressure ventilation
Protect airway from foreign material 
Apply tracheal or bronchial suction

Question 24

Routes of Intubation

Answer 24

Oral
Nasal
Tracheal
Pharyngotomy

Question 25

What are the types of ET Tubes?

Answer 25

PVC, rubber or silicone
Cuffed or uncuffed
Cuff types

Question 26

Murphy ET tube

Answer 26

can be cuffed or uncuffed

has a murphy eye that allows gas flow if end of tube is obstructed

Question 27

Cole ET tube

Answer 27

Uncuffed
Used commonly in avian patients
has a “shoulder” that seals against the glottis

Question 28

Wire-reinforced ET tube

Answer 28

Used to prevent collapse of tube lumen when patients are placed in extreme flexion (usually ophtho procedures)
Cannot use for MRI

Question 29

Passive Scavenging Systems

Answer 29

Exhaust directly to atmosphere

F air canister

Question 30

Active Scavenging Systems

Answer 30

Piped vacuum

Question 31

F air canister

Answer 31

absorbs halogenated agents (anesthetic vapors)

does not scavenge N2O