Breathing Systems

Question 1

Two types of breathing systems

Answer 1

Rebreathing

Non-rebreathing

Question 2

Rebreathing tube types

Answer 2

1. Circle/Y piece

2. Universal F

Question 3

Non-rebreathing tube types

Answer 3

1. Mapleson D
2. Mapleson F
3. Bain

Question 4

Components of the Rebreathing system

Answer 4

1. Fresh gas and O2 flush
2. Unidirectional valves (inspiratory and expiratory)
3. Breathing hoses
4. CO2 absorber
5. Adjustable pressure limiting valve aka pop-off valve
6. Reservoir bag

Question 5

Rebreathing system advantages

Answer 5

1. Lower fresh gas flow rate
2. Saves money
3. Decreases pollution
4. Patient breathes warm humidified air

Question 6

Rebreathing system disadvantages

Answer 6

1. More components and potential for leaks

2. Increased resistance for smaller patients (

Question 7

Pop-off valve

Answer 7

Limits pressure buildup in the system

Question 8

Position of the pop-off valve

Answer 8

ALWAYS OPEN

Unless checking for leaks or administering positive pressure ventilation

Question 9

Consequences of leaving the pop-off valve closed

Answer 9

Increases pressure in breathing system

Results in possible cardiopulmonary injury

Question 10

Breathing system pressure gauge

Answer 10

SHOULD ALWAYS BE ZERO

Except: performing leak checks or providing positive pressure ventilation

Question 11

Most common CO2 absorber medium

Answer 11

Soda lime

Calcium hydroxide with small amounts of sodium hydroxide and crystal violet (colour indicator)

Question 12

Colour change in soda lime

Answer 12

White- fresh

Violet- exhausted

Question 13

Signs of exhaustion

Answer 13

1. Increase in tidal CO2
2. Increased ventilation, HR/BP (then drop) if light enough
3. Rebreathing capnograph
4. Respiratory acidosis
5. Red mucous membranes due to carbon monoxide production/inhalation

Question 14

Reservoir bag function

Answer 14

Observe ventilation, inspiratory reserve, administer manual positive pressure ventilation

Question 15

Calculation for reservoir bag size

Answer 15

Tidal volume = 10-20mL/kg x 6

Round UP if between sizes

Question 16

Oxygen flow rate-

Rebreathing Small animal

Answer 16

Induction/ Recovery= 50-100 mL/kg/min O2

Maintenance= 20-50mL/kg/min O2

Question 17

Oxygen flow rate

Rebreathing Large animal

Answer 17

Induction/ Recovery= 20-50 mL/kg/min O2

Maintenance= 10-20mL/kg/min O2

Question 18

Non-rebreathing system components

Answer 18

1. Fresh gas
2. Non-rebreathing tubes
3. APL (mapleson D) or open/close (mapleson F) valve
4. Reservoir bag

Question 19

Non-rebreathing Advantages

Answer 19

1. Very light with minimal dead space

2. Minimal resistance to ventilation (better for

Question 20

Non-rebreathing Disadvantages

Answer 20

1. High Gas flow rate
2. More expensive to run larger patients
3. Increased environmental pollution
4. Gas cold and dry

Question 21

Non-rebreathing Oxygen flow rates

Answer 21

2-3x tidal volume in most cases

200-300mL/kg/min O2

Question 22

Indications for endotracheal intubation

Answer 22

1. Maintain patent airway
2. Protect airway from foreign material
3. Provide intermittent positive pressure ventilation (IPPV)
4. Apply tracheal or bronchial suction
5. Administer oxygen
6. Deliver inhalant anesthesia

Question 23

Benefits of intubation

Answer 23

1. Reduced anatomical deadspace

2. Maintain inhalant anesthesia with minimal environmental contamination (with properly inflated cuff)

Question 24

Routes of Intubation

Answer 24

1. Oral
2. Nasal
3. External pharyngotomy
4. Tracheostomy

Question 25

E-tube materials

Answer 25

PVC, rubber, or silicone

Question 26

Purpose of cuff

Answer 26

Protects airway and environment from contamination

Question 27

Types of e-tubes

Answer 27

1. Murphy- most common 2. McGill 3. Wire reinforced (do not use with MRI) 4. Cole- avian 5. Tracheostomy

Question 28

What type of tube provides the least air resistance

Answer 28

Larger radium and shorter length (Poiseuille's law)

Question 29

Cat e-tube sizing

Answer 29

3.5-4.5mm generally

Question 30

Dog e-tube sizing

Answer 30

8.0-12mm depending on size of dog | 14-16mm for giant breed dogs

Question 31

Sheep e-tube sizing

Answer 31

10-12mm

Question 32

Horse e-tube sizing

Answer 32

26-30mm

Question 33

Safe e-tube inflation

Answer 33

No audible release of gas around e-tube when pop-off is closed and reservoir bag is squeezed to 20cmH2O Air should be escaping at 30cmH2O- prevents over inflation

Question 34

Potential complications of intubation

Answer 34

1. Laryneal damage- small animal espeically 2. Tracheal damage - over inflated cuff - moving/twisting of inflated cuff 3. Tube obstruction 4. Endobronchial intubation (hypoxemia, tachypnea, cynosis) 5. ETT inhalation/ingestion

Question 35

Purpose of scavenging

Answer 35

Collection and transport of waste gasses from the anesthetic machine to a safe disposal area

Question 36

Types of scavengers

Answer 36

Active and passive

Question 37

Elements of a scavenger

Answer 37

1. Collecting system (APL valve) 2. Transfer system/interface 3. Receiving system 4. Disposal system

Question 38

Olfacotry ppm of gasses

Answer 38

>= 125ppm

Question 39

Exposure limits to anesthetic gasses

Question 40

Scavenging principles

Answer 40

1. Scavenge everything | 2. No leak technique (

Question 41

Passive scavenging system medium

Answer 41

Charcoal F-air canisters; does not scavenge nitrous oxide

Question 42

Passive scavenging piping

Answer 42

Atmosphere (window etc)

Question 43

Active scavenging system

Answer 43

Piped vacuum (WHITE drop and tubing)

Question 44

Charcoal scavenging advantages

Answer 44

1. Absorbs hydrocarbons 2. Does not release to ozone 3. Portable

Question 45

Charcoal Scavenging disadvantages

Answer 45

1. Does not absorb N2O 2. Limited flow 3. Added resistance 4. Weigh before use and record weight 5. Discard with 50grams+ or after 8-12 hours continuous use

Question 46

Active scavenging system flow rate capacity

Answer 46

30L/min