Airway Management

Question 1

Why is airway management important?

Answer 1

Allows delivery of oxygen and inhaled anaesthetic gas
Allows scavenging and environmental protection
Allows IPPV
Ventilator support in ICU
Protects airway
Allows airway management during bronchoscopy

Question 2

Consequence of loss of airway reflexes under anaesthesia

Answer 2

Prone to airway obstruction

Question 3

IPPV

Answer 3

Intermittent positive pressure ventilation
Close valve, gently squeeze bag, chest will inflate, open valve allowing patient to exhale passively

Question 4

How does airway management protect the airway

Answer 4

Prevents secretions blocking it
Particularly when carrying out oral/ pharyngeal procedures

Question 5

Source of oxygen in practice

Answer 5

Cylinders, Oxygen concentrators (need power supply- must have back up)

Question 6

Cuffed endotracheal tubes

Answer 6

Check before use
Stops secretions passing through oesophagus from stomach or to mouth

Question 7

Murphy Eye

Answer 7

Stops secretions blocking tube

Question 8

One lung intubation

Answer 8

When the tube is too long, goes down a single bronchi and only one lung is ventilated

Question 9

How to measure length of endotracheal tube

Answer 9

Incisors to thorax

Question 10

How estimate size of endotracheal tube

Answer 10

tracheal palpation most accurate, can measure against nose

Question 11

Lidocaine spray for intubation

Answer 11

Use in cats not dogs
Wait after spraying

Question 12

Red rubber endotracheal tubes

Answer 12

crack over time + non-repairable
Prone to kinking & irritant
Not possible to visualise blockages
Low volume high pressure cuff- can lead to tracheal trauma

Question 13

PVC % Silicone endotracheal tubes

Answer 13

Recommended
Disposable but reused
Less prone to kinking
Allows visualisation of blockages
Usually high volume low pressure cuff
less risk of tracheal trauma

Question 14

Armoured Endotracheal tubes

Answer 14

Wire coil embedded in wall,, indicated in surgeries where neck is very flexed
resist kinking
Impossibel to reduce dead space- Mechanical or equipment dead space is made up of the endotracheal tube extending beyond the patient’s incisors, patient monitor adaptors !can’t cut armoured tube so this will be longer!
Mechanical dead space gas is the first gas inhaled at the beginning of the each respiratory cycle. As the mechanical dead space volume increases, less fresh gas can move into the patient’s alveoli to participate in gas exchange.

Contraindicated in MRI

Question 15

Cole Tubes

Answer 15

Emergency and paediatric use
Shoulder of tube should impact in the larynx to provide a gas tight seal
Movement or IPPV tends to dislodge tube
Useful in exotic animal anaesthesia
Cole tubes are an uncuffed tube that has a smaller diameter at the patient (distal) end relative to the machine (proximal) end. The distal smaller diameter portion of the tube is inserted into the trachea to a point where the shoulder contacts the larynx, forming a seal. However, Cole tubes will not produce the same degree of airway security compared with a standard cuffed tube and are normally only used in very small patients for short-term intubation

Question 16

Laryngeal Mask Airways

Answer 16

Sit around larynx with inflated cushion- don’t go into trachea
Effectiveness in rabbits?
Can be used to protect airway in the same ways as ETT
IPPV is possible
Channels to divert regurgitation can be incorporated
Useful for short procedures and bronchoscopy
Always use capnography

Question 17

Masks

Answer 17

Large range of sizes
Should cover mouth but not whole head (avoid eyes)
Beware of dead space
Transparent preferable
Useful for supplemental oxygen
Not recommended for anaesthesia induction

Question 18

Pre- oxygenation

Answer 18

Use nasal prongs, catheter or mask
Humidify oxygen- particularly is oxygenation over a long time

Question 19

Oxygen cage

Answer 19

Non invasive way to deliver oxygen

Question 20

Complications due to high pressure/ low volume (from red rubber and some silicone ETT) exerting pressure on small part of tracheal mucosa

Answer 20

Tracheitis or pressure necrosis
Tracheal strictures
Tracheal ruptures in extreme cases

Question 21

When changing position of animal with ETT

Answer 21

Always disconnect breathing system

Question 22

Cuff inflation

Answer 22

Always do carefully, preferably with manometer, or listen for leaks

Question 23

Cleaning and storage of ETT and LMAs

Answer 23

Keep covered, store on wall brackets
Insufficient rinsing of ETT causes tracheitis
LMAs need to be thoroughly dries or tend to degrade

Question 24

In case of airway blockage

Answer 24

Use suction device
know how to put together
Use swab on a stick as alternative

Question 25

Assessing adequacy of airway

Answer 25

watch patient and reservoir bag
Capnograph & ETCO2 -> alveolar ventilation

Question 26

SA breath/min under GA

Answer 26

8-15

Question 27

Equine breaths/min under GA

Answer 27

6-8

Question 28

PEEP valves

Answer 28

keep airway open between breaths by maintaining positive pressure
prevent alveoli closing
not common in primary practice

Question 29

what is dead space

Answer 29

The air inspired during a normal breath VT is divided into:

Alveolar volume VA, the volume of air which reaches perfused alveoli.

Dead space VD, the volume of inspired air that plays no part in gas exchange; that is, the air remaining in either the conducting airways or non-perfused alveoli.