Airway management

Question 1

Why is airway protection and ventilatory support vital after induction of anaesthesia?

Answer 1

• Laryngeal and pharyngeal tissues relax
• No swallowing reflex
• Respiratory depression and apnoea

Question 2

What is the function of a laryngoscope?

Answer 2

Retraction of pharyngeal tissue to allow direct visualisation of the larynx to facilitate intubation

Question 3

Why should you select the smallest face mask possible during anaesthesia?

Answer 3

To minimise environmental pollution

Smallest possible - minimise dead space between FGF and patient

Question 4

What is the function of an endotracheal tube?

Answer 4

Delivery of FGF directly into the lungs

Allow positive pressure ventilation

Protects lungs fro contamination from gastric contents

Question 5

What are the advantages of using an ET tube with a cuff?

What is the potential disadvantage?

Answer 5

1. +
   
   1. Airway protected from aspiration
   2. No leakage of inhalation agents
   3. Better mechanical/ manual ventilation
2. -
   
   1. Increased risk of damage to respiratory mucosa

Question 6

Describe the difference between the two types of endotracheal cuff.

Answer 6

1. High pressure, low volume
   
   1. Better airway protection
   2. Higher pressure exerted over a smaller area
   3. Higher chance of mucosal damage
2. Low pressure, high volume
   
   1. Pressure is spread over wider area
   2. Less risk of damage
   3. More likely to leak past small folds

Question 7

How should you select an appropriate ET tube size?

Answer 7

Choose the widest diameter that will easily pass through the larynx

Choose the shortest tube that can be easily secured

Question 8

When would it be appropriate/ inappropriate to use a laryngeal mask?

Answer 8

• +
  
  • Can’t intubate
  • Short procedure
  • Multiple anaesthetics
• -
  
  • When IPPV is needed
  • When at risk of gastric reflux

Question 9

Why are cats at risk of laryngospasm?

How can this be solved?

Answer 9

They have a very sensitive larynx

Apply a local anaesthetic spray to the area

Question 10

Describe the differences in anatomy of horses, ruminants and pigs and how this affects ET tube placement.

Answer 10

1. Horse - straight larynx, can’t visualise larynx (blind)
2. Ruminants - angled downwards larynx, may be able to visualise in small, xxx cows, ++ salivation
3. Pig - angled at 90 degrees to oral cavity, can be visualised, requires two rotations

Question 11

How can you confirm ET tube is in the correct position?

Answer 11

• Visualisation using laryngoscope
• Simultaneous thoracic and reservoir bag movement
• Capnograph
• Air coming out of the ETT
• Neck palpation - can feel = probably in the oesophagus

Question 12

Describe a route of emergency airway access if you are unable to place an ET tube (eg FB)

Answer 12

Transtracheal needle

Tracheostomy

Urinary catheter through the larynx to provide O2

Question 13

What is meant by the FRC?

Answer 13

Functional residual capacity - the volume of air present in the lungs at the end of passive expiration

Question 14

How is gas exchange maintained during times of apnoea?

Answer 14

Through the FRC

Question 15

What are the negative effects of ventilation during anaesthesia?

Answer 15

• Causes positive intrathoracic pressure during inspiration
  
  • decreases venous return to the heart and CO
• Ventilatory associated lung injury - excessive volume or pressure
• Activates RAAS - ADH production and fluid retention