Airway Management

Question 1

What are the airway concerns specific to a patient undergoing bimaxillary osteotomy?

Answer 1

This is a shared airway case

• Nasal intubation, with risk of epistaxis and trauma
• Risk of damage to tube
• Lack of access to patient’s head intraoperatively
• May have comorbidities that make airway difficult

The patient may require jaw wiring or inter maxillary fixation

• Difficult reintubation
• Risk of retained throat pack
• Risk of undetected postoperative bleeding

Question 2

Other than nasal intubation, how might you manage the airway for a maxillo-facial operation?

Answer 2

Retromolar intubation
Submental intubation
Tracheostomy

Question 3

What measures can be taken to reduce the risk of intraoperative bleeding?

Answer 3

Head up position
Avoid hypertension
Local anaesthesia with adrenaline
Tranexamic acid

Question 4

What are the benefits of TIVA for maxillofacial surgery?

Answer 4

Reduced post operative nausea and vomiting
Reduced coughing on emergence
Easier to manage intraoperative hypertension

Question 5

What measures should be taken to avoid a retained throat pack?

Answer 5

Label the patient’s forehead
Label the tube
Leave part of the pack visible
Checklist in patient’s care plan or notes
Include pack in swab count

Question 6

Which lasing medium is used for laryngeal tumour surgery and why?

Answer 6

CO2 gas
Far infrared 10 600nm
Cutting and coagulation

Argon is used for dermatology
Ho:YAG is used for lithotripsy
Ruby for tattoo removal
Nd:YAG for GI bleeding

Question 7

According to NAP-4, where did 20% of all airway incidence occur?

Answer 7

Intensive care unit

Question 8

What history and examination features are particularly of relevance to airway management in a patient undergoing thyroidectomy?

Answer 8

Duration of goitre - a large, chronic goitre is a risk factor for post-operative tracheomalacia

Ability to lie flat, stridor or shortness of breath, and whether this is positional

Vocal changes

Ability to palpate below thyroid, evidence of retrosternal extension

Tracheal deviation

Evidence of superior vena cava obstruction - Pemberton’s sign

Question 9

What investigations should be performed prior to a patient undergoing thyroidectomy?

Answer 9

Thyroid function - risk of intraoperative thyroid storm

Echocardiogram and ECG

Chest xray

CT neck and thorax to assess trachea and retrosternal extension

Full blood count as risk of intraoperative bleeding

Spirometry - may demonstrate fixed upper airway obstruction

Question 10

What would severe stridor immediately after extubation suggest?

Answer 10

Bilateral recurrent laryngeal nerve palsy

Question 11

What is the immediate management of an expanding neck haematoma?

Answer 11

• 100% oxygen
  
  • Remove clips/sutures
  • Sit patient upright
  • Return to theatre
  • Prepare for difficult airway with ENT surgeon on standby for emergency awake tracheostomy

Question 12

How can you perform a Valsalva manoevure during an operation, and what is its purpose?

Answer 12

• Switch from ventilator to manual ventilation
  
  • Close APL valve to at least 40cmH2O
  • Squeeze bag until pressure 30cmH2O
  • Hold for at least ten seconds
  • Purpose is to raise intrathoracic pressure and therefore jugular venous pressure
  • This will exaggerate any venous bleeding allowing the surgeon to detect and treat it

Question 13

What factors increase risk of sore throat post operatively?

Answer 13

Large ET tube
High cuff pressure
Difficult intubation
Longer anaesthetic
Nasogastric tube
Non-humidified breathing system

Question 14

How can the risk of dental injury be reduced?

Answer 14

Preoperative dental exam
LMA
Regional anaesthesia
Blind nasal intubation
Bite block
Deep extubation
Senior operator

Question 15

What are the commonest nerve injuries due to positioning during anaesthesia?

Answer 15

Brachial plexus injury
Ulnar nerve injury
Common fibular nerve injury

Question 16

What are the features of common peroneal nerve palsy?

Answer 16

Foot drop
Weak dorsiflexion and eversion
Weak extensor hallucis longus
Paraesthesia over dorsolateral foot and ankle

Question 17

What is the definition of a difficult airway?

Answer 17

There are many ways to define the concept of a difficult airway, but anything along the lines of the following will earn you the marks:

A clinical situation in which an anaesthetist experiences difficulty with facemask ventilation, supraglottic device ventilation, tracheal intubation or all three

More than two attempts at intubation using direct layngoscopy

Using adjuncts to direct laryngoscopy

Using an alternative device or technique following failed intubation with direct laryngoscopy

Remember that the Cormack and Lehane grades 3 and 4 relate to difficult laryngoscopy rather than a difficult airway.

Question 18

What are the contraindications to awake fibreoptic intubation?

Answer 18

Patient refusal
Allergy to local anaesthesia
Stridulous patient or upper airway obstruction
Coagulopathy and epistaxis
Base of skull fracture
Penetrating eye injury
Inexperienced operator

Question 19

What do the intrinsic muscles of the larynx do?

Answer 19

Cricothyroid - Tenses vocal cords
Thyroarytenoid and vocalis - Relax vocal cords
Lateral cricoarytenoid and transverse arytenoids - Adduction of cords
Posterior cricoarytenoid - Abduction of vocal cords

Question 20

Which nerves innervate the vocal cords?

Answer 20

Recurrent laryngeal nerve supplies all the intrinsic laryngeal muscles with the exception of the cricothyroid muscle
It also supplies sensation to the subglottic mucosa
External branch of the superior laryngeal nerve supplies cricothyroid
The internal branch supplies sensation to the glottis, supraglottic region and inferior aspect of the epiglottis

Question 21

How can you prepare the airway prior to awake fibreoptic intubation?

Answer 21

The airway needs to be topicalised with local anaesthetic, and optimised by drying secretions.

Glycopyrrolate 4 µg kg−1 IM one hour prior to intubation
- Not only does this reduce secretions but it also increases the effect of the local anaesthetic
- The IM route avoids the tachycardia and anxiety seen when given IV

Lidocaine up to 9mg/kg, often with a vasoconstrictor such as phenylephrine - as seen in co-phenylcaine
- This can be administered by nebuliser, using an atomiser as in the video in the post above, or through the scope itself
- Trans-tracheal injection of local anaesthesia is very effective for anaesthetising the cords and trachea

If you perform a trans-tracheal injection with a cannula and leave the cannula in situ, it can be also used for rescue oxygenation as well as guidewire insertion for an emergency tracheostomy if required.

Question 22

What is the maximum acceptable dose of topical mucosal lidocaine and what percentage of nebulised lidocaine is systemically absorbed?

Answer 22

9mg/kg
20-25%

Question 23

What are the predictors of difficult laryngoscopy?

Answer 23

This can be divided into patient factors and pathology factors:

Patient Factors
- Previous difficult intubation
- Neck immobility or instability - Rheumatoid Arthritis
and Ankylosing Spondylitis
- Obesity and acromegaly
- Previous airway surgery
- Previous neck surgery
- Congenital - Pierre-Robin, Treacher Collins, Down’s and Klippel-Feil syndromes feature in the Final FRCA rather frequently

Pathology Factors
- Infective causes
- Dental abscess
- Ludwig’s angina
- Epiglottitis
- Croup
- Neoplastic causes
- Tongue and oral tumours
- Laryngeal tumours
- Thyroid tumours and goitre
- Radiotherapy to mouth/neck - very strong
predictor
- Trauma
- Unstable cervical spine fracture
- Facial fractures
- Airway oedema
- Airway burns

Question 24

What airway options are there for anaesthesia for airway stenting?

Answer 24

Endotracheal tube can be used for flexible bronchoscopy
Supraglottic airways can reduce coughing, while allowing easy access to upper trachea
THRIVE can be used for tubeless surgery
If using a rigid bronchoscope, usually remifentanil and propofol TIVA with jet ventilation

Question 25

What are your primary airway concerns during airway stenting?

Answer 25

This is a shared airway, requiring clear communication between surgeon and anaesthetist

It may be difficult to maintain anaesthesia with inhalational agents

Airway loss could occur at any time

Conscious sedation with local anaesthetic topicalisation can reduce risk of airway loss in cases where flexible bronchoscopy is appropriate

THRIVE may be very helpful during sedation

If using general anaesthesia, relaxation of the trachealis muscle can precipitate obstruction, particularly in high grade and proximal lesions

Question 26

How would you prepare a patient preoperatively for airway stenting?

Answer 26

MDT management - anaesthetist, respiratory team, thoracics, radiology

Oncology +/- palliative care team input

Understanding of ceiling of care and treatment goals
Informed consent, understanding of risks and benefits

Appropriate imaging - Multi-detector CT with 3D reconstruction

Understanding of what type of stent, and method of insertion (flexible bronchoscopy can be done under sedation)

Adequate rescue planning for airway management should complete obstruction occur

Optimisation of co-morbidities

Lung function testing and Echocardiography are often helpful

Question 27

Which malignancies may require airway stenting?

Answer 27

Lung cancers
Lymphoma
Oesophageal
Thyroid
Sarcoma
Metastasis from external primary

Question 28

What are the complications of airway stenting?

Answer 28

Early complications

• Airway obstruction
• Trauma due to bronchoscopy
• Barotrauma from ventilation
• Bleeding
• Air embolism
• Pneumothorax and tension pneumothorax
• Hypoventilation and hypoxia

Late complications

• Stent migration
• Stent breakdown
• Stenosis
• Erosion into surrounding tissue
• Chronic infection
• Granuloma formation

Question 29

According to the RCoA what are the most valuable independent predictors of difficult facemask ventilation?

Answer 29

BMI over 26
Age over 55 years
Edentulous
Significant factial hair
History of snoring or sleep apnoea

Question 30

What factors from the history and examination are of importance in an airway assessment?

Answer 30

Any previous problems with airway or anaesthesia
History of significant oesophageal reflux
History of sleep apnoea
Body mass index and presence of obesity
Mouth opening and inter-incisor distance
Mallampati score
Dentition and presence of loose teeth
Thyromental, sternomental or thyrosternal distance
Jaw protrusion
C spine mobility
Previous neck irradiation

Question 31

What acronyms did Murphy and Walls come up with?

Answer 31

MOANS - difficult facemask ventilation
- Mask seal
- Obesity
- Age
- No teeth
- Snoring or stiff

RODS - difficult supraglottic airway insertion
- Reduced mouth opening
- Obstruction
- Distorted airway
- Stiff neck or lungs

LEMON - difficult intubation
- Look externally
- Evaluation - mouth opening <5cm, TMD <6cm
- Mallampati
- Obstruction
- Neck mobility

Question 32

What factors on bedside examination would predict difficult laryngoscopy?

Answer 32

Receding jaw
Poor dentition
Short neck
Large tongue
Reduced neck mobility
Craniofacial abnormalities or trauma
Halo-thoracic brace
C spine collar
Stridor and difficulty swallowing secretions - evidence of obstruction

Stridor suggests that at some point between trachea and mouth, the airway is less than 4mm in diameter.

Question 33

What are the components of the Wilson score?

Answer 33

BMI
Jaw protrusion
Neck mobility
Receding mandible
Buck teeth

Question 34

What questions are we trying to answer with a preoperative airway assessment?

Answer 34

Any previous airway problems?
How easy is it going to be to facemask ventilate?
How easy is it going to be to use a supraglottic airway?
How easy is it going to be to intubate?
How likely are they to aspirate?
Will they be a safe extubation?
Any respiratory disease?
Is the surgery likely to impact on the airway?

Question 35

How is atlanto-axial subluxation classified?

Answer 35

Anterior - 80% (loss of transverse ligament integrity)
Vertical - 10% (destruction of lateral masses of C1)
Posterior - 5% (destruction of odontoid peg)
Lateral - 5% (destruction of C1/C2 facet joints)