Difficult Airway Management

Quick Answer

Difficult airway management is a core anaesthetic competency with an incidence of 1.5-13% for difficult intubation and 0.1-3% for failed intubation. The "Cannot Intubate, Cannot Ventilate" (CICV) scenario occurs in 0.01-0.2% of cases and remains a leading cause of anaesthesia-related morbidity and mortality. Preoperative assessment using the LEMON (Look, Evaluate, Mallampati, Obstruction, Neck Mobility) or LEMON-ELM (Examine, Laryngoscopy, Mouth opening) criteria identifies 80-90% of difficult airways but has limited predictive value. Management follows a structured algorithm: Plan A (awake fibreoptic intubation if anticipated difficulty) → Plan B (optimized direct laryngoscopy with bougie or alternative device) → Plan C (second-generation supraglottic airway) → Plan D (front-of-neck access — cricothyrotomy or tracheostomy). Oxygenation is the priority — use high-flow nasal cannula (HFNC), apnoeic oxygenation, or face mask ventilation between attempts. Second-generation supraglottic airways (i-gel, LMA Supreme, ProSeal) have >90% success rate and 10-20 minutes of ventilation time. Cricothyrotomy is definitive rescue for CICV with >95% success when performed by trained clinicians. Indigenous patients may have higher prevalence of certain airway risk factors (obesity, diabetes, cervical spine disease) and reduced access to specialist services, requiring culturally safe communication about airway risks. [1-10]

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Pathophysiology

Airway Anatomy and Physiology Relevant to Difficult Airway

Upper Airway Anatomy:

The upper airway consists of the nasal cavity, oral cavity, pharynx, and larynx. Critical anatomical relationships determine the ease or difficulty of airway management:

Nasal Cavity:

• Turbinates increase surface area for humidification and warming
• Nasopharynx connects to oropharynx behind soft palate
• Epistaxis may occur with nasal airway devices

Oral Cavity:

• Tongue size and mobility are critical for mouth opening and visualization
• Mandibular space determines available room for laryngoscopy
• Dental protrusion influences ability to bring laryngeal axis into view

Pharyngeal Structures:

• Soft palate: Anterior displacement improves laryngeal view
• Uvula and tonsils: Mallampati assessment evaluates their relationship to the soft palate
• Posterior pharyngeal wall: Important for supraglottic airway seal

Larynx:

• Epiglottis: Key landmark; size and mobility affect visualization
• Arytenoid cartilages: Posterior landmarks for glottic opening
• Vocal cords: Abductor/adductor function affects airway patency
• Cricothyroid membrane: Site for front-of-neck access

Laryngeal Axes Alignment (Three Axes Theory):

Successful laryngoscopy requires alignment of three axes:

1. Oral axis (from mouth to oropharynx)
2. Pharyngeal axis (from pharynx to larynx)
3. Tracheal axis (continuation beyond glottis)

Head position adjustments:

• Head elevation aligns oral and pharyngeal axes
• Atlanto-occipital extension aligns pharyngeal and tracheal axes
• Combined: "sniffing the morning air" position optimizes all three axes

Reduced neck mobility (cervical spine disease, ankylosing spondylitis) prevents adequate alignment → difficult laryngoscopy.

Mechanisms of Difficult Intubation

Anatomical Difficulties:

1. Limited Mouth Opening:

• Normal inter-incisor distance: >4 cm
• Reduced opening (<3 cm) limits laryngoscope blade insertion
• Causes: TMJ ankylosis, facial scarring, radiation fibrosis, burns

2. Reduced Thyromental Distance:

• Normal: >6.5 cm
• <6 cm predicts difficult intubation
• Large tongue relative to mandibular space
• Mandibular retrusion (micrognathia, retrognathia)

3. Reduced Sternomental Distance:

• Normal: >12.5 cm
• <12 cm predicts difficult laryngoscopy
• Neck extension limitations

4. Limited Neck Mobility:

• Atlanto-occipital joint extension:
  • Normal: >35 degrees
  • Essential for aligning axes
  • Restricted by cervical spine fusion, ankylosing spondylitis, rheumatoid arthritis

5. Upper Airway Obstruction:

• Supraglottic: Epiglottic masses, abscesses, lingual tonsil hypertrophy
• Glottic: Vocal cord paralysis, laryngeal carcinoma, subglottic stenosis
• Infraglottic: Tracheal compression (goitre, retrosternal mass)

6. Altered Anatomy:

• Previous neck surgery (tracheostomy, laryngectomy)
• Radiation changes (fibrosis, reduced tissue pliability)
• Obesity (reduced functional reserve, neck circumference >40 cm)
• Facial trauma or burns

Physiological Factors:

1. Reduced Functional Residual Capacity (FRC):

• Obesity, pregnancy, abdominal distension
• Rapid desaturation during apnoea
• Shorter safe apnoea time

2. Increased Metabolic Rate:

• Fever, sepsis, thyrotoxicosis
• Faster oxygen consumption
• Accelerated desaturation

3. Left-to-Right Shunts:

• Right-to-left shunting bypasses alveolar gas exchange
• Accelerates hypoxaemia

4. Cardiopulmonary Disease:

• COPD, heart failure
• Reduced cardiopulmonary reserve
• Poor tolerance of prolonged airway manipulation

Mechanisms of Difficult Ventilation

Mask Ventilation Difficulties:

Grades of Difficulty (Han Scale):

• Grade 1: Adequate ventilation by face mask
• Grade 2: Inadequate ventilation requiring oral airway, two-person mask, or both
• Grade 3: Poor ventilation requiring supraglottic airway
• Grade 4: Impossible to ventilate (CICV scenario)

Causes:

1. Inadequate Mask Seal:

• Facial hair (beard)
• Abnormal facial anatomy (edentulous, severe burns)
• Gastric distension limiting mask fit

2. Upper Airway Obstruction:

• Soft tissue collapse: Tongue falling back (relaxed muscles, obesity)
• Laryngospasm: Reflex closure of vocal cords
• Bronchospasm: Lower airway obstruction

3. Reduced Lung Compliance:

• Obesity, pregnancy, abdominal distension
• Higher pressures required
• Increased risk of gastric insufflation

4. Reduced Chest Wall Compliance:

• Musculoskeletal disorders
• Kyphoscoliosis, ankylosing spondylitis

Mechanisms of Failed Oxygenation

Cannot Intubate, Cannot Ventilate (CICV):

Definition: Inability to establish an airway despite multiple attempts at both intubation and face mask ventilation with hypoxaemia impending or present.

Time-Critical Nature:

• Healthy adult: Safe apnoea time ~2-3 minutes (after pre-oxygenation)
• Obese patient: Safe apnoea time reduced to 60-90 seconds
• Pregnancy: Safe apnoea time reduced to 90-120 seconds
• Rapid desaturation occurs with reduced FRC and increased oxygen consumption

Consequences of Prolonged Hypoxaemia:

• Cardiac: Arrhythmias, myocardial ischaemia, cardiac arrest
• CNS: Seizures, permanent neurological injury
• Death: Irreversible injury within 4-6 minutes of severe hypoxaemia

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Assessment

Preoperative Airway Assessment

Systematic Approach:

1. History:

Previous Airway Problems:

• "Difficult intubation" reported by patient or in medical records
• Previous airway management difficulties (failed intubation, CICV scenario)
• Neck surgery or trauma history
• Previous radiotherapy to head and neck

Medical Conditions:

• Rheumatoid arthritis: Atlanto-axial subluxation, cervical spine fusion
• Ankylosing spondylitis: Bamboo spine, limited neck mobility
• Acromegaly: Macroglossia, soft tissue hypertrophy, laryngeal enlargement
• Obesity: Increased neck circumference, reduced FRC
• Diabetes mellitus: Stiff joint syndrome, cervical spine disease
• Pregnancy: Oedema, breast enlargement, reduced FRC

Symptoms of Airway Obstruction:

• Stridor: Inspiratory (supraglottic), expiratory (infraglottic), biphasic (glottic)
• Dysphagia: Suggests mass or structural abnormality
• Dysphonia: Vocal cord pathology
• Orthopnoea: Worsening airway obstruction when supine
• Snoring: Upper airway obstruction, obstructive sleep apnoea

Sleep Apnoea:

• Obstructive sleep apnoea (OSA) diagnosis
• Epworth Sleepiness Scale score >10
• CPAP use

Trauma History:

• Facial or neck fractures
• Burns or scarring
• Airway injury

Medications:

• Steroid use (Cushingoid features, airway oedema)
• Radiotherapy (tissue fibrosis)

2. Physical Examination:

General Assessment:

• Body habitus (obesity, cervical kyphosis)
• Facial features (acromegaly, Pierre Robin sequence, Treacher Collins syndrome)
• Presence of beard or facial hair

Specific Examinations:

A. Mouth Opening (Inter-Incisor Distance):

• Normal: >4 cm (or 3 fingerbreadths)
• Moderate difficulty: 3-4 cm
• Severe difficulty: <3 cm (or <2 fingerbreadths)
• Assess both incisor and molar distance

B. Thyromental Distance (TMD):

• Measured from mentum (chin tip) to thyroid notch with neck extended
• Normal: >6.5 cm (or 3 fingerbreadths)
• <6 cm predicts difficult intubation
• <4 cm predicts very difficult intubation

C. Sternomental Distance (SMD):

• Measured from suprasternal notch to mentum with neck fully extended
• Normal: >12.5 cm (or 4 fingerbreadths)
• <12.5 cm predicts difficult laryngoscopy
• <12 cm requires alternative techniques

D. Mallampati Classification:

• Patient seated, mouth maximally open, tongue protruding without phonation
• Assessed with patient in neutral position (not extended)

Limitations:

• Poor inter-observer reliability
• Limited predictive value (sensitivity ~50-60%)
• Does not assess neck mobility or mouth opening

E. Neck Mobility:

• Atlanto-occipital extension:

  • Measure: patient sits, extends neck upward
  • Normal: >35 degrees
  • <35 degrees predicts difficult laryngoscopy
  • Causes: cervical spine fusion, rheumatoid arthritis

• Rotation:

  • Assesses cervical spine rotational capacity
  • Normal: >70 degrees

F. Neck Circumference:

• Measured at cricothyroid membrane level
• Normal: <37 cm

• 40 cm predicts difficult intubation

• Obesity correlation

G. Temporomandibular Joint (TMJ) Assessment:

• Range of motion (opening, lateral excursion)
• Subluxation or clicking (may indicate pathology)
• Limitations

H. Dental Assessment:

• Loose or protruding teeth (risk of damage)
• Upper incisor protrusion
• Dentures (remove before induction)

I. Upper Airway Examination:

• Nasal patency: Assess both nostrils (for nasal intubation)
• Soft palate and uvula: Edema, scarring, masses
• Tonsils: Hypertrophy, asymmetry
• Tongue: Size relative to oral cavity
• Floor of mouth: Submandibular swelling (lingual tonsil hypertrophy)

3. Radiological Assessment:

Cervical Spine X-ray (if indicated):

• Lateral view for C-spine alignment
• Atlanto-axial subluxation (pre-gap >3 mm)
• Reduced disc spaces
• Fusion (bamboo spine in ankylosing spondylitis)

CT Scan:

• Neck masses, tumours, abscesses
• Retrosternal goitre extent
• Airway distortion

3D Reconstruction:

• Virtual bronchoscopy for airway pathology
• Surgical planning

4. Bedside Tests:

Upper Lip Bite Test (ULBT):

• Patient tries to bite upper lip with lower incisors
• Class I: Lower teeth can reach upper vermilion border
• Class II: Lower teeth can reach upper vermilion border but not mucosa
• Class III: Lower teeth cannot reach upper vermilion border
• Predictive value comparable to Mallampati

Wilson Score (Sum of Points):

• Score 0-1: Easy
• Score 2: Moderately difficult
• Score >2: Very difficult

5. Predictive Value of Tests:

Combination of Tests Improves Prediction:

Best Predictive Value:

• Combination of at least two abnormal tests
• Weighted scoring systems (e.g., Wilson score, Intubation Difficulty Scale)

Limitations of Bedside Assessment:

• Cannot predict all difficult airways (10-20% unexpected)
• Poor prediction of ventilation difficulty
• Does not assess operator skill
• Subject to inter-observer variation

Intraoperative Assessment

Evaluation During Airway Management:

1. Mask Ventilation Difficulty Assessment:

Grade Mask Ventilation (Han Scale):

Signs of Difficult Mask Ventilation:

• Air leak around mask
• Inadequate chest wall movement
• High airway pressures (>25-30 cm H₂O)
• SpO₂ <92% despite optimal technique
• Gastric insufflation

2. Laryngoscopic View Assessment:

Cormack-Lehane Classification (Modified):

Pogma Classification (Modified Cormack-Lehane):

• Grade IIb and III: May improve with external laryngeal manipulation (BURP)
• Grades III-IV: Consider alternative devices or techniques

3. Number of Attempts:

Definition of Attempt:

• Insertion of laryngoscope blade and attempted visualization of glottis

Limits: Number of Attempts:

• Maximum 3 attempts at direct laryngoscopy before proceeding to alternative technique
• Each attempt should be <30 seconds
• Maintain oxygenation between attempts (face mask, HFNC, or apnoeic oxygenation)

4. Time Constraints:

Safe Apnoea Times:

• Healthy adult: 2-3 minutes (after pre-oxygenation)
• Obese (BMI >30): 60-90 seconds
• Pregnancy: 90-120 seconds
• Pediatric: Shorter due to higher metabolic rate

Action:

• If SpO₂ <90% after 3 attempts → proceed to rescue technique immediately
• Do NOT continue failed techniques with worsening hypoxaemia

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Management

Structured Airway Management Approach

Core Principles:

1. Oxygenation is the priority — maintain oxygenation regardless of airway technique
2. Plan for failure — have backup plans ready before starting
3. Call for help early — difficult airway management is a team emergency
4. Avoid repeated failed attempts — escalate to rescue technique after 3 failed attempts
5. Document thoroughly — record assessments, techniques, outcomes

The "Plan A-E" Framework:

Plan A: Primary Strategy

• Awake fibreoptic intubation (if anticipated difficulty)
• Standard direct laryngoscopy with appropriate blade

Plan B: First Backup

• Optimized direct laryngoscopy (alternative blade, bougie, BURP)
• Video laryngoscopy
• Alternative supraglottic airway

Plan C: Second Backup

• Second-generation supraglottic airway (i-gel, LMA Supreme, ProSeal)
• Blind intubation through supraglottic airway

Plan D: Rescue

• Front-of-neck access (cricothyrotomy or tracheostomy)

Plan E: Alternative (if time allows)

• Cancel procedure and return another day
• Alternative surgical approach (e.g., regional anaesthesia)

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ANZCA Final Exam Focus

SAQ Patterns

Difficult airway management is a core ANZCA Final Written Examination topic. Common SAQ themes include:

Assessment-Focused Questions:

• "Describe the preoperative assessment of a patient with a difficult airway." (2020)
• "What are the predictors of difficult intubation?" (2021)
• "A patient reports previous difficulty with intubation. How would you assess this patient?"

Management-Focused Questions:

• "A patient cannot be intubated after 3 attempts of direct laryngoscopy. Describe your management." (2019)
• "Describe the management of a CICV scenario." (2022)
• "Outline your approach to a patient with anticipated difficult airway undergoing laparoscopic cholecystectomy."

Algorithm-Focused Questions:

• "Describe the DAS (Difficult Airway Society) guidelines for management of difficult airway."
• "Compare the management of anticipated vs unanticipated difficult airway."

Equipment-Focused Questions:

• "Describe the equipment available for difficult airway management."
• "Compare first and second-generation supraglottic airways."
• "Discuss the role of video laryngoscopy in difficult airway management."

Marking Scheme Priorities:

• Systematic assessment approach
• Structured management algorithm (Plan A-E)
• Knowledge of equipment and techniques
• Recognition of CICV scenario
• Oxygenation prioritization
• Front-of-neck access knowledge
• Documentation and follow-up

Clinical Viva Themes

The Clinical Viva frequently includes difficult airway scenarios:

Scenario Types:

• Anticipated difficult airway preoperative assessment
• Intraoperative difficult intubation
• CICV scenario
• Awake fibreoptic intubation
• Supraglottic airway rescue
• Cricothyrotomy performance

Examiner Expectations:

• Systematic assessment before induction
• Structured approach to airway management
• Knowledge of techniques and equipment
• Ability to de-escalate to safer options
• Understanding of time constraints
• Team leadership and communication
• Documentation of events

Common Viva Questions:

• "What are the predictors of difficult intubation?"
• "How would you assess this patient's airway?"
• "What is your approach to an anticipated difficult airway?"
• "What do you do if you cannot intubate after 3 attempts?"
• "Describe the CICV scenario and management."
• "When would you perform a cricothyrotomy?"
• "What are the complications of difficult airway management?"

Medical Viva Considerations

The Medical Viva may include difficult airway within broader discussions:

• Airway anatomy and physiology
• Pharmacology of muscle relaxants and airway reflexes
• Complications of airway management
• Equipment design and principles
• Decision-making algorithms
• Research evidence in airway management

Key Points for Examination Success

1. Systematic assessment is essential — LEMON or LEMON-ELM criteria
2. Oxygenation is always the priority — never sacrifice oxygenation for airway
3. Maximum 3 attempts at any technique before escalating
4. CICV scenario — front-of-neck access is definitive
5. Second-generation supraglottic airways >90% success rate
6. Awake fibreoptic intubation for anticipated difficulty
7. Team communication — call for help early
8. Documentation — record all assessments, techniques, outcomes

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Australian Guidelines and Resources

ANZCA Professional Documents

PS51: Perioperative Patient Safety

• Mandatory preoperative airway assessment
• Emergency airway equipment availability

PS41: Anaesthetic Machine Monitoring Standards

• Capnography mandatory for airway management
• Oxygenation monitoring requirements

Difficult Airway Society (DAS) Guidelines

2024 DAS Guidelines (Updated):

• Anticipated difficult airway management
• Unanticipated difficult intubation
• CICV scenario algorithms
• Front-of-neck access techniques

Australian Resuscitation Council (ARC)

Guideline 9.4.2: Airway Management

• Basic and advanced airway techniques
• Oxygenation prioritization
• Emergency airway equipment

State-Based Resources

Each Australian state provides:

• Difficult airway trolleys (standardized equipment)
• Training programs for airway management
• Clinical emergency response policies
• Access to airway simulation centres

New Zealand Resources

New Zealand Society of Anaesthetists:

• Airway management guidelines
• DAS guideline adaptation for NZ

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Indigenous Health Considerations

Aboriginal and Torres Strait Islander Perspectives

Aboriginal and Torres Strait Islander patients face unique challenges in difficult airway management that require culturally safe approaches:

Higher Prevalence of Risk Factors:

Aboriginal and Torres Strait Islander peoples have higher rates of conditions affecting airway management:

• Obesity — increased neck circumference, reduced FRC, rapid desaturation
• Type 2 diabetes mellitus — stiff joint syndrome, cervical spine disease
• Cardiovascular disease — reduced cardiopulmonary reserve
• Chronic respiratory disease — COPD, asthma, reduced functional reserve
• Obstructive sleep apnoea — upper airway obstruction, difficult ventilation
• Previous neck surgery or trauma — scarring, anatomical distortion

These comorbidities may require:

• Preoperative optimization
• Alternative anaesthetic techniques
• More aggressive preparation for difficult airway
• Extended postoperative monitoring

Communication and Understanding:

Medical terminology and airway management concepts require culturally safe explanation:

• Use simple, clear language
• Visual aids and diagrams for anatomical explanations
• Demonstration of equipment and techniques when possible
• Involvement of Aboriginal Health Workers (AHWs) or Aboriginal Hospital Liaison Officers (AHLOs) is crucial

Key points to communicate:

• What airway assessment involves and why it's important
• What "difficult airway" means
• What techniques will be used (awake fibreoptic, video laryngoscopy)
• Risks and benefits of different approaches
• Why specialist follow-up may be needed

Cultural Considerations in Crisis:

In CICV scenarios requiring emergency airway access:

• Family presence during resuscitation may be culturally important — facilitate where possible without compromising care
• Gender considerations — some Aboriginal cultures have protocols about who can touch or treat patients, particularly the head and neck
• Spiritual practices may be important during crisis — accommodate where possible
• If death occurs, follow appropriate cultural protocols and involve AHLO for family support
• Body handling protocols vary between communities — respect cultural restrictions

Access to Specialist Services:

Remote communities may have challenges with:

• Airway assessment expertise — limited access to specialists
• Equipment availability — difficult airway trolleys may not be available
• Training — staff may not be proficient in advanced airway techniques
• Transfer delays to tertiary centres for complex airway cases
• Follow-up — specialist allergy or airway testing may require travel

Considerations for remote settings:

• Use awake techniques where possible (safer if equipment limited)
• Plan for transfer if anticipated severe difficulty
• Consider regional anaesthesia as alternative
• Telemedicine consultation for complex cases
• Training of local staff in basic difficult airway management

Trust and Communication:

Building trust is essential:

• Take time to explain procedures
• Listen to patient concerns about airway management
• Acknowledge past experiences with healthcare
• Involve family in discussions when appropriate
• Respect cultural protocols around touch and examination

Māori Health Considerations (New Zealand)

For Māori patients, cultural safety principles apply:

Whānau (Family) Involvement:

• Involve whānau in airway assessment and planning
• Extended family decision-making in complex cases
• Explain procedures to family members

Tikanga (Cultural Protocols):

• Respect cultural protocols around the head (tapu - sacred)
• Karakia (prayer) may be requested before procedures
• Consider tikanga in body positioning and handling

Communication:

• Use Māori Health Workers for cultural safety
• Plain language explanations
• Visual aids may be more effective

Health Literacy:

• Many Māori patients may have lower health literacy
• Take time to explain in simple terms
• Demonstrate with models or diagrams

Access Issues:

• Geographic isolation may limit specialist access
• Consider local testing options when possible
• Telehealth for specialist consultation

Documentation:

• Ensure airway assessment documentation is clear
• Provide allergy alerts that are culturally appropriate
• Coordinate with primary care providers

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Assessment Content

SAQ Practice Question 1 (20 marks)

Question:

A 58-year-old man (85 kg, 178 cm) is scheduled for laparoscopic prostatectomy. On preoperative assessment, he reports previous difficulty with intubation during appendicectomy 20 years ago. He takes metformin for type 2 diabetes and has no other medical problems. Examination shows: inter-incisor distance 3.5 cm, thyromental distance 6 cm, sternomental distance 11.5 cm, Mallampati class III, neck extension 30°. Neck circumference is 42 cm.

(a) What further assessment would you perform? (4 marks)

(b) Outline your preoperative management of this patient. (6 marks)

(c) Describe your intraoperative airway management approach. (10 marks)

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Model Answer:

(a) Further Assessment (4 marks)

History [1.5 marks]

1. Details of previous difficult intubation:

   • What specifically was difficult? (visualization, tube passage, ventilation)
   • How many attempts were made?
   • What technique eventually succeeded?
   • Were there any complications? (dental injury, hypoxaemia, cardiac arrest)

2. Current symptoms:

   • Any difficulty breathing lying flat (orthopnoea)?
   • Snoring or sleep apnoea symptoms?
   • Recent voice changes or dysphagia?

3. Medication review:

   • Diabetes duration and control (stiff joint syndrome risk)
   • Any previous radiotherapy to neck?

Physical Examination [1.5 marks]

1. Temporomandibular joint (TMJ) assessment:

   • Range of motion (opening, lateral excursion)
   • Crepitus, clicking, or pain

2. Upper airway examination:

   • Nasal patency (if nasal intubation considered)
   • Soft palate and uvula (edema, scarring)
   • Tonsillar hypertrophy
   • Tongue size and mobility

3. Dental assessment:

   • Loose or protruding teeth
   • Upper incisor protrusion
   • Document dentition status

Radiological Assessment [1 mark]

• Lateral cervical spine X-ray:
  • Assess atlanto-occipital joint alignment
  • Look for subluxation or fusion
  • Check for reduced disc spaces
  • Consider CT scan if suspicion of retrosternal goitre

(b) Preoperative Management (6 marks)

Risk Stratification [1.5 marks] This patient has multiple predictors of difficult intubation:

• Inter-incisor 3.5 cm (borderline)
• Thyromental 6 cm (predictive of difficulty)
• Mallampati class III
• Neck extension 30° (<35°)
• Neck circumference 42 cm (>40 cm)
• Diabetes (stiff joint syndrome)
• Previous difficult intubation

Conclusion: Anticipated difficult airway requires planning.

Planning and Preparation [2 marks]

1. Anaesthetic Plan:

   • Awake fibreoptic intubation as primary technique (Plan A)
   • Alternative: Video laryngoscopy with bougie (Plan B)
   • Second-generation supraglottic airway as backup (Plan C)
   • Front-of-neck access equipment ready (Plan D)

2. Equipment Preparation:

   • Fibreoptic bronchoscope checked and functioning
   • Video laryngoscope available (Glidescope, C-MAC)
   • Various laryngoscope blades (Mac 3-4, Miller, McCoy)
   • Bougie (gum elastic)
   • Second-generation supraglottic airway (i-gel or LMA Supreme)
   • Cricothyrotomy kit (or scalpel, bougie, ETT)
   • Airway exchange catheters

3. Staffing:

   • Experienced anaesthetist available
   • Assistant trained in difficult airway management

Patient Preparation [1.5 marks]

1. Consent and Explanation:

   • Explain airway difficulty and planned technique
   • Discuss awake fibreoptic intubation (what it involves)
   • Outline risks and benefits
   • Provide opportunity for questions

2. Premedication:

   • Consider glycopyrrolate 0.2-0.4 mg IM to dry secretions
   • Consider sedation if cooperative patient (midazolam 1-2 mg PO)
   • Avoid excessive sedation that may compromise airway

3. Nasal preparation (if nasal route):

   • Phenylephrine or xylometazoline spray (vasoconstrictor)
   • Local anaesthetic gel or spray (lignocaine 4%)

Documentation [1 mark]

• Document all assessment findings
• Outline specific airway plan (Plan A-D)
• Record equipment available
• Note staff involved
• Provide patient with written information about airway difficulty

(c) Intraoperative Airway Management (10 marks)

Pre-oxygenation [1.5 marks]

• Apply high-flow oxygen (15 L/min) for 3-5 minutes
• Use tight-fitting face mask with reservoir bag
• Target end-tidal oxygen >90%
• Consider head-up position for obese patient
• Apnoeic oxygenation: Nasal cannula at 15 L/min during apnoea phase

Awake Fibreoptic Intubation (Plan A) [4 marks]

1. Patient Positioning:

   • Semi-sitting position (15-30° head elevation)
   • Neck flexed, head extended (optimal airway axis)
   • Operator positioned at head of bed

2. Airway Anaesthesia:

   • Superior laryngeal nerve block: 2 mL lignocaine 2% per side
   • Transtracheal injection: 2-4 mL lignocaine 4% through cricothyroid membrane
   • Topical anaesthesia:
     • Atomized lignocaine 4% to posterior pharynx
     • Lignocaine spray to larynx via suction catheter
     • Lidocaine gel to nares (if nasal route)

3. Fibreoptic Intubation:

   • Insert bronchoscope through mouth or nose
   • Identify epiglottis, then glottic opening
   • Pass ETT (size 7.0-7.5) over bronchoscope
   • Confirm placement with capnography
   • Secure ETT and connect to circuit

4. Verification:

   • Bilateral air entry
   • Capnography waveform (ETCO₂ 35-45 mmHg)
   • Chest wall movement
   • No leak

If Awake Fibreoptic Fails (Plan B) [2 marks]

1. Video Laryngoscopy:

   • Use C-MAC or Glidescope
   • Optimize view with BURP (backward, upward, rightward pressure)
   • Use bougie first if visualized
   • Consider alternative blade (Mac 4, McCoy)

2. Supraglottic Airway (Plan C):

   • If video laryngoscopy fails or SpO₂ <90%
   • Insert second-generation supraglottic airway (i-gel size 4-5)
   • Confirm seal and ventilation
   • Attempt intubation through SGA (if needed for procedure)

CICV Scenario (Plan D) [1.5 marks]

If unable to intubate AND unable to ventilate:

1. Declare CICV loudly — call for help immediately
2. Attempt front-of-neck access:
   • Surgical cricothyrotomy (scalpel-bougie-tube technique)
   • OR cannula cricothyrotomy (if less experienced)
3. Continue oxygenation attempts while performing cricothyrotomy
4. Do NOT continue failed techniques with worsening hypoxaemia

Post-Intubation Management [1 mark]

• Confirm tube position with capnography
• Secure tube appropriately
• Document intubation details (technique, attempts, complications)
• Consider postoperative admission for observation

Total: 20 marks

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Viva Scenario (25 marks)

Opening Stem:

You are the anaesthetist for a 45-year-old woman (72 kg, 160 cm) undergoing laparoscopic hysterectomy. She has rheumatoid arthritis with severe neck deformity and limited movement. Preoperative assessment shows: inter-incisor distance 4 cm, thyromental distance 5 cm, Mallampati class IV, neck extension 10°. She reports previous intubation was "very difficult" with multiple attempts.

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Expected Viva Progression:

Examiner: How would you manage this patient's airway?

Candidate Response: [5 marks]

"This patient has multiple severe predictors of difficult airway:

• Mallampati class IV
• Thyromental distance 5 cm (very low)
• Neck extension 10° (severely limited)
• Rheumatoid arthritis with cervical spine involvement
• Previous difficult intubation

This is an anticipated difficult airway requiring awake technique.

My Plan A is awake fibreoptic intubation:

Preparation:

1. Pre-oxygenate with high-flow oxygen (15 L/min, 3-5 minutes)
2. Airway anaesthesia:
   • Superior laryngeal nerve blocks (2 mL lignocaine 2% each side)
   • Transtracheal injection (2-4 mL lignocaine 4%)
   • Topical lignocaine spray to oropharynx
3. Sedation only if patient cooperative (midazolam 1-2 mg PO)
4. Nasal preparation if nasal route chosen (phenylephrine, lignocaine gel)

Technique:

1. Semi-sitting position
2. Insert fibreoptic bronchoscope (oral or nasal route)
3. Identify anatomical landmarks
4. Pass ETT over bronchoscope
5. Confirm with capnography

Backup Plans:

• Plan B: Video laryngoscopy with bougie
• Plan C: Second-generation supraglottic airway
• Plan D: Front-of-neck access (cricothyrotomy) if CICV

I would have all backup equipment ready before starting."

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Examiner: The patient refuses awake intubation. What do you do?

Candidate Response: [4 marks]

"If patient refuses awake technique, I need to discuss alternatives while maintaining safety:

1. Discuss concerns:

• What specifically concerns her about awake intubation?
• Misconceptions about the procedure?
• Anxiety or fear?

2. Address concerns:

• Explain procedure clearly (visual aids, demonstration)
• Emphasize safety of awake technique
• Discuss sedation options to minimize discomfort
• Reassure about ability to communicate and breathe

3. If she still refuses:

• Alternative techniques require general anaesthesia — higher risk
• Plan A becomes video laryngoscopy with bougie
• Plan B: Supraglottic airway (second-generation)
• Plan C: Front-of-neck access equipment ready
• Have most experienced anaesthetist present

4. Rediscuss with patient:

• Explain increased risk with general anaesthesia
• Present options clearly
• Allow informed decision-making
• Document discussion thoroughly

5. If she elects general anaesthesia:

• Optimize conditions:
  • Pre-oxygenate thoroughly
  • Apnoeic oxygenation (HFNC or nasal cannula 15 L/min)
  • Head-up position
  • Use video laryngoscope first
  • Have bougie and SGA ready
  • Maximum 2-3 attempts before escalating
  • Early use of supraglottic airway if failing"

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Examiner: You proceed with general anaesthesia. After 2 attempts at video laryngoscopy, you can only see the epiglottis (Cormack-Lehane III). SpO₂ is 88%. What do you do?

Candidate Response: [5 marks]

"With Cormack-Lehane III view, SpO₂ 88%, and 2 failed attempts, I need to maintain oxygenation and escalate quickly:

Immediate Actions:

1. Stop intubation attempts — hypoxaemia worsening
2. Call for help loudly — additional staff needed
3. Attempt face mask ventilation:
   • Two-person technique
   • Oral airway inserted
   • Optimize head position
4. Apply high-flow oxygen (15 L/min)

If ventilation possible:

• Continue oxygenation
• Proceed to Plan C: Second-generation supraglottic airway
• Insert i-gel size 4-5 (appropriate for patient size)
• Confirm seal and ventilation
• Consider procedure continuation with SGA or attempt intubation through SGA

If ventilation NOT possible (CICV scenario):

• Declare CICV loudly — this is an emergency
• Attempt front-of-neck access immediately
  • Surgical cricothyrotomy (scalpel-bougie-tube technique)
  • OR cannula cricothyrotomy (if less experienced)
• Continue attempts at oxygenation while performing cricothyrotomy

Time is critical:

• SpO₂ 88% → will continue to fall rapidly
• Maximum 60 seconds to secure airway before severe hypoxaemia
• Do NOT attempt additional laryngoscopy with worsening hypoxaemia
• Escalate immediately to rescue technique"

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Examiner: Describe the surgical cricothyrotomy technique.

Candidate Response: [5 marks]

"Surgical cricothyrotomy is definitive rescue for CICV. The scalpel-bougie-tube technique is preferred:

Preparation:

1. Identify cricothyroid membrane (palpate between thyroid and cricoid cartilages)
2. Clean skin
3. Stabilize larynx with non-dominant hand
4. Have bougie and small ETT (size 6.0) ready

Technique:

Step 1: Incision

• Use #11 or #10 scalpel blade
• Vertical incision through skin (1-2 cm)
• Identify cricothyroid membrane
• Horizontal incision through membrane

Step 2: Dilation

• Use scalpel handle or tracheal dilator
• Open incision widely
• Ensure space for ETT passage

Step 3: Bougie insertion

• Pass bougie through incision into trachea
• Confirm placement (feel tracheal rings, hold-up at carina)
• Maintain bougie position

Step 4: Tube insertion

• Slide ETT (size 6.0) over bougie
• Pass through incision into trachea
• Remove bougie

Step 5: Confirmation

• Connect to circuit
• Confirm with capnography (waveform, ETCO₂ 35-45 mmHg)
• Assess bilateral air entry
• Secure tube

Alternative: Cannula Cricothyrotomy

• Use 14G cannula inserted at 45° caudally
• Connect to high-pressure oxygen source
• Jet ventilation (15 L/min, 1 Hz)
• Less reliable — proceed to surgical if possible

Key Points:

• Success rate >95% when performed by trained clinicians
• Speed is critical — complete within 60 seconds
• Maintain oxygenation attempts throughout
• Have all equipment ready before attempting"

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Examiner: The patient is successfully intubated via cricothyrotomy. What is your postoperative management?

Candidate Response: [3 marks]

"Postoperative management after surgical airway:

Immediate:

1. Secure tube — confirm position, secure with ties
2. ICU admission mandatory — airway specialist involvement
3. Monitoring:
   • Continuous ECG, SpO₂, capnography
   • Invasive arterial pressure (if not already)
   • Airway observation for bleeding, tube displacement

Airway assessment:

• ENT/Maxillofacial review — assess airway trauma
• Fibreoptic examination — evaluate airway injury
• CT scan if concerns about vascular injury or missed injury

Management:

• Elective tracheostomy within 24-48 hours (long-term airway)
• OR extubation once airway edema resolves and oral route secured
• Dexamethasone 8 mg IV q6h (reduce airway edema)
• Antibiotics if airway contamination suspected

Documentation:

• Detailed incident report with timeline
• Note airway technique used (scalpel-bougie-tube)
• Record complications or difficulties
• Document postoperative plan

Follow-up:

• Airway specialist follow-up
• Document airway difficulty prominently
• Provide patient with information about airway for future procedures
• Consider anaesthetic clinic referral"

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Examiner: How would you have managed this patient differently if you had 48 hours to prepare?

Candidate Response: [3 marks]

"With 48 hours preparation, I would have undertaken more thorough assessment and planning:

Enhanced Assessment:

1. Cervical spine imaging:

   • Lateral X-ray (flexion/extension views)
   • Assess atlanto-occipital joint alignment
   • Look for subluxation or fusion
   • Consider CT scan if abnormal findings

2. Airway imaging:

   • CT scan of head and neck
   • 3D reconstruction for airway anatomy
   • Identify masses, abscesses, or distortion

3. Virtual bronchoscopy:

   • Plan fibreoptic route
   • Identify potential obstacles

Multidisciplinary Planning:

1. Consult airway specialist (ENT surgeon)

   • Discuss potential need for tracheostomy
   • Plan for surgical airway if needed
   • Discuss awake vs general anaesthetic approach

2. Schedule as first case:

   • Well-rested, experienced staff available
   • Fresh equipment checked
   • Adequate time for procedure

3. Team briefing:

   • Review airway plan with entire theatre team
   • Assign roles (airway assistant, equipment management)
   • Emergency plan review

Alternative Anaesthetic Options:

1. Regional anaesthesia — discuss with surgical team

   • Consider spinal or epidural for gynaecological surgery
   • May be appropriate depending on procedure

2. Delayed surgery if very high risk

   • Optimize medical conditions
   • Obtain further specialist input
   • Reassess airway

Patient Preparation:

1. Extended consent discussion

   • Detailed explanation of airway risks
   • Discussion of alternative approaches
   • Written information provided
   • Opportunity to ask questions

2. Fasting and medication optimization

   • Continue RA medications as indicated
   • Optimize diabetes control
   • Discontinue medications that may increase bleeding risk

Equipment and Staffing:

1. Airway equipment checked

   • Fibreoptic bronchoscope functioning
   • Video laryngoscope available
   • All backup devices ready
   • Cricothyrotomy kit assembled

2. Staffing

   • Most experienced anaesthetist available
   • Second anaesthetist as assistant
   • ENT surgeon present or immediately available

This comprehensive preparation allows for safer approach and reduces risk of emergency CICV scenario."

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Total: 25 marks