Difficult Airway Management

Quick Answer

One-liner: Difficult airway is the clinical scenario where a trained practitioner experiences difficulty with face-mask ventilation, intubation, or SGA placement—requiring systematic optimisation, rescue strategies, and readiness for emergency surgical airway (CICO/FONA).

The difficult airway occurs in 1-6% of emergency department intubations and carries mortality of 25-30% if mismanaged, particularly in the "Can't Intubate, Can't Oxygenate" (CICO) scenario [1]. The key to success is prediction, preparation, optimisation, and early declaration of CICO with immediate front-of-neck access (FONA). Australian practice follows the Vortex approach and DAS/ANZCA guidelines, emphasising that death from hypoxia is preventable if FONA is performed without delay [2].

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ACEM Exam Focus

Primary Exam Relevance

• Anatomy: Cricothyroid membrane location (13mm height × 22-30mm width), thyroid/cricoid cartilages, external landmarks (Adam's apple, sternal notch), neck zones, laryngeal nerve anatomy [3]
• Physiology: Oxygen cascade, functional residual capacity (FRC), safe apnoea time (adults 3-8 min, children 1-3 min), desaturation curve, alveolar gas equation, preoxygenation physiology [4]
• Pharmacology: Neuromuscular blockers (suxamethonium vs rocuronium), sugammadex reversal, induction agents (ketamine vs propofol), opioids for haemodynamic blunting [5]

Fellowship Exam Relevance

• Written: SAQs on CICO algorithm, difficult airway prediction (LEMON/MOANS/RODS), complications of emergency airway, bougie vs stylet, VL vs DL evidence [6]
• OSCE: Resuscitation stations requiring airway rescue, SGA insertion, declaration of CICO, FONA demonstration on manikin, team leadership and communication [7]
• Key domains tested: Medical Expert, Communicator, Collaborator, Leader

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Key Points

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Epidemiology

Australian/NZ Specific Data

• NAP4 (4th National Audit Project): Major airway complications more common in ICU/ED (61%) than operating theatre—higher risk of death/brain damage outside OR [14]
• Remote/Rural: RFDS retrieval data shows higher difficult airway rates in resource-limited settings—telemedicine support recommended [15]
• Indigenous populations: Higher rates of obesity, OSA, and diabetic stiff joint syndrome contributing to difficult airways—cultural safety essential [16]

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Definitions

What is a Difficult Airway?

The Difficult Airway is defined as a clinical situation in which a conventionally trained clinician experiences difficulty with one or more of [17]:

1. Difficult face-mask ventilation: Unable to provide adequate ventilation due to inadequate seal, excessive gas leak, or excessive resistance
2. Difficult laryngoscopy: Cannot visualise any portion of glottis with conventional laryngoscopy after multiple attempts
3. Difficult intubation: Requires multiple attempts or devices; Cormack-Lehane Grade III-IV
4. Difficult SGA placement: Requires multiple attempts, devices, or fails to provide adequate ventilation
5. Difficult surgical airway: Abnormal anatomy precluding standard FONA technique

Can't Intubate, Can't Oxygenate (CICO)

CICO Definition: Failure to oxygenate the patient despite optimal attempts with face mask, supraglottic airway, AND endotracheal tube [18]

This is a life-threatening emergency requiring immediate front-of-neck access (FONA). Do not wait for cardiac arrest.

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Difficult Airway Prediction

LEMON Assessment (Difficult Laryngoscopy/Intubation)

MOANS Assessment (Difficult Bag-Mask Ventilation)

RODS Assessment (Difficult SGA Placement)

SMART Assessment (Difficult Surgical Airway/FONA)

The 3-3-2 Rule

Cormack-Lehane Grading

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The Vortex Approach

Cognitive Aid for Airway Emergency

The Vortex approach is an Australian cognitive aid developed by Nicholas Chrimes to prevent fixation error and ensure timely progression to FONA in CICO [23].

The Three Lifelines

                    ┌─────────────────────┐
                    │    FACE MASK        │
                    │   (Lifeline 1)      │
                    └──────────┬──────────┘
                               │
              ┌────────────────┼────────────────┐
              │                │                │
              ▼                ▼                ▼
    ┌─────────────────┐  ┌──────────┐  ┌─────────────────┐
    │     3 best      │  │ Optimise │  │     3 best      │
    │    attempts     │←─┤ between  ├─→│    attempts     │
    │    (max)        │  │ attempts │  │    (max)        │
    └─────────────────┘  └──────────┘  └─────────────────┘
              │                                 │
              │     ┌─────────────────────┐     │
              └────→│  SUPRAGLOTTIC AIRWAY│←────┘
                    │    (Lifeline 2)     │
                    └──────────┬──────────┘
                               │
              ┌────────────────┼────────────────┐
              │                │                │
              ▼                ▼                ▼
    ┌─────────────────┐  ┌──────────┐  ┌─────────────────┐
    │     3 best      │  │ Optimise │  │     3 best      │
    │    attempts     │←─┤ between  ├─→│    attempts     │
    │    (max)        │  │ attempts │  │    (max)        │
    └─────────────────┘  └──────────┘  └─────────────────┘
              │                                 │
              │     ┌─────────────────────┐     │
              └────→│  ENDOTRACHEAL TUBE  │←────┘
                    │    (Lifeline 3)     │
                    └──────────┬──────────┘
                               │
                               ▼
               ALL THREE LIFELINES FAILED
               + CANNOT OXYGENATE PATIENT
                               │
                               ▼
                    ┌─────────────────────┐
                    │       C I C O       │
                    │  ==================  │
                    │  FRONT-OF-NECK      │
                    │  ACCESS (FONA)      │
                    │  Scalpel-Bougie-Tube│
                    └─────────────────────┘

Key Vortex Principles

1. Maximum 3 attempts at each lifeline (provided you are still oxygenating)
2. Optimise between attempts: Change something—operator, technique, equipment, position, paralysis
3. "Green zone": Patient is oxygenated—you have time to troubleshoot
4. "CICO zone": Cannot oxygenate—immediate FONA, no more upper airway attempts
5. Do not fixate on one technique—if not working, move to next lifeline
6. Declare CICO verbally: Say it out loud so the team knows

Optimisation Between Attempts

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DAS/ANZCA Algorithm: Plan A-D

Plan A: Primary Intubation

Goal: Successful first-pass intubation with optimal conditions

1. Optimise position: Ramped position, ear-to-sternal notch alignment
2. Preoxygenate: 3 minutes tidal breathing or 8 vital capacity breaths, target EtO2 over 85%
3. Apnoeic oxygenation: Nasal prongs at 15L/min during attempt
4. Maximum 3 attempts (+ 1 by most experienced operator)
5. Use video laryngoscopy if predicted difficult airway
6. Use bougie for Cormack-Lehane IIb or worse

Plan B: Supraglottic Airway

Goal: Oxygenate via SGA if intubation fails

1. Insert 2nd generation SGA (i-gel, LMA ProSeal, LMA Supreme)
2. Maximum 3 attempts with optimisation
3. If ventilating via SGA: Consider intubating through SGA or waking patient
4. If NOT ventilating: Proceed to Plan C

Plan C: Final Attempt at Face Mask Ventilation

Goal: Last attempt at upper airway oxygenation before FONA

1. Optimise paralysis: Ensure full neuromuscular blockade
2. Two-person technique: One holds mask, one squeezes bag
3. Adjuncts: Oral and nasal airways
4. Maximum 1 minute: Do not delay FONA

Plan D: Emergency Front-of-Neck Access (FONA)

Goal: Immediate surgical access when CICO declared

CICO Declaration: "This is CICO. I am performing front-of-neck access now."

Scalpel-Bougie-Tube Technique (DAS 2015/2025 recommended) [24]:

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Emergency Front-of-Neck Access (FONA)

Indications for FONA

Scalpel-Bougie-Tube Technique (Gold Standard)

This is the recommended emergency cricothyroidotomy technique in Australia/NZ and internationally [25].

Equipment Required (CICO Kit)

Step-by-Step Technique

Step 1: Position and Landmark Identification (5-10 seconds)

1. Extend neck maximally (if no C-spine concern)
2. "Laryngeal handshake": Non-dominant hand stabilises larynx
3. Identify cricothyroid membrane (CTM):
   • Midline, between thyroid and cricoid cartilages
   • Soft depression below Adam's apple
   • Average size: 13mm (height) × 22-30mm (width)
4. If landmarks impalpable: Make 8-10cm vertical midline incision to expose anatomy

Step 2: Vertical Skin Incision (2-3 seconds)

• Large vertical incision through skin over CTM
• Length: 4-8cm (generous incision = better access)
• Stabilise larynx with non-dominant hand throughout

Step 3: Horizontal Stab Through CTM (2-3 seconds)

• Transverse (horizontal) stab through CTM with scalpel
• Incise entire width of membrane
• Turn blade 90° (sharp edge caudal) to keep hole open

Step 4: Bougie Insertion (2-3 seconds)

• Slide coudé-tip bougie alongside blade into trachea
• Direct bougie caudally (toward feet)
• Confirm tracheal placement: Feel clicks of tracheal rings or resistance at carina

Step 5: Tube Railroading (5-10 seconds)

• Lubricate 6.0mm cuffed ETT
• Railroad over bougie into trachea
• Rotate 90° anticlockwise as entering CTM to reduce hang-up
• Remove bougie once tube in place

Step 6: Confirmation and Securing (10-15 seconds)

• Inflate cuff
• Confirm with capnography (gold standard)
• Secure tube
• Ventilate and reassess

Alternative FONA Techniques

Impalpable CTM ("Can't Feel It")

In 5-10% of patients, the CTM cannot be palpated (obesity, oedema, tumour, previous surgery) [26].

Approach for Impalpable CTM:

1. Attempt "laryngeal handshake": Feel for thyroid cartilage moving
2. Ultrasound (if available and trained): Rapid landmark identification
3. If landmarks truly impalpable:
   • Make 8-10cm vertical midline incision from chin to sternal notch
   • Blunt dissection through subcutaneous tissue
   • Identify trachea and CTM by feel
   • Complete scalpel-bougie-tube technique

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Video Laryngoscopy

Role in Difficult Airway Management

Video laryngoscopy (VL) has become first-line for predicted difficult airways and is increasingly used as default in emergency airway management [27].

VL vs Direct Laryngoscopy: Evidence

VL Devices Available in Australia/NZ

VL Technique Tips

1. Insert midline (unlike DL where tongue is swept left)
2. Do not over-advance—stay in vallecula or lift epiglottis
3. Eye on screen, not mouth—trust the video
4. Optimise tube delivery—stylet with anterior curve, bougie often helpful
5. Avoid "sword fighting"—if tube won't pass, use bougie

When to Use VL First

• Predicted difficult airway (any positive LEMON component)
• Failed first DL attempt
• Cervical spine immobilisation
• Limited mouth opening
• Obesity
• Blood/secretions in airway
• Trainee/learning

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Bougie Technique

The Bougie: Essential Airway Adjunct

The bougie (also called Eschmann stylet or gum elastic bougie) is a critical tool for difficult intubation [33].

Evidence for Bougie Use

• BEAM trial (2018): Bougie-first approach had higher first-pass success (98% vs 87%) and fewer complications than stylet-first in ED intubation [34]
• Recommended as first-line adjunct in difficult airways (DAS/ANZCA guidelines)
• Particularly useful for Cormack-Lehane grade IIb-III views

Bougie Technique

1. Position bougie: Coudé (angled) tip anterior
2. Insert under vision: Slide bougie toward glottis with laryngoscope in place
3. Aim for anterior commissure: If view is poor, aim for anterior (12 o'clock)
4. Feel for "clicks": Tracheal rings confirm placement (60-90% sensitivity)
5. Railroad tube: Keep bougie still, slide lubricated ETT over it
6. Rotate tube: 90° anticlockwise rotation reduces arytenoid hang-up
7. Confirm placement: Capnography mandatory

Bougie Indications

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Supraglottic Airways as Rescue

Role of SGA in Difficult Airway

Supraglottic airways (SGAs) are the critical "rescue" device when intubation fails [35].

Second-Generation SGAs (Preferred)

SGA Insertion Tips

1. Full paralysis helps—especially if jaw tight
2. Jaw thrust by assistant during insertion
3. Gel-based lubricant on posterior aspect
4. Correct size selection:
   • Size 3: under 50kg
   • Size 4: 50-70kg
   • Size 5: over 70kg
5. Check seal pressure: Aim for seal over 25 cmH2O

Intubation Through SGA

If SGA providing adequate ventilation but patient needs definitive airway:

• Use intubating LMA (Fastrach) or Ambu AuraGain
• Pass ETT through SGA with or without fibreoptic guidance
• Remove SGA after ETT confirmed in place

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Equipment Preparation

The Difficult Airway Trolley

Every ED must have a dedicated difficult airway trolley, checked daily [36].

Essential Equipment List

CICO Kit Configuration

Minimum contents for CICO kit:

1. Scalpel with size 10 or 20 blade
2. Bougie (with coudé tip)
3. Cuffed 6.0mm ETT
4. 10mL syringe (for cuff)
5. Water-based lubricant
6. Tape or tie

This kit should be immediately accessible (on trolley or attached to it) and checked daily.

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Human Factors and Team Communication

Why Human Factors Matter

NAP4 findings: Human factors were contributory in 40% of major airway complications [37].

Key issues identified:

• Fixation error: Repeated attempts at failed technique
• Delayed CICO declaration: Reluctance to "give up"
• Poor communication: Team unaware of status
• Inadequate planning: No backup strategy
• Equipment failures: Unfamiliar devices, missing equipment

Closed-Loop Communication

Role Assignment (Airway Emergency)

Declaring CICO

Say it clearly and loudly:

"This is a CICO situation. I am proceeding to front-of-neck access. Please prepare scalpel, bougie, and 6.0 tube."

Everyone must hear and acknowledge. The team then:

• Stops upper airway attempts
• Hands FONA equipment
• Continues oxygenation attempts if possible while FONA prepared
• Documents time of declaration

Cognitive Aids

Use cognitive aids (Vortex poster, DAS algorithm) on the wall in resus bay:

• Reduces memory burden
• Provides shared mental model
• Prompts team to progress
• Visible to all team members

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Special Populations

Paediatric Considerations

Paediatric FONA:

• Under 8 years: Needle cricothyroidotomy with jet ventilation is traditional recommendation
• Scalpel techniques increasingly used in older children
• CTM is very small in infants—consider percutaneous tracheostomy if time permits

Pregnancy

• Increased difficult airway risk: Airway oedema, breast hypertrophy, weight gain [38]
• Rapid desaturation: Reduced FRC, increased oxygen consumption
• Left lateral tilt: Maintain until airway secured
• Smaller ETT: Consider 6.5-7.0mm (oedema reduces glottic size)
• Early SGA use: Lower threshold for rescue
• CICO still requires FONA: Do not delay—foetal survival depends on maternal survival

Obesity

• High risk of difficult airway: BMV, intubation, SGA all more difficult [39]
• Ramped position: Essential—ear at level of sternal notch
• Rapid desaturation: Reduced FRC, higher O2 consumption
• Consider awake intubation if predicted very difficult
• Impalpable CTM: May need larger incision for FONA
• Use VL first-line: Better views than DL
• Second-generation SGA: Higher seal pressures

Elderly

• Increased aspiration risk: Slower reflexes, reduced lower oesophageal sphincter tone
• Cervical degeneration: Limited neck extension
• Dentition: Loose teeth, edentulous (affects BMV)
• Reduced physiological reserve: Less tolerance for hypoxia/hypotension
• Dose adjustments: Reduced induction agent and paralytic doses

Cervical Spine Injury

• Maintain MILS: Manual in-line stabilisation during intubation
• Remove front of collar: Allows mouth opening while assistant maintains stabilisation
• VL preferred: Better views with reduced neck movement
• Bougie helpful: Anterior approach often needed
• Fibreoptic option: Awake fibreoptic intubation in cooperative patient

Indigenous Health

Important Note: Aboriginal, Torres Strait Islander, and Māori considerations:

• Higher comorbidity burden: Diabetes (stiff joint syndrome), obesity, OSA—all increase difficult airway risk
• Cultural safety: Explain all procedures clearly, involve family if patient wishes
• Interpreter services: Use trained interpreters for complex consent discussions
• Remote communities: May present late with advanced pathology (large neck masses, etc.)
• Retrieval considerations: Plan for potential RFDS transfer early
• Post-procedure care: Ensure culturally appropriate follow-up and support
• Shared decision-making: Respect patient and family autonomy in decisions about airway management

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Preoxygenation and Apnoeic Oxygenation

Preoxygenation Targets

Techniques

Apnoeic Oxygenation

Purpose: Extend safe apnoea time by delivering oxygen during laryngoscopy attempts

Technique:

• Nasal cannula at 15L/min (standard)
• Or HFNO at 60-70L/min (if available)
• Continue throughout intubation attempts

Evidence:

• Extends safe apnoea time by 2-5 minutes [40]
• Particularly beneficial in obese and critically ill
• Recommended in all emergency intubations

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Physiologically Difficult Airway

Definition

The physiologically difficult airway refers to patients with deranged physiology who are at high risk of peri-intubation complications (hypotension, cardiac arrest) even with technically successful intubation [41].

High-Risk Physiological States

Push-Dose Pressors

Have ready before induction in physiologically unstable patient:

• Phenylephrine 100mcg/mL (mix 10mg/10mL, draw 1mL = 1mg, dilute to 10mL = 100mcg/mL)
• Epinephrine 10mcg/mL (dilute 1:1000 in 100mL = 10mcg/mL)
• Give 50-200mcg phenylephrine or 10-20mcg epinephrine for peri-intubation hypotension

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Complications of Emergency Airway Management

Immediate Complications

FONA Complications

Post-Intubation Care

1. Confirm tube position: Capnography (gold standard), auscultation, CXR
2. Secure tube: Tape or tie, note depth (cm at teeth)
3. Ventilate: Protective ventilation (6-8 mL/kg IBW, PEEP 5-10)
4. Sedate/Paralyse: Ongoing sedation ± paralysis
5. Insert NGT: Decompress stomach (aspiration prevention)
6. Document: Record all attempts, drugs, ETT size and depth, complications

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Remote and Rural Considerations

Pre-Hospital Difficult Airway

• Limited resources: May only have basic equipment
• Environment: Poor lighting, patient access, movement (ambulance, helicopter)
• Decision-making: SGA may be definitive airway for transport
• Telemedicine: Retrieval physician guidance via video link

Resource-Limited Settings

RFDS Retrieval Considerations

• Early consultation: Call retrieval for advice before difficult airway attempt
• Double setup: Always prepare for CICO
• Definitive airway preferred: ETT preferred over SGA for long transport
• Video call guidance: Retrieval specialist can talk through FONA if needed
• Document everything: Comprehensive handover to receiving team

Telemedicine in Airway Emergency

• Video link to airway expert (retrieval, anaesthetics)
• Real-time guidance through difficult situations
• Support for CICO declaration and FONA
• Available via RFDS, state retrieval services

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Pitfalls and Pearls

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Viva Practice

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OSCE Scenarios

Station 1: CICO Declaration and FONA

Format: Resuscitation/Procedural Time: 11 minutes Setting: ED resuscitation bay with manikin

Candidate Instructions:

You are the emergency physician in charge of a resuscitation. A 45-year-old male with epiglottitis has been induced for RSI. Multiple intubation and SGA attempts have failed. SpO2 is 65% and falling. The nursing staff tell you they cannot ventilate the patient. Demonstrate your management including any procedures required.

Examiner Instructions:

• Manikin set up for FONA procedure
• Candidate should declare CICO verbally
• Candidate should demonstrate scalpel-bougie-tube technique
• Time starts when candidate enters room
• At 5 minutes, prompt "SpO2 is now 45%, what are you going to do?"

Actor/Patient Brief:

• Playing role of ED nurse
• Provide information when asked: "We've tried face mask twice, i-gel size 4 and 5, three ETT attempts with video laryngoscope. Nothing working."
• When candidate declares CICO: "What do you need me to get?"

Marking Criteria:

Expected Standard:

• Pass: ≥7/11
• Key discriminators: Early CICO declaration, correct technique sequence, team leadership

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Station 2: Difficult Airway Assessment and Planning

Format: History and Planning Time: 11 minutes Setting: ED cubicle

Candidate Instructions:

A 58-year-old male is booked for procedural sedation for reduction of a dislocated shoulder. The ED nurse is concerned he may be a difficult airway. Assess this patient's airway and formulate an airway management plan. Explain your plan to the examiner.

Examiner Instructions:

• Patient has: BMI 38, Mallampati IV, mouth opening 2.5 fingers, thyromental distance 2 fingers, limited neck extension, beard
• Candidate should perform LEMON/MOANS/RODS assessment
• Candidate should formulate a safe plan (may include deferring sedation)

Actor/Patient Brief:

• BMI appears obese, short neck
• When asked to open mouth: "I can only open it this much" (2.5 fingers)
• When asked to extend neck: "My neck is stiff, I can't move it much"
• If asked about snoring: "My wife says I snore terribly and stop breathing at night"

Marking Criteria:

Expected Standard:

• Pass: ≥7/11
• Key discriminators: Complete assessment, recognition of multiple predictors, safe plan

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Station 3: Rescue SGA Insertion

Format: Procedural Time: 11 minutes Setting: Resuscitation bay with manikin

Candidate Instructions:

You are managing an airway emergency. Intubation has failed twice and the patient's SpO2 is dropping. You have decided to insert a supraglottic airway as rescue. Demonstrate SGA insertion on this manikin and describe your technique.

Examiner Instructions:

• Manikin set up for SGA insertion
• Provide i-gel (size 4) and LMA Supreme (size 4) as options
• Assess technique and troubleshooting
• After first insertion, say "The SGA is in but you cannot ventilate adequately, what do you do?"

Marking Criteria:

Expected Standard:

• Pass: ≥7/11
• Key discriminators: Correct technique, troubleshooting response

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SAQ Practice

Question 1: CICO Algorithm (8 marks)

Stem: A 52-year-old woman undergoes RSI for status epilepticus. After induction, the anaesthetic registrar is unable to intubate despite three attempts with video laryngoscopy. Bag-mask ventilation is difficult, with SpO2 falling to 70%.

Question: Outline the steps you would take from this point. (8 marks)

Model Answer:

1. Declare "failed intubation" and call for help (0.5 marks)
2. Optimise bag-mask ventilation - two-person technique, adjuncts (oral/nasal airway), jaw thrust (1 mark)
3. Continue apnoeic oxygenation - nasal prongs 15L/min (0.5 marks)
4. Insert supraglottic airway (Plan B) - second-generation SGA (i-gel or LMA Supreme) (1 mark)
   • Maximum 3 attempts with optimisation between each (0.5 marks)
5. If SGA fails - final attempt at bag-mask (Plan C) with full optimisation (0.5 marks)
6. If cannot oxygenate with any technique - Declare CICO verbally (1 mark)
7. Perform front-of-neck access (Plan D) - scalpel-bougie-tube technique (1 mark)
   • Vertical skin incision, horizontal stab through CTM (0.5 marks)
   • Bougie insertion with confirmation of tracheal rings (0.5 marks)
   • Railroad 6.0mm ETT over bougie (0.5 marks)
8. Confirm placement with capnography, secure tube (0.5 marks)

Examiner Notes:

• Accept: Vortex terminology (lifelines), mentioning specific SGA devices
• Do not accept: More than 3 ETT attempts, waiting for cardiac arrest before FONA

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Question 2: Difficult Airway Prediction (6 marks)

Stem: A 68-year-old male presents with sepsis requiring intubation. He is obese (BMI 36), has a short neck, limited mouth opening, and history of radiation therapy to the neck for laryngeal cancer 5 years ago.

Question: Using the LEMON mnemonic, identify the features that predict a difficult airway in this patient. (6 marks)

Model Answer:

• L - Look externally: Obesity, short neck = likely difficult (1 mark)
• E - Evaluate 3-3-2: Limited mouth opening suggests less than 3 fingers inter-incisor distance = difficult (1 mark)
• M - Mallampati: Not assessed but obesity suggests likely high grade (0.5 marks)
• O - Obstruction/Obesity: BMI 36 = obesity; history of laryngeal cancer = possible obstruction or distorted anatomy (1.5 marks)
• N - Neck mobility: Previous radiation causes fibrosis and limits neck extension; short neck limits positioning (1 mark)

Additional concern (1 mark):

• SMART assessment: Previous radiation and surgery = high risk of difficult FONA (landmarks may be distorted, fibrosis)

Examiner Notes:

• Accept: Mentioning MOANS/RODS features that overlap (obesity affects BMV, radiation affects SGA)
• Key point: Multiple predictors = high-risk case requiring expert help

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Question 3: Video Laryngoscopy Evidence (6 marks)

Stem: Your department is considering purchasing video laryngoscopes.

Question: Outline the evidence supporting the use of video laryngoscopy compared to direct laryngoscopy for emergency intubation. (6 marks)

Model Answer:

1. First-pass success: VL has higher first-pass success rates (85-91%) compared to DL (75-84%) - OR 1.5-2.0 favouring VL (1.5 marks)

2. Glottic visualisation: VL provides better glottic views in 92-99% of cases vs 80-90% for DL; typically 1-2 Cormack-Lehane grade improvement (1.5 marks)

3. Difficult airways: VL particularly superior in predicted difficult airways (C-spine immobilisation, obesity, limited mouth opening) with success rates of 90-95% vs 60-75% (1 mark)

4. Complication rates: Similar overall complication rates between VL and DL in meta-analyses (0.5 marks)

5. Training/Learning: VL allows supervision (both can see screen), may improve training (0.5 marks)

6. Caveats: VL requires tube delivery optimisation (stylet curve, bougie); bloody/secretion-filled airways may obscure view; some learning curve; cost considerations (1 mark)

Examiner Notes:

• Accept: Referencing specific trials (BEAM, DEVICE, etc.)
• Key message: VL is superior for visualisation and first-pass success; first-line for predicted difficult airway

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Question 4: Preoxygenation Physiology (6 marks)

Stem: Explain the physiological principles behind preoxygenation and apnoeic oxygenation in emergency airway management.

Question: Describe the physiology of preoxygenation and how apnoeic oxygenation extends safe apnoea time. (6 marks)

Model Answer:

Preoxygenation:

1. Denitrogenation: Replaces nitrogen in FRC with oxygen (1 mark)

   • FRC is the main oxygen reservoir during apnoea (~30mL/kg in adults)
   • Normal FRC contains ~450mL O2; after preoxygenation ~3000mL O2

2. Oxygen stores: Increases total body oxygen stores from ~1500mL to ~4000mL (0.5 marks)

3. Targets: EtO2 over 85% confirms adequate denitrogenation; SpO2 ≥98% before induction (0.5 marks)

4. Techniques: 3 minutes tidal breathing OR 8 vital capacity breaths with high-flow O2 (0.5 marks)

Apnoeic oxygenation:

1. Aventilatory mass flow: During apnoea, oxygen diffuses from alveoli to blood at ~250mL/min, but CO2 only rises ~8-16mL/min (due to buffering/CO2 stores) (1.5 marks)

2. Negative pressure gradient: This creates a net negative pressure in alveoli, drawing oxygen in from upper airway if oxygen-rich gas is present (pharyngeal insufflation) (1 mark)

3. Effect: Extends safe apnoea time by 2-5 minutes in most patients (0.5 marks)

4. Technique: Nasal cannula 15L/min or HFNO 60L/min throughout laryngoscopy attempts (0.5 marks)

Examiner Notes:

• Accept: Discussion of FRC variations (reduced in obesity, pregnancy)
• Key concepts: Denitrogenation, aventilatory mass flow, pharyngeal insufflation

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Australian Guidelines and Context

ARC/ANZCOR Guidelines

• ANZCOR Guideline 4: Airway management in cardiac arrest - SGA acceptable alternative to ETT
• ANZCOR Guideline 11.6: Adult advanced life support - includes airway management
• Key differences from AHA/ERC: ARC emphasises SGA as equivalent to ETT in cardiac arrest

ANZCA Professional Documents

• PS61: Guidelines on Sedation and/or Analgesia for Diagnostic and Interventional Procedures
• PG56: Guidelines on Equipment to Manage a Difficult Airway During Anaesthesia
• Position on CICO: Scalpel-bougie-tube technique endorsed as primary FONA approach

Therapeutic Guidelines Australia

• Recommendations align with international standards: DAS/ANZCA/ARC algorithms
• Equipment standards: Define minimum equipment for airway management in Australian facilities

State-Specific Protocols

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Remote/Rural Considerations

Pre-Hospital Airway Management

• Paramedic scope: Variable SGA and ETT skills depending on training level
• RFDS capabilities: Advanced airway with retrieval physician
• Decision-making: May need to accept SGA as definitive for transport

Resource-Limited Settings

Retrieval Medicine Considerations

• Pre-retrieval advice: Call early for predicted difficult airway
• Double setup: Always prepare for CICO before induction
• Telemedicine support: Video guidance for FONA if needed
• Documentation: Comprehensive handover to receiving hospital

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References

Guidelines

1. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth. 2015;115(6):827-848. PMID: 26556848

2. Chrimes N. The Vortex: a universal 'high-acuity implementation tool' for emergency airway management. Br J Anaesth. 2016;117(Suppl 1):i20-i27. PMID: 27566790

3. Ahmad I, El-Boghdadly K, Iliff H, et al. Difficult Airway Society 2025 guidelines for management of unanticipated difficult tracheal intubation in adults. Br J Anaesth. 2026;136(1):283-307. PMID: 41203471

Key Evidence

4. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2012;59(3):165-175. PMID: 22050948

5. Kornas RL, Owyang CG, Sakles JC, et al. Evaluation and Management of the Physiologically Difficult Airway: Consensus Recommendations From Society for Airway Management. Anesth Analg. 2021;132(2):395-405. PMID: 33060492

6. Law JA, Duggan LV, Asselin M, et al. Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Can J Anaesth. 2021;68(9):1405-1436. PMID: 34105065

7. Karamchandani K, Wheelwright J, Yang AL, et al. Emergency Airway Management Outside the Operating Room. Anesth Analg. 2021;133(3):648-662. PMID: 34153007

8. Walls RM, Brown CA 3rd, Bair AE, Pallin DJ; NEAR II Investigators. Emergency airway management: a multi-center report of 8937 emergency department intubations. J Emerg Med. 2011;41(4):347-354. PMID: 20434289

9. Kheterpal S, Han R, Tremper KK, et al. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology. 2006;105(5):885-891. PMID: 17065880

10. Cook TM, Woodall N, Frerk C; Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project. Part 1: anaesthesia. Br J Anaesth. 2011;106(5):617-631. PMID: 21447488

11. Joffe AM, Aziz MF, Posner KL, et al. Management of Difficult Tracheal Intubation: A Closed Claims Analysis. Anesthesiology. 2019;131(4):818-829. PMID: 31335549

12. Cook TM, Woodall N, Harper J, Benger J; Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project. Part 2: intensive care and emergency departments. Br J Anaesth. 2011;106(5):632-642. PMID: 21447489

13. Langvad S, Hyldmo PK, Nakstad AR, et al. Emergency cricothyrotomy - a systematic review. Scand J Trauma Resusc Emerg Med. 2013;21:43. PMID: 23718757

14. Cook TM, Woodall N, Frerk C. NAP4: Serious Airway Events in UK Anaesthesia, ICU and ED. Summary Report. Royal College of Anaesthetists. 2011.

15. Fitzgerald M, Broder J, Pham K, et al. Remote airway management in emergency medicine. Emerg Med Australas. 2018;30(5):608-617. PMID: 29939438

16. Australian Institute of Health and Welfare. Indigenous health statistics. AIHW. 2023.

17. Apfelbaum JL, Hagberg CA, Connis RT, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2022;136(1):31-81. PMID: 34762729

18. Heard AMB, Green RJ, Eakins P. The formulation and introduction of a 'can't intubate, can't ventilate' algorithm into clinical practice. Anaesthesia. 2009;64(6):601-608. PMID: 19453312

19. Reed MJ, Dunn MJ, McKeown DW. Can an airway assessment score predict difficulty at intubation in the emergency department? Emerg Med J. 2005;22(2):99-102. PMID: 15662057

20. Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. Anesthesiology. 2000;92(5):1229-1236. PMID: 10781266

21. Ramachandran SK, Mathis MR, Tremper KK, et al. Predictors and clinical outcomes from failed Laryngeal Mask Airway Unique: a study of 15,795 patients. Anesthesiology. 2012;116(6):1217-1226. PMID: 22510864

22. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology. 2005;103(2):429-437. PMID: 16052126

23. Chrimes N, Fritz P. The Vortex approach to airway management. Airway Management Meeting. Melbourne. 2013.

24. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth. 2015;115(6):827-848. PMID: 26556848

25. Heard A, Stamm A, Green R. Can't Intubate, Can't Oxygenate: An Emergency Cricothyroidotomy Training Course. Anaesth Intensive Care. 2013;41:784.

26. Aslani A, Ng SC, Engman A, et al. Location of the cricothyroid membrane in obese and non-obese women. Br J Anaesth. 2018;120(5):1086-1091. PMID: 29661385

27. Lewis SR, Butler AR, Parker J, et al. Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation. Cochrane Database Syst Rev. 2016;11:CD011136. PMID: 27844477

28. Mosier JM, Joshi R, Hypes C, et al. The Physiologically Difficult Airway. West J Emerg Med. 2015;16(7):1109-1117. PMID: 26759664

29. Aziz MF, Dillman D, Fu R, Brambrink AM. Comparative effectiveness of the C-MAC video laryngoscope versus direct laryngoscopy in the setting of the predicted difficult airway. Anesthesiology. 2012;116(3):629-636. PMID: 22261795

30. Mosier JM, Whitmore SP, Bloom JW, et al. Video laryngoscopy improves intubation success and reduces esophageal intubations compared to direct laryngoscopy in the medical intensive care unit. Crit Care. 2013;17(5):R237. PMID: 24125064

31. Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope video-laryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Can J Anaesth. 2012;59(1):41-52. PMID: 22042705

32. Hypes CD, Stolz U, Sakles JC, et al. Video laryngoscopy improves odds of first-attempt success at intubation in the intensive care unit. Ann Am Thorac Soc. 2016;13(3):382-390. PMID: 26569601

33. Driver BE, Prekker ME, Klein LR, et al. Effect of Use of a Bougie vs Endotracheal Tube and Stylet on First-Attempt Intubation Success Among Patients With Difficult Airways Undergoing Emergency Intubation: A Randomized Clinical Trial. JAMA. 2018;319(21):2179-2189. PMID: 29800096

34. Driver BE, Prekker ME, Reardon RF, et al. Success and Complications of the Bougie and Endotracheal Tube vs Endotracheal Tube and Stylet in Critically Ill Patients Undergoing Tracheal Intubation: The BOUGIE Trial. JAMA Netw Open. 2021;4(8):e2120689. PMID: 34406399

35. Wiles MD, Iliff HA, Brooks K, et al. Airway management in patients with suspected or confirmed cervical spine injury. Anaesthesia. 2024;79(8):856-868. PMID: 38699880

36. Australian and New Zealand College of Anaesthetists. PG56 Guidelines on Equipment to Manage a Difficult Airway During Anaesthesia. ANZCA. 2024.

37. Flin R, Fioratou E, Frerk C, et al. Human factors in the development of complications of airway management: preliminary evaluation of an interview tool. Anaesthesia. 2013;68(8):817-825. PMID: 23738696

38. Mushambi MC, Kinsella SM, Popat M, et al. Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics. Anaesthesia. 2015;70(11):1286-1306. PMID: 26449292

39. De Jong A, Molinari N, Pouzeratte Y, et al. Difficult intubation in obese patients: incidence, risk factors, and complications in the operating theatre and in intensive care units. Br J Anaesth. 2015;114(2):297-306. PMID: 25431308

40. Patel A, Nouraei SA. Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways. Anaesthesia. 2015;70(3):323-329. PMID: 25388828

41. Society for Airway Management. Physiologically Difficult Airway Consensus Statement. Anesth Analg. 2021;132:395-405.

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Appendix: Quick Reference Cards

CICO Algorithm Card

┌─────────────────────────────────────────────────┐
│                  CICO PATHWAY                    │
├─────────────────────────────────────────────────┤
│  ❌ Cannot intubate (3 attempts + 1 expert)     │
│  ❌ Cannot BMV (3 optimised attempts)           │
│  ❌ Cannot SGA (3 optimised attempts)           │
├─────────────────────────────────────────────────┤
│  📢 DECLARE: "THIS IS CICO - FONA NOW"          │
├─────────────────────────────────────────────────┤
│  SCALPEL-BOUGIE-TUBE                            │
│  1. Large VERTICAL skin incision                │
│  2. HORIZONTAL stab through CTM                 │
│  3. BOUGIE into trachea (feel rings)            │
│  4. TUBE 6.0mm over bougie                      │
│  5. Confirm with CAPNOGRAPHY                    │
└─────────────────────────────────────────────────┘

LEMON Assessment Card

┌─────────────────────────────────────────────────┐
│              LEMON - Difficult ETT               │
├─────────────────────────────────────────────────┤
│  L - Look externally (trauma, obesity, beard)   │
│  E - Evaluate 3-3-2 rule                        │
│  M - Mallampati (III-IV = difficult)            │
│  O - Obstruction / Obesity                      │
│  N - Neck mobility                              │
└─────────────────────────────────────────────────┘

Equipment Checklist

┌─────────────────────────────────────────────────┐
│            DIFFICULT AIRWAY CHECKLIST            │
├─────────────────────────────────────────────────┤
│  □ Video laryngoscope + blades                  │
│  □ Bougie (×2)                                  │
│  □ ETT (6.0-8.0) with stylet                    │
│  □ i-gel / LMA (sizes 3,4,5)                    │
│  □ Oral/nasal airways                           │
│  □ CICO kit (scalpel, bougie, 6.0 ETT)          │
│  □ Capnography                                  │
│  □ Suction (Yankauer + DuCanto)                 │
│  □ Push-dose pressors drawn up                  │
│  □ Second operator available                    │
└─────────────────────────────────────────────────┘