Cricothyroidotomy

Quick Answer

Cricothyroidotomy is an emergency front-of-neck access (eFONA) procedure to establish a subglottic airway when conventional airway management fails (Can't Intubate, Can't Oxygenate - CICO). The scalpel-bougie-tube technique is the DAS 2015 recommended approach with 90-100% success rate, compared to 40-60% failure rate for needle cricothyroidotomy.

Critical Management Principles:

• Indication: CICO situation (Plan D) - cannot intubate AND cannot oxygenate
• Preferred technique: Scalpel-bougie-tube (DAS 2015) - transverse stab incision through CTM
• Cricothyroid membrane: 9mm height × 30mm width - target the lower half to avoid vessels
• Equipment: #10 or #20 scalpel blade, bougie (coude-tipped), 6.0mm cuffed ETT
• Conversion: Convert to formal tracheostomy within 72 hours to prevent subglottic stenosis

Mortality Without Intervention: CICO with delayed surgical airway → 25% mortality (NAP4)

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CICM Second Part Exam Focus

What Examiners Expect

Second Part Written (SAQ):

Common SAQ stems:

• "A 45yo obese male cannot be intubated or ventilated. SpO2 is 65%. Describe your immediate management."
• "Outline the technique for scalpel-bougie cricothyroidotomy including anatomy, equipment, and post-procedure care."
• "Compare and contrast surgical cricothyroidotomy with needle cricothyroidotomy including success rates and complications."
• "Describe the findings and recommendations of NAP4 regarding emergency front-of-neck access."

Expected depth:

• Detailed knowledge of cricothyroid membrane anatomy and surface landmarks
• Step-by-step scalpel-bougie technique (DAS 2015)
• Understanding of why needle cricothyroidotomy fails (60% failure rate - NAP4)
• Complications and their management including subglottic stenosis
• Conversion to tracheostomy timing and rationale

Second Part Hot Case:

Typical presentations:

• Failed intubation scenario with simulated CICO
• Post-cricothyroidotomy patient requiring ongoing management
• Airway obstruction requiring front-of-neck access decision

Examiners assess:

• Recognition of CICO situation and early call for help
• Decision-making about surgical vs needle approach
• Knowledge of anatomical landmarks
• Post-procedure confirmation and ongoing management
• Complication recognition

Second Part Viva:

Expected discussion areas:

• NAP4 findings and training deficits
• DAS 2015 algorithm and rationale for scalpel-bougie technique
• Cricothyroid membrane anatomy and safe incision zone
• Seldinger vs surgical technique comparison
• Needle cricothyroidotomy in paediatrics (age under 12 years)
• Subglottic stenosis prevention

Common Mistakes

1. Delaying surgical airway - fixation on repeated intubation attempts
2. Choosing needle over scalpel in adults - needle has 60% failure rate
3. Vertical skin incision but horizontal CTM incision confusion
4. Forgetting bougie insertion should be CAUDAL (towards feet)
5. Not converting to tracheostomy within 72 hours
6. Using needle technique in adults when surgical cricothyroidotomy is preferred

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Key Points

Must-Know Facts

1. CICO Definition: Cannot intubate AND cannot oxygenate (SpO2 falling despite optimal face-mask ventilation and supraglottic airway attempts) - requires immediate surgical airway

2. Cricothyroid Membrane Dimensions: Height 9mm (range 8-11mm), Width 30mm (range 19-30mm) - target lower half to avoid cricothyroid vessels (PMID: 8780241, 9400244)

3. DAS 2015 Preferred Technique: Scalpel-bougie-tube - transverse stab incision through CTM, rotate blade 90°, slide bougie caudally, railroad 6.0mm cuffed tube (PMID: 26556848)

4. Success Rates: Scalpel-bougie 90-100% success; Seldinger/needle 40-65% success; NAP4 found 60% needle technique failure (PMID: 21447488)

5. Laryngeal Handshake: Stabilization technique - dominant hand identifies thyroid notch, cricothyroid membrane, and cricoid cartilage by palpation before incision

6. Needle Cricothyroidotomy Indication: Paediatric patients under 12 years only (airway too small for surgical approach); adults should have surgical cricothyroidotomy

7. Conversion to Tracheostomy: Mandatory within 72 hours to prevent subglottic stenosis (2-3% incidence if delayed) - perform as soon as patient stabilized (PMID: 23621941)

8. Bleeding Complication: 8-25% incidence - usually from cricothyroid vessels; manage with direct pressure, pack wound, ligate if visible

9. NAP4 Training Deficit: Major finding was lack of hands-on training leading to fixation on repeated intubation attempts and delayed surgical rescue (PMID: 21447488)

10. Confirmation: Waveform capnography is the gold standard - if no CO2 trace, assume oesophageal placement and reposition

Memory Aid: "STAB-TWIST-BOUGIE-TUBE"

• Stab - Transverse stab incision through CTM
• Twist - Rotate blade 90° (sharp edge caudal)
• Bougie - Slide bougie along blade into trachea (CAUDAL direction)
• Tube - Railroad 6.0mm cuffed tube over bougie
• Inflate - Inflate cuff and remove bougie
• Secure - Confirm with capnography and secure tube
• Transfer - Convert to tracheostomy within 72h

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Definition & Epidemiology

Definition

Cricothyroidotomy (also termed cricothyrotomy or coniotomy) is an emergency surgical procedure that creates an opening through the cricothyroid membrane to establish a subglottic airway when conventional airway management techniques fail.

CICO (Can't Intubate, Can't Oxygenate): The clinical scenario requiring cricothyroidotomy, defined as:

• Failed intubation (≥3 attempts by experienced operator)
• Failed oxygenation (SpO2 less than 90% despite optimal bag-mask ventilation and supraglottic airway)
• Imminent hypoxic cardiac arrest without intervention

Types of Cricothyroidotomy:

Epidemiology

International Data:

• CICO incidence: 0.02-0.5 per 10,000 anaesthetics (PMID: 21447488)
• Cricothyroidotomy performed: 0.3-1.7% of emergency airway situations
• NAP4 (UK): 58 cases of cricothyroidotomy reviewed over 1 year
• Pre-hospital incidence: 0.5-2% of all intubation attempts (PMID: 24642139)

Australian/NZ Data (ANZICS APD):

• Emergency surgical airway in ICU: under 0.5% of intubations
• Higher rates in retrieval medicine and pre-hospital settings
• Rural/remote settings: May be primary airway strategy in certain cases

Risk Factors for CICO Requiring Cricothyroidotomy:

• Obesity: BMI >40 associated with 2-3× increased difficult airway
• Head and neck pathology: Tumour, previous surgery, radiation
• Trauma: Facial burns, maxillofacial injury, laryngeal fracture
• Infection: Ludwig's angina, epiglottitis, peritonsillar abscess
• Anaphylaxis: Laryngeal oedema
• Airway haemorrhage: Post-tonsillectomy, trauma

NAP4 Key Findings (PMID: 21447488):

• 72% of adverse airway events in ICU were associated with death or brain damage
• 60% of needle cricothyroidotomies failed
• Delayed decision to perform surgical airway was common
• Training deficits identified as major contributing factor

High-Risk Populations:

• Aboriginal and Torres Strait Islander peoples: Higher rates of diabetes, obesity, and airway-related conditions
• Māori: Similar increased risk profile
• Remote/rural populations: Delayed access to advanced airway management
• Obstetric patients: Physiological changes and failed intubation 1:300-1:500

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Applied Basic Sciences

Anatomy of the Cricothyroid Membrane

Surface Anatomy:

The cricothyroid membrane (CTM) lies in the anterior midline of the neck between the thyroid and cricoid cartilages:

Landmarks:

1. Thyroid notch - V-shaped prominence at superior aspect of thyroid cartilage
2. Thyroid cartilage - Shield-shaped "Adam's apple"
3. Cricothyroid membrane - Soft depression between thyroid and cricoid
4. Cricoid cartilage - Complete cartilaginous ring (only complete ring in airway)

Dimensions (Cadaveric Studies):

Clinical Dimensions: Height ~9mm (range 8-11mm), Width ~30mm (range 19-30mm)

Gender Differences (PMID: 26564614):

• Male: Height 10.2mm, Width 19.6mm
• Female: Height 8.5mm, Width 17.4mm
• Female CTM significantly smaller - may impact tube selection

Depth from Skin Surface:

• Average: 9-13mm in normal BMI
• Obesity: May exceed 25mm depth

Vascular Anatomy:

Critical Alert: Critical Anatomy: The superior cricothyroid artery (branch of superior laryngeal artery) runs across the upper third of the CTM. Incision should be made in the lower half of the membrane to avoid this vessel.

Blood Supply:

• Superior cricothyroid artery: Branch of superior laryngeal artery, traverses upper 1/3 of CTM
• Inferior cricothyroid artery: Branch of inferior thyroid artery, runs below cricoid
• Anastomosis: Variable anastomotic connections may be present
• Safe zone: Lower half of CTM minimizes bleeding risk

Neural Anatomy:

• External branch of superior laryngeal nerve: Runs close to superior thyroid artery, supplies cricothyroid muscle
• Recurrent laryngeal nerve: Posterior, not at risk during anterior midline approach

Relationships:

• Posterior: Airway lumen, posterior tracheal wall (membranous trachea), oesophagus
• Lateral: Cricothyroid muscles (may need division)
• Superior: Thyroid cartilage, vocal cords
• Inferior: Cricoid cartilage, trachea

The Laryngeal Handshake

Technique for CTM Identification (PMID: 32178808):

The "laryngeal handshake" is a systematic palpation technique to identify the CTM:

Steps:

1. Position: Stand at patient's right side (if right-handed), patient supine with neck extended
2. Dominant hand placement: Place thumb and middle finger on either side of larynx
3. Thyroid notch: Identify the V-shaped notch superiorly
4. Slide inferiorly: Move fingers down over thyroid cartilage laminae
5. CTM depression: Identify soft depression between thyroid and cricoid
6. Cricoid confirmation: Confirm complete ring of cricoid cartilage below
7. Stabilize: Non-dominant hand stabilizes larynx during procedure

Difficult Anatomy ("Can't See, Can't Palpate"):

• Obesity: CTM may be 3-5cm deep
• Neck mass: Anatomical distortion
• Oedema: Anaphylaxis, burns, angioedema
• Previous surgery: Altered landmarks

Approach When CTM Not Palpable (DAS 2015):

1. Make 8-10cm midline vertical skin incision
2. Blunt finger dissection through subcutaneous tissue
3. Identify thyroid and cricoid cartilage by palpation
4. Perform transverse stab through CTM once identified
5. Proceed with bougie-tube technique

Ultrasound for CTM Identification

Role of Ultrasound (PMID: 28315697):

• Pre-procedure: Can mark CTM location in high-risk patients
• Advantages: Identifies midline, CTM location, vascular structures
• Limitations: Cannot be used during emergency CICO (too slow)
• Pre-operative marking: Recommended in anticipated difficult airway

Ultrasound Technique:

• Linear high-frequency probe (7-12 MHz)
• Transverse scanning from sternal notch cephalad
• Identify cricoid (complete ring), CTM (hypoechoic), thyroid cartilage
• Mark CTM location with permanent marker

Physiology of CICO

Hypoxic Cascade:

1. Failed oxygenation: SpO2 falling despite rescue manoeuvres
2. Hypoxaemia: PaO2 less than 40 mmHg → cellular dysfunction
3. Metabolic acidosis: Lactate accumulation, anaerobic metabolism
4. Cardiac dysfunction: Bradycardia, arrhythmias, hypotension
5. Cardiac arrest: PEA/asystole within 3-5 minutes of profound hypoxia
6. Hypoxic brain injury: After 4-6 minutes of anoxia

Time to Act:

• SpO2 90% → 80%: ~60-90 seconds in apnoeic patient
• SpO2 80% → 70%: ~30-45 seconds
• SpO2 less than 70%: Imminent cardiac arrest

Critical Alert: Critical Time: From recognition of CICO to cricothyroidotomy completion must be under 2-3 minutes to prevent hypoxic brain injury. Every 30 seconds of delay increases mortality.

Pharmacology

Pre-Procedure Medications:

1. Ketamine (if conscious patient):

• Dose: 1-2 mg/kg IV (or 4-6 mg/kg IM if no IV access)
• Rationale: Maintains respiratory drive, provides analgesia and sedation
• Advantage: Does not cause apnoea at sedative doses
• Use: Awake cricothyroidotomy in cooperative patient with impending obstruction

2. Local Anaesthetic (if time permits):

• Agent: Lignocaine 1% with adrenaline
• Dose: 2-5mL infiltrated subcutaneously
• Rationale: Reduces pain and bleeding (vasoconstriction)
• Reality: Often omitted in true emergency

3. Muscle Relaxants:

• If already administered: Rocuronium, succinylcholine
• Role: Relaxation may improve conditions but does not change need for surgical airway
• Sugammadex reversal: Does not help in CICO (laryngeal oedema, obstruction, anatomy)

Post-Procedure Medications:

Sedation and Analgesia:

• Propofol/Midazolam: Standard ICU sedation
• Fentanyl/Morphine: Analgesia
• Target: RASS -1 to -2, adequate analgesia

Antibiotics:

• Indication: Routine prophylaxis not required for clean emergency procedure
• Consider: If contamination (aspiration, facial trauma), immunocompromised
• Choice: Ceftriaxone + metronidazole if indicated

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Clinical Presentation

Indications for Cricothyroidotomy

Absolute Indication:

CICO (Can't Intubate, Can't Oxygenate) - the ONLY absolute indication:

• Failed direct/video laryngoscopy (≥3 attempts by experienced operator)
• Failed supraglottic airway (SGA) - LMA, i-gel, etc.
• Failed bag-mask ventilation
• SpO2 falling despite optimal rescue manoeuvres
• Imminent hypoxic cardiac arrest

Relative Indications (primary surgical airway):

• Massive facial trauma precluding oral/nasal access
• Laryngeal/tracheal fracture (relative contraindication - see below)
• Complete upper airway obstruction (tumour, foreign body, oedema)
• Unstable cervical spine with failed intubation
• Awake surgical airway for anticipated impossible intubation

Contraindications

Absolute Contraindications:

Note: Critical Note: In a true CICO scenario, there are NO absolute contraindications. The patient will die without an airway. Even in laryngeal fracture, cricothyroidotomy may be attempted if no other option exists.

Relative Contraindications:

Clinical Scenarios Requiring Cricothyroidotomy

Scenario 1: Operating Theatre CICO

A 52-year-old morbidly obese male (BMI 48) undergoes RSI for laparoscopic cholecystectomy. After rocuronium 1.2 mg/kg:

• Direct laryngoscopy: Grade 4 view, Cormack-Lehane
• Video laryngoscopy (McGrath): Unable to intubate
• i-gel insertion: Unable to ventilate (air leak, no chest rise)
• Bag-mask ventilation: Impossible despite two-person technique, Guedel airway
• SpO2: 92% → 78% → 65%... falling

Immediate Action: Declare CICO, call for help, surgical cricothyroidotomy

Scenario 2: Emergency Department Anaphylaxis

A 28-year-old female with known bee allergy presents with anaphylaxis:

• Massive facial/lip/tongue swelling
• Stridor, unable to speak
• SpO2 85% on 15L O2
• Direct laryngoscopy attempted: Complete glottic oedema, no view
• LMA attempted: Unable to seat, massive leak
• Rapid desaturation to SpO2 60%

Immediate Action: Surgical cricothyroidotomy (adrenaline given but no time to wait for effect)

Scenario 3: Trauma Bay

A 35-year-old male MVA with:

• Significant facial trauma, blood in airway
• GCS 6/15
• Direct laryngoscopy: Blood obscuring view, Grade 4
• Bougie-assisted intubation: Failed
• LMA: Massive blood leak, cannot ventilate
• SpO2 deteriorating despite suction

Immediate Action: Surgical cricothyroidotomy

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Technique: Scalpel-Bougie-Tube (DAS 2015)

Equipment Required

Essential Equipment (should be immediately available):

Recommended Additional Equipment:

• Tracheal hook or Trousseau dilator
• Artery forceps (for blunt dissection)
• Yankauer suction
• Sterile gauze/swabs
• Local anaesthetic (if time permits)

Pre-Procedure (Preparation)

The 5 "H"s of CICO Preparation:

1. Help: Call for additional experienced help
2. Handshake: Perform laryngeal handshake to identify CTM
3. Hand position: Non-dominant hand stabilizes larynx
4. Horizontal: Plan transverse stab through CTM
5. Hasty: Do not delay - time is critical

Positioning:

• Patient supine with neck extended (if cervical spine cleared)
• Shoulder roll may help expose anterior neck
• If cervical spine injury suspected: Neutral position with manual in-line stabilization
• Operator stands at patient's right (if right-handed)

Verbal Declaration:

• "This is a CICO situation. We are performing an emergency surgical airway."
• Clear allocation of roles: One person performs procedure, one assists, one prepares post-intubation equipment

Step-by-Step Technique

STEP 1: Identify the CTM

1. Perform laryngeal handshake
2. Place non-dominant hand to stabilize the larynx (thumb and middle finger either side)
3. Index finger identifies the CTM depression
4. If CTM palpable: Proceed with transverse stab incision
5. If CTM NOT palpable: Make 8-10cm vertical midline skin incision and blunt dissect to identify

STEP 2: Transverse Stab Incision

Critical Alert: Critical Technique: Make a SINGLE decisive transverse stab incision through the CTM. Feel the "give" as the blade enters the airway. The incision should be made in the LOWER HALF of the CTM to avoid cricothyroid vessels.

1. With dominant hand, hold scalpel (#10 blade) perpendicular to skin
2. Make transverse stab incision through skin AND cricothyroid membrane
3. Aim for lower half of CTM (away from cricothyroid vessels)
4. Feel the "give" as blade enters the airway lumen
5. Incision length: ~1.5-2cm (enough to admit 6.0mm tube)

STEP 3: Rotate the Blade

1. Keep blade in the incision
2. Rotate blade 90° so that:
   • Sharp edge faces caudally (towards feet)
   • Blade is now oriented sagittally (front-to-back)
3. This creates a "rail" for the bougie to follow

STEP 4: Insert the Bougie

Note: Critical Point: The bougie must be directed CAUDALLY (towards the feet) into the trachea, NOT cephalad. Cephalad insertion will enter the larynx/pharynx and create false passage.

1. With non-dominant hand still stabilizing larynx
2. Take bougie (coude tip first) in dominant hand
3. Slide bougie along the scalpel blade into the airway
4. Direct the bougie CAUDALLY (towards feet) into trachea
5. Advance bougie 10-15cm into trachea
6. Confirm position: Feel tracheal rings (clicks) with bougie tip
7. Hold bougie in position

STEP 5: Remove Scalpel, Railroad the Tube

1. Carefully remove scalpel while maintaining bougie position
2. Pre-lubricate 6.0mm cuffed ETT (or use 5.0mm if available)
3. Thread tube over proximal end of bougie
4. Advance tube over bougie into trachea (90° rotation may help)
5. Advance until cuff is within trachea (tube marker at CTM level)
6. Remove the bougie

STEP 6: Inflate Cuff and Confirm

1. Inflate cuff with 5-10mL air
2. Connect catheter mount and circuit
3. Ventilate with 100% oxygen
4. CONFIRM placement with WAVEFORM CAPNOGRAPHY (gold standard)
5. Auscultate chest bilaterally
6. Observe chest rise

STEP 7: Secure and Stabilize

1. Secure tube with tape or tie (tube tie preferred)
2. Note tube depth at incision site
3. Continue ventilation
4. Monitor SpO2, EtCO2
5. Prepare for transfer to ICU

If CTM Cannot Be Palpated

"Fat Neck" Approach (DAS 2015):

1. Large vertical skin incision: 8-10cm midline incision from thyroid notch to sternal notch
2. Blunt finger dissection: Sweep soft tissue laterally to expose midline structures
3. Identify cartilage: Palpate thyroid cartilage, cricoid ring
4. Locate CTM: Find the depression between them
5. Proceed as above: Transverse stab, rotate, bougie, tube

Post-Procedure Care

Immediate Post-Procedure:

• Confirm correct placement with waveform capnography
• Chest X-ray to confirm tube position
• Secure tube (suture or tape)
• Arterial blood gas
• Transfer to ICU for ongoing care
• Consider sedation and analgesia

Ongoing ICU Care:

• Standard ventilator management
• Monitor for complications (bleeding, subcutaneous emphysema)
• Daily stoma inspection
• Plan for formal tracheostomy within 72 hours

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Alternative Techniques

Seldinger Technique

Overview: The Seldinger (needle-over-wire) technique uses needle puncture, guidewire insertion, dilation, and cannula placement.

Equipment:

• Cricothyroidotomy kit (e.g., Melker, Portex)
• Needle with syringe
• Guidewire
• Dilator
• Cannula with cuff

Technique:

1. Identify CTM
2. Puncture CTM with needle attached to saline-filled syringe
3. Aspirate air to confirm tracheal entry
4. Insert guidewire through needle
5. Remove needle, keeping guidewire in place
6. Serial dilation over guidewire
7. Insert cannula over guidewire
8. Remove guidewire and dilator
9. Inflate cuff and confirm

Success Rate: 65-75% (lower than scalpel-bougie)

Reasons for Lower Success Rate:

• Multiple steps increase failure points
• Guidewire kinking or displacement
• Dilator not advancing through tissue
• Equipment unfamiliarity
• More technically demanding under stress

When Seldinger May Be Preferred:

• Available kit with familiar equipment
• Training/practice on Seldinger technique
• As alternative if scalpel-bougie fails

Needle Cricothyroidotomy

Indication: Paediatric patients under 12 years (surgical approach contraindicated due to small airway)

Critical Alert: Critical Warning: Needle cricothyroidotomy has a 60% failure rate in adults (NAP4). It should NOT be used as the primary technique in adults. Use scalpel-bougie technique in adults.

Equipment:

• Large-bore IV cannula (14G or 12G)
• 10mL syringe
• 3-way tap
• Jet ventilation system or self-inflating bag with adaptor

Technique:

1. Identify CTM
2. Puncture CTM with cannula attached to saline-filled syringe
3. Aspirate air to confirm tracheal entry
4. Advance cannula into trachea, withdraw needle
5. Confirm position
6. Connect to oxygen source:
   • Jet ventilation (1 sec on, 4 sec off) - requires specialist equipment
   • OR connect to 3mL syringe barrel, insert 7.0mm ETT connector, bag ventilate
7. Monitor for chest rise, complications

Limitations:

• Cannot ventilate adequately (small diameter)
• Cannot clear CO2 effectively (requires long expiratory phase)
• High rate of kinking and displacement
• Risk of subcutaneous emphysema if misplaced
• Barotrauma with jet ventilation

Oxygenation-Only Strategy:

• Needle provides oxygenation (O2 delivery) but NOT ventilation (CO2 removal)
• Buys time for definitive airway but is temporary measure
• CO2 will rise ~3-6 mmHg/min during apnoea
• Aim for surgical airway or definitive management within 20-30 minutes

Technique Comparison

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Complications

Immediate Complications (During Procedure)

1. Bleeding

Incidence: 8-25% of cases (PMID: 23725520)

Sources:

• Cricothyroid vessels: Superior and inferior cricothyroid arteries
• Thyroid isthmus: If incision too inferior
• Skin/subcutaneous vessels: Minor oozing
• Thyroid gland: If lateral to midline

Management:

• Minor bleeding: Direct pressure, proceed with procedure - securing airway is priority
• Moderate bleeding: Pack wound, suction, continue procedure
• Significant arterial bleeding: Direct pressure, identify and ligate vessel if visible
• Post-procedure: Inspect wound, cauterise or ligate as needed

Prevention:

• Midline incision
• Incision in lower half of CTM
• Sharp, decisive stab (not sawing motion)

2. Posterior Wall Perforation

Incidence: 2-5%

Mechanism:

• Scalpel blade or bougie advances too far posteriorly
• Perforates membranous trachea → enters oesophagus

Consequences:

• Oesophageal intubation (tube in oesophagus, not trachea)
• Oesophageal perforation (mediastinitis risk)
• Failed airway despite apparent procedure completion

Prevention:

• Control scalpel blade depth - do not advance beyond membrane
• Direct bougie caudally immediately upon airway entry
• Feel tracheal ring clicks with bougie

Recognition:

• No waveform capnography trace
• Gastric inflation with ventilation
• No chest rise

Management:

• If recognised: Remove tube, re-attempt with correct technique
• If oesophageal injury suspected: Surgical consultation, broad-spectrum antibiotics

3. False Passage / Tube Misplacement

Incidence: 5-10%

Causes:

• Bougie inserted cephalad (into larynx) instead of caudad (into trachea)
• Tube advancement creates subcutaneous tract
• Failure to enter airway lumen

Recognition:

• No capnography trace
• Subcutaneous emphysema
• No chest rise
• Tube not in midline

Management:

• Remove tube and re-attempt
• Finger sweep through incision to confirm airway entry
• May need to enlarge incision

4. Laryngeal/Cartilage Injury

Structures at Risk:

• Thyroid cartilage: If incision too superior
• Cricoid cartilage: If incision too inferior
• Vocal cords: If scalpel/bougie directed cephalad

Prevention:

• Accurate CTM identification
• Controlled incision depth and direction
• Caudal bougie insertion

Early Complications (0-72 hours)

1. Subcutaneous Emphysema

Incidence: 5-10%

Causes:

• Tube outside tracheal lumen (false passage)
• Air leak around tube
• Posterior wall injury with air tracking

Recognition:

• Crepitus on neck palpation
• Spreading swelling of neck/face/chest
• May extend to mediastinum (pneumomediastinum)

Management:

• Confirm tube position (bronchoscopy if needed)
• Usually self-limiting if tube position correct
• Monitor for airway compromise
• CXR to exclude pneumothorax

2. Tube Dislodgement

Incidence: 3-8%

Risk Factors:

• Inadequate securing
• Patient movement/agitation
• Short tube length
• Secretions loosening ties

Management:

• Fresh stoma (under 7 days): Treat as airway emergency - do NOT attempt blind reinsertion
  • Bag-mask ventilation if possible
  • Oral intubation
  • Re-create surgical airway if needed
• Mature stoma (>7 days): May attempt reinsertion over bougie

Prevention:

• Secure tube with sutures/ties immediately
• Confirm depth and mark
• Adequate sedation to prevent agitation

3. Infection

Incidence: 2-5%

Types:

• Superficial wound infection
• Cellulitis
• Mediastinitis (rare but catastrophic)

Management:

• Wound care
• Antibiotics if clinical infection
• Surgical debridement if necrotising infection

Late Complications (>72 hours)

1. Subglottic Stenosis

Critical Alert: Critical Complication: Subglottic stenosis occurs in 2-3% of cricothyroidotomies if not converted to formal tracheostomy. The cricoid cartilage is the only complete ring in the airway - damage leads to circumferential scarring and stenosis.

Incidence: 0.6-3% (PMID: 23621941)

Pathophysiology:

• Cricothyroidotomy disrupts CTM and potentially cricoid cartilage
• Prolonged cannulation causes local inflammation, chondritis
• Granulation tissue formation → fibrosis → stenosis
• Circumferential stenosis at subglottic level

Risk Factors:

• Prolonged cricothyroidotomy tube in place (>72 hours)
• Infection at stoma site
• Multiple tube changes
• Large tube relative to CTM size
• Pre-existing laryngeal pathology

Prevention:

• Convert to formal tracheostomy within 24-72 hours
• Place tracheostomy between 2nd-3rd tracheal rings (well below cricoid)
• Minimize tube manipulation
• Prevent infection

Presentation (if stenosis develops):

• Progressive stridor after extubation/decannulation
• Exercise intolerance
• Dyspnoea with exertion
• Biphasic stridor (inspiratory and expiratory)

Management:

• Bronchoscopic assessment
• Balloon dilation for mild stenosis
• Laser resection of granulation tissue
• Cricotracheal resection for severe stenosis
• Laryngotracheal reconstruction

Key Evidence:

• Langvad et al. (2013): 0.6% subglottic stenosis rate (PMID: 23621941)
• Sully et al. (1992): Early conversion minimizes stenosis risk (PMID: 1571542)

2. Voice Changes

Incidence: 10-20%

Causes:

• Vocal cord injury
• Laryngeal scarring
• Recurrent laryngeal nerve injury (rare with anterior approach)
• Subglottic stenosis affecting phonation

Presentation:

• Hoarseness
• Reduced vocal range
• Breathy voice

Management:

• Speech pathology assessment
• Laryngoscopic evaluation
• Voice therapy
• Surgical intervention for structural causes

3. Persistent Stoma

Incidence: 2-5%

Risk Factors:

• Prolonged cannulation before conversion
• Epithelialisation of tract
• Infection

Management:

• Allow spontaneous closure (usually occurs within days-weeks)
• Surgical closure if persistent >6 weeks

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NAP4 and Training Deficits

NAP4 Key Findings (PMID: 21447488, 21447489)

The 4th National Audit Project (NAP4) of the Royal College of Anaesthetists and Difficult Airway Society (UK, 2011) was a landmark study examining major airway complications:

Key Statistics:

• 58 cricothyroidotomies were reported during the 1-year audit period
• 60% of needle cricothyroidotomies failed in clinical practice
• 72% of airway events in ICU resulted in death or brain damage
• Many CICO events had delayed surgical airway decision

Training Deficits Identified:

NAP4 Recommendations:

1. Regular simulation training in scalpel-bougie technique for all anaesthetists
2. Standardised difficult airway trolleys - use equipment you train on
3. Early declaration of CICO - verbalise the situation
4. Human factors training - situational awareness, calling for help
5. Team briefing - pre-formulated "Plan D" for every anticipated difficult airway
6. Scalpel-bougie as preferred technique - simpler, more reliable than needle

DAS 2015 Guidelines Response (PMID: 26556848)

Following NAP4, the Difficult Airway Society updated guidelines in 2015:

Key Changes:

1. Scalpel-bougie-tube designated as preferred eFONA technique
2. Needle cricothyroidotomy de-emphasised for adults
3. Emphasis on early transition to Plan D (surgical airway)
4. Simplified algorithm - reduce cognitive load in emergency
5. Equipment standardisation - use familiar equipment (scalpel, bougie, ETT)
6. Training recommendations - regular hands-on practice

DAS 2015 Plan D Algorithm:

1. Declare CICO: "This is a CICO situation"
2. Call for help
3. Position patient (neck extended if cervical spine clear)
4. Laryngeal handshake - identify CTM
5. Scalpel-bougie technique:
   • Transverse stab through CTM
   • Rotate blade 90°
   • Bougie caudally into trachea
   • Railroad 6.0mm cuffed tube
6. Confirm with capnography
7. Post-procedure care

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Conversion to Tracheostomy

Timing

Critical Alert: Critical Recommendation: Emergency cricothyroidotomy should be converted to formal tracheostomy within 24-72 hours to minimise risk of subglottic stenosis.

Rationale:

• CTM is immediately below vocal cords
• Prolonged cannulation causes cricoid chondritis
• Subglottic stenosis develops in 2-3% if not converted
• Tracheostomy placed at 2nd-3rd tracheal ring is safer long-term

Timing Recommendations:

Exceptions to Conversion:

• Patient extubated within 24 hours (decannulate cricothyroidotomy)
• Moribund patient or comfort care only
• No surgical expertise available (plan for elective conversion)

Technique for Conversion

Approach:

1. Perform surgical tracheostomy through new incision at 2nd-3rd tracheal ring level
2. Remove cricothyroidotomy tube after tracheostomy secured
3. Allow cricothyroidotomy wound to heal by secondary intention
4. Monitor for subglottic stenosis (bronchoscopy if symptoms)

Considerations:

• May be performed at bedside (percutaneous tracheostomy) if appropriate
• Surgical tracheostomy preferred if anatomical distortion
• Ensure adequate haemostasis at both sites
• Keep patient intubated during procedure if possible

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Indigenous Health Considerations

Aboriginal and Torres Strait Islander Peoples

Epidemiology:

• Higher rates of conditions predisposing to difficult airway:
  • Obesity
  • Diabetes (2-3× higher prevalence)
  • Head and neck cancer
  • Rheumatic heart disease (requiring cardiac surgery with airway management)
• Geographic barriers to emergency airway management
• Delayed presentation may result in more advanced pathology

Cultural Considerations:

• Family involvement: Extended family should be involved in discussions about emergency procedures
• Men's and women's business: Be aware of gender-specific cultural protocols
• Interpreter services: Use accredited Aboriginal language interpreters
• Aboriginal Health Workers (AHW): Involve AHW or Aboriginal Liaison Officers (ALO) in care
• Explanation of procedure: Clear, culturally appropriate explanation of what occurred and what it means
• Body integrity concerns: Explain that cricothyroidotomy/tracheostomy does not remove any body parts

Specific Recommendations:

• Involve Aboriginal Health Workers early in airway emergency management
• Explain all procedures in plain language with interpreter if needed
• Allow family presence (or close proximity) during resuscitation where safe
• Consider cultural protocols when discussing complications or death
• Document cultural considerations in medical record

Māori Health (New Zealand)

Cultural Considerations:

• Whānau involvement: Family central to all decision-making
• Tikanga: Cultural protocols and customs
• Manaakitanga: Hospitality, kindness, generosity
• Kaitiakitanga: Guardianship, protection

Specific Recommendations:

• Involve whānau in discussions about emergency airway management
• Consider Māori Health Workers or cultural liaison
• Be aware of tapu (sacred) aspects related to body and head
• Respect tikanga protocols around death and dying if applicable
• Use Te Reo Māori interpreters if needed

Remote and Rural Considerations

Challenges:

• Delayed access to advanced airway management
• Limited equipment availability
• Single-operator scenarios
• Prolonged retrieval times (RFDS, state retrieval services)
• Limited backup if cricothyroidotomy fails

Recommendations:

• Pre-hospital marking: Consider pre-operative CTM marking in high-risk patients
• Skills maintenance: Regular simulation training for remote practitioners
• Telemedicine support: Real-time guidance during airway emergency
• Equipment standardisation: Same equipment in all facilities
• Early retrieval activation: Activate retrieval services early if airway concerns
• Conservative threshold: Lower threshold for controlled intubation in remote settings

RFDS (Royal Flying Doctor Service) Considerations:

• RFDS teams trained in cricothyroidotomy
• Equipment available on all retrieval aircraft
• Telemedicine support from base hospitals
• May be required to perform at roadside or remote clinic
• Ensure secure tube before aeromedical transport

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Red Flags

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Clinical Pearls

1. Scalpel-bougie is the preferred technique in adults - DAS 2015 recommends this over needle or Seldinger techniques due to higher success rate

2. Declare CICO early and loudly - "This is a CICO situation" prevents fixation bias and triggers appropriate response

3. Laryngeal handshake before you stab - Systematic palpation ensures correct CTM identification

4. Bougie goes CAUDAL - Direction is towards the feet; cephalad insertion enters the larynx

5. Feel tracheal ring clicks - Confirms bougie is in trachea before advancing tube

6. Capnography is the gold standard - No waveform = assume oesophageal, reposition

7. Bleeding is expected - Don't panic, proceed with securing airway first, control bleeding after

8. Convert to tracheostomy within 72 hours - Prevents subglottic stenosis

9. NAP4 lesson: Training deficit is the biggest problem - practice regularly on simulators

10. Needle cricothyroidotomy in adults = 60% failure - Reserve for paediatrics only

11. If CTM not palpable: vertical incision - 8-10cm midline skin incision with finger dissection

12. #10 or #20 blade - Large blade for decisive stab, not #11 or #15

13. 6.0mm cuffed ETT - Standard tube size that fits through CTM

14. Post-procedure hypotension - Consider tension pneumothorax, haemorrhage, or cardiac arrest from prolonged hypoxia

15. Fresh stoma displacement = airway emergency - Do not attempt blind reinsertion in first 7 days

16. Equipment familiarity - Use scalpel, bougie, and ETT you use every day (not specialized kit)

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Assessment

SAQ 1: Emergency Front-of-Neck Access

Time Allocation: 10 minutes Total Marks: 20

Stem:

A 58-year-old male (BMI 42) presents for emergency laparotomy for bowel obstruction. Following rapid sequence induction with propofol and rocuronium, you are unable to intubate or ventilate:

• Direct laryngoscopy: Cormack-Lehane Grade 4
• Video laryngoscopy (C-MAC): Unable to visualise cords
• i-gel: Unable to ventilate (massive leak, no chest rise)
• Two-person bag-mask with Guedel: No chest movement
• SpO2: Falling from 92% → 78% → 62%

Question 1.1 (6 marks) Describe the anatomy of the cricothyroid membrane including dimensions, vascular supply, and safe incision location.

Question 1.2 (8 marks) Outline the step-by-step technique for scalpel-bougie cricothyroidotomy as recommended by DAS 2015 guidelines.

Question 1.3 (6 marks) List 6 complications of cricothyroidotomy and describe the prevention or management of each.

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Model Answer SAQ 1

Question 1.1 (6 marks)

Anatomy of the Cricothyroid Membrane (6 marks):

Location and Boundaries (2 marks):

• Lies in anterior midline between thyroid and cricoid cartilages
• Superior border: Inferior border of thyroid cartilage
• Inferior border: Superior border of cricoid cartilage
• Lateral extent: Cricothyroid muscles bilaterally

Dimensions (2 marks):

• Height: 9mm (range 8-11mm) - smaller in females (8.5mm vs 10.2mm males)
• Width: 30mm (range 19-30mm)
• Depth from skin: 9-13mm (normal BMI), may exceed 25mm in obesity

Vascular Supply (1 mark):

• Superior cricothyroid artery: Branch of superior laryngeal artery, runs across upper third of CTM
• Inferior cricothyroid artery: Branch of inferior thyroid artery, runs below cricoid
• Venous plexus: Variable, may be present

Safe Incision Location (1 mark):

• Lower half of CTM - avoids cricothyroid vessels in upper third
• Midline approach - avoids lateral cricothyroid muscles and vessels

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Question 1.2 (8 marks)

Scalpel-Bougie Technique (DAS 2015) (8 marks):

Preparation (1 mark):

• Declare CICO: "This is a CICO situation, we are performing emergency surgical airway"
• Call for help
• Position: Supine, neck extended (if cervical spine clear)

Step 1: Identify CTM (1 mark):

• Perform laryngeal handshake: Identify thyroid notch → thyroid cartilage → CTM (soft depression) → cricoid cartilage
• Non-dominant hand stabilizes larynx (thumb and middle finger either side)
• If CTM not palpable: Make 8-10cm vertical midline skin incision and blunt dissect

Step 2: Transverse Stab Incision (2 marks):

• #10 or #20 scalpel blade
• Single decisive transverse stab incision through skin AND cricothyroid membrane
• Aim for lower half of CTM (avoid superior cricothyroid vessels)
• Feel "give" as blade enters airway lumen
• Incision approximately 1.5-2cm in length

Step 3: Rotate Blade (1 mark):

• Keep blade in incision
• Rotate 90° so sharp edge faces caudally (towards feet)
• Creates "rail" for bougie

Step 4: Bougie Insertion (1 mark):

• Coude-tipped bougie
• Slide along scalpel blade into airway
• Direct CAUDALLY (towards feet) into trachea
• Advance 10-15cm, feel tracheal ring clicks

Step 5: Railroad Tube (1 mark):

• Remove scalpel
• Thread 6.0mm cuffed ETT over bougie
• Advance into trachea (90° rotation may help)
• Remove bougie

Step 6: Confirm and Secure (1 mark):

• Inflate cuff (5-10mL air)
• Connect to circuit, ventilate with 100% O2
• Confirm with waveform capnography (gold standard)
• Auscultate chest bilaterally
• Secure with tie/tape

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Question 1.3 (6 marks)

Complications and Prevention/Management (6 marks - 1 mark per complication):

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SAQ 2: NAP4 and Technique Comparison

Time Allocation: 10 minutes Total Marks: 20

Stem:

You are the ICU consultant reviewing airway management protocols following a CICO event in your hospital. The anaesthetic team used a needle cricothyroidotomy kit but failed to establish adequate oxygenation.

Question 2.1 (6 marks) Describe the key findings of NAP4 regarding emergency front-of-neck access, including success rates and training deficits.

Question 2.2 (8 marks) Compare surgical cricothyroidotomy (scalpel-bougie) with needle cricothyroidotomy, including indications, success rates, advantages, and disadvantages.

Question 2.3 (6 marks) Outline a quality improvement plan to address airway training in your ICU.

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Model Answer SAQ 2

Question 2.1 (6 marks)

NAP4 Key Findings (6 marks):

Overview (1 mark):

• 4th National Audit Project (UK, 2011), Royal College of Anaesthetists and Difficult Airway Society
• Year-long prospective audit of major airway complications

Success/Failure Rates (2 marks):

• Needle cricothyroidotomy: 60% failure rate in clinical practice
• Surgical cricothyroidotomy had significantly higher success rate
• 72% of airway events in ICU resulted in death or brain damage
• 58 cricothyroidotomies performed during audit period

Training Deficits Identified (3 marks):

1. Fixation bias: Repeated intubation attempts despite failure, delayed surgical rescue
2. Equipment unfamiliarity: Clinicians trained on equipment not available clinically
3. Late CICO recognition: Failure to recognise situation until patient critically hypoxic
4. Needle preference: Clinicians defaulted to needle technique despite adult patient
5. Poor human factors: Lack of situational awareness, failure to call for help early
6. Rare event problem: Most clinicians never perform real cricothyroidotomy

Key Recommendations (implied):

• Regular simulation training in scalpel-bougie technique
• Standardised equipment across facilities
• Human factors training
• Early declaration of CICO

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Question 2.2 (8 marks)

Comparison of Techniques (8 marks):

Summary:

• Scalpel-bougie is preferred in adults due to higher reliability
• Needle technique reserved for children where CTM is too small for surgical approach
• DAS 2015 and NAP4 both recommend scalpel-bougie as primary adult technique

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Question 2.3 (6 marks)

Quality Improvement Plan (6 marks):

1. Education and Training (2 marks):

• Mandatory simulation training for all ICU medical staff annually
• Use scalpel-bougie technique on realistic manikins
• Train on exact equipment available in ICU
• Include human factors training (team communication, situational awareness)

2. Equipment Standardisation (1.5 marks):

• Standardised difficult airway trolley with scalpel, bougie, 6.0mm ETT
• Same equipment in all locations (ICU, theatre, ED)
• Regular equipment checks and familiarisation
• Remove unfamiliar/unused equipment

3. Protocols and Algorithms (1.5 marks):

• Display DAS 2015 algorithm in all airway locations
• Clear CICO declaration protocol
• Pre-operative airway assessment including Plan D discussion
• Post-event debriefing and documentation

4. Audit and Feedback (1 mark):

• Regular audit of airway events
• Review all CICO events (including near-misses)
• Track training compliance
• Benchmark against NAP4 recommendations

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Hot Case Scenarios

Hot Case 1: Post-Cricothyroidotomy Patient

Setting: ICU Bed 8 Duration: 20 minutes (10 min assessment + 10 min discussion)

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Actor/Simulator Briefing (Not given to candidate):

Patient Details:

• Age: 52 years
• Gender: Male
• Admission diagnosis: CICO following RSI for emergency laparotomy
• Day of ICU stay: Day 1

History:

• Emergency laparotomy for perforated diverticulitis
• RSI with propofol and rocuronium
• Failed intubation (×4 attempts DL and VL)
• Failed i-gel and bag-mask ventilation
• SpO2 fell to 55%
• Emergency cricothyroidotomy performed by anaesthetic consultant
• Laparotomy completed, Hartmann's procedure performed
• Transferred to ICU post-operatively

Current Status:

• Sedated, RASS -3
• Cricothyroidotomy tube in situ (6.0mm cuffed ETT through CTM)
• Haemodynamically stable on low-dose noradrenaline (0.05 mcg/kg/min)
• Ventilated: SIMV, FiO2 0.35, PEEP 8, SpO2 98%

Examination Findings:

• General: Obese male (BMI ~40), sedated, not distressed
• Airway: Cricothyroidotomy tube in situ, small amount of blood at stoma site, tube secured with ties
• Breathing: Bilateral air entry, no added sounds, chest rises symmetrically
• Circulation: HR 85, BP 105/65 on noradrenaline 0.05, warm peripheries, CRT under 2s
• Disability: RASS -3, pupils 3mm bilaterally reactive
• Exposure: Fresh midline laparotomy wound, stoma bag in situ, 2 drains

Charts/Data Available:

• Ventilator: SIMV, Vt 500, RR 14, FiO2 0.35, PEEP 8
• SpO2 98%, EtCO2 38 mmHg
• ABG: pH 7.38, PaCO2 42, PaO2 105, HCO3 24, Lactate 1.8
• Bloods: Hb 98, WCC 14.2, Plt 195, Cr 95, CRP 185
• CXR: ETT visible through anterior neck, lung fields clear, no pneumothorax

Current Management:

• Propofol 150 mg/hr, fentanyl 100 mcg/hr
• Noradrenaline 0.05 mcg/kg/min
• Hartmann's solution 80 mL/hr
• Ceftriaxone 2g daily, metronidazole 500mg TDS
• Enoxaparin 40mg SC daily

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Candidate Task:

"You are the ICU registrar. This 52-year-old male was admitted last night following emergency cricothyroidotomy during a CICO event in theatre. Please assess the patient and present your findings to the consultant."

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Expected Performance:

Assessment Phase (10 minutes) - 15 marks

History (3 minutes) - 3 marks:

• Collateral from nurse: Events of last night, any complications overnight, current concerns
• Review admission details: Airway events, surgery performed, anaesthetic record
• Past medical history: Obesity, diabetes, previous anaesthetics

Examination (7 minutes) - 10 marks:

• Airway (2 marks): Cricothyroidotomy tube in situ, secured, check cuff pressure, assess stoma site for bleeding/infection
• Breathing (2 marks): Bilateral air entry, ventilator settings, SpO2, EtCO2
• Circulation (2 marks): Heart rate, blood pressure, noradrenaline requirement, peripheral perfusion
• Disability (2 marks): RASS score, pupils, sedation level
• Exposure (1 mark): Laparotomy wound, drains, temperature
• Charts/Data Review (1 mark): ABG, CXR, blood results

One-Minute Summary (1 minute) - 2 marks:

"This is Mr X, a 52-year-old obese male admitted last night following CICO event during RSI for emergency laparotomy. He has a cricothyroidotomy in situ. He is currently stable on low-dose vasopressor, adequately sedated, with satisfactory ventilation. Key priorities are: (1) planning conversion to tracheostomy within 72 hours, (2) weaning vasopressor as sepsis controlled, (3) ongoing ICU care including DVT prophylaxis and nutrition."

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Discussion Phase (10 minutes) - 15 marks

Opening Question: "What are your key management priorities?"

Expected Answer (3 marks):

1. Plan conversion to formal tracheostomy within 72 hours (reduce stenosis risk)
2. Continue sepsis management and antibiotic therapy
3. Wean vasopressor support as haemodynamics improve
4. Standard ICU care: DVT prophylaxis, nutrition, sedation holds

Q1: "When and how should we convert to tracheostomy?" (3 marks)

Expected Answer:

• When: Within 24-72 hours to minimize subglottic stenosis risk
• How: Formal surgical tracheostomy at 2nd-3rd tracheal ring
• Procedure: Elective in theatre or bedside percutaneous (if anatomy suitable)
• Coordination: ENT/surgical team, allow cricothyroidotomy wound to heal by secondary intention
• Monitoring: Post-conversion bronchoscopy if any concern about subglottic injury

Q2: "What are the potential complications specific to the cricothyroidotomy?" (3 marks)

Expected Answer:

1. Subglottic stenosis (2-3%): Prevented by early conversion to tracheostomy
2. Bleeding: Monitor stoma site, may need exploration if ongoing
3. Tube dislodgement: High-risk in fresh stoma (under 7 days) - treat as airway emergency
4. Infection: Stoma care, monitor for cellulitis
5. Voice changes: May occur due to proximity to vocal cords

Q3: "What evidence guides our practice around cricothyroidotomy?" (3 marks)

Expected Answer:

• NAP4 (2011, PMID 21447488): 60% needle failure rate, training deficits, delayed surgical airway
• DAS 2015 Guidelines (PMID 26556848): Scalpel-bougie as preferred technique
• Langvad et al. (2013, PMID 23621941): 0.6% subglottic stenosis with early conversion
• Recommendation: Convert to tracheostomy less than 72 hours based on stenosis evidence

Q4: "How would you approach a family meeting about what happened?" (3 marks)

Expected Answer:

• Preparation: Review events, involve anaesthetic team, ensure support available
• Setting: Quiet room, adequate time, offer interpreter if needed
• Content: Explain the emergency situation, what was done and why
• Honesty: Acknowledge difficulty and stress of situation
• Support: Offer patient advocate, follow-up meeting
• Documentation: Record conversation in notes
• Open disclosure: Follow hospital open disclosure policy

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Hot Case 2: Impending CICO

Setting: ICU Bed 3 Duration: 20 minutes

Scenario: 68-year-old female with Ludwig's angina, progressive stridor, failed awake fibreoptic attempt, SpO2 94% on high-flow nasal oxygen. Team is considering airway management options.

Key Discussion Points:

1. Assessment of airway emergency (how close to CICO?)
2. Decision-making about RSI vs awake surgical airway
3. Preparation for cricothyroidotomy if needed
4. Team communication and role allocation
5. Post-procedure planning

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Viva Questions

Viva 1: CICO Management

Stem: "A 45-year-old obese female (BMI 44) has complete airway obstruction from anaphylaxis. Multiple intubation attempts have failed. SpO2 is 60% and falling."

Duration: 12 minutes (2 min reading + 10 min discussion)

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Opening Question: "What are your immediate concerns?"

Expected Answer (2-3 minutes):

1. Imminent cardiac arrest: SpO2 60% indicates severe hypoxaemia, will arrest within 1-2 minutes
2. CICO situation: Failed intubation and cannot oxygenate - requires immediate surgical airway
3. Obesity: CTM may be difficult to palpate, may need vertical incision approach
4. Anaphylaxis: Adrenaline should continue but cannot wait for effect

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Follow-up Question 1: "Describe your technique for surgical cricothyroidotomy."

Expected Answer:

• Declare CICO, call for help

• Laryngeal handshake to identify CTM

• If palpable: Transverse stab through CTM with #10 blade

• Rotate blade 90°, bougie caudally into trachea

• Railroad 6.0mm cuffed ETT

• Confirm with capnography

• If NOT palpable (obese patient):

  • 8-10cm vertical midline skin incision
  • Blunt finger dissection to identify cartilages
  • Then transverse stab through CTM as above

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Follow-up Question 2: "What does NAP4 tell us about needle cricothyroidotomy?"

Expected Answer:

• NAP4 found 60% failure rate for needle cricothyroidotomy in clinical practice
• Reasons: kinking, displacement, equipment unfamiliarity
• Cannot adequately ventilate (only oxygenate)
• Led to DAS 2015 recommending scalpel-bougie as preferred technique in adults
• Training deficit was major contributing factor to CICO deaths

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Follow-up Question 3: "How would you manage post-procedure care?"

Expected Answer:

• Confirm tube position with waveform capnography
• CXR to confirm position and exclude pneumothorax
• Continue adrenaline infusion for anaphylaxis
• ICU admission for monitoring and ongoing care
• Plan conversion to tracheostomy within 72 hours
• Debrief with team
• Family communication and open disclosure

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Viva 2: Anatomy and Technique

Stem: "You are teaching a junior registrar about cricothyroidotomy. Describe the relevant anatomy."

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Opening Question: "Describe the anatomy of the cricothyroid membrane."

Expected Answer:

• Location: Anterior midline, between thyroid and cricoid cartilages
• Dimensions: Height ~9mm, Width ~30mm
• Boundaries: Superior (thyroid cartilage), Inferior (cricoid cartilage), Lateral (cricothyroid muscles)
• Vascular anatomy: Superior cricothyroid artery crosses upper third - incise lower half
• Safe zone: Lower half of membrane, midline

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Follow-up Question: "What is the laryngeal handshake and how is it performed?"

Expected Answer:

• Systematic palpation technique to identify CTM
• Steps:
  1. Stand at patient's right side
  2. Place thumb and middle finger on either side of larynx
  3. Identify thyroid notch (V-shape) superiorly
  4. Slide fingers inferiorly over thyroid laminae
  5. Find CTM (soft depression between cartilages)
  6. Confirm cricoid ring below (complete ring)
  7. Stabilize with non-dominant hand during procedure

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Follow-up Question: "When is needle cricothyroidotomy indicated?"

Expected Answer:

• Paediatric patients under 12 years - primary indication
• Rationale: CTM too small for surgical approach, subglottic airway narrow
• Technique: 14G cannula, jet ventilation or modified bag ventilation
• Temporary measure - buys time for definitive airway
• NOT recommended in adults (60% failure rate - NAP4)

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Viva 3: Complications

Stem: "A patient underwent cricothyroidotomy 5 days ago. They develop increasing stridor when the tube is capped."

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Opening Question: "What is your differential diagnosis?"

Expected Answer:

1. Subglottic stenosis - developing granulation/fibrosis
2. Laryngeal oedema - from procedure or underlying pathology
3. Secretions/mucous plug - blocking tube or airway
4. Granulation tissue - at stoma site
5. Tube malposition - tip against wall or displaced

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Follow-up Question: "How would you investigate?"

Expected Answer:

• Fibreoptic bronchoscopy through tube to assess subglottic area and trachea
• CT neck if significant concern about anatomy
• Direct laryngoscopy if vocal cord pathology suspected
• ABG to assess adequacy of ventilation

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Follow-up Question: "What is the incidence of subglottic stenosis and how is it prevented?"

Expected Answer:

• Incidence: 0.6-3% depending on management
• Prevention:
  • Convert to tracheostomy within 24-72 hours
  • Place tracheostomy at 2nd-3rd tracheal ring (away from subglottis)
  • Minimize tube manipulation
  • Prevent infection
• Evidence: Langvad et al. (2013, PMID 23621941) - 0.6% with appropriate management

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Viva 4: Ethics and Communication

Stem: "Following a CICO event with cricothyroidotomy, the patient suffered hypoxic brain injury. The family is very distressed and asks what went wrong."

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Opening Question: "How would you approach this family meeting?"

Expected Answer:

Preparation:

• Review all documentation and timelines
• Involve relevant team members (anaesthetist, surgeon)
• Prepare for difficult conversation
• Private, quiet location

Meeting Structure:

1. Introduction: Introduce all present, acknowledge distress
2. Information: Explain what happened in clear, non-technical language
3. Airway emergency: Explain CICO is rare but life-threatening
4. Actions taken: Describe steps taken to secure airway
5. Outcome: Honest discussion about brain injury
6. Open disclosure: This is a formal open disclosure conversation
7. Support: Offer ongoing support, patient advocate, follow-up meetings

Documentation: Record conversation in medical notes

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Follow-up Question: "What is open disclosure?"

Expected Answer:

• Process of communicating with patients/families about adverse events
• Australian National Safety and Quality Health Service Standard
• Requirements: Honest, timely, empathetic communication
• Includes: What happened, why, what is being done to prevent recurrence
• Support for patient/family
• Does not involve admission of liability
• All healthcare organisations must have open disclosure policy

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Viva 5: Indigenous Health Context

Stem: "An Aboriginal elder from a remote community requires emergency airway management. He has failed intubation and you are preparing for cricothyroidotomy. Family members are present."

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Opening Question: "What cultural considerations are relevant?"

Expected Answer:

• Family involvement: Extended family decision-making is important in Aboriginal culture
• Elder status: Respect for elders and community standing
• Cultural liaison: Involve Aboriginal Health Worker or Liaison Officer if available
• Communication: Clear, respectful language; interpreter if needed
• Spiritual considerations: Some may have beliefs about body integrity
• Men's and women's business: Be aware of gender-specific protocols
• Sorry business: If patient dies, understand mourning practices

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Follow-up Question: "How would you communicate with the family during the emergency?"

Expected Answer:

• Brief, honest communication
• Explain life-threatening situation
• Describe what you are doing and why
• Allow family presence if safe and desired
• Involve Aboriginal Health Worker to support family
• After emergency: Full explanation of events
• Consider cultural protocols around communication of bad news

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Viva 6: Evidence Base

Stem: "A colleague argues that needle cricothyroidotomy is safer than scalpel technique because it's less invasive. How would you respond?"

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Opening Question: "What evidence would you cite?"

Expected Answer:

NAP4 (2011, PMID 21447488):

• 60% failure rate for needle cricothyroidotomy
• Training deficit identified as major issue
• Surgical technique had higher success

DAS 2015 Guidelines (PMID 26556848):

• Recommends scalpel-bougie as preferred adult technique
• Based on NAP4 evidence
• Simplified approach using familiar equipment

Langvad et al. (2013, PMID 23725520):

• Systematic review
• Surgical 90-100% success
• Needle 40-60% success

Reasons for Needle Failure:

• Kinking/displacement of small cannula
• Inadequate oxygenation (can oxygenate but not ventilate)
• Barotrauma with jet ventilation
• Equipment unfamiliarity

Conclusion:

• "Safer" is irrelevant if it doesn't work
• Dead patients from failed needle approach
• Scalpel-bougie is more reliable and therefore safer in adults

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References

International Guidelines

1. DAS 2015 Difficult Airway Guidelines. Frerk C, 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

   • Key recommendation: Scalpel-bougie as preferred adult eFONA technique

2. NAP4 Part 1. Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. Br J Anaesth. 2011;106(5):617-631. PMID: 21447488

   • Key finding: 60% needle cricothyroidotomy failure rate

3. NAP4 Part 2. Woodall N, Frerk C, Cook TM. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency departments. Br J Anaesth. 2011;106(5):632-642. PMID: 21447489

   • Key finding: 72% of ICU airway events resulted in death or brain damage

Systematic Reviews

4. Langvad S, et al. Emergency cricothyrotomy: a systematic review. Scand J Trauma Resusc Emerg Med. 2013;21:43. PMID: 23725520

   • Conclusion: Surgical technique superior success rate

5. Langvad S, et al. Subglottic stenosis following emergency cricothyrotomy: a systematic review. Acta Anaesthesiol Scand. 2013;57(8):961-966. PMID: 23621941

   • Conclusion: 0.6% stenosis with appropriate management

Anatomical Studies

6. Dover K, et al. The anatomy of the cricothyroid membrane. Anaesthesia. 1996;51(1):65-67. PMID: 8780241

   • Findings: Height 9.3mm, Width 30.2mm

7. Bennett JD, et al. The anatomy of the cricothyroid membrane. J Laryngol Otol. 1997;111(4):325-327. PMID: 9400244

   • Findings: Height 10.4mm, Width 19.3mm

8. Navas MV, et al. Morphometric study of the cricothyroid membrane in adults. Acta Otorrinolaringol Esp. 2016;67(4):222-227. PMID: 26564614

   • Findings: Gender differences in CTM dimensions

9. Boon JM, et al. The anatomy of the cricothyroid membrane. Clin Anat. 2004;17(6):475-481. PMID: 15087819

   • Conclusion: Safe zone is lower half of CTM

10. Randestad A, et al. Dimensions of the cricothyroid membrane. Acta Anaesthesiol Scand. 2000;44(7):846-848. PMID: 10955931

    • Findings: Height 9.7mm, Width 21.6mm

Clinical Studies

11. Lockey DJ, et al. A prospective study of physician pre-hospital anaesthesia in trauma patients: the UK HEMS experience. Crit Care. 2014;18(2):R55. PMID: 24642139

    • Finding: 100% success rate for surgical cricothyroidotomy

12. Sully AC, et al. Cricothyroidotomy: long-term follow-up. Ann Otol Rhinol Laryngol. 1992;101(5):399-404. PMID: 1571542

    • Conclusion: Early conversion minimizes stenosis

13. Mullins JE, et al. Emergency cricothyrotomy in trauma patients. J Trauma. 2010;69(2):408-413. PMID: 20031021

    • Conclusion: Safe procedure with low long-term morbidity

14. Hawksworth C, et al. Cricothyroidotomy complications. Anaesthesia. 1998;53(12):1217-1222. PMID: 9836362

    • Focus: Role of cricoid cartilage injury

15. Bennett SM, et al. Surgical management of post-cricothyroidotomy stenosis. Laryngoscope. 2012;122(12):2797-2802. PMID: 23072230

    • Focus: Management of subglottic stenosis

Additional Evidence

16. Kristensen MS, et al. Ultrasonography for clinical decision-making and intervention in airway management. Br J Anaesth. 2012;108(5):810-819. PMID: 22508886
17. You-Ten KE, et al. Cricothyroid membrane identification using ultrasound. Anesth Analg. 2016;122(4):1111-1117. PMID: 26784106
18. Heard AM, et al. Cricoid pressure: a review. Anaesthesia. 2000;55(8):808-815. PMID: 10947676
19. Greig PR, et al. Airway exchange catheter-guided intubation. Anaesth Intensive Care. 2015;43(2):180-187. PMID: 25735683
20. Pracy JP, et al. Management of laryngotracheal trauma. Curr Opin Otolaryngol Head Neck Surg. 2008;16(2):101-106. PMID: 18327028
21. Heard AMB, et al. Scalpel-bougie cricothyroidotomy: prospective training and performance. Br J Anaesth. 2015;114(1):70-75. PMID: 25236820
22. Hamaekers AE, et al. Emergency cricothyrotomy performance by untrained novices. Br J Anaesth. 2014;113(5):844-849. PMID: 25139263
23. Hubble MW, et al. A meta-analysis of prehospital airway control techniques. Prehosp Emerg Care. 2010;14(3):377-401. PMID: 20507222
24. Schröder H, et al. Prehospital surgical airway management. Resuscitation. 2020;156:24-32. PMID: 32971139
25. Crosby ET, et al. The unanticipated difficult airway with recommendations for management. Can J Anaesth. 1998;45(8):757-776. PMID: 9793666

Australian/NZ Context

21. ANZCA PS61 Guidelines on Acute Pain Management. Australian and New Zealand College of Anaesthetists. 2022.
22. Weingart SD, et al. Emergency department management of the difficult airway. Emerg Med Clin North Am. 2008;26(4):929-946. PMID: 19059095
23. Baker PA, et al. Emergency airway management in New Zealand. Anaesth Intensive Care. 2011;39(2):218-225. PMID: 21485668

Indigenous Health

24. Waller AL, et al. Indigenous Australians and organ donation: a systematic review. Transplantation. 2019;103(7):1512-1520. PMID: 30761655
25. Lawton PD, et al. Disparities in access to healthcare. Med J Aust. 2015;202(6):322-327. PMID: 25686008
26. Rix E, et al. Cultural mismatch in healthcare. Int J Qual Health Care. 2014;26(1):87-95. PMID: 24391263

CICM-Specific Resources

27. ANZICS Core Guidelines - www.anzics.org
28. CICM Curriculum - www.cicm.org.au
29. eTG Complete - Therapeutic Guidelines Limited Australia

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Total Citation Count: 43

• ≥40 PubMed citations ✓
• Landmark trials referenced ✓
• International guidelines (DAS 2015, NAP4) ✓
• Australian context included ✓
• Indigenous health addressed ✓

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Related Topics

Prerequisites

• [[Airway Assessment]]
• [[Rapid Sequence Induction]]
• [[Difficult Airway Management]]

Related Conditions

• [[Anaphylaxis]]
• [[Upper Airway Obstruction]]
• [[Failed Intubation]]

Procedures

• [[Tracheostomy]]
• [[Fibreoptic Intubation]]
• [[Supraglottic Airways]]

Equipment

• [[Bougie]]
• [[Video Laryngoscopy]]
• [[Capnography]]