Difficult Airway in ICU

Quick Answer

Difficult airway in ICU is intubation complicated by patient, anatomical, or situational factors. Unlike elective theatre intubation, ICU airway management occurs in physiologically unstable patients with limited oxygen reserve, hypotension, and reduced time for preparation. The MACOCHA score ≥3 predicts difficult intubation (sensitivity 81%, specificity 75%). Management requires systematic preparation using cognitive aids (Vortex approach, DAS guidelines), video laryngoscopy as first-line, preoxygenation optimization, and immediate escalation to surgical airway (scalpel cricothyroidotomy) in "Cannot Intubate, Cannot Oxygenate" (CICO) scenarios.

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CICM Exam Focus

Second Part Written Exam

Likely SAQ Domains:

• Predictors of difficult airway in ICU vs operating theatre
• Differences between RSI in theatre and ICU
• Management algorithm for failed intubation
• Indications and technique for emergency surgical airway
• Role of cognitive aids and team resource management

High-Yield Topics:

• MACOCHA score components and predictive value
• Preoxygenation strategies (NIV, HFNC, apnoeic oxygenation)
• Video laryngoscopy vs direct laryngoscopy in critically ill
• Vortex approach to airway emergency
• Scalpel-bougie cricothyroidotomy technique
• Post-intubation hypotension prevention

Viva Voce

Common Scenarios:

• 68-year-old with septic shock, MACOCHA score 7, failed first intubation attempt
• Morbidly obese ICU patient with ARDS requiring urgent intubation
• Trauma patient with C-spine immobilization and facial injuries
• CICO scenario requiring front-of-neck access

Expected Knowledge:

• Systematic pre-intubation checklist
• Plans A, B, C, D for failed intubation
• Recognition of CICO and immediate surgical airway
• Human factors and crew resource management
• CICM PS57 professional standards

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Key Points

1. ICU intubation is high-risk: Peri-intubation adverse events occur in 45% of ICU intubations (INTUBE study), including hypoxemia (9%), hypotension (43%), and cardiac arrest (2-4%). [1]

2. MACOCHA score predicts difficulty: Score ≥3 indicates high risk of difficult intubation (Cormack-Lehane III/IV or greater than 2 attempts). Components: Mallampati III/IV (5 points), Apnea/OSA (2), Cervical spine immobility (1), Opening mouth below 3cm (1), Coma GCSbelow 8 (1), Hypoxia SpO₂below 80% (1), Anesthesiologist non-available (1). [2]

3. Preoxygenation is critical: NIV or HFNC for 3 minutes is superior to standard face mask in preventing desaturation. Target EtO₂ greater than 90%. Apnoeic oxygenation (15L nasal cannula or 60L HFNC) extends safe apnoea time. [3,4]

4. Video laryngoscopy first-line: VL improves first-pass success and reduces esophageal intubation compared to direct laryngoscopy in ICU patients. Hyperangulated blades allow visualization "around the corner" in difficult anatomy. [5]

5. Recognize CICO early: Cannot Intubate, Cannot Oxygenate is a time-critical emergency. Maximum 3 attempts at intubation and 3 at supraglottic airway before declaring CICO. Immediate scalpel cricothyroidotomy is definitive. [6]

6. Hemodynamic optimization prevents arrest: Post-intubation hypotension occurs in 25-46% and independently predicts mortality. Start norepinephrine infusion pre-induction in shock states (SI greater than 0.9). Use push-dose pressors (phenylephrine 100mcg) for immediate rescue. [7,8]

7. Cognitive aids reduce errors: Checklists, Vortex approach, and DAS algorithms offload cognitive burden during crisis. Closed-loop communication and designated team leader are essential human factors. [9]

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Clinical Overview

Definition and Scope

Difficult airway in the ICU context encompasses:

Anatomical Difficulty

• Difficult bag-mask ventilation (BMV): Inability to maintain SpO₂ greater than 90% or EtCO₂ 10-45 mmHg with proper technique
• Difficult laryngoscopy and intubation: Cormack-Lehane Grade III/IV view or greater than 2 attempts required
• Difficult supraglottic airway placement: Inability to achieve ventilation with i-gel/LMA
• Difficult surgical airway: Inability to identify landmarks for cricothyroidotomy

Physiological Difficulty

• Hypoxemia: Baseline SpO₂ below 93% despite supplemental oxygen (rapid desaturation during apnoea)
• Hemodynamic instability: Shock index greater than 0.9, pre-existing vasopressor requirement
• Metabolic derangement: Severe acidosis, hypercarbia (loss of respiratory compensation leads to arrest)
• Raised intracranial pressure: Brief hypoxia or hypercarbia precipitates herniation

Situational Difficulty

• Time pressure: Crash intubation without full preparation
• Environmental: Limited space, poor lighting, out-of-theatre location
• Operator inexperience: Junior staff, unfamiliarity with equipment
• Team factors: Poor communication, role confusion, cognitive overload

The "ICU Airway" vs "Theatre Airway"

Critical differences between elective operating theatre intubation and ICU intubation:

The NAP4 audit (4th National Audit Project) identified ICU as a high-risk location for airway-related adverse events, with 25% of ICU-related events resulting in death or brain damage compared to 5% in operating theatres. [10]

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Epidemiology

Incidence

Difficult intubation in ICU:

• Overall incidence: 10-23% of all ICU intubations
• MACOCHA score ≥3: Difficult intubation occurs in 40-55% vs 3-8% with score below 3 [2]
• Cormack-Lehane Grade III/IV: 12-18% of ICU patients vs 1-4% in operating theatre [11]

Failed intubation:

• First-pass success rate in ICU: 65-85% (vs greater than 95% in theatre)
• Failed intubation (≥3 attempts or unable to intubate): 0.5-3%
• CICO incidence: 0.1-0.5% of all ICU intubations [12]

Complications:

• Hypoxemia (SpO₂ below 80%): 9-25%
• Severe hypoxemia (SpO₂ below 70%): 2-6%
• Hypotension (SBP below 90 mmHg): 25-46%
• Cardiac arrest: 2-4% (mostly PEA from hypotension/hypoxia)
• Aspiration: 2-5%
• Esophageal intubation: 0.5-2% (higher with direct laryngoscopy vs video) [1,13]

Risk Factors

Patient factors:

• Obesity (BMI greater than 35): Reduced FRC, difficult positioning, rapid desaturation
• Age greater than 65 years: Reduced physiological reserve
• OSA: Mallampati III/IV, risk of upper airway collapse
• Facial trauma: Blood, edema, distorted anatomy
• C-spine immobilization: Restricted neck extension, poor laryngoscopic view
• Burns/angioedema: Progressive airway edema

Disease factors:

• Septic shock: Vasodilated, catecholamine-depleted
• ARDS/pneumonia: Severe hypoxemia, high shunt fraction
• Traumatic brain injury: Raised ICP, cannot tolerate hypoxia/hypercarbia
• Upper GI bleeding: Blood in airway, aspiration risk

Situational factors:

• Emergency intubation: No time for full assessment or optimization
• Out-of-hours: Reduced senior support, unfamiliar team
• Operator inexperience: below 50 lifetime intubations

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Pathophysiology

Why ICU Patients Decompensate During Intubation

1. Reduced Functional Residual Capacity (FRC)

Normal FRC provides an "oxygen reservoir" during apnoea. In ICU patients:

• Obesity: Abdominal contents compress diaphragm → FRC ↓ by 30-50%
• ARDS/pneumonia: Consolidated lung unable to store oxygen
• Supine positioning: FRC ↓ by 20% vs upright
• Critical illness: Muscle weakness, atelectasis, pleural effusions

Effect: Safe apnoea time reduced from 8-10 minutes (healthy adult) to 30-90 seconds in critically ill obese patient with ARDS. [14]

2. High Oxygen Consumption (VO₂)

• Sepsis, burns, trauma: VO₂ ↑ by 30-50% above baseline
• Fever: Each 1°C ↑ temperature → VO₂ ↑ by 10%
• Agitation/pain: VO₂ ↑ by 20-40%

Effect: Oxygen stored in FRC is consumed faster, accelerating desaturation.

3. Intrapulmonary Shunt

• ARDS, pneumonia, pulmonary edema: Right-to-left shunt (perfusion without ventilation)
• Shunt fraction greater than 30%: Even 100% FiO₂ cannot fully correct hypoxemia

Effect: Preoxygenation less effective, rapid desaturation despite high-flow oxygen.

4. Hemodynamic Instability

Transition from negative to positive pressure ventilation:

• Spontaneous breathing: Negative intrathoracic pressure → ↑ venous return
• Positive pressure: ↑ intrathoracic pressure → ↓ venous return → ↓ preload → ↓ cardiac output

Induction agent effects:

• Propofol: Direct myocardial depression + vasodilation → hypotension in 30-60%
• Midazolam: Vasodilation, especially in hypovolemia
• Etomidate: Relatively hemodynamically neutral but adrenal suppression
• Ketamine: Sympathomimetic (↑ BP, HR) but causes hypotension in catecholamine-depleted patients

Result: Post-intubation hypotension in 25-46%, leading to end-organ hypoperfusion and increased risk of cardiac arrest. [7]

5. Loss of Respiratory Drive

• Induction agents + neuromuscular blockade → complete apnoea
• If BMV or intubation fails → no backup spontaneous ventilation
• Hypoxia + hypercarbia + acidosis → cardiac arrest (typically PEA)

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Airway Assessment in ICU

MACOCHA Score (CICM Favourite)

Validated specifically for ICU difficult intubation prediction. [2]

Interpretation:

• Score ≥3: High risk (difficult intubation in 40-55%)
• Score 0-2: Low risk (difficult intubation in 3-8%)

Performance:

• Sensitivity: 81%
• Specificity: 75%
• Negative predictive value: 98% (score 0 strongly suggests easy intubation)
• AUC: 0.89 (excellent discrimination)

Clinical Application:

• Score ≥3: Senior operator, video laryngoscopy, double setup (surgical airway prepared)
• Score ≥5: Consider awake fiberoptic intubation if time permits

LEMON Assessment

Emergency medicine tool, less validated in ICU but widely used:

L — Look Externally

• Facial trauma, blood, beard, large tongue, short neck, protruding incisors

E — Evaluate 3-3-2 Rule

• 3 fingers: Mouth opening (inter-incisor distance)
• 3 fingers: Hyoid-mental distance
• 2 fingers: Thyroid-hyoid distance

M — Mallampati Score

• Class I-II: Low risk
• Class III-IV: High risk (difficulty correlates with class)

O — Obstruction

• Epiglottitis, abscess, tumor, hematoma, angioedema

N — Neck Mobility

• C-spine immobilization, ankylosing spondylitis, arthritis → restrict neck extension

Additional ICU-Specific Factors

Physiological assessment:

• Shock index (HR ÷ SBP): greater than 0.9 predicts post-intubation hypotension and cardiac arrest [15]
• P/F ratio (PaO₂ ÷ FiO₂): below 150 indicates severe hypoxemia → rapid desaturation
• Base excess: <-6 mmol/L indicates severe acidosis → loss of respiratory compensation during apnoea

Situational assessment:

• Time available: Emergent vs urgent vs elective
• Location: ICU bed vs CT scanner vs ward
• Operator experience: Intubations performed in last 6 months
• Team availability: Second senior operator, anesthesia backup

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Preparation for Intubation

The ICU Intubation Checklist

Checklist use reduces severe hypoxemia (SpO₂ below 80%) from 23% to 12% and reduces post-intubation hypotension. [16]

EQUIPMENT (The "7 Ps")

1. Plan (A, B, C, D declared)
2. Preoxygenation device (NIV, HFNC, BVM with PEEP)
3. Position (ramped, ear-to-sternal-notch)
4. Pharmacology (induction, paralytic, pressors drawn up)
5. Passage (ETT checked, bougie, stylet, laryngoscope tested)
6. Proof (waveform capnography ready)
7. Post-intubation (ventilator settings, sedation infusion)

Detailed Checklist:

Preoxygenation Strategies

Goal: Denitrogenate functional residual capacity (FRC), replacing N₂ with O₂ to extend safe apnoea time.

Standard methods:

• Tidal volume breathing: 3 minutes of 100% O₂ via tight-fitting face mask
• Vital capacity breathing: 8 deep breaths in 60 seconds

ICU-optimized methods (superior in hypoxemic patients):

1. Non-Invasive Ventilation (NIV)

• CPAP 10 cmH₂O or BiPAP (IPAP 15, EPAP 5)
• FiO₂ 100%
• Duration: 3-5 minutes
• Evidence: Reduces desaturation (SpO₂ below 80%) from 25% to 12% vs standard face mask in hypoxemic patients [3]
• Mechanism: PEEP recruits atelectatic alveoli, increases FRC

2. High-Flow Nasal Cannula (HFNC)

• Flow: 60 L/min
• FiO₂: 100%
• Duration: 5 minutes
• Advantages: Patient comfort, can remain in place for apnoeic oxygenation
• Evidence: Non-inferior to NIV for preoxygenation; apnoeic oxygenation extends time to SpO₂ below 90% by 60-90 seconds [4,17]

3. Bag-Valve-Mask (BVM) with PEEP

• Two-person technique (E-C clamp seal + bag squeeze)
• PEEP valve 10 cmH₂O attached
• FiO₂ 100% (ensure high-flow oxygen connected)

Target endpoint:

• EtO₂ greater than 90% (if available)
• SpO₂ 100% (less reliable in critically ill)
• Minimum 3 minutes of adequate preoxygenation

Apnoeic Oxygenation (ApOx)

Continuous oxygen delivery during apnoea (between paralysis and tube placement):

• Mechanism: Oxygen moves from pharynx → alveoli via "mass flow" (alveolar oxygen consumption creates negative pressure gradient)
• Technique: Nasal cannula at 15 L/min or HFNC at 60 L/min placed under preoxygenation mask
• Evidence: Extends time to desaturation by 60-90 seconds; most beneficial in patients with low P/F ratio (below 150) [4]

Positioning

Standard position ("Sniffing the morning air"):

• Occiput elevated 8-10 cm
• Atlantooccipital extension
• Aligns oral-pharyngeal-laryngeal axes

Ramped position (obese patients, ESSENTIAL):

• Goal: Ear-to-sternal-notch horizontal alignment
• Method: Stack blankets/pillows under head, shoulders, upper back
• Effect:
  • Improves laryngoscopic view (often 1-2 Cormack-Lehane grades better)
  • Facilitates bag-mask ventilation
  • Increases FRC (gravity pulls abdomen away from diaphragm)
  • Reduces aspiration risk (head above stomach)
• Evidence: Ramped position improves first-pass success from 60% to 84% in obese ICU patients [18]

Reverse Trendelenburg (ICU bed):

• Head-of-bed elevated 20-30°
• Reduces aspiration risk
• Improves oxygenation by increasing FRC
• Note: Must still ramp obese patients even with bed elevation

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Pharmacology

Induction Agents

ICU selection strategy:

• Hemodynamically stable: Propofol (smooth, short-acting)
• Shock, hypotension, SI greater than 0.9: Etomidate (least hemodynamic impact)
• Bronchospasm, reactive airway: Ketamine (bronchodilator)
• Raised ICP: Propofol (reduces ICP) but risk-benefit if shocked; avoid ketamine
• Status epilepticus: Propofol (anticonvulsant)

Dose reduction principles:

• Shock states: Reduce propofol to 0.5-1 mg/kg, etomidate to 0.15 mg/kg
• Elderly (greater than 70 years): Reduce dose by 30-50%
• Never omit induction agent to avoid awareness and sympathetic surge

Neuromuscular Blocking Agents (Paralytics)

Contraindications to succinylcholine:

• Hyperkalemia (K⁺ greater than 5.5 mmol/L)
• Burns (greater than 48 hours post-injury, risk of lethal hyperkalemia)
• Denervation injuries (spinal cord injury, stroke, Guillain-Barré) greater than 48-72 hours
• Crush injury greater than 24 hours
• Malignant hyperthermia (personal or family history)
• Neuromuscular disease (muscular dystrophy, myotonia)

Modified Rapid Sequence Induction (RSI) in ICU:

• Standard RSI: No bag-mask ventilation after paralytic (risk of gastric insufflation → aspiration)
• ICU modification: If patient desaturates (SpO₂ below 90%), gentle bag-mask ventilation is permitted (hypoxia is more dangerous than aspiration risk)

Hemodynamic Support

Pre-intubation fluid resuscitation:

• Fluid bolus: 500 mL crystalloid over 10-15 minutes (if fluid-responsive)
• Caution: Avoid large volumes in cardiogenic shock or fluid overload

Vasopressors:

Push-dose pressors (immediate rescue):

• Phenylephrine: 100 mcg IV bolus (pure α₁ agonist, vasoconstriction)

  • "Use if: Tachycardic (HR greater than 100) and hypotensive"
  • "Effect: ↑ SVR, reflex bradycardia, duration 5-10 minutes"
  • "Risk: Decreases cardiac output"

• Norepinephrine: 10-20 mcg IV bolus (α₁ + β₁)

  • "Use if: Bradycardic or normal HR and hypotensive"
  • "Effect: ↑ SVR + ↑ inotropy, duration 2-5 minutes"
  • Preferred in most ICU shock states

Continuous infusions (pre-emptive):

• Norepinephrine: Start 0.05-0.1 mcg/kg/min before induction if:
  • Shock index greater than 0.9
  • Already on low-dose vasopressors
  • Systolic BP below 100 mmHg despite fluid bolus
• Goal: Maintain MAP greater than 65 mmHg throughout intubation

Evidence: Starting vasopressors pre-intubation reduces post-intubation hypotension from 46% to 24% and reduces cardiac arrest from 4% to 1%. [8]

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Intubation Technique

Video Laryngoscopy vs Direct Laryngoscopy

Video laryngoscopy (VL) is first-line in ICU.

Evidence:

• Cochrane review: VL reduces failed intubation (RR 0.41, 95% CI 0.26-0.66) and esophageal intubation (RR 0.36, 95% CI 0.15-0.87) vs direct laryngoscopy in ICU [5]
• First-pass success: VL 85% vs DL 72% (pbelow 0.001)
• Improves view in difficult anatomy (C-spine immobilization, obesity, facial trauma)

VL advantages:

• Allows "seeing around the corner" with hyperangulated blades (GlideScope, McGrath, King Vision)
• Less force required, less cervical spine movement
• Teaching tool (screen visible to assistant)
• Facilitates bougie placement under direct vision

VL limitations:

• "Eye-hand dissociation" (screen view vs hand position)
• Blade fogging in high-humidity environments
• Tube delivery can be difficult (steeper angle) → always use bougie or stylet

Direct laryngoscopy (DL) indications:

• VL not available
• VL failure (blood, secretions obscuring camera)
• Operator more experienced with DL

Blade selection:

• Macintosh (curved): Tip in vallecula, lifts epiglottis indirectly (more common)
• Miller (straight): Tip lifts epiglottis directly (better in anterior larynx, large tongue)

Bougie (Tracheal Tube Introducer)

The bougie is ESSENTIAL in difficult airways.

When to use:

• Prophylactic: Any anticipated difficult intubation (MACOCHA ≥3)
• Rescue: Cormack-Lehane Grade III/IV (only epiglottis or no glottic structures visible)

Technique:

1. Advance bougie anteriorly, aiming for arytenoids
2. Feel "clicks" as bougie passes over tracheal rings (tactile confirmation)
3. Hold-up sign: Bougie stops at 25-30 cm (bronchial obstruction confirms tracheal placement)
4. Railroad ETT over bougie (rotate 90° counterclockwise if resistance at glottis)
5. Remove bougie, inflate cuff, confirm with capnography

Evidence: Bougie use increases first-pass success from 69% to 82% in Cormack-Lehane Grade III views. [19]

Delayed Sequence Intubation (DSI)

Indication: Agitated, combative, or hypoxemic patient unable to tolerate preoxygenation.

Concept: "Procedural sedation for the procedure of preoxygenation."

Technique:

1. Ketamine 1-1.5 mg/kg IV slowly over 60 seconds (dissociative dose)
2. Wait 2-3 minutes for dissociation (patient calm, maintains respiratory drive)
3. Preoxygenate for 3 minutes with NIV/HFNC/BVM (patient now tolerates mask)
4. Optimize positioning
5. Give paralytic once SpO₂ maximized
6. Intubate

Evidence: Weingart et al. (Ann Emerg Med 2015): DSI increased mean SpO₂ from 89.9% to 98.8% with no adverse events attributed to ketamine. [20]

Caution:

• Rare risk of laryngospasm (give ketamine slowly)
• Vomiting/aspiration risk (lower than risk of hypoxic arrest in combative patient)

Awake Fiberoptic Intubation (AFOI)

Indications:

• Predicted CICO scenario: Known difficult airway + cannot bag-mask ventilate
• Upper airway obstruction: Angioedema, epiglottitis, tumor (risk of complete obstruction with paralysis)
• Unstable C-spine with anticipated very difficult intubation
• Severe facial trauma with unrecognizable anatomy

Prerequisites:

• Cooperative patient
• Time available (not for crash intubation)
• Experienced operator
• Topical anesthesia and sedation equipment

Topical anesthesia:

• "Spray as you go": Lidocaine 2-4% via bronchoscope working channel
• Nebulized lidocaine: 4-5 mL of 4% lidocaine via nebulizer (10-15 minutes)
• Nerve blocks: Superior laryngeal nerve block, transtracheal injection (cricothyroid membrane)
• Maximum safe dose: Lidocaine 4-5 mg/kg

Sedation:

• Ketamine infusion: 0.5 mg/kg bolus, then 0.25-0.5 mg/kg/hr (maintains respiratory drive)
• Dexmedetomidine: 0.5-1 mcg/kg load over 10 min, then 0.2-0.7 mcg/kg/hr (maintains airway reflexes)
• Target: Cooperative sedation (responds to commands, maintains spontaneous ventilation)

Technique:

1. Position: Semi-upright (30-45°)
2. Topicalize airway (10-15 minutes for full effect)
3. Load ETT onto fiberoptic scope (lubricate)
4. Advance scope via nostril (preferred) or mouth
5. Identify landmarks: Epiglottis → Arytenoids → Vocal cords
6. Pass scope through cords into trachea (confirm tracheal rings, carina)
7. Railroad ETT over scope into trachea
8. Remove scope, confirm placement with capnography
9. Induce general anesthesia and paralysis

Advantages:

• Patient maintains spontaneous ventilation throughout
• If unable to pass scope, patient still breathing (abort and reassess)

Disadvantages:

• Time-consuming (15-30 minutes)
• Patient discomfort (cooperation essential)
• Blood/secretions obscure view
• Requires specialized equipment and training

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Failed Intubation Algorithms

DAS (Difficult Airway Society) Guidelines - Adapted for ICU

Plan A: Initial Intubation Attempt

Goal: Successful intubation OR maintain oxygenation.

Key actions:

• Maximum 3 attempts at laryngoscopy (4th attempt by senior if available)
• Optimize each attempt:
  • "Position: Ear-to-sternal-notch, head-of-bed up"
  • "Equipment: Switch to video laryngoscopy if not already using"
  • "Adjuncts: Bougie, external laryngeal manipulation (BURP)"
  • "Paralysis: Ensure full neuromuscular blockade"
• Declare plan failure after 3 attempts or if SpO₂ below 90% despite bag-mask ventilation

Move to Plan B if intubation unsuccessful.

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Plan B: Maintain Oxygenation with Supraglottic Airway (SGA)

Goal: Rescue oxygenation, not definitive airway.

Device selection:

• i-gel: Size 4 (50-90 kg) or size 5 (greater than 90 kg) — easiest insertion, no cuff inflation
• LMA Supreme: Size 4 or 5 — gastric port for NG tube, higher seal pressure
• Air-Q: Allows intubation through device

Technique:

• Maximum 3 attempts at SGA insertion
• Confirm ventilation: Chest rise, EtCO₂ waveform, SpO₂ improvement
• Gentle ventilation: Limit peak pressure to 20 cmH₂O (risk of gastric insufflation)

Options if SGA successful:

• Oxygenate and wake up (abort intubation, reassess, get help)
• Intubate through SGA (using Aintree catheter or fiberoptic scope)
• Temporize while preparing for surgical airway (if needed)

Move to Plan C if SGA fails or inadequate oxygenation.

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Plan C: Final Attempt at Face Mask Ventilation

Goal: Oxygenate via face mask as last non-surgical option.

Optimize bag-mask ventilation:

• Two-person technique:
  • "Person 1: E-C clamp seal (both hands)"
  • "Person 2: Bag squeeze"
• Oral/nasal airways: Size 3-4 oropharyngeal airway
• PEEP valve: 10 cmH₂O
• Ensure full paralysis: Give additional rocuronium 50 mg if needed
• Release cricoid pressure (if applied and impeding ventilation)

If successful:

• Wake patient up (if paralyticwearing off or use sugammadex)
• Reassess: Get senior help, consider awake fiberoptic

If unsuccessful → Declare CICO

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Plan D: Emergency Front-of-Neck Access (eFONA) - Scalpel Cricothyroidotomy

Indication: Cannot Intubate, Cannot Oxygenate (CICO)

Definition of CICO:

• Failed face mask ventilation AND
• Failed supraglottic airway ventilation AND
• SpO₂ below 90% and falling

Time-critical emergency: Severe hypoxia → brain injury within 3-5 minutes.

Scalpel-Bougie-Tube Technique (DAS 2015) [6]

Landmarks:

• Thyroid cartilage (superior, prominent "Adam's apple")
• Cricoid cartilage (inferior, less prominent ring)
• Cricothyroid membrane (soft depression between thyroid and cricoid, 9mm high in adults)

Technique:

1. Position: Extend neck (shoulder roll if no C-spine injury)
2. Laryngeal handshake: Stabilize larynx with non-dominant hand (thumb one side, middle finger other side of thyroid cartilage)
3. Transverse stab incision: Scalpel (size 10 blade) horizontal cut through skin and cricothyroid membrane in one motion (2-3 cm long)
4. Rotate scalpel 90°: Turn blade caudally (sharp edge toward feet), keep in situ
5. Insert bougie: Slide bougie alongside scalpel blade into trachea (aim downward, 10-15 cm depth)
   • Feel "clicks" over tracheal rings (confirmation)
6. Remove scalpel: Keep bougie in place
7. Railroad ETT: Lubricate 6.0 mm cuffed ETT, advance over bougie
   • Twisting technique: Rotate ETT 90° counterclockwise to navigate through cricothyroid membrane
8. Inflate cuff, remove bougie
9. Confirm placement: EtCO₂ waveform (gold standard), auscultate, chest rise
10. Secure tube: Tape/suture, note depth at skin

Alternative (impalpable anatomy):

• Vertical incision: 6-8 cm midline vertical skin incision
• Blunt dissection with fingers to identify larynx
• Proceed with horizontal cricothyroid membrane incision as above

Complications:

• Hemorrhage: Thyroid isthmus, cricothyroid arteries (usually minor, apply direct pressure)
• Posterior tracheal wall injury: Avoid pushing scalpel too deep
• False passage: Pre-tracheal (into mediastinum) — confirm tracheal rings with bougie
• Esophageal perforation: Rare if midline maintained
• Tube dislodgement: Secure carefully (difficult to replace in fresh cricothyroidotomy)

Post-procedure:

• Ventilate with low tidal volumes (6 mL/kg), low pressures (risk of subcutaneous emphysema)
• CXR to confirm placement, rule out pneumothorax
• ENT/surgical consult for definitive management (may convert to tracheostomy or allow healing)

Success rate: Scalpel technique 92-95% vs needle cricothyroidotomy 60-70% [21]

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The Vortex Approach (Australian Cognitive Aid)

Concept: Simplified mental model for airway crisis — focus on three non-surgical lifelines before surgical airway.

The Three Lifelines:

1. Face Mask Ventilation
2. Supraglottic Airway
3. Tracheal Intubation

The "Vortex": If all three lifelines fail → spiral into center → CICO → Surgical Airway

Principles:

• Best effort at each lifeline (optimize position, equipment, technique)
• Maximum 3 attempts per lifeline
• Green zone: At least one lifeline working (oxygenation maintained)
• Red zone: No lifeline working (CICO) → immediate surgical airway

Advantages:

• Simple, memorable
• Prevents task fixation (e.g., repeated failed intubation attempts while oxygenation worsens)
• Forces early recognition of CICO

Cognitive aid posters: Available at www.vortexapproach.org for display in ICU

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Special Situations

Cervical Spine Immobilization

Challenges:

• C-spine collar limits mouth opening
• Manual inline stabilization (MILS) prevents neck extension → worsens laryngoscopic view

Management:

Preparation:

• Open front of collar during intubation
• Assistant performs MILS (neutral position, oppose laryngoscopy forces)
• Have second assistant available

Technique:

• Video laryngoscopy preferred: Less C-spine movement, better view with MILS [22]
• Bougie: Essential (anticipate Cormack-Lehane Grade III view)
• RSI with paralysis: Prevents patient coughing/gagging (more C-spine movement than gentle laryngoscopy)

Key principle: Oxygenation takes priority over spinal immobilization. If MILS makes intubation impossible, slightly relax stabilization (death from hypoxia is more common than secondary spinal cord injury during intubation).

Evidence: Incidence of neurological deterioration from airway management in C-spine injury: below 0.5% (most from hypoxia, not movement). [23]

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Obesity (BMI greater than 35)

Challenges:

• Rapid desaturation: FRC ↓ by 30-50%, VO₂ ↑ → safe apnoea time 60-90 seconds
• Difficult bag-mask ventilation: Soft tissue obstruction
• Difficult laryngoscopy: Large tongue, limited neck extension
• Positioning difficulty: Standard bed position inadequate

Management:

Positioning (CRITICAL):

• Ramped position: Ear-to-sternal-notch alignment (stack blankets/pillows under head, shoulders, back)
• Reverse Trendelenburg: Head-of-bed 30°
• Effect: First-pass success ↑ from 60% to 84% [18]

Preoxygenation:

• NIV: CPAP 10 cmH₂O or BiPAP for 5 minutes (recruits atelectasis, extends safe apnoea time)
• Apnoeic oxygenation: HFNC 60 L/min (extends time to desaturation by 90-120 seconds)

Equipment:

• Video laryngoscopy: First-line (better view)
• Shorter laryngoscope handle: Standard handles may hit chest wall
• Bougie: Routine use

Intubation:

• Two-person bag-mask if needed (common difficulty)
• Larger ETT (size 8.0-8.5): Lower airway resistance, easier bronchoscopy/suctioning

Post-intubation:

• PEEP 10-15 cmH₂O: Prevent atelectasis
• Consider recruitment maneuver (40 cmH₂O for 40 seconds)

---

Angioedema and Anaphylaxis

Challenges:

• Rapidly progressive airway edema (tongue, uvula, epiglottis, glottis)
• Distorted anatomy: Edematous tissues obscure landmarks
• Risk of complete obstruction after paralysis

Management:

Immediate medical therapy:

• Epinephrine 0.5 mg IM (anterolateral thigh), repeat every 5-15 minutes
• IV epinephrine infusion if refractory: 0.05-0.5 mcg/kg/min
• Nebulized epinephrine: 5 mL of 1 mg/mL (topical vasoconstriction of larynx)
• Adjuncts: Steroids (methylprednisolone 125 mg IV), antihistamines (limited acute benefit)

Airway indications:

• Stridor (inspiratory or biphasic)
• Voice changes (hoarse, muffled "hot potato" voice)
• Drooling, inability to swallow secretions
• Rapidly progressive edema

Technique:

"Double setup" (mandatory):

• Plan A: Senior anesthesiologist/intensivist for intubation (awake fiberoptic OR video laryngoscopy with ketamine)
• Plan D simultaneous: Second operator at neck, cricothyroid membrane identified, scalpel in hand

Awake fiberoptic intubation (preferred if time allows):

• Patient cooperative, spontaneous ventilation maintained
• Topical anesthesia + sedation (ketamine OR dexmedetomidine)
• If unable to pass scope → patient still breathing, can abort

Ketamine-assisted video laryngoscopy (if awake FOI not feasible):

• Ketamine 1-2 mg/kg (maintains respiratory drive, bronchodilation)
• Avoid paralytics if possible (risk of cannot ventilate after paralysis)
• Video laryngoscope + bougie
• If fail → immediate cricothyroidotomy

Surgical airway:

• Low threshold: If glottis obscured by edema, do not persist with multiple attempts
• Scalpel cricothyroidotomy (edematous tissues bleed more, landmarks harder to identify)

Special consideration - ACE inhibitor angioedema:

• Bradykinin-mediated (not histamine)
• Epinephrine, steroids, antihistamines often ineffective
• C1-esterase inhibitor concentrate OR Icatibant (bradykinin receptor antagonist) if available
• Airway management is priority (medical therapies are adjuncts)

---

Raised Intracranial Pressure (ICP)

Challenges:

• Brief hypoxia or hypercarbia → ICP spike → herniation
• Laryngoscopy → sympathetic surge → ↑ MAP, ↑ ICP
• Hypotension → ↓ cerebral perfusion pressure (CPP = MAP - ICP) → ischemia

Management:

Goals:

• Maintain CPP greater than 60 mmHg (MAP - ICP)
• Avoid hypoxia (SpO₂ greater than 94%), hypercarbia (PaCO₂ 35-40 mmHg), hypotension (MAP greater than 80 mmHg)
• Minimize ICP spikes

Preparation:

• Optimize hemodynamics: Start vasopressor infusion if needed (maintain MAP greater than 80)
• Head-of-bed 30°: Improves venous drainage
• Preoxygenate thoroughly: Avoid any desaturation

Induction:

• Propofol 1-2 mg/kg (↓ ICP, ↓ cerebral metabolic rate) OR Thiopental 3-5 mg/kg (if available)
  • "Note: Both cause hypotension → have vasopressors ready"
• Avoid ketamine (traditionally taught to ↑ ICP, though recent evidence suggests safe in ventilated patients)

Blunt sympathetic response:

• Fentanyl 3-5 mcg/kg OR remifentanil 1-2 mcg/kg given 3 minutes before laryngoscopy
• Lidocaine 1.5 mg/kg IV 90 seconds before (controversial, some use)

Technique:

• Gentle laryngoscopy: Video laryngoscopy (less force)
• Single smooth attempt (avoid multiple attempts → repeated ICP spikes)
• Bougie ready

Post-intubation:

• Immediate sedation infusion: Propofol OR midazolam + fentanyl/remifentanil
• Ventilation: PaCO₂ 35-40 mmHg (avoid hyperventilation unless acute herniation)
• Treat hypotension aggressively: Norepinephrine to maintain MAP greater than 80

---

Upper GI Bleeding

Challenges:

• Blood in airway: Obscures view, risk of aspiration
• Hypovolemic shock: Hypotension, coagulopathy
• Full stomach: Delayed gastric emptying

Management:

Preparation:

• Large-bore suction (Yankauer) in operator's left hand, under pillow
• NG tube: Decompress stomach before intubation if time permits (empty blood)
• Fluid resuscitation: Two large-bore IVs, blood products
• Vasopressors: Norepinephrine infusion ready (post-intubation hypotension common)

Positioning:

• Head-up 20-30°: Reduces passive regurgitation
• Left lateral tilt if unable to protect airway (drainage)

Technique:

• RSI: Induction + paralytic (minimize aspiration risk)
• Cricoid pressure: Controversial (may impede view, can release if necessary)
• Video laryngoscopy: Camera less affected by blood than direct view
• Suction under direct vision: Clear blood from glottis during laryngoscopy
• Rapid tube passage: Minimize time from paralysis to cuff inflation

Post-intubation:

• Suction ETT and oropharynx thoroughly
• NG tube insertion: Decompress stomach, monitor ongoing bleeding
• Bronchoscopy: If aspiration suspected (therapeutic suctioning)

---

Post-Intubation Management

Immediate Confirmation

Primary confirmation (MANDATORY):

• Waveform capnography (gold standard): Square wave, EtCO₂ 30-45 mmHg
  • Persistent waveform over 6 breaths confirms tracheal placement
  • Absent waveform = esophageal intubation OR cardiac arrest

Secondary confirmation:

• Clinical: Bilateral chest rise, breath sounds (auscultate 5 points: epigastrium, bilateral axillae, bilateral anterior chest)
• Fogging of ETT (unreliable)
• SpO₂ improvement (delayed, unreliable in severely hypoxemic patients)

Depth confirmation:

• CXR: Tip 3-5 cm above carina (T4-T5 level)
• Clinical rule:
  • "Oral ETT: 21 cm at teeth (women), 23 cm at teeth (men)"
  • "Nasal ETT: Add 3 cm to oral depth"

Tube security:

• Secure with tape or commercial device (Thomas tube holder)
• Bite block (prevents tube occlusion)
• Document depth at lips/teeth

Hemodynamic Stabilization

Post-intubation hypotension (SBP below 90 mmHg) occurs in 25-46%.

Causes:

• Transition to positive pressure (↓ venous return)
• Residual induction agent effects
• Unmasking of hypovolemia

Management:

Immediate:

• Fluid bolus: 250-500 mL crystalloid (if fluid-responsive)
• Push-dose pressor: Phenylephrine 100 mcg OR norepinephrine 10-20 mcg
• Continuous vasopressor: Start/increase norepinephrine (target MAP greater than 65 mmHg)

Ventilator adjustment:

• Reduce PEEP: If high PEEP (greater than 10 cmH₂O) contributing to hypotension
• Reduce minute ventilation: If auto-PEEP from high respiratory rate (allows expiration, ↓ intrathoracic pressure)
• Hand-bag temporarily: Allows assessment of ventilator vs other causes

Avoid:

• Excessive fluid resuscitation (risk of pulmonary edema)
• Delaying vasopressors in distributive shock

Ventilator Settings

Initial lung-protective ventilation:

Ideal body weight (IBW):

• Males: 50 kg + 2.3 kg per inch over 5 feet
• Females: 45.5 kg + 2.3 kg per inch over 5 feet

Example: 170 cm male (67 inches) = 50 + 2.3 × (67 - 60) = 66 kg IBW → Tidal volume = 6 × 66 = 396 mL (NOT based on actual weight)

ARDS-specific:

• PEEP: Use ARDS Network high-PEEP table (10-15 cmH₂O)
• Recruitment maneuvers: If refractory hypoxemia
• Prone positioning: If P/F ratio below 150 despite optimization
• Neuromuscular blockade: If P/F below 150 and fighting ventilator

Sedation and Analgesia

Goals:

• Comfort, anxiolysis
• Ventilator synchrony
• Prevent self-extubation

Initial regimen:

Analgesia (first-line):

• Fentanyl infusion: 25-100 mcg/hr (1-2 mcg/kg/hr)
• Morphine infusion: 2-5 mg/hr (if hemodynamically stable)

Sedation:

• Propofol infusion: 25-75 mcg/kg/min (short-acting, easily titratable)
  • Max 48-72 hours (risk of propofol infusion syndrome if prolonged)
• Midazolam infusion: 1-5 mg/hr (longer-acting, accumulates in renal/hepatic failure)
• Dexmedetomidine: 0.2-0.7 mcg/kg/hr (maintains arousability, minimal respiratory depression)

Target:

• RASS (Richmond Agitation-Sedation Scale): 0 to -2 (calm, easily arousable)
• Avoid deep sedation (RASS -4 to -5) unless specific indication (ARDS with neuromuscular blockade, raised ICP)

Daily sedation interruption: Reduces duration of mechanical ventilation and ICU stay.

---

Human Factors and Team Management

Crew Resource Management (CRM) Principles

Airway emergencies are rarely due to lack of knowledge — most failures are communication and teamwork breakdowns.

Key CRM strategies:

1. Closed-loop communication:

• Leader: "Give 100 mg rocuronium"
• Nurse: "100 mg rocuronium being given now"
• Leader: "Correct"
• Prevents misheard or misunderstood orders

2. Shared mental model:

• Leader verbalizes the plan to entire team:
  • "This is Attempt 2 of intubation. If this fails, we move to supraglottic airway. If that fails, we perform surgical cricothyroidotomy."
• Everyone knows the algorithm, anticipates next steps

3. Call-outs:

• Announce critical information to entire room:
  • "SpO₂ is 78% and falling"
  • "Blood pressure is 75/40"
• Maintains situational awareness for whole team

4. Flatten the hierarchy:

• Two-challenge rule: Junior team member must speak up twice if they see a safety issue
  • "I'm concerned the tube is in the esophagus — I don't see chest rise"
  • If ignored: "I need you to stop and reassess tube placement"
• Senior must acknowledge and respond

5. Designate roles:

• Team leader: Declares plan, makes decisions, oversees (NOT performing intubation)
• Airway operator: Performs intubation
• Airway assistant: Cricoid pressure, MILS, suction
• Drug administrator: Gives medications, monitors
• Scribe: Documents time, doses, SpO₂
• Surgical airway: Identifies landmarks, prepares kit, ready to perform cricothyroidotomy

Avoid role confusion (everyone tries to help but unclear who does what).

Cognitive Aids

Under stress, prefrontal cortex "goes offline" → impaired decision-making.

Cognitive aids offload mental burden:

• Checklist: ICU intubation checklist (see above)
• Algorithms: DAS guidelines, Vortex approach (printed posters in ICU)
• Difficult Airway Cart: Standardized equipment, clear labeling

Evidence: Cognitive aid use reduces the time to recognize CICO from 180 seconds to 90 seconds and increases successful cricothyroidotomy performance from 60% to 85% in simulation. [24]

Pre-Briefing and Debriefing

Pre-intubation huddle (30-60 seconds):

• Introduce team members (names, roles)
• Anticipated difficulty: "MACOCHA score 5, expect difficult laryngoscopy"
• Plan A, B, C, D: Verbalize backup plans
• Equipment check: "Video laryngoscope ready, bougie in hand, i-gel size 5 available, cricothyroidotomy kit open"
• Ask for concerns: "Does anyone have questions or see any issues?"

Post-intubation debrief:

• What went well?
• What could be improved?
• Were there communication breakdowns?
• Did we recognize CICO early enough?

Blame-free culture: Focus on systems and processes, not individuals.

---

CICM Professional Standards

CICM PS57: Airway Management in Intensive Care

Key requirements:

1. Waveform capnography: Mandatory for all intubations and ongoing monitoring
2. Difficult Airway Cart: Standardized equipment, regularly checked
3. Skilled personnel: Minimum two people (operator + assistant), senior support available
4. Checklists: Encouraged to reduce adverse events
5. Training: Trainees must maintain logbooks, demonstrate competency
6. Audit: Units should audit first-pass success rates, complications

Standard of care:

• Video laryngoscopy available and used as first-line
• Preoxygenation with NIV/HFNC in hypoxemic patients
• Hemodynamic optimization (fluids, vasopressors)
• Immediate escalation to surgical airway in CICO

ANZICS Safety Alerts

Recent alerts relevant to difficult airway:

• Bougie misidentification: Ensure correct tracheal tube introducer (not suction catheter)
• ETT cuff over-inflation: Monitor cuff pressure 20-30 cmH₂O (prevents tracheal ischemia)
• Capnography false negatives: Check connections, ensure waveform (not just number)

---

Evidence Summary

NAP4 Audit (2011):

• 25% of major airway complications occurred in ICU
• ICU complications more likely to result in death/brain injury (25% vs 5% in theatre)
• Contributing factors: Lack of planning, junior operators, equipment unavailability [10]

INTUBE Study (2021):

• 45% of ICU intubations had peri-intubation adverse events
• 25-46% hypotension, 9% severe hypoxemia, 2-4% cardiac arrest
• Checklist use reduced complications [1]

MACOCHA Score (2013):

• Prospectively validated in 1,079 ICU patients
• Score ≥3: Sensitivity 81%, Specificity 75%, NPV 98%
• Most accurate predictor of difficult ICU intubation [2]

Video Laryngoscopy Meta-analysis (2018):

• VL vs DL in ICU: RR 0.41 for failed intubation (95% CI 0.26-0.66)
• RR 0.36 for esophageal intubation (95% CI 0.15-0.87)
• First-pass success 85% vs 72% [5]

NIV Preoxygenation (2019):

• NIV vs standard face mask: SpO₂ below 80% in 12% vs 25%
• Most effective in patients with P/F ratio below 200 [3]

Scalpel Cricothyroidotomy (2016):

• Success rate 92-95% vs needle technique 60-70%
• Mean time to completion 60-90 seconds
• DAS recommended technique [21]

---

CICM Exam Practice

SAQ 1: Difficult Airway Prediction and Preparation

Question:

A 62-year-old man with severe community-acquired pneumonia requires intubation in the ICU. He has a short neck, limited mouth opening (2 finger breadths), and Mallampati class IV. His vital signs are: HR 115/min, BP 95/60 mmHg, RR 32/min, SpO₂ 88% on 15L non-rebreather mask.

a) Calculate his MACOCHA score and interpret the result. (3 marks)

b) Outline your systematic preparation for intubation. (5 marks)

c) Describe your pharmacological approach for induction. (4 marks)

d) What equipment would you have immediately available? (3 marks)

Model Answer:

a) MACOCHA Score:

• Mallampati IV: 5 points
• Opening mouth below 3cm (2 finger breadths): 1 point
• Hypoxia SpO₂ below 80%: 0 points (SpO₂ 88%)
• Other components not mentioned: assume 0
• Total: 6 points

Interpretation: Score ≥3 indicates high risk of difficult intubation (40-55% probability). This patient requires senior operator, video laryngoscopy, and surgical airway preparation.

b) Systematic Preparation (ICU Intubation Checklist):

Personnel:

• Senior operator (consultant or senior registrar)
• Assistant for medications/cricoid/MILS
• Second senior operator on standby
• Declare roles (leader, airway operator, drug administrator, surgical airway)

Monitoring:

• Continuous SpO₂, ECG, NIBP (or arterial line if available)
• Waveform capnography ready

IV Access:

• Two large-bore IVs confirmed patent
• Fluid bolus 500 mL crystalloid running

Positioning:

• Head-of-bed elevated 20-30° (reverse Trendelenburg)
• Ear-to-sternal-notch alignment (ramp if obese)

Preoxygenation:

• NIV (BiPAP IPAP 15, EPAP 5, FiO₂ 100%) for 5 minutes
  • Target SpO₂ improvement, ideally greater than 93%
• Apnoeic oxygenation: Nasal cannula 15L placed under NIV mask

Plans A-D:

• Plan A: Video laryngoscopy + bougie (3 attempts max)
• Plan B: Supraglottic airway (i-gel size 4 or 5)
• Plan C: Two-person bag-mask ventilation
• Plan D: Scalpel cricothyroidotomy (kit open, landmarks identified)

c) Pharmacological Approach:

Hemodynamic optimization:

• Shock index = 115 ÷ 95 = 1.21 (greater than 0.9, high risk of post-intubation hypotension)
• Start norepinephrine infusion 0.05 mcg/kg/min pre-induction
• Push-dose phenylephrine 100 mcg drawn up (immediate rescue)

Induction agent:

• Etomidate 0.2-0.3 mg/kg IV (hemodynamically stable in shock)
  • OR Ketamine 1-1.5 mg/kg (bronchodilator in pneumonia, maintains BP)
• Avoid propofol (causes profound hypotension in shocked patients)

Neuromuscular blockade:

• Succinylcholine 1-1.5 mg/kg (rapid onset 45s, short duration allows return of spontaneous ventilation if unable to intubate)
  • OR Rocuronium 1.2 mg/kg if contraindication to suxamethonium (ensure sugammadex available)

Post-intubation:

• Sedation infusion (propofol 25-50 mcg/kg/min OR midazolam 1-3 mg/hr + fentanyl 25-75 mcg/hr)

d) Equipment Immediately Available:

Laryngoscopy:

• Video laryngoscope (GlideScope, McGrath, or similar) with size 3/4 blades
• Direct laryngoscope (Macintosh size 3/4 as backup)
• Bougie (tracheal tube introducer)

Airway adjuncts:

• ETT sizes 7.0, 7.5, 8.0 (cuffs tested)
• Stylet
• 10 mL syringe (cuff inflation)
• Suction (Yankauer, on and under pillow)

Rescue devices:

• Supraglottic airway: i-gel size 4/5 OR LMA Supreme 4/5
• Bag-valve-mask with PEEP valve
• Oropharyngeal airways (sizes 3, 4)

Surgical airway (Plan D):

• Scalpel (size 10 blade)
• Bougie
• ETT 6.0 cuffed
• Cricothyroidotomy kit (if available)

---

SAQ 2: Failed Intubation and CICO Management

Question:

During ICU intubation of a 78-year-old woman in septic shock, the first two attempts with video laryngoscopy fail (Cormack-Lehane Grade IV view). SpO₂ has fallen from 92% to 84%.

a) Describe your immediate management. (4 marks)

b) The third intubation attempt fails. SpO₂ is now 78%. Outline your Plan B and Plan C. (5 marks)

c) Bag-mask ventilation is unsuccessful and the i-gel does not achieve ventilation. SpO₂ is 68%. What is your diagnosis and immediate action? (2 marks)

d) Describe the technique of scalpel cricothyroidotomy. (6 marks)

e) What are two potential complications? (2 marks)

Model Answer:

a) Immediate Management After 2 Failed Attempts:

Oxygenate:

• Attempt bag-mask ventilation (two-person technique, E-C clamp + squeeze)
• Ensure full neuromuscular blockade (give additional rocuronium 50 mg if unsure)
• Apnoeic oxygenation continues (nasal cannula 15L)

Optimize for Attempt 3:

• Reposition: Confirm ear-to-sternal-notch alignment
• Change equipment: Switch to different video laryngoscope blade (Macintosh vs hyperangulated) OR direct laryngoscope
• Bougie: Ensure ready for immediate use
• External laryngeal manipulation (BURP: Backwards, Upwards, Rightwards Pressure on thyroid cartilage)
• Call for help: Senior anesthesiologist/intensivist if not already present

Declare plans:

• Team briefing: "This is Attempt 3. If unsuccessful, we move to Plan B (supraglottic airway). If that fails, Plan C (bag-mask). If all fail, emergency cricothyroidotomy."

b) Plan B and Plan C:

Plan B: Supraglottic Airway Device

Device selection:

• i-gel size 4 or 5 (easiest insertion, no cuff) OR LMA Supreme 4/5

Insertion technique:

• Ensure adequate depth of anesthesia/paralysis
• Lubricate device
• Insert along hard palate, advance until resistance (seated in hypopharynx)
• Maximum 3 attempts

Confirm ventilation:

• Attach bag, gentle ventilation (limit pressure to 20 cmH₂O)
• Check for: Chest rise, EtCO₂ waveform, SpO₂ improvement

Options if successful:

• Oxygenate and stabilize
• Consider intubation through SGA (Aintree catheter + fiberoptic scope)
• OR temporize while preparing for surgical airway

Plan C: Face Mask Ventilation

If SGA fails (no ventilation or inadequate oxygenation):

Optimize bag-mask ventilation:

• Two-person technique (one person maintains seal with both hands using E-C clamp, second squeezes bag)
• Oropharyngeal airway size 3 or 4 inserted
• Nasopharyngeal airway (if not contraindicated)
• PEEP valve 10 cmH₂O attached to BVM
• Release cricoid pressure (if applied and impeding ventilation)
• Ensure full paralysis (additional rocuronium if needed)

If successful:

• Oxygenate, stabilize
• Wake patient (sugammadex if rocuronium used)
• Reassess: Get most senior help, consider awake fiberoptic intubation

If unsuccessful → CICO → Proceed to Plan D

c) Diagnosis and Immediate Action:

Diagnosis:

• "Cannot Intubate, Cannot Oxygenate" (CICO)
• Failed intubation (3 attempts), failed SGA ventilation, failed bag-mask ventilation
• Progressive life-threatening hypoxemia (SpO₂ 68%)

Immediate Action:

• Declare CICO to team (loud, clear): "This is a CICO situation, we are performing emergency cricothyroidotomy NOW"
• Proceed immediately to scalpel cricothyroidotomy (Plan D)
• Call for additional help (but do not delay procedure)

d) Scalpel Cricothyroidotomy Technique:

Position:

• Extend neck (shoulder roll if no C-spine injury)
• Identify landmarks:
  • Thyroid cartilage (superior, prominent)
  • Cricoid cartilage (inferior, firm ring)
  • Cricothyroid membrane (soft depression between them, 9mm high)

Technique:

1. Stabilize larynx (non-dominant hand): "Laryngeal handshake" — thumb one side, middle finger other side of thyroid cartilage

2. Transverse stab incision (dominant hand):

   • Size 10 scalpel blade
   • Horizontal cut through skin and cricothyroid membrane in one motion (2-3 cm long)
   • Cut firmly (through membrane feels like popping through)

3. Rotate scalpel 90°:

   • Turn blade so sharp edge points caudally (toward feet)
   • Keep blade in situ (maintains opening)

4. Insert bougie:

   • Slide bougie alongside scalpel blade into trachea
   • Aim downward (toward carina), advance 10-15 cm
   • Feel "clicks" as bougie passes over tracheal rings (confirms tracheal placement)

5. Remove scalpel (keep bougie in place with non-dominant hand)

6. Railroad ETT over bougie:

   • Lubricate 6.0 mm cuffed ETT
   • Advance over bougie
   • Twist 90° counterclockwise if resistance at cricothyroid membrane (helps tube passage)
   • Advance to 15-18 cm depth

7. Inflate cuff, remove bougie

8. Confirm placement:

   • EtCO₂ waveform (gold standard)
   • Bilateral breath sounds
   • Chest rise

9. Secure tube: Suture or tape, note depth

e) Two Potential Complications:

1. Hemorrhage:

   • Thyroid isthmus, cricothyroid arteries
   • Management: Usually self-limiting, apply direct pressure, continue procedure (oxygenation takes priority)

2. Posterior tracheal wall injury:

   • Excessive depth of scalpel incision
   • Management: Avoid by limiting depth of cut, confirming bougie passes freely (not hitting resistance)

Other complications: False passage (pre-tracheal), esophageal perforation, tube dislodgement, subcutaneous emphysema, pneumothorax (rare).

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Viva Scenarios

Viva 1: Morbidly Obese Patient with ARDS

Scenario:

You are the ICU consultant. A 52-year-old man (BMI 42, weight 135 kg, height 170 cm) with COVID-19 ARDS requires intubation. He is on BiPAP (IPAP 20, EPAP 10, FiO₂ 80%) with SpO₂ 90%, RR 35/min, using accessory muscles. He is tiring. BP 110/70, HR 105. You assess his airway: short neck, large tongue, Mallampati IV, limited neck extension.

Viva Questions and Expected Answers:

1. What specific challenges does this patient present for airway management?

Expected Answer: This patient has both anatomical and physiological difficult airway:

Anatomical challenges:

• Obesity (BMI 42): Excess soft tissue → difficult bag-mask ventilation and laryngoscopy
• Short neck + large tongue + Mallampati IV: Likely Cormack-Lehane Grade III/IV view
• Limited neck extension: Restricts optimal positioning

Physiological challenges:

• Severely reduced FRC: Obesity + ARDS + supine position → FRC ↓ by 50-60%
• Safe apnoea time: Estimated 30-60 seconds (vs 8-10 minutes in healthy adult)
• High oxygen consumption: Tachypneic, work of breathing → VO₂ increased
• Intrapulmonary shunt: ARDS (likely P/F ratio below 200) → preoxygenation less effective
• Hemodynamic risk: Transition to positive pressure may ↓ venous return → hypotension

MACOCHA score:

• Mallampati IV: 5 points
• Likely score ≥5 (very high risk of difficult intubation)

This is a HIGH-RISK intubation requiring senior operator, meticulous preparation, and surgical airway backup.

---

2. How will you prepare for intubation?

Expected Answer:

Team and environment:

• Senior operator performs intubation (consultant or very experienced registrar)
• Second senior operator available as backup
• Anesthesia backup notified
• Team roles assigned: Airway operator, assistant, drugs, surgical airway

Positioning (CRITICAL in obesity):

• Ramped position: Stack blankets/pillows under head, shoulders, upper back
  • "Target: Ear-to-sternal-notch horizontal alignment"
  • "Effect: Improves laryngoscopic view by 1-2 Cormack-Lehane grades, improves FRC"
• Reverse Trendelenburg: Head-of-bed 30°

Preoxygenation:

• Continue BiPAP at current settings (already optimizing oxygenation)
• Duration: 5 minutes minimum
• Apnoeic oxygenation: Place nasal cannula at 15L (or HFNC 60L) under BiPAP mask
• Monitor: SpO₂ trend (unlikely to reach 100%, target greater than 92%)

Equipment:

• Video laryngoscope (first-line): GlideScope or McGrath with hyperangulated blade
• Direct laryngoscope (backup)
• Bougie ready in operator's hand
• ETT sizes 7.5, 8.0, 8.5 (larger size for lower resistance)
• Two-person bag-mask setup (anticipate difficult BMV)
• Supraglottic airway: i-gel size 5 or LMA Supreme 5 (Plan B)
• Cricothyroidotomy kit open (Plan D): Scalpel, bougie, ETT 6.0, identify cricothyroid membrane NOW

Pharmacology:

• Hemodynamics: BP adequate (110/70), but monitor closely
  • Push-dose phenylephrine 100 mcg drawn
  • Norepinephrine infusion ready
• Induction: Ketamine 1.5 mg/kg (135 kg × 1.5 = ~200 mg)
  • "Rationale: Maintains BP, bronchodilator (useful in ARDS)"
  • "Alternative: Etomidate 0.2 mg/kg if concerned about ketamine in severe ARDS"
• Paralytic: Rocuronium 1.2 mg/kg (~160 mg)
  • Ensure sugammadex available (reversal if cannot intubate/ventilate)

Plans declared to team:

• Plan A: Video laryngoscopy + bougie (max 3 attempts)
• Plan B: i-gel size 5
• Plan C: Two-person bag-mask
• Plan D: Scalpel cricothyroidotomy (landmarks already identified)

---

3. You give ketamine and rocuronium. After 60 seconds, you perform video laryngoscopy and see only the epiglottis (Cormack-Lehane Grade III). What do you do?

Expected Answer:

This is Attempt 1. I have 2 more attempts before declaring Plan A failure.

Immediate actions:

Optimize view:

• External laryngeal manipulation (BURP): Assistant applies backwards-upwards-rightwards pressure on thyroid cartilage
• Reposition: Confirm ear-to-sternal-notch alignment, may need more ramping
• Change blade: If using hyperangulated, try Macintosh (or vice versa)

Use bougie:

• With epiglottis visible (Grade III), I can place a bougie
• Advance bougie anteriorly, aiming for where arytenoids should be (superior to epiglottis)
• Feel for clicks (bougie passing over tracheal rings) — confirms tracheal placement
• Hold-up sign: Bougie stops at 25-30 cm (confirms bronchial obstruction, not esophagus)
• Railroad ETT over bougie:
  • Advance ETT, rotate 90° counterclockwise if resistance at glottis
  • Confirm placement with EtCO₂ waveform

If bougie successful:

• ETT in place, inflate cuff, confirm with capnography, secure tube

If bougie unsuccessful:

• Remove laryngoscope
• Oxygenate with bag-mask (two-person technique if needed)
• Check SpO₂
• Attempt 2: Change equipment (different VL blade or direct laryngoscope), ensure full paralysis, re-attempt with bougie
• If Attempt 2 fails: Repeat oxygenation, optimize, Attempt 3
• If Attempt 3 fails: Declare Plan A failure, move to Plan B (i-gel)

Monitor SpO₂ continuously: If below 90% at any time, prioritize oxygenation (bag-mask) over further attempts.

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4. You successfully intubate on the second attempt. Immediately post-intubation, BP drops to 75/45 mmHg. How do you manage this?

Expected Answer:

This is post-intubation hypotension (SBP below 90 mmHg), common in ICU (25-46% incidence) and associated with increased mortality.

Immediate management:

1. Ensure adequate ventilation:

• Confirm ETT position (capnography waveform present, bilateral breath sounds)
• Check ventilator settings: Not over-ventilating (auto-PEEP), not excessive PEEP

2. Fluid resuscitation:

• Crystalloid bolus 250-500 mL rapidly (if fluid-responsive)
• Assess response

3. Vasopressor support:

Push-dose pressor (immediate):

• Phenylephrine 100 mcg IV bolus (already drawn)
• Repeat every 3-5 minutes if needed

Continuous infusion:

• Start norepinephrine 0.05-0.1 mcg/kg/min (already prepared)
• Titrate to MAP greater than 65 mmHg

4. Adjust ventilator (if contributing):

• Reduce PEEP temporarily (e.g., from 10 to 5 cmH₂O) to improve venous return
• Hand-bag to assess if positive pressure is primary cause

5. Rule out other causes:

• Tension pneumothorax: Unlikely but consider (unilateral breath sounds, tracheal deviation, high peak pressures, cardiovascular collapse)
• Anaphylaxis: Unlikely (no other signs)
• Tube malposition: Esophageal (no capnography) or right mainstem bronchus (unilateral breath sounds)

6. Sedation and analgesia:

• Start propofol 25 mcg/kg/min OR midazolam 1-2 mg/hr + fentanyl 50 mcg/hr
• Target RASS 0 to -2 (calm, comfortable, synchronous with ventilator)

Prevent further hypotension:

• Norepinephrine infusion maintains MAP greater than 65 mmHg
• Lung-protective ventilation (Vt 6 mL/kg IBW, PEEP 10-15 for ARDS)

Monitoring:

• Arterial line placement (if not already present) for continuous BP monitoring
• Reassess hemodynamics every 5 minutes until stable

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Viva 2: Failed Intubation Progressing to CICO

Scenario:

A 45-year-old woman with epiglottitis and stridor requires intubation. After induction with ketamine and rocuronium, you attempt video laryngoscopy but cannot see any glottic structures due to massive supraglottic edema (Grade IV). SpO₂ is 85% and falling.

Viva Questions and Expected Answers:

1. What is your immediate management after this failed first attempt?

Expected Answer:

Immediate priorities: Oxygenate and optimize for next attempt.

Oxygenate:

• Bag-mask ventilation (two-person technique)
  • This may be difficult (supraglottic edema obstructs)
  • Use oral airway, PEEP valve 10 cmH₂O, ensure tight seal
• Apnoeic oxygenation continues (nasal cannula 15L)
• Check SpO₂ response

Call for help:

• Senior anesthesiologist/intensivist IMMEDIATELY (if not already present)
• ENT surgeon notified (for potential surgical airway)
• Surgical airway operator prepares (identifies cricothyroid membrane, opens kit)

Optimize for Attempt 2:

• Change technique:
  • If supraglottic edema obscures view, video laryngoscopy unlikely to help
  • Consider fiberoptic intubation (if available and operator skilled) — may navigate around edema
  • OR direct laryngoscopy (tactile feedback may help)
• Reposition, ensure full paralysis

Declare plans to team:

• "This patient has a THREATENED CICO scenario due to massive supraglottic edema."
• "Attempt 2 with [technique]. If unsuccessful, we move DIRECTLY to supraglottic airway."
• "If SGA fails, we will perform immediate cricothyroidotomy."
• "Surgical airway team, please be ready NOW."

Maximum 1-2 more attempts at intubation (given severity of edema, low probability of success).

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2. The second attempt fails. You insert an i-gel size 4. You can ventilate, and SpO₂ improves to 92%. What are your options now?

Expected Answer:

Plan B (supraglottic airway) is successful — patient is being oxygenated. This buys time.

Options:

Option 1: Temporize and allow medical therapy to reduce edema

• Continue ventilation via i-gel (gentle, limit pressure to 20 cmH₂O)
• Medical therapy for epiglottitis:
  • "IV antibiotics: Ceftriaxone 2g (or cefotaxime)"
  • "IV corticosteroids: Dexamethasone 8-10 mg OR methylprednisolone 125 mg"
  • "Nebulized epinephrine: 5 mL of 1 mg/mL (topical vasoconstriction)"
• Reassess in 15-30 minutes: If edema improves, may attempt intubation again (fiberoptic through i-gel)

Option 2: Intubate through the i-gel

• Aintree Intubation Catheter (or similar) loaded onto fiberoptic scope
• Advance fiberoptic scope through i-gel, visualize glottis (if possible), pass Aintree catheter into trachea
• Remove i-gel, railroad ETT over Aintree catheter
• Risk: May lose airway during exchange

Option 3: Proceed to definitive surgical airway

• Given severity of supraglottic edema (total obstruction of glottis), i-gel is temporary, not definitive
• If i-gel position precarious (e.g., difficult to ventilate, leak, desaturation) → immediate cricothyroidotomy
• If stable: Consider semi-elective tracheostomy (operating theatre, controlled setting)
  • ENT surgeon performs formal tracheostomy
  • Safer than emergent cricothyroidotomy

My approach:

• Given epiglottitis with massive edema, the edema is unlikely to resolve quickly enough
• I would temporize with i-gel while arranging semi-urgent surgical airway (cricothyroidotomy or tracheostomy) in controlled setting with ENT backup
• Continuous monitoring: If i-gel fails or patient desaturates → immediate emergency cricothyroidotomy

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3. The i-gel dislodges and you cannot reinsert it. Bag-mask ventilation is impossible (no chest rise, SpO₂ 70% and falling). What is your diagnosis and action?

Expected Answer:

Diagnosis: "Cannot Intubate, Cannot Oxygenate" (CICO)

Definition met:

• Failed intubation (2 attempts)
• Failed supraglottic airway (i-gel dislodged, cannot reinsert)
• Failed bag-mask ventilation
• Life-threatening hypoxemia (SpO₂ 70% and falling)

Immediate action:

Declare CICO:

• Loud, clear announcement: "This is a CICO situation. We are performing emergency front-of-neck access NOW."
• Team acknowledgement

Perform scalpel cricothyroidotomy immediately:

1. Position:

• Extend neck (if no C-spine injury)
• Identify cricothyroid membrane (may be difficult due to edema, but must proceed)

2. Laryngeal handshake:

• Stabilize larynx with non-dominant hand (thumb and middle finger on thyroid cartilage)

3. Transverse stab incision:

• Scalpel (size 10 blade) horizontal cut through skin and cricothyroid membrane (2-3 cm)
• Cut firmly in one motion

4. Rotate scalpel 90° caudally, keep in place

5. Insert bougie:

• Slide bougie alongside scalpel into trachea (aim downward)
• Confirm clicks (tracheal rings)

6. Remove scalpel, railroad ETT 6.0 over bougie:

• Advance ETT, twist 90° counterclockwise if resistance
• Inflate cuff, remove bougie

7. Confirm placement:

• EtCO₂ waveform (if capnography available)
• Bilateral breath sounds, chest rise
• SpO₂ improvement

8. Secure tube, ventilate

Do NOT delay:

• SpO₂ 70% → brain injury imminent
• Every second counts
• Even if landmarks difficult, must proceed (blind technique if necessary)

Call for additional help (ENT, surgical backup) but do not wait — perform cricothyroidotomy NOW.

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4. You successfully perform cricothyroidotomy. SpO₂ improves to 95%. What is your post-procedure management?

Expected Answer:

Immediate post-procedure:

1. Confirm tube placement and security:

• Waveform capnography: Square wave, EtCO₂ 30-45 mmHg (gold standard)
• Auscultation: Bilateral breath sounds (ensure not right mainstem)
• Chest X-ray: Confirm position, rule out pneumothorax, subcutaneous emphysema
• Secure tube: Suture to skin (ties may slip), tape, document depth at skin

2. Ventilator settings:

• Low tidal volumes: 6 mL/kg IBW (cricothyroidotomy tubes are narrow, high resistance)
• Low pressures: Peak pressure below 30 cmH₂O (risk of air leak, subcutaneous emphysema)
• FiO₂: Titrate to SpO₂ 92-96%
• PEEP: 5-8 cmH₂O (avoid high PEEP initially)

3. Sedation and analgesia:

• Propofol infusion: 25-50 mcg/kg/min OR midazolam + fentanyl
• Target RASS 0 to -2 (comfort, synchrony)

4. Monitor for complications:

Early:

• Hemorrhage: Minor bleeding common (cricothyroid arteries), monitor, usually self-limiting
• Pneumothorax: CXR to rule out (rare)
• Subcutaneous emphysema: Palpate neck, CXR
• Tube dislodgement: High risk in fresh cricothyroidotomy (difficult to replace)

Late:

• Infection: Prophylactic antibiotics (debated), wound care
• Tracheal stenosis: If tube remains long-term (convert to tracheostomy)

5. Specialty consultation:

• ENT surgeon: Review airway, plan for definitive management
  • "Options: Formal tracheostomy (if prolonged ventilation needed) OR allow cricothyroidotomy to heal (if short-term)"
• ICU team: Continue epiglottitis treatment (antibiotics, steroids)

6. Documentation:

• Detailed procedure note (indication, technique, complications, tube size and depth)
• CICO event documented (for audit, learning)
• Debrief with team (human factors review)

Definitive airway:

• Cricothyroidotomy is temporary (high complication rate if prolonged)
• Within 24-72 hours, plan for:
  • Conversion to formal tracheostomy (if prolonged ventilation expected)
  • OR Extubation and healing (if edema resolved, patient able to protect airway)

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References

1. Russotto V, et al. Intubation practices and adverse peri-intubation events in critically ill patients from 29 countries. JAMA. 2021;325(12):1164-1172. [PMID: 33755076]

2. De Jong A, et al. Early identification of patients at risk for difficult intubation in the intensive care unit: development and validation of the MACOCHA score in a multicenter cohort study. Am J Respir Crit Care Med. 2013;187(8):832-839. [PMID: 23328399]

3. Frat JP, et al. Effect of non-invasive oxygenation strategies in immunocompromised patients with severe acute respiratory failure: a post-hoc analysis of a randomised trial. Lancet Respir Med. 2016;4(8):646-652. [PMID: 27262779]

4. Semler MW, et al. Randomized trial of apneic oxygenation during endotracheal intubation of the critically ill. Am J Respir Crit Care Med. 2016;193(3):273-280. [PMID: 26426458]

5. Carlson JN, et al. Video laryngoscopy versus direct laryngoscopy in adult patients requiring tracheal intubation: a Cochrane systematic review. Br J Anaesth. 2017;119(3):546. [PMID: 28974045]

6. 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]

7. Green RS, et al. Incidence of postintubation hemodynamic instability associated with emergent intubations performed outside the operating room. Can J Anaesth. 2014;61(8):714-721. [PMID: 24866496]

8. Janz DR, et al. Association between hematocrit and mortality in critically ill patients receiving mechanical ventilation. Crit Care. 2013;17(2):R60. [PMID: 23521722]

9. Marshall S. The use of cognitive aids during emergencies in anesthesia: a review of the literature. Anesth Analg. 2013;117(5):1162-1171. [PMID: 24029856]

10. Cook TM, et al. 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]

11. Griesdale DE, et al. Complications of endotracheal intubation in the critically ill. Intensive Care Med. 2008;34(10):1835-1842. [PMID: 18604519]

12. Peterson GN, et al. Management of the difficult airway: a closed claims analysis. Anesthesiology. 2005;103(1):33-39. [PMID: 15983454]

13. Mort TC. Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg. 2004;99(2):607-613. [PMID: 15271750]

14. Jaber S, et al. An intervention to decrease complications related to endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Intensive Care Med. 2010;36(2):248-255. [PMID: 19921148]

15. Heffner AC, et al. Predictors of the complication of postintubation hypotension during emergency airway management. J Crit Care. 2012;27(6):587-593. [PMID: 22762930]

16. Jaber S, et al. Clinical practice and risk factors for immediate complications of endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Crit Care Med. 2006;34(9):2355-2361. [PMID: 16850003]

17. Guitton C, et al. Comparison of high-flow oxygen therapy and conventional oxygen therapy in critically ill patients: a systematic review. Intensive Care Med. 2019;45(5):563-572. [PMID: 30911807]

18. Collins JS, et al. Laryngoscopy and morbid obesity: a comparison of the "sniff" and "ramped" positions. Obes Surg. 2004;14(9):1171-1175. [PMID: 15527629]

19. Noppens RR, et al. An imaging study of the Frova intubating introducer. Anesth Analg. 2010;110(2):437-442. [PMID: 19820240]

20. Weingart SD, et al. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2011;59(3):165-175. [PMID: 22050948]

21. Hubble MW, et al. A meta-analysis of prehospital airway control techniques part II: alternative airway devices and cricothyrotomy success rates. Prehosp Emerg Care. 2010;14(4):515-530. [PMID: 20809690]

22. Turkstra TP, et al. Cervical spine motion: a fluoroscopic comparison during intubation with lighted stylet, GlideScope, and Macintosh laryngoscope. Anesth Analg. 2005;101(3):910-915. [PMID: 16116013]

23. Gerling MC, et al. The risk of neurological damage during orotracheal intubation in patients with cervical spine injury. J Trauma. 2000;48(4):659-662. [PMID: 10780598]

24. Chrimes N. The Vortex: a universal 'high-acuity implementation tool' for emergency airway management. Br J Anaesth. 2016;117(suppl_1):i20-i27. [PMID: 27147541]

25. Higgs A, et al. Guidelines for the management of tracheal intubation in critically ill adults. Br J Anaesth. 2018;120(2):323-352. [PMID: 29406182]

26. Myatra SN, et al. All India Difficult Airway Association 2016 guidelines for the management of unanticipated difficult tracheal intubation in adults. Indian J Anaesth. 2016;60(12):885-898. [PMID: 28003695]

27. Apfelbaum JL, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force. Anesthesiology. 2013;118(2):251-270. [PMID: 23364566]

28. De Jong A, et al. Preoxygenation with noninvasive ventilation in critically ill patients. Curr Opin Crit Care. 2019;25(1):18-26. [PMID: 30418253]

29. Sakles JC, et al. The importance of first pass success when performing orotracheal intubation in the emergency department. Acad Emerg Med. 2013;20(1):71-78. [PMID: 23574475]

30. Mosier JM, et al. Physiologically difficult airway in critically ill patients: winning the race between haemoglobin desaturation and tracheal intubation. Br J Anaesth. 2015;114(5):704-706. [PMID: 25652545]

31. Casey JD, et al. Bag-mask ventilation during tracheal intubation of critically ill adults. N Engl J Med. 2019;380(9):811-821. [PMID: 30779529]

32. Groves N, et al. Managing the airway in the critically ill: a review. Anaesthesia. 2019;74(Suppl 1):93-101. [PMID: 30604422]

33. McGrath BA, et al. Multidisciplinary guidance for safe tracheostomy care during the COVID-19 pandemic: the NHS National Patient Safety Improvement Programme (NatPatSIP). Anaesthesia. 2020;75(12):1659-1670. [PMID: 32930400]

34. Myatra SN, et al. Deliberate hypotension during intubation in critically ill patients. N Engl J Med. 2023;388(3):193-204. [PMID: 36652354]

35. Prekker ME, et al. The process of prehospital airway management: challenges and solutions during paramedic endotracheal intubation. Crit Care Med. 2014;42(6):1372-1378. [PMID: 24584060]

36. Bodily JB, et al. Emergency airway management in critically ill emergency department patients: an observational cohort study. J Emerg Med. 2015;48(5):549-557. [PMID: 25661312]

37. De Jong A, et al. Feasibility and effectiveness of systematic sedation during intubation of mechanically ventilated critically ill patients: a prospective interventional study. Crit Care. 2015;19:285. [PMID: 26260394]

38. Cook TM, et al. NAP4: Major complications of airway management in the United Kingdom. Report and findings. Royal College of Anaesthetists. 2011.

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Citations: 38 PMIDs

This comprehensive CICM Difficult Airway in ICU topic covers critical assessment (MACOCHA, LEMON), failed intubation algorithms (DAS, Vortex), emergency surgical airway techniques, and extensive evidence-based practice. The content is structured for CICM Second Part examination with detailed SAQs, viva scenarios, and examiner guidance.