What are the guidelines and steps for intubation, including types, sedation dosages, and contraindications?

Intubation Guidelines: Step-by-Step Approach, Types, Sedation Dosages, and Contraindications

The most effective management of intubation requires immediate recognition of potential difficulties, securing the airway with the most experienced operator available, and following a structured algorithmic approach that prioritizes oxygenation above all other considerations. 1

Airway Assessment and Planning

Pre-Intubation Assessment

• Assess for difficult airway risk factors using MACOCHA score (score ≥3 predicts difficult intubation) 2
• Evaluate:
  • Airway anatomy (Mallampati classification, neck mobility, mouth opening)
  • Body habitus (obesity significantly increases risk - 2× higher with BMI >30,4× higher with BMI >40) 1
  • Previous difficult intubation history
  • Identify cricothyroid membrane using "laryngeal handshake" technique 2
  • Assess cardiorespiratory status (hemodynamic optimization improves outcomes) 2

Team Assembly and Equipment Preparation

• Assign clear roles to team members
• Prepare equipment and drugs
• Discuss Plans A, B, C, and D for airway management
• Determine whether awakening is an option if intubation fails 2

Types of Intubation

1. Routine/Low-Risk Intubation

   • Normal airway at induction with no anticipated difficulties
   • No general risk factors present 2

2. At-Risk Intubation

   • Pre-existing airway difficulties (obesity, OSA, aspiration risk)
   • Peri-operative airway deterioration (distorted anatomy, hemorrhage, edema)
   • Restricted airway access (shared airway, limited head/neck movement) 2

3. Awake Fiberoptic Intubation (AFOI)

   • Gold standard for predicted difficult airway
   • Requires balanced sedation for patient comfort while maintaining ventilation 3

4. Rapid Sequence Intubation (RSI)

   • Indicated for patients at risk of aspiration
   • Uses neuromuscular blocking agents, induction drugs, and adjunctive medications 4

Step-by-Step Intubation Procedure

Step 1: Positioning and Preoxygenation

• Position patient with head elevated 25-30° when tolerated 2
• For optimal positioning:
  • Flex lower cervical spine and extend upper cervical spine ("sniffing position")
  • For obese patients: ramping (external auditory meatus level with sternal notch)
  • Ensure firm bed mattress for optimal cricoid pressure application 2
• Preoxygenate with tight-fitting facemask, 10-15 L/min of 100% oxygen for 3 minutes
• For hypoxemic patients, use CPAP (5-10 cm H₂O) or non-invasive ventilation 2

Step 2: Induction and Sedation

• Midazolam Dosing 5:

  • Unpremedicated adults <55 years: 0.3-0.35 mg/kg IV
  • Unpremedicated adults >55 years: 0.3 mg/kg IV
  • Patients with severe systemic disease: 0.2-0.25 mg/kg IV
  • Premedicated patients: 0.15-0.35 mg/kg IV
  • Administer over 20-30 seconds, allowing 2 minutes for effect
  • May use increments of 25% of initial dose if needed

• Opioid Options:

  • Fentanyl: 1.5-2 mcg/kg IV (5 minutes before induction)
  • Remifentanil: Effective for AFOI due to short half-life 3

Step 3: Laryngoscopy and Intubation

1. First Attempt:

   • Use Macintosh laryngoscope with optimum external laryngeal manipulation (OELM) or BURP (backward, upward, rightward pressure) if needed 2
   • If grade 3 or 4 view persists, proceed to alternative techniques

2. Alternative Techniques:

   • Eschmann tracheal tube introducer ("bougie") for grade 3 views 2
   • Alternative direct laryngoscopes (McCoy, straight laryngoscope)
   • Video laryngoscopy (shown to be at least as good as, often better than direct laryngoscopy) 6

3. Verification of Placement:

   • Confirm with waveform capnography
   • Observe bilateral chest rise
   • Auscultate bilateral breath sounds

Step 4: Post-Intubation Management

• Secure tube properly
• Initiate post-intubation sedation promptly (within 15 minutes) 7
• Continuous Sedation Options 5:
  • Midazolam: Initial infusion rate 0.02-0.10 mg/kg/hr (1-7 mg/hr)
  • Loading dose if needed: 0.01-0.05 mg/kg
  • Adjust rate by 25-50% based on sedation assessment
  • Decrease rate by 10-25% every few hours to find minimum effective rate

Rescue Techniques for Failed Intubation

Plan B: Secondary Tracheal Intubation

• Maximum 4 attempts while maintaining oxygenation and anesthesia
• Use supraglottic airway device (LMA or ILMA) with maximum 2 insertion attempts 2

Plan C: Maintenance of Oxygenation

• Consider fiberoptic intubation through LMA/ILMA
• Verify ventilation, oxygenation, anesthesia, and cardiovascular stability 2

Plan D: Can't Intubate, Can't Ventilate

• Proceed to front-of-neck airway access
• Surgical technique preferred over needle cricothyroidotomy due to higher success rate 1

Extubation Guidelines

Preparation for Extubation

• Ensure adequate oxygenation (SpO₂ >92% on FiO₂ ≤0.4)
• Confirm effective spontaneous breathing
• Verify complete reversal of neuromuscular blockade
• Perform cuff leak test
• Confirm hemodynamic stability 1

Extubation Procedure

1. Position patient appropriately
2. Pre-oxygenate with 100% oxygen
3. Suction oropharyngeal secretions
4. Apply positive pressure via breathing circuit
5. Deflate cuff and remove tube during positive pressure
6. Provide supplemental oxygen post-extubation 1

Contraindications and Cautions

Absolute Contraindications

• Complete upper airway obstruction
• Severe maxillofacial trauma where oral/nasal intubation would enter cranial vault

Relative Contraindications

• Unstable cervical spine injury (requires modified approach)
• Severe coagulopathy (for nasal intubation)
• Using succinylcholine in patients with neuromuscular disorders 1

Common Pitfalls to Avoid

• Delayed recognition of respiratory failure
• Inadequate preparation for difficult airway
• Multiple intubation attempts without changing approach
• Failure to call for help early
• Proceeding with surgery despite borderline respiratory status
• Extubating without confirming adequate reversal of neuromuscular blockade 1

Remember that intubation is an elective process that requires careful planning and execution. The goal is to ensure uninterrupted oxygen delivery, avoid airway stimulation, and have a backup plan that permits ventilation and re-intubation with minimal difficulty should extubation fail 2.