Intubation
Kristin Barkley, DNP, CRNA
Quick Facts
- Intubation is the process of inserting an endotracheal tube (ETT) through the nose or mouth into the mid-trachea to deliver anesthetic gases and oxygen, and to protect the lungs from aspiration or contamination.
- Performed either under deep anesthesia or while the patient is awake with light sedation to preserve spontaneous ventilation.
- Decision to proceed with standard induction, awake intubation, or invasive airway should be based on airway assessment and anticipated difficulty (See Difficult Airway Algorithm).
- Comprehensive history, airway evaluation, and diagnostic review help predict ventilation and intubation challenges.
Procedure Guide
Airway Assessment – Predicted Difficulty
- Perform thorough airway assessment to identify predictors of difficulty.
- Predictors of difficult intubation:
- Prior difficult intubation
- Small mouth opening (<3 finger breadths)
- Mallampati class III–IV
- Short thyromental distance (<6 cm)
- Short sternomental distance (<12 cm)
- Limited neck mobility
- Limited mandibular protrusion or upper bite test grade 3
- Thick neck circumference (>40 cm)
- Predictors of difficult mask ventilation:
- BMI >30
- Age >55
- Male
- Beard
- Edentulous
- Abnormal neck anatomy (radiation/surgical scarring)
- History of snoring or OSA
Induction Sequence
- Intravenous or inhalation induction: Choice of agent depends on age, comorbidities, and clinical context.
- Rapid Sequence Induction (RSI):
- Used to prevent aspiration in patients with gastroparesis, bowel obstruction, or inadequate NPO time.
- Mask ventilation generally avoided but may be used cautiously until paralysis achieved.
- IV induction agent followed immediately by a rapid-onset paralytic.
- Cricoid pressure may be applied during induction and maintained until ETT confirmation.
- Controversial—can obscure laryngoscopic view or displace esophagus.
Equipment
- Oropharyngeal and nasopharyngeal airways
- Tongue blade
- ETTs (sizes up and down):
- Adult female: 7.0–7.5
- Adult male: 7.5–8.0
- ETT types: oral, nasal, RAE, armored, NIM
- Intubating stylets and bougies
- Direct laryngoscopes:
- Macintosh blade: curved, fits into vallecula
- Miller blade: straight, placed under epiglottis
- Both blades include a left flange to sweep tongue aside
- Video and/or flexible laryngoscopes (see image below)
- Rescue airway (SGA)
- Bag-mask with ETCO₂ monitoring
- Tape or securing device
Direct vs Video Laryngoscopy
- Proceed directly to video laryngoscopy if difficulty anticipated or encountered.
- Consider combined techniques (video + flexible bronchoscope).
- Common devices:
- Glidescope
- McGrath
- Airtraq
- Storz C-MAC
- King Vision
Approach
- Oral
- Nasal
- Tracheostomy/stoma (if present)
SCOPe Guide
Strategies
- Assess patient for awake vs asleep intubation needs.
- Gather all required equipment prior to induction.
- Positioning:
- Sniffing: head elevation 3–7 cm, neck flexed, atlanto-occipital extension.
- Ramped: in obese patients—align sternal notch with external auditory meatus.
Preoxygenation:
-
- 100% O₂ for 3 minutes (tidal breathing) or 8 deep breaths over 1 minute.
- Semi-upright position improves FRC.
- Consider high-flow nasal oxygen for apneic oxygenation in high-risk patients.
- Induce to sufficient depth to blunt laryngoscopy response.
- Tape eyes prior to airway manipulation.
- Mask ventilation: optimize hand position, adjuncts, and jaw support.
- Neuromuscular blockade: optional; monitor with peripheral nerve stimulator.
- Laryngoscopy:
- Open mouth (“scissor” method), insert blade from right side, sweep tongue left.
- Identify epiglottis, lift anteriorly to expose glottis.
- Advance ETT 2 cm beyond cords (~21–23 cm at teeth).
- Remove stylet, inflate cuff, confirm placement.
- Confirmation:
- Bilateral chest rise
- Positive ETCO₂ (sustained waveform for ≥3 breaths)
- Bilateral breath sounds (right mainstem → unilateral)
- Secure tube with tape or commercial device.
Clinical Optimization
- Pre-assess and plan for potential intubation or ventilation difficulty.
- Identify induction agents and airway adjuncts in advance.
- Ensure additional personnel available if needed.
Pearls
- Comprehensive airway assessment is essential.
- Optimize patient positioning and oxygenation before intubation.
- Have a primary plan and backup plan ready.
- Follow the Difficult Airway Algorithm if issues arise.
- STOPMAID mnemonic: Suction, Tools, Oxygen, Position, Monitors, Assistant/Airway devices, IV access, Drugs.
Media
- Types of Video Laryngoscopes
- Types of Blades
- Patient Positioning for Intubation
References
- Airway Management for General Anesthesia in Adults – UpToDate
- Barash PG, Cullen BF, Stoelting RK, et al. Clinical Anesthesia. 8th ed. Wolters Kluwer; 2017: 778–787.
Media Attributions
- str-v-curve-screen
- Video-laryngoscopes-and-supraglottic-airway-devices-A-Video-laryngoscopes-AirWay.tif
- Picture1
