Acute Airway Management & RSI — Part 3: Difficult Airway Management & Surgical Airway

1. The Emergency Difficult Airway Algorithm

The structured approach to the unanticipated difficult airway follows a sequential plan-based algorithm. Each plan represents a progressively more invasive rescue strategy. The key principle is to declare failure early and move to the next plan rather than persisting with a failing technique.^{1 2 3}

1.1 Algorithm Overview

PLAN A: Face-mask ventilation and tracheal intubation
  ├── Optimize: head position, laryngoscope choice, bougie, ELM, suction
  ├── Maximum 3 attempts (+1 by most experienced operator)
  └── If FAILED → PLAN B

PLAN B: Maintaining oxygenation — Supraglottic Airway (SGA)
  ├── Insert second-generation SGA (i-gel, LMA ProSeal, LMA Supreme)
  ├── Maximum 3 insertion attempts (2 recommended)
  ├── If ventilation achieved → decide: wake vs. intubate through SGA vs. proceed with SGA
  └── If FAILED (cannot oxygenate via SGA) → PLAN C

PLAN C: Face-mask ventilation
  ├── Final attempt at oxygenation before FONA
  ├── Two-person technique, adjuncts (OPA, NPA), paralysis if not given
  ├── Consider sugammadex 16 mg/kg if rocuronium was used (to restore spontaneous breathing)
  └── If FAILED → "Cannot Intubate, Cannot Oxygenate" (CICO) → PLAN D

PLAN D: Front-of-Neck Access (FONA)
  ├── Surgical cricothyrotomy (scalpel-bougie-tube technique)
  ├── This is a RESCUE — not a failure; it is the correct management of CICO
  └── Do NOT delay: hypoxic brain injury occurs within 3–5 minutes

1.2 Critical Time Points

Key principle: The decision to perform FONA should be made based on the trajectory of oxygenation and the failure of rescue techniques, not a specific SpO₂ number. Waiting until SpO₂ is critically low before declaring CICO is the single most common error identified in airway catastrophe reviews.³

2. Plan A: Optimizing Tracheal Intubation

2.1 First-Attempt Optimization Strategies

The first attempt at laryngoscopy has the highest probability of success. Each subsequent attempt has a lower success rate and higher complication rate. Data from large airway registries demonstrate:⁴

Recommendation: Maximum 3 laryngoscopy attempts (plus one additional attempt by the most experienced operator available). Each attempt should incorporate a meaningful change in technique.

2.2 Optimization Maneuvers Between Attempts

2.3 The Bougie (Tracheal Tube Introducer)

The gum elastic bougie is a semi-rigid, 60 cm introducer with a coude (angled) tip that can be passed into the trachea when the glottic opening is not fully visible (CL grade IIb–III).^{5 6}

Technique:

1. During laryngoscopy, identify the epiglottis (CL III) or arytenoids (CL IIb)
2. Pass the bougie tip anteriorly under the epiglottis, directing it toward where the glottic opening should be
3. Advance gently — tracheal clicks (bougie tip clicking over tracheal cartilage rings) confirm tracheal placement
4. If the bougie advances > 40 cm without resistance, it may be in the esophagus (esophagus does not have rings and allows passage to stomach without hold-up)
5. If the bougie arrests at 30–35 cm (hold-up sign), it has reached a bronchus, confirming tracheal placement
6. Railroad the ETT over the bougie (rotate ETT 90 degrees counterclockwise if it catches on the arytenoids)
7. Remove the bougie and confirm placement with capnography

Evidence: The BEAM randomized trial demonstrated that bougie-first intubation had a first-pass success rate of 96% compared to 82% for ETT+stylet in emergency intubation of patients with at least one difficult airway predictor.⁵

3. Video Laryngoscopy (VL)

3.1 Overview

Video laryngoscopy uses a camera mounted on or near the laryngoscope blade tip to provide an indirect view of the glottis on a screen, eliminating the need to align the oral, pharyngeal, and laryngeal axes.^{7 8}

3.2 VL Blade Geometries

3.3 Evidence for Video Laryngoscopy

3.4 VL Troubleshooting

4. Plan B: Supraglottic Airways (SGAs)

4.1 Role of the SGA in the Difficult Airway

When intubation fails, the primary rescue device is a supraglottic airway (SGA). SGAs are inserted blindly into the hypopharynx without laryngoscopy and create a seal around the laryngeal inlet, allowing positive-pressure ventilation. Second-generation SGAs (which include a gastric drainage channel) are preferred for emergency use.^{1 10}

4.2 Second-Generation SGA Options

4.3 SGA Sizing Tables

i-gel Sizing

LMA (Classic/ProSeal/Supreme) Sizing

King LT Sizing

4.4 SGA Insertion Technique (i-gel as Exemplar)

1. Select appropriate size based on patient weight
2. Apply lubricant to the posterior and lateral surfaces of the cuff
3. With the patient supine and mouth open, hold the i-gel like a pen with the cuff facing the chin
4. Introduce the leading soft tip into the mouth, pressing posteriorly against the hard palate
5. Advance with a smooth, continuous motion following the curve of the pharynx until definite resistance is felt (the device is seated in the hypopharynx with the tip in the upper esophageal sphincter)
6. Connect to BVM or ventilator circuit
7. Confirm: chest rise, ETCO₂ waveform, bilateral breath sounds
8. Secure the device; insert gastric tube through the gastric channel

4.5 Intubating Through the SGA

If an SGA is placed as a rescue device and the patient requires definitive intubation, an endotracheal tube can be placed through the SGA using a fiberoptic bronchoscope or blindly (with an Aintree intubation catheter).¹¹

Technique — Fiberoptic-guided intubation through SGA:

1. Confirm adequate ventilation through the SGA
2. Load an appropriately sized ETT (typically 6.0 mm for size 3–4 SGA) onto the fiberoptic bronchoscope
3. Pass the bronchoscope through the SGA ventilation channel
4. Visualize the vocal cords through the SGA
5. Advance the bronchoscope through the cords into the trachea
6. Railroad the ETT over the scope through the SGA and into the trachea
7. Inflate the ETT cuff, confirm placement with capnography
8. Remove the SGA by deflating the cuff (if inflatable) and sliding it out over the ETT (may require cutting the SGA)

Aintree intubation catheter technique:

1. Pass the Aintree catheter (19 French, 56 cm exchange catheter) through the SGA
2. Use fiberoptic visualization through the Aintree catheter to guide it into the trachea
3. Remove the SGA over the Aintree catheter
4. Railroad the ETT over the Aintree catheter into the trachea
5. Remove the Aintree catheter and confirm placement

5. Plan C: Rescue Oxygenation

When both intubation (Plan A) and SGA (Plan B) have failed, before proceeding to FONA, a final attempt at face-mask ventilation should be made, along with pharmacologic rescue if applicable.¹

5.1 Optimized BVM Ventilation

5.2 Sugammadex in the CICO Situation

If rocuronium was the NMBA used, administration of sugammadex 16 mg/kg IV can reverse paralysis within 1.5–3 minutes, potentially restoring spontaneous ventilation and allowing the patient to maintain their own airway.¹²

Critical caveat: Sugammadex reversal should NOT delay FONA if the patient is desaturating and oxygenation cannot be maintained. Sugammadex may restore muscle tone but does not reverse the induction agent — the patient may still have a depressed sensorium and may not be able to maintain a patent airway. If rocuronium was given and CICO develops:

1. Give sugammadex 16 mg/kg IV immediately
2. Simultaneously prepare for FONA
3. If oxygenation improves within 2–3 minutes (SpO₂ rising, spontaneous respiratory effort), continue to manage with BVM/SGA + sugammadex
4. If oxygenation does not improve within 2–3 minutes, proceed immediately to FONA

6. Plan D: Front-of-Neck Access (FONA)

6.1 Indication: The CICO Declaration

The “cannot intubate, cannot oxygenate” (CICO) scenario is the most dangerous situation in airway management. It occurs when:

• Tracheal intubation has failed (multiple attempts)
• SGA ventilation has failed
• BVM ventilation has failed or is inadequate
• SpO₂ is falling and the patient cannot be oxygenated by any non-invasive means

At this point, FONA is not optional — it is the only means of preventing death. The decision to perform FONA should be made early, verbalized clearly (“this is a CICO situation — I am performing an emergency cricothyrotomy”), and carried out without delay.^{1 3}

6.2 Anatomy of the Cricothyroid Membrane (CTM)

Palpation technique — the “laryngeal handshake”:

1. Stabilize the larynx with the non-dominant hand (thumb and middle finger on thyroid cartilage laminae)
2. Index finger slides down from the thyroid notch to identify the soft depression of the CTM
3. Continue inferiorly to confirm the hard ring of the cricoid cartilage
4. The CTM is the soft spot between these two hard structures

6.3 Surgical Cricothyrotomy — Scalpel-Bougie-Tube Technique

This is the recommended emergency FONA technique for adults. It is faster and more reliable than needle cricothyrotomy in adults.^{1 13}

Equipment required:

• #20 scalpel blade (or #10 blade)
• Bougie (tracheal tube introducer)
• 6.0 mm cuffed endotracheal tube (or 6.0 cuffed tracheostomy tube)

Step-by-step technique:

Alternative — “Scalpel-finger-bougie” technique:

• After the horizontal stab through the CTM, insert a gloved finger (little finger or index finger) into the incision to maintain the tract and confirm tracheal entry
• Pass the bougie alongside/through the finger into the trachea
• Railroad the ETT

6.4 Needle Cricothyrotomy and Transtracheal Jet Ventilation

Needle cricothyrotomy is the insertion of a large-bore cannula (12–14 gauge in adults, 18 gauge in children) through the CTM to provide emergency oxygenation. It is not a definitive airway and has significant limitations.¹⁴

Technique:

1. Identify the CTM
2. Stabilize the larynx with non-dominant hand
3. Attach a 12–14 gauge over-the-needle catheter to a syringe (partially filled with saline or air)
4. Puncture the CTM at a 45° caudal angle, aspirating as you advance
5. Aspiration of air confirms tracheal entry
6. Advance the catheter over the needle into the trachea; remove the needle
7. Attach to jet ventilation system (or emergency ventilation setup)

Jet ventilation through needle cricothyrotomy:

Limitations of needle cricothyrotomy:

• Cannot provide adequate ventilation (CO₂ clearance) — only provides oxygenation
• Risk of barotrauma (especially if upper airway obstructed)
• Catheter kinking, displacement, and subcutaneous placement are common
• Time-limited rescue: must convert to definitive surgical airway within 30–45 minutes

When to use needle cricothyrotomy:

• Pediatric patients < 8–12 years: The cricothyroid membrane is too small for surgical cricothyrotomy; needle cricothyrotomy is the recommended pediatric FONA technique
• When surgical cricothyrotomy equipment is unavailable (rare)
• As a bridge to definitive surgical airway

6.5 Emergent Surgical Tracheostomy

Emergent surgical tracheostomy through the tracheal rings (below the cricoid cartilage) is:

• NOT recommended as the first-line emergency FONA technique — it is slower, requires more dissection, and has higher complication rates than cricothyrotomy in the emergency setting
• Indicated when:
  • Cricothyrotomy is contraindicated (laryngeal fracture, disrupted laryngeal anatomy)
  • Subglottic pathology exists below the CTM
  • Pediatric patients < 8 years (some guidelines recommend needle cricothyrotomy first; others recommend surgical tracheostomy by an experienced surgeon)
  • The procedure is being performed by a surgeon with tracheostomy expertise and time permits
• After emergency cricothyrotomy, elective conversion to a formal tracheostomy should be performed within 24–72 hours if prolonged airway access is needed

7. Failed Airway Algorithm: Decision Points

7.1 Defining “Failed Airway”

7.2 Key Decision: “Can I Oxygenate?”

After failed intubation, the single most important question is: “Can I oxygenate this patient?”

• YES → this is a failed intubation, NOT a failed airway. Time is available. Options:

  • Maintain oxygenation via SGA or BVM
  • Attempt intubation through SGA (fiberoptic-guided)
  • Allow the patient to wake up (if paralysis has worn off or reversed with sugammadex)
  • Call for additional expertise (anesthesiology, ENT, experienced colleague)
  • Consider awake fiberoptic intubation when patient is awake

• NO → this is a CICO emergency. Proceed immediately to FONA. Do not delay for additional intubation or SGA attempts.

7.3 Human Factors in the Failed Airway

National audit data have identified human factors as the primary contributor to airway-related deaths and serious harm.^{3 15}

8. Special Devices and Adjuncts

8.1 Stylets

8.2 Airway Exchange Catheters (AEC)

8.3 Point-of-Care Ultrasound for Airway Management

9. National Audit Findings: Lessons Learned

A landmark national audit project reviewed all major airway complications across an entire national healthcare system over one year, providing the highest-quality evidence on airway-related harm.^{3 15}

9.1 Key National Audit Findings

9.2 Recommendations Derived from National Audit Data

1. Waveform capnography for every intubation and continuously during mechanical ventilation
2. Structured airway assessment before every intubation
3. Written Plans A, B, C, D before induction
4. Maximum attempt limits (3+1)
5. Training in FONA — every clinician who performs intubation must be trained and willing to perform cricothyrotomy
6. Equipment availability — surgical airway kit at every intubation
7. Cognitive aids — printed algorithms displayed in resuscitation areas, intubation checklists