3.8 Rescue Airway Devices, Video Laryngoscopy & Surgical Cricothyrotomy

3.8 Rescue Airway Devices, Video Laryngoscopy & Surgical Cricothyrotomy

Critical care transport clinicians must maintain mastery over advanced rescue airway techniques. When primary intubation attempts fail, rapid transition through a protocolized difficult airway algorithm is required to prevent hypoxic brain injury and cardiac arrest.

---

1. Video Laryngoscopy (VL) Techniques

Video laryngoscopy has revolutionized airway management by providing an indirect view of the glottic opening, improving Cormack-Lehane laryngoscopy grades.

               HYPERANGULATED VIDEO LARYNGOSCOPY STEPS

  1. Look in Mouth  --> Insert blade into midline oral cavity
  2. Look at Screen --> Locate epiglottis & glottis in screen center
  3. Look in Mouth  --> Insert rigid stylet/ETT into oral cavity
  4. Look at Screen --> Guide ETT tip through vocal cords & pop stylet

Hyperangulated Blade Technique & Troubleshooting

1. Four-Step Technique:
   • Step 1 (Look in mouth): Introduce the hyperangulated blade into the midline of the oral cavity, navigating over the tongue.
   • Step 2 (Look at screen): Locate the epiglottis, advance blade tip into the vallecula (or lift epiglottis), and center the vocal cords on the screen.
   • Step 3 (Look in mouth): Carefully introduce the ETT with rigid stylet into the right side of the mouth under direct vision to avoid trauma to soft palate/tonsils.
   • Step 4 (Look at screen): Watch the tube tip pass through the vocal cords. Once the cuff passes the cords, disengage the stylet $2-3 \text{ cm}$ and advance the tube into final position.
2. Troubleshooting 'Good View, Can't Pass Tube':
   • Cause: The hyperangulated blade brings the glottis into view, but the tube angle approaches too steep/anteriorly, hanging up on the anterior tracheal wall or right arytenoid.
   • Resolution: Withdraw the VL blade $1 \text{ cm}$ (deliberately worsening the view slightly to open the hypopharyngeal space), or rotate the ETT $90^\circ$ counter-clockwise during advancement.

---

2. Supraglottic Airway (SGA) Rescue Devices

Second-generation SGAs feature gastric drain channels and higher seal pressures, making them indispensable rescue devices in Cannot Intubate, Cannot Ventilate (CICV) scenarios.

                          SUPRAGLOTTIC AIRWAYS

        i-gel                            King LTS-D
    +-----------+                    +-----------------+
    | Non-inflat|                    | Pharyngeal Cuff |
    | Gel Cuff  |                    | (Large)         |
    +-----+-----+                    +--------+--------+
          |                                   |
    [Gastric Channel]                [Esophageal Cuff] + [Gastric Channel]

Device Comparison

• i-gel: Features a non-inflatable cuff made of medical-grade thermoplastic elastomer that conforms to laryngeal anatomy. Includes a gastric suction channel and built-in bite block. Rapid placement, zero risk of cuff over-inflation.
• King LT-D / LTS-D: Dual-cuff design (large pharyngeal cuff seals oropharynx; small distal cuff seals esophagus). LTS-D includes a gastric drain port. Requires precise volume inflation ($60-80 \text{ mL}$ air for Size 4/5).
• LMA Supreme / ProSeal: Silicone mask design with dual gastric drain tube. Seals up to $30 \text{ cmH}_2\text{O}$ peak inspiratory pressure.

Clinical Limitations & Contraindications

• Intact Gag Reflex / Trismus: May precipitate laryngospasm or vomiting.
• High Peak Pressures ($> 25-30 \text{ cmH}_2\text{O}$): Gas escapes around SGA cuff into stomach or atmosphere (ineffective ventilation in severe ARDS or bronchospasm).
• Massive Upper Airway Disruption / Foreign Body: Ineffective seal.

---

3. Bougie-Assisted Intubation (Endotracheal Tube Introducer)

The gum elastic bougie ($60 \text{ cm}$ length, $15 \text{ French}$ diameter, $40^\circ$ angled Coude tip) dramatically increases first-pass success during difficult laryngoscopy.

                  BOUGIE TACTILE FEEDBACK RECOGNITION

  Tracheal Placement:               Esophageal Placement:
  • Tactile Clicks (65-90%)         • NO Clicks
    (Coude tip bumping rings)       • NO Hold-Up (advances > 40 cm)
  • Hold-Up at 25-35 cm             • Smooth, unrestricted entry
    (Carina/bronchial branching)

Tactile Feedback Confirmation

• Tracheal Clicks: As the Coude tip glides along the anterior wall of the trachea, the clinician feels distinct tactile vibrations as it bumps across cartilaginous tracheal rings ($65-90%$ sensitivity).
• Hold-Up: The bougie advances smoothly until reaching the smaller bronchi at $25-35 \text{ cm}$, where movement stops abruptly (hold-up).
• Esophageal Insertion: No clicks are felt, and the bougie advances past $40 \text{ cm}$ without resistance.

Technique for Cormack-Lehane Grade III View

1. Maintain laryngoscopy view (only epiglottis visible).
2. Advance bougie under epiglottis with Coude tip pointed anteriorly.
3. Feel for tracheal clicks and hold-up.
4. Railroad an lubricated ETT over bougie. If tube catches on the right arytenoid at the glottic opening, rotate tube $90^\circ$ counter-clockwise to allow the bevel to slide past.

---

4. Emergency Surgical Cricothyrotomy

Indicated in the Cannot Intubate, Cannot Ventilate (CICV) failure state when primary intubation and supraglottic rescue devices have failed.

                     SURGICAL CRICOTHYROTOMY LANDMARKS

               Hyoid Bone
                   |
             [ Thyroid Cartilage ]  <-- Adam's Apple
                   |
           === Cricothyrotomy Membrane (CTM) ===  <-- Incision Site
                   |
             [ Cricoid Cartilage ]

A. Scalpel-Bougie-Tube Technique (Open Surgical)

1. Landmark Identification: Perform the Laryngeal Handshake—stabilize the larynx with the non-dominant hand, identifying thyroid cartilage, cricoid cartilage, and the membrane gap between them.
2. Vertical Skin Incision: Make a $2-3 \text{ cm}$ vertical skin incision over the CTM (vertical minimizes bleeding from longitudinal anterior neck veins).
3. Horizontal Membrane Incision: Palpate CTM through incision; push a #11 scalpel blade horizontally through the lower half of the membrane. Rotate blade $90^\circ$ so cutting edge points caudally.
4. Insert Bougie: Slide Coude tip of bougie alongside scalpel into trachea. Confirm tracheal hold-up.
5. Railroad Tube: Advance a cuffed endotracheal tube (size $6.0 \text{ mm ID}$) over bougie into trachea. Inflate cuff, verify $EtCO_2$, and secure.

B. Needle Cricothyrotomy & Transtracheal Jet Ventilation (TTJV)

• Indication: Temporary bridge when surgical open cricothyrotomy cannot be performed immediately or in pediatric patients.
• Technique: Insert a 12-14 gauge angiocatheter attached to a saline-filled syringe through CTM at a $45^\circ$ caudal angle while aspirating until air bubbles freely.
• Jet Ventilation System: Connect catheter to high-pressure oxygen source ($50 \text{ psi}$) with a manual push-button flush valve or transtracheal jet ventilator.
• Critical Safety Hazard: Ventilation requires an unobstructed upper airway for passive exhalation. If complete upper airway obstruction exists, jet ventilation causes progressive air trapping, severe barotrauma, and tension pneumothorax. Expiratory time must be $4-5$ times longer than inspiratory time ($I:E = 1:4 \text{ to } 1:5$). Maximum duration: $30-45 \text{ minutes}$ due to progressive hypercapnia.

---

5. Pediatric Airway Differences & Surgical Rules

CRITICAL RULE: Open surgical cricothyrotomy is strictly CONTRAINDICATED in children $< 8-10$ years old. The small size of the cricothyroid membrane and soft laryngeal structures lead to cricoid ring disruption and permanent subglottic stenosis. Perform needle cricothyrotomy with jet ventilation or tracheostomy.