Difficult Airway Algorithms

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Difficult Airway: Predict & Prep - Trouble Spotting 101

  • Predictors (📌 Mnemonics):
    • LEMON: Look, Evaluate 3-3-2, Mallampati, Obstruction, Neck mobility.
    • MOANS: Mask seal, Obesity/Obstruction, Age >55, No teeth, Stiff lungs/Sleep apnea (difficult BMV).
    • RODS: Restricted mouth, Obstruction, Distorted airway, Stiff lungs/C-spine (difficult EGD).
    • SHORT: Surgery, Hypoxemia, Obstruction, Radiation, Tumor (difficult cricothyrotomy).
  • Assessment:
    • Mallampati Score (I-IV).

      ⭐ Mallampati Class III & IV strongly predict difficult intubation.

    • Thyromental Distance (TMD): < 6 cm (< 3 FBs).
    • Inter-Incisor Gap (IIG): < 3 cm (< 2 FBs).
    • Upper Lip Bite Test (ULBT): Class I-III.
    • Neck: ↓ mobility, short/thick.
  • Prep:
    • Anticipate & get help.
    • Equipment ready (laryngoscopes, ETTs, SGA, VL, cric kit). Modified Mallampati Classification Visual Guide

ASA Airway Algorithm - Charting the Course

  • Goal: Maintain oxygenation. Follow Plan A, B, C, D.
  • Key Decision Point 1: Awake Intubation vs. Intubation after GA.
    • Consider Awake Intubation if: high aspiration risk, anticipated very difficult airway, patient cooperation possible.
  • If Intubation After GA Induction:
    • Attempt laryngoscopy & intubation (max 3 attempts).
    • If intubation fails: Assess ventilation.
      • CAN VENTILATE (Face Mask / LMA): Call for help. Pursue alternative strategies (e.g., LMA, video laryngoscopy, fiberoptic intubation via LMA). Consider awakening patient.
      • CANNOT INTUBATE, CANNOT VENTILATE (CICV): Declare emergency! Call for help.
  • CICV Emergency Pathway:
    • Attempt LMA as rescue if not already definitive.
    • If LMA fails or not feasible: Proceed to Emergency Invasive Airway (e.g., cricothyroidotomy).

⭐ Throughout any difficult airway scenario, continuous administration of 100% oxygen is paramount, unless contraindicated.

Advanced Moves & CICO - Airway Rescue Ops

  • Advanced Adjuncts:
    • Videolaryngoscopy (VL): Improves glottic view (e.g., C-MAC, GlideScope).
    • Intubating LMA (ILMA): For blind or FOB-guided intubation.
    • Flexible Bronchoscopy (FOB): Awake intubation standard; also for asleep difficult airways.
  • CICO: "Can't Intubate, Can't Oxygenate"
    • Declare CICO, Call for Help!
    • Prioritize Oxygenation.
    • Front-of-Neck Access (FONA) is life-saving.
-   **Surgical Cricothyroidotomy:** Scalpel-bougie-tube technique. Faster, higher success.
    +   📌 Mnemonic: **S**calpel, **F**inger/Forceps, **B**ougie, **T**ube.
-   **Needle Cricothyroidotomy:** **14-16G** cannula + TTJV. Risk: barotrauma, CO₂ retention.
-   Definitive airway (tracheostomy) follows.

Cricothyroidotomy step-by-step guide and anatomy

⭐ In CICO, surgical cricothyroidotomy is often preferred over needle cricothyroidotomy for higher success and fewer complications if TTJV expertise is limited.

High‑Yield Points - ⚡ Biggest Takeaways

  • The ASA Difficult Airway Algorithm is key for managing challenging airways.
  • Predictors: Mallampati Class III/IV, thyromental distance < 6 cm, inter-incisor gap < 3 cm, and limited neck mobility.
  • LMA (Laryngeal Mask Airway) is a crucial rescue device, vital in Cannot Intubate, Cannot Ventilate (CICV) scenarios.
  • Emergency cricothyroidotomy is the ultimate rescue for a failed airway.
  • Awake intubation (e.g., fiberoptic) is preferred for anticipated difficult airways.
  • Thorough pre-oxygenation and apneic oxygenation are critical before and during airway management.
  • Video laryngoscopy often improves glottic visualization and intubation success rates in difficult airways.
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