A 48-year-old woman with a BMI of 34 kg/m² presents for pre-anesthetic evaluation before emergency cesarean section. She is a known case of gestational diabetes and has significant facial edema. On airway examination, when she opens her mouth fully and protrudes her tongue, only the hard palate is visible; the soft palate cannot be seen. Her thyromental distance is 5.5 cm, interincisor gap is 2.5 cm, and neck extension is limited due to edema. What is the predicted difficulty of intubation based on her airway assessment?

Explanation

## Comprehensive Airway Assessment in a Difficult Airway Scenario This patient has **multiple red flags** for difficult intubation. A single unfavorable parameter warrants caution; multiple parameters demand a structured difficult airway plan. ### Mallampati Classification in This Patient **Key Point:** This patient has **Mallampati Class IV** — only the hard palate is visible. Class IV has a 50% incidence of difficult intubation and is a strong predictor of problematic laryngoscopy. ### Cumulative Airway Risk Assessment | Parameter | Finding | Risk Level | |-----------|---------|------------| | **Mallampati** | Class IV | Very High | | **Thyromental distance** | 5.5 cm | High (< 6 cm is difficult) | | **Interincisor gap** | 2.5 cm | High (< 3 cm is difficult) | | **Neck mobility** | Limited extension | High (edema-related) | | **BMI** | 34 kg/m² | Moderate (obesity increases risk) | | **Facial edema** | Present | High (airway compromise risk) | **High-Yield:** When **3 or more unfavorable parameters** are present, the incidence of difficult intubation rises sharply. This patient has **5 concurrent risk factors**. ### LEMON Score Interpretation ```mermaid flowchart TD A[LEMON Assessment]:::outcome --> B{Mallampati Class?}:::decision B -->|I-II| C{Thyromental ≥ 6 cm?}:::decision B -->|III-IV| D[Difficult Airway]:::urgent C -->|Yes| E{Interincisor ≥ 3 cm?}:::decision C -->|No| F[Difficult Airway]:::urgent E -->|Yes| G{Neck mobility normal?}:::decision E -->|No| F G -->|Yes| H[Easy Airway]:::outcome G -->|No| F D --> I[Awake Fiberoptic Intubation]:::action F --> I ``` **Clinical Pearl:** In obstetric emergencies (cesarean section), airway edema from pregnancy, preeclampsia, or gestational diabetes can worsen rapidly. Facial edema is a harbinger of laryngeal edema — a potentially catastrophic complication if not anticipated. **Mnemonic:** **DIFFICULT** airway predictors: - **D**istance (thyromental < 6 cm) - **I**ncisor gap (< 3 cm) - **F**acial edema or abnormality - **F**luctuant neck mass - **I**mmobility (neck) - **C**lass (Mallampati III–IV) - **U**nusual anatomy - **L**arge tongue - **T**rismus or TMJ dysfunction ### Recommended Management **Awake fiberoptic intubation is strongly indicated** because: 1. Patient maintains spontaneous ventilation and airway reflexes 2. Allows direct visualization of the larynx and vocal cords 3. Reduces risk of aspiration and hypoxemia 4. Permits assessment of laryngeal edema before induction 5. Provides a controlled, reversible approach in an emergency obstetric case **Warning:** Rapid sequence induction (RSI) with cricoid pressure is contraindicated in this patient. If intubation fails after induction, emergency surgical airway (cricothyrotomy) may be necessary — a high-morbidity outcome in obstetrics. **Tip:** Have a **difficult airway cart** present, including: - Fiberoptic bronchoscope (tested and ready) - Bougie and multiple laryngoscope blades - Supraglottic airway devices - Emergency surgical airway kit - Senior anesthesiologist present during induction