How to manage difficult laryngoscopy and intubation in a short obese female with a short neck and Mallampati (MP) class 3 airway?

Management of Difficult Laryngoscopy and Intubation in a Short Obese Female with Short Neck and Mallampati Class 3

In this high-risk patient, awake intubation using videolaryngoscopy or flexible bronchoscopy should be strongly considered as the primary approach, with preparation for emergency front-of-neck access if needed. 1

Risk Assessment and Prediction

Your patient presents with multiple independent predictors of difficult airway management:

• Mallampati class 3 is associated with difficult intubation in both general and obstetric populations 1
• Short neck is a well-established predictor of difficult laryngoscopy and intubation 1, 2
• Obesity increases the incidence of difficult intubation to 4.2% (compared to general population) and difficult mask ventilation to 2.9% 1
• Neck circumference ≥42 cm (common in obese patients with short necks) significantly increases risk of both difficult mask ventilation and intubation 1, 2
• Female gender with increased neck circumference shows strong correlation with difficult laryngoscopy (Cormack-Lehane score) 3

The combination of these factors places this patient at substantial risk for cannot intubate, cannot ventilate (CICV) scenarios. 1

Primary Management Strategy: Awake Intubation

Awake intubation is advised when oxygenation and manual ventilation may not be guaranteed after induction of anesthesia in a patient who might be difficult to intubate. 1 This patient meets these criteria due to:

• Potential failure to achieve tight facemask seal (obesity, short neck) 1
• Upper airway collapse risk with general anesthesia (obesity) 1
• Poor chest compliance (obesity) 1

Awake Intubation Technique Options:

Videolaryngoscopy is the preferred first-line approach:

• Provides significantly better glottic visualization (Cormack-Lehane improvement, p<0.001) 4
• Higher success rate (99% vs 92% with direct laryngoscopy, p=0.017) 4
• Faster intubation time (40 vs 60 seconds, p=0.0173) 4
• Fewer optimizing maneuvers required (0.5 vs 1.2, p<0.001) 4
• Increases first-attempt success rate in difficult airways 1

Flexible bronchoscopic intubation is an alternative:

• Considered the safest method for extreme airway difficulty 1
• Can be performed via oral or nasal route 1
• High-flow nasal oxygenation during the procedure improves oxygenation and reduces desaturation risk 1

Modified Awake Approach:

• Perform initial awake laryngoscopy with topical anesthesia 1
• If satisfactory laryngeal view obtained, may proceed with general anesthesia induction 1
• This provides safety assessment before committing to full anesthesia 1

Positioning and Preoxygenation

Position the patient in reverse Trendelenburg (head-elevated, semi-seated position):

• Provides mechanical advantage to respiration in obese patients 5
• Improves respiratory parameters including dynamic compliance, minute volume, and oxygenation 5
• Recommended by American Heart Association for pre-oxygenation before rapid sequence induction 5

Apply high-flow nasal oxygen or simple nasal cannula:

• Maintains oxygenation during intubation attempts 1
• Increases apnea time by up to 40% 1
• Reduces peri-intubation desaturation 1

If General Anesthesia Induction Chosen (Higher Risk)

Equipment Preparation:

• Videolaryngoscope immediately available (primary device) 1, 4
• Multiple laryngoscope blade sizes, including straight blade with distal flange (provides better visualization in obese patients) 3
• Supraglottic airway devices (multiple sizes) 1
• Airway adjuncts: bougies, stylets, introducers 1
• Emergency cricothyroidotomy kit at bedside 1

Intubation Sequence:

1. Optimize positioning (reverse Trendelenburg, head-elevated) 5
2. Preoxygenate with high-flow nasal oxygen 1
3. First attempt with videolaryngoscope 1, 4
4. Limit intubation attempts to avoid trauma and complications 1
5. Provide and test mask ventilation after each attempt when feasible 1

Critical Pitfall:

Poor seal and airway obstruction may be significant problems in obese patients with facemask ventilation. 1 If mask ventilation is inadequate:

• Reduce cricoid force if applied 1
• Use two-person technique 1
• Insert nasopharyngeal airway gently (if no trauma) 1
• Move head/neck into sniffing position 1

Failed Intubation Plan

If Intubation Fails but Ventilation Adequate:

• Insert supraglottic airway device (LMA or ProSeal LMA) 1
• ProSeal LMA may have lower obstruction risk (~5%) but increased insertion complexity 1
• Postpone surgery and awaken patient wherever possible 1

If Cannot Intubate, Cannot Ventilate (CICV):

Immediate front-of-neck access is required when rapid development of severe hypoxemia occurs, particularly with bradycardia. 1

Surgical cricothyroidotomy is the definitive technique:

1. Identify cricothyroid membrane 1
2. Stab incision through skin and membrane with scalpel (no. 20 or Minitrach) 1
3. Enlarge incision with blunt dissection 1
4. Apply caudal traction on cricoid cartilage with tracheal hook 1
5. Insert small cuffed tube (6-7mm) and inflate cuff 1
6. Ventilate with low-pressure source and verify position 1

Needle cricothyroidotomy is an alternative but:

• Must be performed by trained individual 1
• Requires immediate conversion to surgical cricothyroidotomy if ventilation fails or complications develop 1
• Less reliable for delivering adequate minute volume 1

Confirmation and Monitoring

• Confirm tracheal intubation using capnography or end-tidal CO2 monitoring 1
• If uncertain about tube location, determine whether to remove and attempt ventilation or use additional confirmation techniques 1
• Monitor continuously for at least 30 minutes post-intubation for signs of complications 6

Key Clinical Pearls

• Neither weight nor BMI alone predict difficult laryngeal exposure 3, 7
• Neck circumference to thyromental distance ratio shows strong correlation with difficult airway (r=0.74-0.77, p<0.000) 7
• Thyromental distance is a moderate predictor (r=0.61-0.70, p<0.000) 7
• Mallampati score alone has limited utility for the laryngoscopist in obese patients 3
• Combined Mallampati and Wilson score has 94.6% diagnostic accuracy in obese patients 8
• Emergency tracheostomy takes too long in CICV situations and results in patient death 1