Predicted Difficult Airway in a Morbidly Obese Patient Requiring Emergency Appendectomy
A 44-year-old man with a body mass index of 47 kg/m² presents with a 12-hour history of right lower quadrant pain and is diagnosed with acute appendicitis. He has obstructive sleep apnea and uses CPAP at home. On examination, his neck circumference is 46 cm, Mallampati class III, mouth opening 3 cm, thyromental distance 6 cm, and he has a short, thick neck. He is anxious, has a full stomach, and his oxygen saturation is 94% on room air. The surgeon requests laparoscopic appendectomy. The patient has no other comorbidities and no known drug allergies. The anesthesia team must decide between awake fiberoptic intubation, video laryngoscopy after rapid sequence induction, or a supraglottic airway. The theatre is equipped with a video laryngoscope, a second-generation supraglottic airway, high-flow nasal oxygen, and a front-of-neck access kit.
1. Justify your primary airway strategy for this patient, weighing the urgency of surgery against the predicted difficulty and aspiration risk.
Read the worked answer
Preferred strategy: Rapid sequence induction with video laryngoscopy as the first attempt, after meticulous preoxygenation, with a clear rescue plan.
Reasoning:
- The patient has multiple predictors of difficult mask ventilation and difficult intubation: BMI 47 kg/m², neck circumference 46 cm, Mallampati III, short thyromental distance, and limited mouth opening. This is an anticipated difficult airway.
- He also has a full stomach and an acute abdomen, so aspiration risk is high. Awake fiberoptic intubation is the classic gold standard for an anticipated difficult airway, but it is poorly tolerated in an anxious patient with a full stomach, and it may take too long in acute appendicitis.
- A supraglottic airway as the primary plan is inappropriate because it does not protect against aspiration and may not seal in a morbidly obese patient.
- Video laryngoscopy after rapid sequence induction balances urgency, aspiration risk, and the need for a controlled intubation attempt.
Execution:
- Preoxygenate in a ramped position with high-flow nasal oxygen and a tight-fitting mask for at least 3–5 minutes.
- Give aspiration prophylaxis, including an H2 blocker and sodium citrate if time allows.
- Optimize the first attempt: experienced operator, video laryngoscope, bougie immediately available, and suction ready.
- Limit attempts and declare a failed airway early if oxygenation cannot be maintained.
2. Describe your stepwise rescue plan if three intubation attempts fail and oxygen saturation falls to 85% despite bag-mask ventilation.
Read the worked answer
Immediate priorities:
- Call for help and declare a failed airway.
- Maintain 100% oxygen and optimize mask ventilation with a two-person technique, oral airway, and ramped position.
- Insert a second-generation supraglottic airway, which allows both ventilation and gastric decompression.
Decision point: If the supraglottic airway oxygenates the patient, stop further intubation attempts. Either proceed with surgery using the supraglottic airway if clinically acceptable, or wake the patient and re-plan electively. Repeated attempts in a hypoxic patient cause trauma, bleeding, and airway edema.
If the supraglottic airway fails and oxygenation cannot be maintained:
- This is a cannot-intubate, cannot-oxygenate emergency.
- Perform front-of-neck access immediately using the scalpel-bougie-tube technique or a cannula technique according to local protocol.
- Do not persist with laryngoscopy.
- Confirm ventilation with capnography and secure the airway.
After stabilization:
- Document the sequence, the number of attempts, and the rescue technique.
- Communicate the difficult airway to the patient and the postoperative team.
- Arrange follow-up and a written difficult airway alert.
3. What postoperative disposition and monitoring would you arrange?
Read the worked answer
Disposition: A high-dependency or intensive care unit bed, not a routine ward bed.
Reasoning:
- The patient has obstructive sleep apnea, a BMI of 47 kg/m², and a difficult airway. He is at risk of opioid-induced respiratory depression, airway obstruction during sleep, and rapid desaturation.
- Any airway manipulation increases the risk of edema and obstruction.
Monitoring and management:
- Continuous pulse oximetry and capnography if available.
- Bring his own CPAP machine or provide CPAP early; do not wait for desaturation.
- Use opioid-sparing multimodal analgesia: regular acetaminophen, NSAIDs if renal function is normal, and a local anesthetic wound infiltration or regional block where feasible.
- Avoid sedatives that blunt respiratory drive.
- Sit him upright, encourage early mobilization, and monitor for nausea and vomiting.
- Have a difficult airway trolley and re-intubation equipment immediately available.
- Document the difficult airway and give the patient a written alert.