Rapid sequence induction and full stomach

Why examiners ask this

Rapid sequence induction is where the examiner tests whether I can defend each component of a technique I perform reflexively: why this relaxant, why cricoid pressure or why not, why I do or do not ventilate, and why I chose to induce this patient at all instead of keeping them awake. It stresses application of knowledge and judgment, and it hides inside many stems: the bowel obstruction, the trauma patient, the laboring woman, the diabetic with gastroparesis, and now the patient on a GLP-1 agonist.

The 60-second answer

Decision points and the "why"

• Who has a full stomach — unfasted patients, bowel obstruction, trauma and pain with opioids, pregnancy beyond the first trimester, symptomatic reflux, gastroparesis from diabetes or GLP-1 agonists, and obesity with symptoms. Where it is uncertain I use gastric ultrasound: a distended antrum with solid content in the right lateral position settles the question.
• Succinylcholine versus rocuronium — succinylcholine gives the fastest, most reliable intubating conditions and wears off, but it raises potassium by about 0.5 mEq/L and is contraindicated after the acute phase of burns, major trauma, denervation and upper motor neuron injury, and in myopathies.³ Rocuronium 1.2 mg/kg gives equivalent conditions at 60 seconds with sugammadex 16 mg/kg as the reversal;⁴ I choose it when succinylcholine is contraindicated or I expect a difficult intubation and want a long, paralyzed, well-oxygenated attempt.
• Cricoid pressure — 10 N awake rising to 30 N at loss of consciousness; the evidence for benefit is weak and it can worsen the view, so I apply it, and I release it if intubation is difficult or a supraglottic airway is needed.¹
• Ventilation during the apneic interval — classic RSI withholds it; I give gentle mask breaths below 15–20 cmH2O in a patient who will desaturate, such as a child, a parturient, or a critically ill patient, because hypoxia kills faster than aspiration does; gentle mask ventilation under cricoid pressure prolongs the time to desaturation.¹ Apneic oxygenation by nasal cannula at up to 15 L/min costs nothing.¹
• Induction agent — propofol in the stable patient, ketamine 1–2 mg/kg or etomidate 0.3 mg/kg in the hypovolemic or septic patient, because the drug I choose determines whether I treat hypotension before or after the tube.
• Position — head-up 20–30° improves preoxygenation and reduces passive regurgitation; head-down protects against aspiration if regurgitation occurs. I choose head-up and tilt down if I see fluid.
• Nasogastric tube — in obstruction I decompress the stomach first and leave the tube in; it does not make cricoid pressure ineffective and it reduces the volume that can come up.

The complication they will inject

The view is grade 3 and the first attempt fails; the saturation is 94% and falling. I keep cricoid on unless it is the problem, and I make one optimized second attempt: bougie, external laryngeal manipulation, a video laryngoscope if the first was direct. If that fails I release cricoid and mask ventilate, because the patient now needs oxygen more than protection, and I place a second-generation supraglottic airway, which protects better against aspiration than a first-generation device, if the mask fails.¹ With oxygenation restored, I decide: wake the patient if succinylcholine was used and the surgery can wait, or intubate through the supraglottic airway with a fiberscope. If the patient regurgitates during this, I turn the head, suction, tilt the table head-down and intubate as soon as I can see the cords, then suction the trachea before the first positive-pressure breath.

Pitfalls that cost points

• Describing "modified RSI" without saying what is modified and why.
• Giving succinylcholine to the burned or paraplegic patient because it was "RSI."
• Treating cricoid pressure as sacred when the view is obscured.
• Forgetting to preoxygenate to an end-tidal target and then being surprised by the desaturation.
• Omitting the GLP-1 agonist question in a stem that mentions weight loss or diabetes.

Rapid-why

Q: Why 1.5 mg/kg of succinylcholine rather than 1 mg/kg? A: It reliably produces full relaxation at 45–60 seconds; lower doses leave a proportion of patients with incomplete conditions at the moment I need them.

Q: Why does sodium citrate matter if I am intubating anyway? A: It raises gastric pH within minutes so that an aspiration, if it occurs, is less injurious; it adds volume, so I give it only immediately before induction.

Q: Should a patient stop a GLP-1 agonist before surgery? A: The 2024 multisociety guidance says most patients continue it; I defer elective surgery during dose escalation or with GI symptoms, use a 24-hour liquid diet for high-risk patients, and use gastric ultrasound when unsure.⁵ If symptomatic and the case cannot wait, I treat them as a full stomach.

Q: Why not just do an awake intubation on every full stomach? A: Topicalization abolishes airway reflexes, so awake intubation does not protect against aspiration; I reserve it for the full stomach with a predicted difficult airway.

Numbers to know

Links

• aspiration, succinylcholine, Anticipated difficult airway and the ASA algorithm, hyperkalemia, General anesthesia for cesarean delivery, Choosing an induction agent
• Atlas: Capnography: waveforms and sudden loss of ETCO2
• ASA Practice Guidelines for Preoperative Fasting (2023 update); multisociety clinical practice guidance on perioperative GLP-1 receptor agonists (2024)