What are the risks and recommendations for rapid sequence induction in a patient with high-grade small bowel obstruction?

Risk of Aspiration During Rapid Sequence Induction for High-Grade Small Bowel Obstruction

Patients with high-grade small bowel obstruction are at extremely high risk of aspiration during rapid sequence induction, and RSI with appropriate modifications is the mandatory approach to minimize this life-threatening complication. 1

Why the Risk is Particularly High

Patients with high-grade small bowel obstruction face multiple compounding aspiration risk factors that make them among the highest-risk patients an anesthesiologist will encounter:

• Bowel and stomach obstruction with distension creates increased intragastric pressure and volume, dramatically elevating regurgitation risk 1
• Emergency nature of surgery means inadequate fasting time and full stomach 1
• Sepsis and opioid administration further impair gastric emptying and protective airway reflexes 1
• Although aspiration of gastric contents is rare, when it occurs the risk of patient death or severe brain injury secondary to hypoxia is extremely high 1

Mandatory Pre-Induction Interventions

Gastric Decompression

Nasogastric tube decompression should be performed when the benefit outweighs the risk in patients at high risk of regurgitation, which definitively includes high-grade small bowel obstruction. 1, 2

• Insert a large-bore nasogastric tube before induction to remove gastric contents and decompress the stomach 1, 3
• The tube should remain in place and be connected to suction during induction—do not withdraw it 3
• Point-of-care ultrasound can help determine gastric volume and effectiveness of decompression 1
• Complications of NGT insertion (nasal bleeding, gagging, esophageal perforation) must be weighed against aspiration risk, but in high-grade obstruction the benefit clearly outweighs these risks 1

Optimal Positioning

• Use semi-Fowler position (head and torso inclined 20-30 degrees) during RSI to reduce aspiration risk and improve first-pass intubation success 1, 2, 4

Preoxygenation Strategy

• Perform rigorous preoxygenation with FiO₂ 1.0 for 3-5 minutes using a completely sealing mask with capnography, targeting FetO₂ >0.9 5
• Consider high-flow nasal oxygen (HFNO) if laryngoscopy is expected to be challenging 2, 4
• For agitated or uncooperative patients, medication-assisted preoxygenation with ketamine can increase oxygen saturation by approximately 8.9% 2, 4

Pharmacologic Management for RSI

Induction Agents

Select induction agents based on hemodynamic status:

• For hemodynamically unstable patients (common in high-grade obstruction with sepsis): use etomidate 0.3 mg/kg or ketamine 1-2 mg/kg 2
• Propofol can be used in hemodynamically stable patients 1
• There is no significant mortality difference between etomidate and other induction agents, but hemodynamic stability must guide selection 1, 2

Neuromuscular Blocking Agents

A neuromuscular blocking agent MUST be administered when a sedative-hypnotic induction agent is used (strong recommendation, low-quality evidence). 1, 2

• Use succinylcholine 1-2 mg/kg OR rocuronium 0.9-1.2 mg/kg for rapid onset and excellent intubation conditions 1, 2
• Rocuronium at 1.0-1.2 mg/kg provides intubation conditions equivalent to succinylcholine 1, 6
• If rocuronium is used, sugammadex MUST be immediately available for potential "cannot intubate/cannot oxygenate" scenarios 2, 4

Cricoid Pressure Controversy

The use of cricoid pressure should follow your country's current standard practice, with important caveats:

• Cricoid pressure was historically considered a cornerstone of RSI to prevent aspiration 1
• Recent evidence shows cricoid pressure may make intubation more difficult and may not reliably prevent aspiration 1
• Apply initial force of 10 N when patient is awake, increasing to 30 N as consciousness is lost 1
• If direct laryngoscopy is difficult, cricoid pressure should be released immediately 1
• The 2023 ERAS Society guidelines recommend using cricoid pressure according to national guidelines rather than as an absolute requirement 1

Critical Pitfalls to Avoid

Do NOT delay for "ideal" conditions

• High-grade small bowel obstruction is a surgical emergency—prolonged delays for optimization may worsen outcomes 1

Do NOT use inadequate muscle relaxant dosing

• Suboptimal dosing (e.g., rocuronium 0.6-0.7 mg/kg) results in less frequent excellent intubation conditions 1
• Use full RSI doses: succinylcholine 1-2 mg/kg or rocuronium 0.9-1.2 mg/kg 1, 2

Do NOT remove the nasogastric tube before induction

• Despite historical teaching, the NGT should remain in place and connected to suction 3
• Cricoid pressure is effective even with a GT in place 3

Do NOT proceed without backup airway equipment

• Have video laryngoscopy, supraglottic airways, and surgical airway equipment immediately available 1
• If intubation fails after maximum three attempts, immediately move to failed intubation plan 1

Do NOT forget post-intubation analgosedation

• When using rocuronium, its longer duration compared to succinylcholine may delay post-intubation sedation, increasing awareness risk 2, 4

The Bottom Line

High-grade small bowel obstruction represents one of the highest aspiration risk scenarios in anesthesia. The combination of gastric decompression via NGT (left in place), semi-Fowler positioning, rigorous preoxygenation, appropriate medication selection with full RSI doses, and immediate availability of backup airway equipment provides the best chance of avoiding this potentially fatal complication. While aspiration remains rare even in this high-risk population, the consequences of death or severe hypoxic brain injury mandate meticulous attention to every component of the RSI sequence. 1