What is the effect of administering a muscle relaxant during rapid sequence induction (RSI) on the likelihood of aspiration in a patient with a high-grade small bowel obstruction?

Administering Muscle Relaxants During RSI in High-Grade Small Bowel Obstruction Does NOT Increase Aspiration Risk—It Is Mandatory for Safe Intubation

A neuromuscular blocking agent MUST be administered when performing rapid sequence induction in patients with high-grade small bowel obstruction, as failure to use muscle relaxants creates suboptimal intubating conditions that dramatically increase the risk of failed intubation, prolonged laryngoscopy attempts, and subsequent hypoxic brain injury or death. 1, 2, 3

The Critical Misunderstanding About Muscle Relaxants and Aspiration

The concern that muscle relaxants increase aspiration risk is based on a fundamental misunderstanding of RSI physiology. Muscle relaxants do not cause aspiration—they prevent the catastrophic complications that occur when intubation fails. 1, 2

• Patients with high-grade small bowel obstruction face extreme aspiration risk due to bowel distension, increased intragastric pressure, inadequate fasting, and often concurrent sepsis and opioid use—not because of muscle relaxant administration 1, 2
• The European Society of Anaesthesiology and Intensive Care makes a strong recommendation (moderate evidence) for mandatory use of fast-acting muscle relaxants such as succinylcholine 1-2 mg/kg or rocuronium 0.9-1.2 mg/kg for RSI 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—making optimal first-pass intubation success the primary safety goal 1, 2

Why Muscle Relaxants Are Protective, Not Harmful

The real danger is NOT the muscle relaxant—it is failed intubation leading to prolonged hypoxia. Multiple failed intubation attempts with inadequate muscle relaxation create the exact scenario where aspiration becomes lethal. 1, 2

• Failed intubation is almost eight times more frequent in patients having rapid sequence induction without adequate neuromuscular blockade 1
• Inadequate muscle relaxation causes laryngeal distortion, poor glottic visualization, and increased likelihood of multiple traumatic laryngoscopy attempts 1
• The short duration of succinylcholine is not a substitute for aggressive airway management—it provides false reassurance while the patient desaturates 4

The Evidence-Based RSI Protocol for High-Grade Small Bowel Obstruction

Pre-Induction Preparation (Mandatory Steps)

• Insert a large-bore nasogastric tube before induction to decompress the stomach and remove gastric contents 2
• Position patient in semi-Fowler position (head and torso inclined 20-30 degrees) to reduce aspiration risk and improve first-pass intubation success 2, 3, 5
• Ensure video laryngoscopy, supraglottic airways, and surgical airway equipment are immediately available in the room 2

Pharmacologic Management (Non-Negotiable)

Induction Agent Selection:

• For hemodynamically unstable patients: etomidate 0.3 mg/kg or ketamine 1-2 mg/kg 2, 5
• For hemodynamically stable patients: propofol 2 mg/kg 2, 5

Neuromuscular Blocking Agent (MANDATORY):

• Succinylcholine 1-2 mg/kg OR rocuronium 0.9-1.2 mg/kg 1, 2, 3, 5
• Critical point: Use FULL RSI doses—lower doses of rocuronium (0.6-0.7 mg/kg) result in less frequent excellent intubating conditions and should be avoided 1
• A Cochrane review confirmed that rocuronium 0.6-0.7 mg/kg provides inferior intubating conditions compared to full doses 1
• When using rocuronium, sugammadex must be immediately available for potential "cannot intubate/cannot oxygenate" scenarios 2, 5

Cricoid Pressure Considerations (Controversial but Contextual)

• Apply initial force of 10 N when patient is awake, increasing to 30 N as consciousness is lost 1
• If direct laryngoscopy is difficult, release cricoid pressure immediately—cricoid pressure may make intubation more difficult and may not reliably prevent aspiration 1
• Cricoid pressure can cause airway obstruction, impede laryngoscope insertion, and distort laryngeal anatomy 1
• Follow your country's current standard practice, but prioritize successful intubation over maintaining cricoid pressure 1

The Failed Intubation Plan

• If intubation fails after maximum three attempts, immediately move to failed intubation plan 1, 2
• Have second-generation supraglottic airway device immediately available 6
• Surgical airway equipment must be in the room before induction begins 2

Common Pitfalls and How to Avoid Them

Pitfall #1: Using inadequate doses of muscle relaxants "to preserve spontaneous ventilation"

• This creates the worst possible scenario: inadequate intubating conditions leading to multiple attempts, trauma, and hypoxia while the patient cannot ventilate spontaneously anyway 1, 2, 4
• Solution: Use full RSI doses (succinylcholine 1-2 mg/kg or rocuronium 0.9-1.2 mg/kg) 1, 2

Pitfall #2: Delaying RSI for "optimization" in high-grade small bowel obstruction

• High-grade small bowel obstruction is a surgical emergency—prolonged delays worsen outcomes 2
• Solution: Perform nasogastric decompression, position appropriately, and proceed with RSI 2

Pitfall #3: Maintaining cricoid pressure during difficult laryngoscopy

• Cricoid pressure can transform a manageable airway into a "cannot intubate" scenario 1
• Solution: Release cricoid pressure immediately if laryngoscopy is difficult 1

Pitfall #4: Not having sugammadex immediately available when using rocuronium

• Rocuronium without available sugammadex creates prolonged paralysis in a "cannot intubate/cannot oxygenate" scenario 2, 5
• Solution: Confirm sugammadex availability before using rocuronium, or use succinylcholine if no contraindications exist 2, 5

The Bottom Line

The aspiration risk in high-grade small bowel obstruction exists because of the bowel obstruction itself—not because of muscle relaxant administration. 1, 2 The muscle relaxant is your tool to achieve rapid, successful first-pass intubation, which is the single most important factor in preventing hypoxic brain injury or death in this extremely high-risk population. 1, 2 Withholding or underdosing muscle relaxants in a misguided attempt to "reduce aspiration risk" actually increases the likelihood of the catastrophic outcome you are trying to prevent. 1, 4