What is the recommended SCAM (Sellick's maneuver, Cricoid pressure, Airway management, and Medications) guideline for rapid sequence induction in a patient?

Rapid Sequence Induction (RSI) Guidelines

Direct Answer

For rapid sequence induction, preoxygenate with 100% oxygen at >10 L/min for 2-3 minutes, apply cricoid pressure at 10 N initially (increasing to 30 N after loss of consciousness), use propofol 2-2.5 mg/kg or thiopental ≥4 mg/kg with rocuronium 0.6-1.2 mg/kg or succinylcholine 1 mg/kg, and be prepared to immediately release cricoid pressure if intubation or ventilation becomes difficult. 1

Preoxygenation Protocol

• Administer 100% oxygen via tight-fitting facemask at fresh gas flow ≥10 L/min for 2-3 minutes to achieve end-tidal oxygen fraction (FetO2) ≥0.9 1, 2
• Consider applying nasal cannulae at 5 L/min oxygen flow before starting preoxygenation to provide apneic oxygenation during laryngoscopy attempts 1, 2
• Position the patient head-up 15-30° and use ramped position in obese patients to improve laryngoscopy view and reduce aspiration risk 2

Cricoid Pressure Application

Apply 10 N force initially in the awake patient, increasing to 30 N (3 kg) after loss of consciousness 1, 3

Critical Technique Points:

• The force can be reduced to 20 N if the patient is positioned head-up 1, 3
• Immediately release cricoid pressure if active vomiting occurs to prevent oesophageal rupture 1, 3
• Release or reduce cricoid pressure immediately if the laryngoscopist reports difficult visualization, difficult mask ventilation, or airway obstruction 1, 3
• When releasing cricoid pressure, do so under direct vision with suction available and be ready to reapply if regurgitation occurs 1
• Remove cricoid pressure for supraglottic airway device insertion 1

Common Pitfalls:

• Excessive force (>30 N) causes airway distortion, patient discomfort, retching, and can trigger aspiration—the very problem you're trying to prevent 1, 3, 4
• Cricoid pressure increases the risk of failed intubation nearly eight-fold during RSI 1
• The oesophagus sits posterolateral (mainly left-sided) to the cricoid ring in 50-91% of patients, not directly posterior as traditionally assumed 1, 3

Induction Agents

Propofol is now preferred over thiopental due to better airway reflex suppression, greater familiarity, easier preparation, and fewer drug errors 1, 5

Dosing:

• Propofol: 2-2.5 mg/kg IV 1, 5
• Thiopental: 4-5 mg/kg IV (if used; doses <4 mg/kg are associated with increased awareness risk) 1, 5
• Have additional doses immediately available if intubation proves difficult 1, 5

Neuromuscular Blocking Agents

Rocuronium 0.6-1.2 mg/kg is the preferred agent with sugammadex backup available 1, 6

Rocuronium Protocol:

• For rapid sequence intubation: 0.6-1.2 mg/kg provides excellent/good intubating conditions in <2 minutes 6
• Standard dose of 0.6 mg/kg provides intubation in median time of 1 minute with 31 minutes of clinical relaxation 6
• Higher dose of 1.2 mg/kg can be used without adverse cardiovascular effects 6
• Have sugammadex 16 mg/kg immediately available for full reversal within 3 minutes if needed 1

Succinylcholine Alternative:

• Succinylcholine 1 mg/kg remains an option but has disadvantages: increases oxygen consumption through depolarizing action causing earlier desaturation, and hypoxia occurs before recovery of neuromuscular activity 1

Critical Dosing Consideration:

• In obese patients, dose rocuronium based on actual body weight, not ideal body weight 6
• Dosing by ideal body weight results in longer time to maximum block, shorter clinical duration, and inadequate intubating conditions 6

Special Population: Obstetric Patients

Rocuronium is NOT recommended for rapid sequence induction in Cesarean section patients 6

• In studies using rocuronium 0.6 mg/kg with thiopental 3-4 mg/kg, intubating conditions were poor or inadequate in 5 of 13 women when intubation was attempted 60 seconds after injection 6
• Even with higher thiopental doses (4-6 mg/kg), no neonate had APGAR scores >7 at 5 minutes 6
• Standard RSI with cricoid pressure remains the approach, but succinylcholine is preferred over rocuronium in this population 1

The "No Ventilation" Controversy

Traditional RSI teaching prohibits positive pressure ventilation until the airway is secured 2

However, current evidence supports a pragmatic approach:

• Cricoid pressure may reduce gastric distension during gentle mask ventilation 1
• Gentle mask ventilation increases time to desaturation in patients at risk with poor respiratory reserve, sepsis, or high metabolic requirements 1
• Consider gentle bag-mask ventilation (pressure <20 cmH2O) after induction to prevent oxygen desaturation, particularly in high-risk patients 5

Failed Intubation Algorithm

If intubation fails after maximum of 3 attempts 1:

1. Maintain 30 N cricoid force initially 1
2. Use face mask oxygenation and ventilation with 1 or 2-person technique (with oral-nasal airway) 1
3. Consider reducing cricoid force if ventilation is difficult 1
4. If face mask ventilation fails (SpO2 <90% with FiO2 1.0), insert supraglottic airway device with cricoid pressure reduced or removed 1
5. If "can't intubate, can't oxygenate" develops, proceed immediately to front-of-neck access 2

Evidence Quality Note

Despite limited high-quality evidence proving efficacy, cricoid pressure remains standard practice in the UK and many countries because aspiration, though rare, carries extremely high mortality and morbidity when it occurs 1, 3. The NAP4 audit identified cases where omission of cricoid pressure led to patient harm or death from aspiration, but found no cases where cricoid pressure itself caused major complications 1, 3.