What is the role of succinylcholine (a depolarizing neuromuscular blocking agent) before intubation?

Role of Succinylcholine Before Intubation

Succinylcholine remains the preferred neuromuscular blocking agent for rapid sequence intubation (RSI) in emergency situations where rapid airway control is essential, particularly in patients at risk for aspiration, due to its unmatched rapid onset (<1 minute) and short duration of action (4-6 minutes). 1, 2

Primary Clinical Role

• Succinylcholine is a depolarizing neuromuscular blocking agent that produces flaccid paralysis within less than one minute after intravenous administration, making it ideal for emergency airway management 2
• The drug is specifically indicated for rapid sequence intubation in patients at increased risk of aspiration, including those with full stomachs, ileus, or requiring emergency cesarean section 1, 3
• Its action profile remains unmatched even after 50+ years in clinical practice, which is why it continues to be considered indispensable in emergency situations despite its side effects 3

Standard Dosing

Adult Patients

• The standard adult dose is 1.0 mg/kg IV for intubation 1
• Research shows that 1.5-2.0 mg/kg provides excellent intubation conditions in 80-87% of patients at 60 seconds, though doses above 1.5 mg/kg offer no additional advantage 4
• Lower doses (0.45-0.6 mg/kg) can provide adequate intubation conditions in emergency patients while allowing more rapid return of spontaneous respiration, though this is not standard practice 5

Pediatric Patients

• Age-specific dosing is critical in children 1:
  • <1 month: 1.8 mg/kg
  • 1 month to 1 year: 2.0 mg/kg
  • 1-10 years: 1.2 mg/kg
  • >10 years: 1.0 mg/kg
• The American Academy of Pediatrics recommends succinylcholine as the first choice during classic rapid sequence induction in pediatric patients when not contraindicated 1

Critical Contraindications

Absolute Contraindications

• History of malignant hyperthermia - succinylcholine is a known trigger and dantrolene must be immediately available wherever it is used 1
• Patients immobilized for >3 days - risk of fatal hyperkalemia 1
• Duchenne muscular dystrophy and other myopathies - can cause cardiac arrest from hyperkalemia 1
• Burns or crush injuries, spinal cord injuries, or neuromuscular diseases - risk of potentially fatal hyperkalemia 1

Special Pediatric Warning

• Hyperkalemia can lead to cardiac arrest, particularly in boys <9 years old with undiagnosed myopathies 1
• Succinylcholine is no longer an option in elective pediatric anesthesia, though it retains value in critical pediatric emergencies 3

Important Side Effects to Anticipate

• Bradycardia, especially in children - pretreatment with atropine is recommended in children aged 28 days to 8 years, particularly those with septic shock, hypovolemia, or when succinylcholine is used 1
• Fasciculations - can increase intracranial pressure and intraocular pressure immediately after injection 2, 6
• Increased intracranial and intraocular pressure - occurs during fasciculation phase and may persist after onset of complete paralysis 2
• No effect on consciousness or pain - must be used only with adequate anesthesia and sedation 2

When to Choose Rocuronium Instead

Rocuronium at 1.0-1.2 mg/kg is the recommended alternative when succinylcholine is contraindicated 1, 7

• Rocuronium provides similar first-pass intubation success rates (74.6% vs 79.4% with succinylcholine) but has a significantly longer duration of action (30-60 minutes vs 4-6 minutes) 1
• The choice between succinylcholine and rocuronium should be based on: desired duration of muscle relaxation, risk of difficult intubation, presence of contraindications to succinylcholine, and whether neuromuscular disease is present or suspected 1
• Sugammadex should be rapidly available when rocuronium is used to allow reversal if needed, particularly in pediatric patients 1
• When rocuronium is used, protocolized post-intubation analgosedation must be implemented to prevent awareness during prolonged neuromuscular blockade 1

Essential Safety Measures

• Personnel skilled in airway management must be present and prepared to respond when succinylcholine is administered 1, 7
• Ventilatory support is mandatory - age-appropriate equipment for suctioning, oxygenation, intubation, and ventilation must be immediately available 1, 7
• Atropine should be available to prevent or treat bradycardia, especially in pediatric patients 1
• Dantrolene must be immediately available wherever succinylcholine is used due to malignant hyperthermia risk 1

Common Pitfall to Avoid

The routine use of succinylcholine as a relaxant for all intubations is questionable - modern techniques (laryngeal mask airway) and newer drugs (rocuronium, remifentanil) make succinylcholine dispensable except for true rapid sequence situations where aspiration risk is present 3. In cases of expected difficult airway, no muscle relaxant should be given initially, as severe hypoxemia can only be prevented by professional airway management while the patient maintains spontaneous ventilation 3.