Succinylcholine Use and Side Effects

Mechanism of Action and Clinical Use

• Succinylcholine is a depolarizing neuromuscular blocking agent that causes prolonged depolarization at the neuromuscular junction, resulting in muscle paralysis 1
• It has a rapid onset and short duration of action, making it useful for rapid sequence intubation, with standard adult dosing for intubation typically 1.0 mg/kg 2
• The American Academy of Pediatrics recommends age-appropriate pediatric dosing: <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 2

Major Side Effects and Complications

Hyperkalemia

• Succinylcholine can cause potentially fatal hyperkalemia in patients with muscle disorders or myopathies, burns or crush injuries, spinal cord injuries, or neuromuscular diseases 3, 2
• The American Academy of Pediatrics notes that hyperkalemia can lead to cardiac arrest, particularly in boys <9 years old 2

Malignant Hyperthermia

• Succinylcholine is a known trigger for malignant hyperthermia in susceptible individuals, according to the British Journal of Anaesthesia 4
• Dantrolene should be immediately available wherever succinylcholine is used, as recommended by the British Journal of Anaesthesia 4

Cardiovascular Effects

• Succinylcholine can cause bradycardia, especially in children, often requiring pretreatment with atropine, as noted by the American Academy of Pediatrics 2

Special Considerations

Drug Interactions

• The American Society of Anesthesiologists recommends that drugs that may enhance neuromuscular blocking action, such as promazine and oxytocin, be used with caution 1
• In patients with nerve agent poisoning or pyridostigmine pretreatment, the dose of succinylcholine should be significantly reduced, as recommended by the American Society of Anesthesiologists 1

Alternatives

• Rocuronium at doses ≥0.9 mg/kg is a suitable alternative when succinylcholine is contraindicated, according to the Anaesthesia journal 5

Absolute Contraindications

• History of malignant hyperthermia is an absolute contraindication for succinylcholine use, as recommended by the British Journal of Anaesthesia 4
• Patients immobilized for more than 3 days, or those with Duchenne muscular dystrophy and other myopathies, should not receive succinylcholine, according to the Intensive Care Medicine journal and the American Academy of Pediatrics 3, 6

Practical Recommendations

• The American Academy of Pediatrics recommends having atropine available to prevent bradycardia, and considering reducing the dose of succinylcholine to shorten recovery time 2
• Ventilatory support is mandatory, and personnel skilled in airway management must be present, as recommended by the American Academy of Pediatrics 2

Guidelines for Succinylcholine Use in Intubation

Indications and Dosing

• The American Society of Anesthesiologists recommends that either rocuronium or succinylcholine can be used for rapid sequence intubation (RSI) when there are no contraindications to succinylcholine, with the choice depending on specific patient factors 7, 8
• Atropine should be administered before intubation in children aged 28 days to 8 years, particularly in those with septic shock, hypovolemia, or when succinylcholine is used, as recommended by the American Academy of Pediatrics 9

Rocuronium as an Alternative

• Rocuronium (0.9-1.2 mg/kg IV) is the recommended alternative when succinylcholine is contraindicated, with no significant difference between rocuronium and succinylcholine in obtaining excellent intubation conditions, according to the American College of Critical Care Medicine 7, 8, 9
• Rocuronium's longer duration of action (30-60 minutes) is its main disadvantage compared to succinylcholine, as noted by the American Society of Anesthesiologists 7, 8

Role of Succinylcholine Before Intubation

Primary Indications

• Succinylcholine is the preferred agent for rapid sequence intubation (RSI) in emergency situations where rapid airway control is essential, particularly in patients at risk for aspiration, according to the American Society of Anesthesiologists 10, 11
• The American Academy of Pediatrics probably recommends succinylcholine as the first choice during classic rapid sequence induction in pediatric patients, with rocuronium reserved for cases where succinylcholine is contraindicated 10

Dosing Recommendations

Pediatric Patients

• Age-specific dosing is critical in children:

Rocuronium as Alternative

• When succinylcholine is contraindicated, the American College of Critical Care Medicine recommends rocuronium at doses ≥0.9 mg/kg (preferably 1.0-1.2 mg/kg) as the alternative neuromuscular blocking agent 10, 11, 12
• Rocuronium at 1.2 mg/kg provides similar first-pass success rates and intubation conditions compared to succinylcholine, though with a longer duration of action (30-60 minutes versus 4-6 minutes), according to the Society of Critical Care Medicine 12, 13
• Sugammadex should be rapidly available when rocuronium is used to allow reversal if needed, particularly in pediatric patients, as recommended by the American Academy of Pediatrics 11

Comparative Evidence: Succinylcholine vs Rocuronium

• The choice between succinylcholine and rocuronium should be based on the desired duration of muscle relaxation, risk of difficult intubation, presence of contraindications to succinylcholine, and whether neuromuscular disease is present or suspected, according to the American Society of Anesthesiologists 10
• A large out-of-hospital RCT found first-pass success rates of 79.4% with succinylcholine (1 mg/kg) versus 74.6% with rocuronium (1.2 mg/kg), as reported in Critical Care Medicine 12

Post-Intubation Care

• When rocuronium is used instead of succinylcholine, protocolized post-intubation analgosedation should be implemented to prevent awareness during the prolonged neuromuscular blockade, as recommended by the Society of Critical Care Medicine 13

Recommended Doses for Intubation

Paralytic Agent Dosing

• The American Society of Anesthesiologists recommends rocuronium 0.9-1.2 mg/kg for excellent intubation conditions within 60 seconds in adults, as an alternative to succinylcholine, with minimal cardiovascular effects, though duration is longer (30-60 minutes vs. 4-6 minutes) 14
• Primary muscle damage (myopathies, Duchenne muscular dystrophy) is an absolute contraindication for succinylcholine, according to the Anaesthesia society guidelines 14

Special Population Adjustments

• The Anaesthesia society guidelines recommend not modifying the initial dose of rocuronium in patients with renal or hepatic failure, as time to onset remains unchanged despite prolonged duration of action 15
• Consider using atracurium or cisatracurium for maintenance dosing in patients with renal or hepatic failure due to organ-independent elimination, as suggested by the Anaesthesia society guidelines 15

Rocuronium as an Alternative to Succinylcholine

Absolute Contraindications to Succinylcholine Requiring Rocuronium

• The European Malignant Hyperthermia Group explicitly identifies succinylcholine as a trigger agent that must be avoided in susceptible patients, and rocuronium should be used instead in patients with known or suspected malignant hyperthermia susceptibility, history of skeletal muscle myopathies, burns or crush injuries beyond 24-48 hours post-injury, denervation syndromes, spinal cord injuries, prolonged immobilization (>3 days), or known succinylcholine allergy 16, 17
• Succinylcholine is a known trigger agent for malignant hyperthermia and is absolutely contraindicated in patients with personal or familial history of this condition, according to the British Journal of Anaesthesia 16, 17, 18

Rocuronium Dosing and Administration

• Rocuronium 0.9-1.2 mg/kg IV provides excellent intubating conditions within 60 seconds in adults, with a duration of action of 30-60 minutes, according to the Critical Care Medicine journal 19
• The 1.2 mg/kg dose of rocuronium provides similar first-pass success rates compared to succinylcholine (79.4% vs 82-84%), as reported in the Critical Care Medicine journal 19

Critical Safety Considerations

• When rocuronium is used, protocolized post-intubation analgosedation must be implemented immediately to prevent awareness during prolonged neuromuscular blockade, as recommended by the Critical Care Medicine journal 19
• Do not assume a negative family history rules out malignant hyperthermia susceptibility - patients can develop MH even after previous uneventful anesthetics, according to the British Journal of Anaesthesia 16, 17
• Do not underdose rocuronium - doses less than 0.9 mg/kg may not provide adequate intubating conditions; use 1.0-1.2 mg/kg for optimal results, as reported in the Critical Care Medicine journal 19
• Do not forget to establish post-intubation sedation protocols when using rocuronium to prevent awareness during the 30-60 minute paralysis period, as recommended by the Critical Care Medicine journal 19