Role of Succinylcholine Before Intubation
Succinylcholine remains the first-line neuromuscular blocking agent for rapid sequence intubation in critically ill adults and children when there are no contraindications, due to its rapid onset (less than 1 minute) and short duration of action (4-6 minutes). 1
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. 1, 2
The drug provides excellent intubation conditions within 60 seconds of administration, which is critical for minimizing the time between loss of consciousness and airway protection. 1, 3
In pediatric patients, succinylcholine is probably recommended as the first choice during classic rapid sequence induction, with rocuronium reserved for cases where succinylcholine is contraindicated. 1
Dosing Recommendations
Adults
Standard adult dosing is 1.0 mg/kg IV for rapid sequence intubation. 4, 3
Doses of 1.5-2.0 mg/kg provide excellent intubating conditions in 80-87% of patients at 60 seconds, though there appears to be no advantage to using doses larger than 1.5 mg/kg. 5
Pediatric Patients
- Age-specific dosing is critical in children: 1, 4
- Less than 1 month: 1.8 mg/kg
- 1 month to 1 year: 2.0 mg/kg
- 1 to 10 years: 1.2 mg/kg
- Greater than 10 years: 1.0 mg/kg
Absolute Contraindications
Succinylcholine must be avoided in specific high-risk populations where it can cause life-threatening complications:
Personal or family history of malignant hyperthermia - succinylcholine is a known trigger and dantrolene must be immediately available wherever it is used. 4
Patients with muscle disorders or myopathies (especially Duchenne muscular dystrophy), as it can cause fatal hyperkalemia and cardiac arrest, particularly in boys under 9 years old. 4
Patients immobilized for more than 3 days, those with burns or crush injuries, spinal cord injuries, or neuromuscular diseases due to upregulation of nicotinic acetylcholine receptors and risk of severe hyperkalemia. 4, 6
Rocuronium as Alternative
When succinylcholine is contraindicated, rocuronium at doses ≥0.9 mg/kg (preferably 1.0-1.2 mg/kg) should be used as the alternative neuromuscular blocking agent. 1
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). 1
The main disadvantage of rocuronium is its prolonged duration of action, which may delay recognition of inadequate post-intubation sedation and potentially increase the risk of patient awareness. 1
Sugammadex should be rapidly available when rocuronium is used to allow reversal if needed, particularly in pediatric patients. 1
Critical Safety Considerations
Hyperkalemia Risk
While traditionally considered relatively contraindicated in hyperkalemic patients, retrospective data from over 40,000 cases showed 100% survival in 38 patients with preoperative potassium ≥5.6 mEq/L who received succinylcholine, with no dysrhythmias or major morbidity. 7
However, extreme caution is still warranted in patients with conditions predisposing to hyperkalemia, as the risk cannot be completely excluded. 7
Cardiovascular Effects
Succinylcholine can cause bradycardia, especially in children, often requiring pretreatment with atropine in pediatric patients aged 28 days to 8 years, particularly those with septic shock or hypovolemia. 4, 6
The drug stimulates both autonomic ganglia and muscarinic receptors, which may cause cardiac rhythm changes including cardiac arrest, effects that are enhanced by halogenated anesthetics. 3
Other Important Side Effects
Succinylcholine causes an increase in intraocular pressure during fasciculation and may cause slight increases in intracranial pressure. 3
The drug has no effect on consciousness, pain threshold, or cerebration and must only be used with adequate anesthesia and sedation. 3
Ventilatory support is mandatory and personnel skilled in airway management must be present when succinylcholine is administered. 4
Comparative Evidence: Succinylcholine vs Rocuronium
A large out-of-hospital RCT of 1,248 patients found first-pass success rates of 79.4% with succinylcholine (1 mg/kg) versus 74.6% with rocuronium (1.2 mg/kg), though this difference did not meet the prespecified noninferiority margin. 1
An ICU-based RCT of 401 critically ill patients found no significant difference in oxygen desaturations, severe desaturations, intubation conditions, or failed first attempts between succinylcholine and rocuronium (0.6 mg/kg), though intubation sequence duration was shorter with succinylcholine (81 vs 95 seconds). 8
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. 1
Common Pitfalls to Avoid
Never use succinylcholine in elective pediatric anesthesia due to the risk of undiagnosed myopathies. 2
Ensure atropine is immediately available before administering succinylcholine to pediatric patients to prevent bradycardia. 4
Do not give anticholinesterase drugs before succinylcholine is metabolized, as they may prolong rather than shorten paralysis. 3
When rocuronium is used instead of succinylcholine, implement protocolized post-intubation analgosedation to prevent awareness during the prolonged neuromuscular blockade. 1