What are the considerations for using succinylcholine (depolarizing neuromuscular blocking agent) in burn patients?

Succinylcholine Use in Burn Patients: Contraindications and Considerations

Succinylcholine is absolutely contraindicated in burn patients beyond the acute phase of injury due to the risk of life-threatening hyperkalemia that can lead to cardiac arrest. 1

Pathophysiology and Risk Period

• Burn injuries cause up-regulation of nicotinic acetylcholine receptors (nAChRs) throughout the muscle membrane, leading to potassium efflux when depolarized by succinylcholine 2, 3
• The risk of hyperkalemia begins approximately 24-48 hours after the burn injury 4
• Peak risk occurs between 7-10 days post-burn 1
• The risk period may extend for up to two years following significant burn injury 5
• The severity of the hyperkalemic response correlates with both the extent of the burn and the post-burn time interval 5

Specific Contraindications

• Succinylcholine is contraindicated in patients "after the acute phase of injury following major burns" according to FDA labeling 1
• The contraindication applies regardless of the serum potassium level prior to administration 1
• Even modest hyperkalemia can be exacerbated to dangerous levels by succinylcholine in burn patients 1, 3
• The risk is dependent on the extent and location of the injury, though the precise threshold is not clearly defined 1

Alternative Approaches

• Rocuronium at doses ≥0.9 mg/kg is the recommended alternative for rapid sequence intubation in burn patients 2, 6, 4
• While rocuronium has a longer duration of action (30-60 minutes vs. 5-10 minutes for succinylcholine), this disadvantage is outweighed by the safety benefit in burn patients 6, 4
• If rapid reversal capability is needed, sugammadex can be considered for reversal of rocuronium-induced neuromuscular blockade 2

Special Considerations

• If succinylcholine must be used in the immediate acute phase of burn injury (first 24 hours), careful cardiac monitoring is essential 1, 5
• Neuromuscular monitoring should be employed when any muscle relaxant is used in burn patients due to altered pharmacodynamics 2
• Burn patients may develop resistance to non-depolarizing muscle relaxants (like rocuronium) starting around day 7 post-burn, requiring higher doses 5

Common Pitfalls

• Failing to recognize that the contraindication applies even when the patient's pre-procedure potassium level is normal 1, 3
• Underestimating the duration of risk, which can extend for months to years after the initial burn injury 5
• Not recognizing that even small doses of succinylcholine can trigger dangerous hyperkalemia in susceptible burn patients 3
• Assuming that the risk applies only to extensive burns, when even moderate burns can create sufficient receptor up-regulation to cause clinically significant hyperkalemia 1, 3

In summary, the risk of potentially fatal hyperkalemia makes succinylcholine use in burn patients beyond the acute phase a dangerous practice that should be avoided. Rocuronium provides a safe and effective alternative for rapid sequence intubation in this patient population.