Is succinylcholine safe to use in the acute phase of a burn injury?

Succinylcholine Use in the Acute Phase of Burn Injury

Succinylcholine is contraindicated in patients during the acute phase of burn injury after 24-48 hours post-burn due to the risk of potentially fatal hyperkalemia. 1

Mechanism and Risk Period

Burn injuries cause significant physiological changes that affect the pharmacodynamics of neuromuscular blocking agents, particularly succinylcholine. These changes include:

• Development of "immature" acetylcholine receptors at the neuromuscular junction starting around day 5-7 post-burn 2
• Upregulation of acetylcholine receptors in the muscle membrane 3
• Release of intracellular potassium when these receptors are stimulated by succinylcholine

The risk of hyperkalemia:

• Begins approximately 24-48 hours after burn injury 4
• Peaks between 7-10 days post-burn 1
• Can persist for up to 2 years after the initial injury 2
• Increases with larger burn surface area (especially >15% total body surface area) 2

FDA Warning and Contraindication

The FDA drug label explicitly states that succinylcholine should be administered with "GREAT CAUTION" to patients during the acute phase following major burns. The label further specifies that succinylcholine is contraindicated "after the acute phase of injury following major burns" due to the risk of severe hyperkalemia which may result in cardiac arrest. 1

Time-Based Guidelines

• First 24 hours post-burn: Succinylcholine may be used with caution
• After 24-48 hours post-burn: Succinylcholine is contraindicated 4
• Peak risk period: 7-10 days post-burn 1
• Duration of contraindication: Up to 2 years after burn injury 2

Alternative Neuromuscular Blocking Agents

When rapid sequence intubation is needed in burn patients after the first 24-48 hours:

• Rocuronium is the recommended alternative to succinylcholine 4
• Higher doses of non-depolarizing agents may be required in burn patients due to resistance that develops approximately 7 days post-burn 2, 5
• Mivacurium may be used at normal dosages as its metabolism is affected by decreased plasma cholinesterase activity in burn patients, which counteracts the receptor-mediated resistance 6

Special Considerations

• The risk of hyperkalemia is directly related to the dose of succinylcholine, the post-burn delay, and the area of burned body surface 2
• The hyperkalemic response and related cardiac complications remain unpredictable 2
• Patients with burns >15% of body surface area experience major physiological changes affecting drug pharmacokinetics 2
• French recommendations for spinal cord injury management note that succinylcholine can be used for emergency induction of anesthesia in the early hours after injury, with a conventional deadline of 48 hours 3

Clinical Approach

1. Assess time since burn injury:

   • If <24 hours: Succinylcholine may be used with caution
   • If >24-48 hours: Avoid succinylcholine completely

2. Evaluate burn extent:

   • Larger burns (>15% TBSA) increase risk of hyperkalemic response

3. Choose alternative agent:

   • Rocuronium is the preferred alternative for rapid sequence intubation
   • Consider higher doses of non-depolarizing agents if >7 days post-burn

4. Monitor closely:

   • If succinylcholine must be used in the first 24 hours, monitor ECG for arrhythmias
   • Be prepared to treat hyperkalemia if it develops

Remember that the risk of hyperkalemia with succinylcholine in burn patients is significant and potentially fatal, making this contraindication absolute rather than relative after the initial 24-48 hour period.