What is the timeframe for hyperkalemia to develop after succinylcholine administration in a patient with muscular dystrophy?

Hyperkalemia After Succinylcholine in Muscular Dystrophy: Timing of Onset

Hyperkalemia and cardiac arrest occur immediately—within minutes—after succinylcholine administration in patients with muscular dystrophy, making this a rapidly fatal complication that demands absolute avoidance of this drug in this population. 1

Immediate Onset and Clinical Presentation

The timeframe is acute and rapid:

• Cardiac arrest can occur within minutes of succinylcholine injection in patients with Duchenne muscular dystrophy (DMD) or other muscular dystrophies 1
• Case reports document cardiac arrest occurring during the induction phase of anesthesia, immediately following a single dose of succinylcholine 2, 3
• One documented case showed cardiac arrest in a 3-year-old boy with unsuspected DMD following a single succinylcholine dose, with associated lack of fasciculations, muscle rigidity, hyperkalemia, myoglobinuria, and massive elevation of serum creatine phosphokinase 3
• Another case reported a 5-year-old boy with Becker muscular dystrophy who sustained cardiac arrest following a single dose during induction, requiring 10 minutes of CPR 2

Pathophysiology Explaining Rapid Onset

The mechanism explains why this happens so quickly:

• Succinylcholine disrupts unstable cell membranes in dystrophic muscle, causing acute rhabdomyolysis and massive potassium release 1
• Upregulated nicotinic acetylcholine receptors migrate across the entire muscle membrane surface and become more ionically active, leading to massive potassium efflux immediately after succinylcholine administration 4
• This is distinct from the delayed hyperkalemia risk (7-10 days post-injury) seen in burn patients or those with denervation injuries 5

Absolute Contraindication

Succinylcholine is absolutely contraindicated in patients with known or suspected muscular dystrophy, including DMD, Becker dystrophy, and skeletal muscle myopathies 1, 5:

• The FDA label explicitly lists skeletal muscle myopathies as an absolute contraindication 5
• The American College of Chest Physicians states succinylcholine is widely recognized as contraindicated in DMD patients, with numerous reports of sudden death due to hyperkalemic cardiac arrest 1
• Young patients with previously unsuspected DMD have been diagnosed only after sudden death from hyperkalemic cardiac arrest during general anesthesia 1

Safe Alternative Approach

Use rocuronium ≥0.9 mg/kg (preferably 1.0-1.2 mg/kg) as the alternative for rapid sequence intubation 4, 6:

• Rocuronium provides similar intubation conditions without the hyperkalemia risk 4, 6
• Have sugammadex immediately available for reversal if needed 6
• The longer duration of action (30-60 minutes vs. 4-6 minutes) is an acceptable trade-off for the critical safety benefit 4, 6

Critical Warning Signs

If cardiac arrest occurs immediately after succinylcholine administration in any patient:

• Suspect hyperkalemia immediately and treat aggressively with calcium, insulin/glucose, and hyperventilation 4
• The American Academy of Pediatrics warns that cardiac arrest occurring immediately after succinylcholine may be due to hyperkalemia, particularly in young patients 4
• This may be the first presentation of previously undiagnosed muscular dystrophy 1, 3