Is succinylcholine (SCh) safe to use in a patient with hyperkalemia?

Succinylcholine is Contraindicated in Patients with Hyperkalemia

Succinylcholine should NOT be used in patients with pre-existing hyperkalemia due to the risk of life-threatening cardiac arrhythmias and cardiac arrest. The FDA drug label explicitly warns that succinylcholine "should be administered with GREAT CAUTION to patients suffering from electrolyte abnormalities" and states it may "induce serious cardiac arrhythmias or cardiac arrest due to hyperkalemia" in these patients 1.

Understanding the Mechanism and Risk

Succinylcholine normally increases serum potassium by 0.5-1.0 mEq/L in healthy patients 2, 3. However, when administered to patients who already have elevated potassium levels, this additional increase can push potassium into the lethal range, triggering:

• Ventricular fibrillation 2, 4
• Cardiac arrest 1, 4
• Severe bradycardia progressing to asystole 1

Absolute Contraindications

The FDA drug label lists specific contraindications where succinylcholine is absolutely prohibited 1:

• Acute phase injury (7-10 days post-injury) following:

  • Major burns 5, 1
  • Multiple trauma 5, 1
  • Extensive denervation of skeletal muscle 5, 1
  • Upper motor neuron injury 5, 1

• Chronic conditions causing receptor upregulation:

  • Neuromuscular diseases 6, 5
  • Skeletal muscle myopathies 1
  • Prolonged immobilization (≥3 days) 6, 5
  • Spinal cord injury 5

Additional High-Risk Scenarios Requiring Great Caution

Even if not absolute contraindications, the following conditions warrant extreme caution or avoidance 1:

• Chronic abdominal infection 1
• Subarachnoid hemorrhage 1
• Conditions causing central/peripheral nervous system degeneration 1
• Massive digitalis toxicity 1
• Sepsis with prolonged critical illness 4

The Safer Alternative: Rocuronium

Rocuronium (≥0.9 mg/kg) is the recommended alternative for rapid sequence intubation in hyperkalemic patients 5. Key advantages include:

• Does not increase potassium levels 3
• Provides adequate intubating conditions within 60-90 seconds 5
• Can be rapidly reversed with sugammadex if needed 5
• Duration of 30-60 minutes, which is acceptable given the safety benefit 5

Limited Evidence for "Modest" Hyperkalemia

While one retrospective study found no adverse events in 38 patients with potassium 5.6-6.0 mEq/L who received succinylcholine 7, this evidence has significant limitations:

• The 95% confidence interval for risk was 7.9%, which is not negligible 7
• This contradicts FDA warnings and multiple case reports of cardiac arrest 1, 2, 4
• The study authors themselves acknowledge this "almost certainly grossly overestimates" safety 7

Given the availability of safe alternatives like rocuronium, there is no justification for using succinylcholine in hyperkalemic patients, even with "modest" elevations.

Critical Clinical Pitfalls to Avoid

• Do not assume chronic renal failure patients are "stable" - their baseline hyperkalemia can become lethal with succinylcholine 1
• Do not use succinylcholine in septic patients - they are at high risk for exaggerated potassium release 4
• Pretreatment with defasciculating doses of non-depolarizing agents does NOT adequately protect against hyperkalemia in high-risk patients 6, 1
• If cardiac arrest occurs immediately after succinylcholine, suspect hyperkalemia and treat aggressively with calcium, insulin/glucose, and hyperventilation 6, 4

Emergency Hyperkalemia Management if Succinylcholine Was Given

If succinylcholine was inadvertently administered to a hyperkalemic patient 8, 4:

• Immediate IV calcium gluconate or chloride to stabilize cardiac membranes 8
• Insulin with glucose to shift potassium intracellularly 8, 4
• Sodium bicarbonate IV if acidotic 4
• Albuterol 10-20 mg nebulized as adjunctive therapy 8
• Prepare for cardiac arrest with defibrillator and resuscitation equipment immediately available 4