Contraindications to Succinylcholine
Succinylcholine is absolutely contraindicated in patients with personal or familial history of malignant hyperthermia, skeletal muscle myopathies, known hypersensitivity, and after the acute phase of injury (typically 7-10 days post-injury) following major burns, multiple trauma, extensive denervation of skeletal muscle, or upper motor neuron injury due to the risk of fatal hyperkalemia. 1
Absolute Contraindications (FDA-Labeled)
The FDA drug label clearly defines the following as absolute contraindications 1:
- Personal or familial history of malignant hyperthermia
- Skeletal muscle myopathies (including Duchenne muscular dystrophy and other primary muscle diseases)
- Known hypersensitivity to succinylcholine
- Post-acute phase injuries (after 7-10 days following):
- Major burns
- Multiple trauma
- Extensive denervation of skeletal muscle
- Upper motor neuron injury
The hyperkalemia risk in these injury states increases over time, typically peaking at 7-10 days post-injury, though the precise onset and duration remain somewhat variable depending on injury extent and location 1.
Strong Relative Contraindications (Use with GREAT CAUTION per FDA)
The FDA mandates "GREAT CAUTION" in the following scenarios due to severe hyperkalemia risk 1:
- Electrolyte abnormalities (pre-existing hyperkalemia)
- Massive digitalis toxicity
- Chronic abdominal infection
- Subarachnoid hemorrhage
- Conditions causing central/peripheral nervous system degeneration
- Narrow angle glaucoma or penetrating eye injury (due to increased intraocular pressure)
Guideline-Based Contraindications
The 2020 Anaesthesia guidelines provide additional clarity on neuromuscular conditions 2:
Succinylcholine is NOT recommended in:
- Primary muscle damage (myopathies) - causes generalized contraction with rhabdomyolysis
- Up-regulation of nicotinic acetylcholine receptors - occurs with:
- Chronic motor deficits
- Extensive and deep burns (after several days)
- Prolonged critical illness
- Chronic damage to motoneurons
These conditions can cause life-threatening hyperkalemia beginning days after the neurological/muscle lesions develop and persisting for an extended period 2.
Special Populations
Pediatric Patients
Succinylcholine is no longer recommended for elective pediatric anesthesia due to reports of cardiac arrest in children with occult neuromuscular disease 3, 4. It retains value only in critical pediatric situations requiring rapid onset and short duration 3.
Myasthenia Gravis
While not absolutely contraindicated, patients with myasthenia show resistance to succinylcholine (requiring higher doses), making it a poor choice 2.
Atypical Pseudocholinesterase
Use with extreme caution or avoid entirely in patients homozygous for atypical plasma cholinesterase gene, as metabolism will be severely impaired 1.
Critical Timing Considerations
A key pitfall is the temporal nature of contraindications related to receptor up-regulation. Succinylcholine may be safe immediately after injury but becomes contraindicated as receptor changes develop over subsequent days. The risk window typically begins several days post-injury and peaks at 7-10 days, but can persist indefinitely depending on the underlying condition 1.
Clinical Context
The 2023 Critical Care Medicine guidelines suggest either rocuronium or succinylcholine may be used for RSI when there are no known contraindications to succinylcholine 5. This reinforces that the decision hinges entirely on screening for the contraindications listed above.
Research from ICU populations found that 70.9% of ICU patient-days had at least one contraindication to succinylcholine, with 11.3% at high risk for hyperkalemic complications 6. This underscores the importance of systematic screening before use, particularly in critically ill patients.
Malignant Hyperthermia Risk
Succinylcholine carries inherent risk of triggering malignant hyperthermia, a potentially fatal hypermetabolic crisis. Risk increases with concomitant volatile anesthetics. Patients with specific RYR1 or CACNA1S gene variants should be presumed malignant hyperthermia susceptible 7. Early signs include masseter spasm, which may progress to generalized rigidity, tachycardia, and hyperpyrexia 1.