Succinylcholine — when NOT to give
Succ contraindications + hyperK risks
Mnemonic device
Crush + Burn + Denervate + MD + MH
Mapping
Crush
Crush injury > 24 hr — upregulated extra-junctional ACh receptors → massive K release
Burn
Major burns > 24 hr (≥10% TBSA) — same mechanism; can persist 1-2 yr
Denerv
Upper motor neuron lesion (stroke, spinal cord injury) > 24 hr — upregulated receptors
MD
Muscular dystrophy (Duchenne, Becker) — rhabdo + hyperK + cardiac arrest possible without warning
MH
MH susceptibility — known trigger
K+
Hyperkalemia (>5.5 mEq/L) — already-elevated K + succ can push into arrhythmia
Eye
Open globe + glaucoma — transient ↑ IOP (controversial; modern evidence less concerning but classically taught)
AChE
Pseudocholinesterase deficiency (homozygous: paralysis 4-8 hr; heterozygous: prolonged ~30-60 min)
Clinical note: Use rocuronium 1.2 mg/kg (sugammadex 16 mg/kg available for rescue reversal) instead of succinylcholine when contraindicated. Onset comparable for rapid sequence intubation.