See also: [[Heat-related illness]] > **Diagnosis** > - [[EtCO2 monitoring|↑ ETCO2]] > - masseter spasm > - ↑ BP, tachycardia, arrhythmias > - fevers (later) **causes** - ==suxamethonium== - volatile anaesthetic agents - extensive muscular trauma - amide type local anaesthetics - cardiac glycosides - a/w muscular dystrophies, osteogenesis imperfect , pheochromacytopma **cause** - defect in excitaiton contraction coupling in skeletal and cardiac muscle → reduced Ca2+ reuptake by smooth muscle endoplasmic reticulum - ↑ intracellular Ca2+ → ↑ glycogen metabolism, ↑ ATP production → ↑ ATP production **findings** - 25% within 5 min of precipitant, 50% within 1-2 hours - can occur up to 11 hours post precipitant - ↑ ETCO2 and masseter spasm early signs - ETCO2 2-3x normal - increased arterial-venous O2 gradient - ↑ CK **complications** - AKI and rhabdo - acute pulmonary oedema - ARDS - coagulopathy - cerebral oedema - compartment syndromes **treatment** - stop offending agent - 100% O2 compensate for ↑ consumption - Hyperventilate - IV fluid bolus - *dantroline* - 2.5mg/kg IV bolus (9 vials for a 70kg person) - additional 1-2 mg/kg Q5 min up to 10mg/kg - then 1mg/kg/hour - cooling measures as for accidental [[Heat-related illness|hyperthermia]] - correct electrolyte disturbances (glucose, PO4, K+) - correct metabolic acidosis and coagulopathy - cerebral protection - Arrhythmia management - Avoid lignocaine - Procainamide or verapamil may be appropriate > Dantrolene reduces muscular tone by ↓ intracellular calcium and ↑ uptake by sarcoplasmic reticulum ## Dantrolene side effects - CNS - depression, vertigo - GIT - nausea/vomiting - derm : photosensitivty, rash - GUT: haematuria