In patients with severe symptoms, treatment is directed toward ensuring adequate ventilation and hemodynamic stability The treatment is the same as that of anaphylaxis, see Chapter 85 Allergic Emergencies Fluids and vasopressor support may be needed to treat hypotension Pharmacologic treatment includes administration of antihistamines, corticosteroids, and if necessary, adrenergic agents Both diphenhydramine and cimetidine have been used successfully to treat the symptoms of scombroid poisoning In the event of severe bronchospasm, other bronchodilators, including inhaled β2 -agonists may be necessary adjuncts Ciguatera Ciguatera is an illness endemic to the South Pacific but in the continental United States it is largely confined to the lower Atlantic states However, because it does occasionally appear in the United States or may occur in recent visitors from endemic areas, its clinical manifestations should be recognized Ciguatera results from ingestion of a toxin elaborated by the dinoflagellate, Gambierdiscus toxicus This parasite is ingested by small fish, which begin to concentrate the toxin As predators ingest those small fish, the toxin ascends the food chain until ingested by humans The fish that most commonly harbor ciguatoxin include barracuda, grouper, red snapper, and parrot fish The physiologic actions of ciguatoxin are primarily neurologic The toxin decreases CNS concentrations of γ-aminobutyric acid (GABA) and dopamine This action occurs in conjunction with sodium channels being “locked open,” permitting unrestricted sodium ingress The clinical picture of ciguatera poisoning begins to 36 hours after ingestion of contaminated fish After a brief period of nausea and vomiting, patients develop weakness or paresthesias, particularly perioral A hallmark of ciguatera toxin is the reversal of hot–cold sensation In severe cases there may be coma Toxic manifestations may persist for days to months after significant exposure The diagnosis of ciguatera intoxication is clinical, based on the history of ingestion of a fish known to carry this toxin GI decontamination is ineffective because symptoms appear many hours after ingestion of contaminated fish Management of ciguatera is supportive, with specific attention should to CNS status and its effects on airway and ventilation IV mannitol has shown great promise in reversing many of the neurologic manifestations, particularly coma It is administered in a dose of 0.5 to g/kg via an in-line filter Paralytic Shellfish Poisoning