Venomous snake bites: clinical diagnosis and treatment

Snake bites are life-threatening injuries that can require intensive care. The diagnosis and treatment of venomous snake bites is sometimes difficult for clinicians because sufficient information has not been provided in clinical practice. Here we review the literature to present the proper management of bites by mamushi, habu, and yamakagashi snakes, which widely inhabit Japan and other Asian countries. No definite diagnostic markers or kits are available for clinical practice; therefore, definitive diagnosis of snake-venom poisoning requires positive identification of the snake and observation of the clinical manifestations of envenomation. Mamushi (Gloydius blomhoffii) bites cause swelling and pain that spreads gradually from the bite site. The platelet count gradually decreases due to the platelet aggregation activity of the venom and can decrease to <100,000/mm(3). If the venom gets directly injected into the blood vessel, the platelet count rapidly decreases to <10,000/mm(3) within 1 h after the bite. Habu (Protobothrops flavoviridis) bites result in swelling within 30 min. Severe cases manifest not only local signs but also general symptoms such as vomiting, cyanosis, loss of consciousness, and hypotension. Yamakagashi (Rhabdophis tigrinus) bites induce life-threatening hemorrhagic symptoms and severe disseminated intravascular coagulation with a fibrinolytic phenotype, resulting in hypofibrinogenemia and increased levels of fibrinogen degradation products. Previously recommended first-aid measures such as tourniquets, incision, and suction are strongly discouraged. Once airway, breathing, and circulation have been established, a rapid, detailed history should be obtained. If a snake bite is suspected, hospital admission should be considered for further follow-up. All venomous snake bites can be effectively treated with antivenom. Side effects of antivenom should be prevented by sufficient preparation. Approved antivenoms for mamushi and habu are available. Yamakagashi antivenom is used as an off-label drug in Japan, requiring clinicians to join a clinical research group for its use in clinical practice.