毒蛇咬伤台湾经验Snake Bites in Taiwan
毒蛇咬伤, 抗蛇毒血清, 出血性毒毒素, 神经性毒毒素Snake Bites; Antivenin; Hemorrhagic Venom; Neurotoxic Venom
《Advances in Clinical Medicine》, Vol.1 No.3, 2011-12-29
台湾地处亚热带，地形多高山、丛林，气候温暖潮湿，是毒蛇生长繁殖的最佳环境。其中有6种毒蛇的咬伤较为常见且常有严重的临床症状，较有流行病学上的意义，它们是赤尾鲐(Trimeresurus stejnegeri)、龟壳花(T.mucrosquamatus)、眼镜蛇(Naja naja atra)、雨伞节(Bungarus multicinctus)、百步蛇(Deinagkistrodon acutus)、锁蛇(Daboia russelli formosensis)(2)。赤尾鲐、龟壳花及百步蛇咬伤主要以出血症状为主，一般称之出血性毒蛇。眼镜蛇和雨伞节咬伤因其具神经毒性，故称之为神经性毒蛇。锁炼蛇在动物实验及临床上兼具神经及出血症状，另外归为两者兼有之毒蛇。出血性毒毒素可造成咬伤处肿胀、淤血、疼痛；严重时并可导致血凝不全、全身性出血等症状。神经性毒毒素可以作用于运动神经与肌肉接合处，而造成横纹肌不收缩，迅速导致呼吸麻痹。混合性毒毒素具有神经毒性、溶血、横纹肌溶解及肾毒性等症状。赤尾鲐的咬伤是台湾最常见的毒蛇咬伤，龟壳花次之，眼镜蛇咬伤占第三位，不过赤尾鲐咬伤有集中在台湾中部的倾向，雨伞节咬伤占第四位，锁炼蛇占第五位、百步蛇咬伤个案在六大毒蛇中反而最少，不过锁炼蛇及百步蛇咬伤主要以台湾东南部为主[4,22-23]。一般毒蛇咬伤后在4~6小时即会有症状出现，此时应尽速给予正确的抗蛇毒血清（量及种类），雨伞节咬伤尚需考虑插管使用呼吸器维持呼吸，若4~6小时内未出现症状，则最好观察6~12小时确定无症状再离院，无症状的毒蛇咬伤并不需给予抗蛇毒血清治疗，仅需一般症状治疗。蛇咬时应保持冷静，辨别蛇种及蛇的大小，并注意有无听到嘶嘶的喷气声以帮助医护人员诊断。抗蛇毒血清使用的剂量依咬伤的严重度、病人体重及咬伤后的时间长短给予不同的剂量，根据大多数毒物专家建议大人与小孩毒蛇咬伤应给予相同剂量，饭匙倩咬伤为6~12瓶、雨伞节咬伤为2~4瓶、龟壳花咬伤为2~4瓶、赤尾鲐咬伤为1~2瓶、百步蛇咬伤为2~4瓶、锁链蛇咬伤为2~4瓶，抗蛇毒血清以静脉滴注30~60分钟，毒蛇咬伤后4小时内给予效果最好，超过8小时才注射效果较差。急诊医护人员应根据毒蛇咬伤的病史，临床进展的症状及实验室的检查报告来决定适时给予何种抗蛇毒血清的注射量，滴注期间应密切注意病患各种生理现象的变化，才能降低毒蛇咬伤的死亡率。Located at the juncture of tropical and subtropical regions, Taiwan has a warm and humid climate with abundant precipitation and food, which coupled with the island’s diverse vegetation and landscape, makes it a suitable environment for many snake species. Among these, there are six kinds of poisonous snake with epidemiological significance. Three species induce hemorrhagic symptoms (Trimeresurus mucrosquamatus, TM; Trimeresurus stejnegeri, TS; and Deinagkistrodon acutus, DA); two species induce neurotoxic symptoms (Naja naja atra, NA; and Bungarus multicinctus, BM); the other species induces hemorrhagic and neurotoxic symptoms (Vipera russelli formosensis. VR).The hemorrhagic venom causes disorders of the clotting cascade such as prolonged bleeding, primary fibrinolysis and disseminated intravascular coagulopathy. The neurotoxic venom provokes respiratory distress from weakened respiratory muscles, blurred vision, diplopia, dysarthria, dysphagia, dysphonia and paralysis of extremity muscles. The mixed envenomation manifests as a combination of neurotoxic and hemorrhagic effects previously described, as well as rhabdomyolysis and acute renal failure. The identification of snake species is important if antivenom is to be used. However, the species is not ably identified if the patient or companion fails to see or catch the responsible snake. Although these unidentifiable snakes could be non-venomous, venomous species are not uncommon. Therefore, guidelines for snakebite identification based on clinical symptoms and laboratory analysis is important to improve clinical diagnosis of snakebites. In Taiwan, T. stejnegeri bites are the most common. The second is T. mucrosquamatus. Naja naja atra is the third, Bungarus multicinctus is the forth and Vipera russelli formosen-sis is the fifth. Deinagkistrodon acutus is the least. Bites by Deinagkistrodon acutus and Vipera russelli for-mosensis generally occur in the south and east parts of the island. Aggressive antivenom treatment can reduce snakebite mortality rate, but for Bungarus multicinctus bites, maintaining the patient’s airway and supporting their ventilation is vital to reducing mortality rate in addition to antivenom treatment. For dry bites or no en-venomation, the patient should be observed for at least 6 - 12 hours before discharged. The emergency physi-cian should determine the severity of envenomation and predominate venom activity before decide what type of antivenin to administer, how much, and over what period. History of exposure, local effect and systemic syndromes of envenomation, progression of symptoms and signs, laboratory data obtained in emergency de-partment should guide the decision for antivenom therapy. The freeze-dried antivenom was diluted with 50 - 100 mL of normal saline and infused intravenously for half to one hour. The poisonous snake bites in the lat-ter 4 hours to give the effect to be best, surpasses 8 hours only then to inject the effect to be bad. The dosage most toxicologists used for treating pediatric patients with snakebites was the same as that for adults. In gen-eral, 6 - 12 vials of antivenom against neurotoxic venom were used for Naja atra bite and 2 - 4 vials for Bun-garus multicinctus; 1 - 2 vials of antivenom against hemotoxic venom was used for Trimeresurus stejnegeri and 2 - 4 vials for Trimeresurus mucrosquamatus; 2 - 4 vials of anti-Deinagkistrodon acutus were used for Deinagkistrodon acutus and 2 - 4 vials of anti-Vipera russelli formosensis were used for Vipera russelli for-mosensis bite. During the infusion, the blood pressure, consciousness and skin reaction were evaluated. Keeping the varied clinical manifestations of snake bite in mind is important for effective management. Ready availability and appropriate use of antivenin, close monitoring of patients and institution of ventilatory support, all help reduce mortality.