Paudyal B P
Department of Medicine, Patan Hospital, Lalitpur.
JNMA J Nepal Med Assoc. 2008 Oct-Dec;47(172):251-8.
Acute poisoning by organophosphorus (OP) compounds is a major global clinical problem, with thousands of deaths occurring every year. Most of these pesticide poisoning and subsequent deaths occur in developing countries following a deliberate self ingestion of the poison. Metacid (Methyl parathion) and Nuvan (Dichlorovos) are commonly ingested OP pesticides; Dimethoate, Profenofos, and Chlorpyrifos are other less frequently ingested compounds in Nepal. The toxicity of these OP pesticides is due to the irreversible inhibition of acetylcholinesterase (AChE) enzyme leading to accumulation of acetylcholine and subsequent over-activation of cholinergic receptors in various parts of the body. Acutely, these patients present with cholinergic crisis; intermediate syndrome and delayed polyneuropathy are other sequel of this form of poisoning. The diagnosis depends on the history of exposure to these pesticides, characteristic manifestations of toxicity and improvements of the signs and symptoms after administration of atropine. The supportive treatment of OP poisoning includes the same basic principles of management of any acutely poisoned patient i.e., rapid initial management of airways, breathing, and circulation. Gastric lavage and activated charcoal are routinely used decontamination procedures, but their value has not been conclusively proven in this poisoning. Atropine is the mainstay of therapy, and can reverse the life threatening features of this acute poisoning. However, there are no clear cut guidelines on the dose and duration of atropine therapy in OP poisoning. Cholinesterase reactivators, by regenerating AChE, can reverse both the nicotinic and muscarinic effects; however, this benefit has not been translated well in clinical trials. All these facts highlight that there are many unanswered questions and controversies in the management of OP poisoning and there is an urgent need for research on this aspect of this common and deadly poisoning.
有机磷（OP）化合物急性中毒是一个重大的全球临床问题，每年导致数千人死亡。这些农药中毒及随后的死亡大多发生在发展中国家，系患者故意自行摄入毒物所致。杀螟松（甲基对硫磷）和敌敌畏（二氯vos）是常见的经口摄入的OP农药；乐果、丙溴磷和毒死蜱是尼泊尔其他较少经口摄入的化合物。这些OP农药的毒性是由于乙酰胆碱酯酶（AChE）酶的不可逆抑制，导致乙酰胆碱积累，进而使身体各部位的胆碱能受体过度激活。急性中毒时，这些患者会出现胆碱能危象；中间综合征和迟发性多发性神经病是这种中毒形式的其他后遗症。诊断取决于接触这些农药的病史、毒性的特征性表现以及给予阿托品后体征和症状的改善情况。OP中毒的支持性治疗包括对任何急性中毒患者进行管理的相同基本原则，即对气道、呼吸和循环进行快速的初始处理。洗胃和活性炭是常规使用的去污程序，但它们在这种中毒中的价值尚未得到确凿证实。阿托品是治疗的主要药物，可逆转这种急性中毒危及生命的特征。然而，关于OP中毒时阿托品治疗的剂量和持续时间，尚无明确的指南。胆碱酯酶复活剂通过使AChE再生，可逆转烟碱样和毒蕈碱样作用；然而，这种益处在临床试验中并未得到很好的体现。所有这些事实都表明，在OP中毒的管理方面存在许多未解决的问题和争议，迫切需要对这种常见且致命的中毒的这一方面进行研究。
