Allergy Asthma Proc. 2012 May-Jun;33 Suppl 1:80-83. doi: 10.2500/aap.2012.33.3557.
Anaphylaxis is a sudden-onset, immediate reaction that implies a risk of death. Think of a "rule of 2's" for anaphylaxis implying that reactions usually begin within 2 minutes to 2 hours after injection, infusion, ingestion, contact, or inhalation. Fatalities can be from asphyxiation from laryngeal or oropharyngeal swelling, collapse from hypotensive shock, cardiac arrest, or acute severe bronchoconstriction causing respiratory failure and arrest. When there is activation of mast cells and basophils in anaphylaxis, chemical mediators are detectable. The preformed mediators from mast cells include histamine, tryptase, carboxypeptidase A, and proteoglycans (heparin and chondroitin sulfates). Newly synthesized mediators include prostaglandin D(2), leukotriene D(4), and platelet-activating factor. Crucial actions of the mediators include an abrupt increase in vascular permeability, vascular smooth muscle relaxation, and bronchial smooth muscle contraction. Anaphylaxis can be classified into immunologic, nonimmunologic, or idiopathic based on the associated mechanism. For example, immunologic causes of anaphylaxis are those mediated by IgE antibodies acting through the FcεR I (foods, insect venom, and beta-lactam antibiotics) whereas non-IgE immunologic anaphylaxis is mediated without presence of antiallergen IgE antibodies or via FcεRI activation (radiographic contrast material). Nonimmunologic anaphylaxis involves mast cell mediator release such as occurs with exercise, cold temperature exposure, or from medications such as opioids or vancomycin. Idiopathic anaphylaxis involves mast cell activation (acutely elevated urine histamine or serum tryptase) and activated lymphocytes. Because anaphylaxis is a medical emergency, the drug of choice is epinephrine, not H(1)-receptor antagonists.
过敏反应是一种突然发作的即刻反应，意味着有死亡的风险。对于过敏反应，可以考虑“2 规则”，即反应通常在注射、输注、摄入、接触或吸入后 2 分钟至 2 小时内开始。死亡可能是由于喉头或口咽肿胀导致窒息、低血压性休克引起的衰竭、心脏骤停或急性严重支气管痉挛导致呼吸衰竭和骤停。当过敏反应中肥大细胞和嗜碱性粒细胞被激活时，可检测到化学介质。肥大细胞预先形成的介质包括组胺、类胰蛋白酶、羧肽酶 A 和糖蛋白（肝素和硫酸软骨素）。新合成的介质包括前列腺素 D(2)、白三烯 D(4)和血小板激活因子。介质的关键作用包括血管通透性突然增加、血管平滑肌松弛和支气管平滑肌收缩。根据相关机制，过敏反应可分为免疫性、非免疫性或特发性。例如，过敏反应的免疫原因是 IgE 抗体通过 FcεR I（食物、昆虫毒液和β-内酰胺类抗生素）介导，而非 IgE 免疫性过敏反应是在没有抗过敏原 IgE 抗体存在的情况下通过 FcεRI 激活（造影剂）介导的。非免疫性过敏反应涉及肥大细胞介质释放，如运动、暴露于寒冷温度或药物（如阿片类药物或万古霉素）引起的释放。特发性过敏反应涉及肥大细胞激活（尿组胺或血清类胰蛋白酶水平急性升高）和活化的淋巴细胞。由于过敏反应是一种医疗紧急情况，因此首选药物是肾上腺素，而不是 H(1)-受体拮抗剂。
