Grauman Neander Nels, Loner Carly A, Rotoli Jason M
Department of Emergency Medicine, University of Rochester Medical Center, Rochester, New York.
J Emerg Med. 2018 May;54(5):685-689. doi: 10.1016/j.jemermed.2018.01.038. Epub 2018 Apr 5.
Methemoglobinemia can be a potentially lethal condition due to the hypoxic stress placed on the body. In pregnancy, the deleterious effects can be even more catastrophic. The benefits of treatment in all patients, especially in those who are pregnant, must outweigh the inherent risks of the therapies used to treat methemoglobinemia.
We present a case of a 26-year-old Hispanic pregnant female at 30 weeks gestation presenting to the emergency department for chest pain, hypoxia, and cyanosis. She was subsequently diagnosed with methemoglobinemia, treated with methylene blue, and admitted to the intensive care unit with toxicology and obstetrics consultations. As an outpatient, the patient underwent genetic testing and was diagnosed with homozygous cytochrome b5 reductase deficiency as the etiology of the methemoglobinemia. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Methemoglobinemia is a rare, potentially lethal, but treatable condition. In the setting of pregnancy, methemoglobinemia can pose a significant risk to the mother and fetus by causing acute hypoxia. Because methemoglobinemia can be acquired or congenital, treatments vary based on the etiology. Methylene blue is the mainstay treatment for symptomatic methemoglobinemia of levels > 20%. The teratogenic risks of methylene blue require risk-benefit analysis and discussion with the patient before utilization. Systemic maternal administration is theorized to be of lowest risk to the fetus. In this case, methylene blue was used safely as an emergent therapy for congenital methemoglobinemia during pregnancy.
由于身体受到缺氧应激，高铁血红蛋白血症可能是一种潜在的致命病症。在妊娠期间，其有害影响可能更具灾难性。对所有患者，尤其是孕妇进行治疗的益处必须超过用于治疗高铁血红蛋白血症的疗法所固有的风险。
我们报告一例26岁西班牙裔妊娠30周的孕妇，因胸痛、缺氧和发绀到急诊科就诊。她随后被诊断为高铁血红蛋白血症，接受亚甲蓝治疗，并在毒理学和产科会诊后入住重症监护病房。门诊时，患者接受了基因检测，被诊断为纯合子细胞色素b5还原酶缺乏，这是高铁血红蛋白血症的病因。
为什么急诊医生应该了解这个情况？：高铁血红蛋白血症是一种罕见的、潜在致命但可治疗的病症。在妊娠情况下，高铁血红蛋白血症可通过导致急性缺氧对母亲和胎儿构成重大风险。由于高铁血红蛋白血症可以是后天获得的或先天性的，治疗方法因病因而异。亚甲蓝是治疗高铁血红蛋白水平>20%的有症状患者的主要治疗方法。亚甲蓝的致畸风险需要在使用前进行风险效益分析并与患者讨论。理论上，母体全身给药对胎儿的风险最低。在本病例中，亚甲蓝被安全地用作妊娠期先天性高铁血红蛋白血症的紧急治疗方法。
