比心【翻译】Icebear52【校对】itsmelan
配图、英文稿均来自©Osmosis
Bronchiol- refers to the small airways of the lungs and -itis means inflammation, so bronchiolitis is inflammation of the small airways in the lungs. It’s most often caused by infection from the respiratory syncytial virus or RSV. It mostly affects young children - causing illness in nearly every child at some point in their life.
Bronchiol-（支气管）指的是肺部的细小气管，而-itis指炎症，因此bronchiolitis细支气管炎指的就是肺部细小呼吸道炎症，通常由呼吸道合胞病毒（respiratory syncytial virus, RSV）感染引起。通常年龄较小的儿童容易受到影响——几乎每个孩子都因此患过病。
呼吸道合胞病毒
The name respiratory syncytial virus comes from the virus causing cells lining the respiratory tract to merge, forming a large multinucleated “cell” called a syncytia.
呼吸道合胞病毒的命名源于该病毒会造成呼吸道内膜的细胞融合，形成多核巨“细胞”合胞体。
Respiratory syncytial virus is part of the Pneumoviridae family, and it’s transmitted when an infected person sneezes or coughs, spreading thousands of droplets containing the virus into the surrounding area, up to about two meters or six feet away. These droplets can then land in the mouths or noses of people nearby, or get inhaled into the lungs. The virus can also survive on surfaces for a few hours, so it’s possible to get the virus by touching a surface, like a contaminated doorknob, and then touching your own eyes, nose, or mouth.
呼吸道合胞病毒属于肺病毒科，感染者打喷嚏或咳嗽时会传播病毒，向周围散布数千个含有病毒的小液滴，覆盖范围约有2米远。这些小液滴会落入附近人们的口鼻中，或者由肺部吸入。合胞病毒也可以在物体表面存活几个小时，因此手摸了污染的物体，如沾有病毒的门把手，再触摸你的眼睛、鼻子或嘴巴也可能会感染病毒。
Upon entering the body, the virus encounters the epithelial cells lining the nasopharynx which is the part of your throat nearest your nose. It creates some local damage, and then works its way down the respiratory tree, kind of like a secret agent rappelling down a rope of mucus. It goes down past the trachea and main bronchi to eventually reach the bronchioles - it’s primary target.
病毒进入体内后会遇到鼻咽部的上皮细胞，鼻咽指的是靠近鼻子的喉咙处。病毒在这里造成一定局部损伤后继续向下进入肺部支气管，有点像秘密特工抓着黏液的绳子下降。经过气管和主支气管后，病毒最终到达细支气管——它的主要目标。
Respiratory syncytial virus is an enveloped virus with a linear negative-sense strand of RNA, which means that once the virus enters its RNA into a respiratory epithelial cell, that strand has to get converted into a complementary sense strand in order to get translated. The cell is forced to use it’s energy and organelles to make viral proteins - basically turning into a virus factory. The new viruses invade neighboring cells, creating multinucleated syncytia out of some while destroying others.
呼吸道合胞病毒是具有包膜的单链反义RNA病毒，这表示一旦病毒RNA进入呼吸上皮细胞，需要先转化成互补的正链才能进行翻译。细胞被迫使用自身的能量和细胞器，生产病毒所需蛋白质——基本上变成了病毒工厂。产生的新病毒会侵入相邻的细胞，产生多核合胞体，或者破坏其他的细胞。
The cellular destruction attracts nearby immune cells, like natural killer cells whose job it is to kill the virus-infected cells. Immune cells release various chemokines which creates an inflammatory reaction that makes epithelial cells secrete more mucus and makes the blood vessels in the walls of the airways more leaky.
遭到破坏的细胞会吸引附近的免疫细胞，如自然杀伤细胞，它主要负责杀死病毒感染的细胞。免疫细胞释放多种趋化因子，产生炎症反应，使上皮细胞分泌更多黏液，并且使气管壁上的血管渗透性增加。
More immune cells and more fluid enters the damaged areas, creating inflammation and swelling. The extra fluid in the walls of the airway, makes the walls thicker and narrows the airway. Children typically have narrower airways than adults to begin with, so this additional narrowing of the airways affects them the most, and largely explains why they disproportionately suffer from bronchiolitis.
受损区域的免疫细胞和液体越来越多，造成炎症和肿胀。气管壁中额外的液体使气管壁变厚，气管因此变窄。通常儿童的气管本来就比成人的窄，因此气管变窄对儿童影响更大，这也解释了为什么儿童更容易患细支气管炎。
In addition, dead cells and mucus slide into the airway forming mucus plugs which can trap air behind the plug. Over time, trapped air slowly diffuses into the bloodstream, and tiny airways collapse - a process called atelectasis. Sometimes, the mucus plugs end up acting like one way valves, allowing air to enter, but not escape the bronchioles. In other words, air keeps going in with each inhalation until the lungs are really inflated, but the air can’t escape during exhalation - this is called air-trapping.
此外，坏死的细胞和黏液滑入气管形成黏液栓，并将空气堵在栓后。随着时间的推移，这一段空气会慢慢扩散到血液中，细小气管萎缩内陷——这就是肺不张（atelectasis）的形成过程。有时，黏液栓会形成一个单向阀，空气能进去却出不来，换句话说就是在吸气时，肺部不断吸入气体膨胀，呼气时气体却难以排出——这就是气体潴留。
Both atelectasis and air-trapping can sometimes be seen in the different regions of the lungs at the same time like in this chest X-ray. Atelectasis and air-trapping both reduce the lung’s ability to bring in oxygen and get rid of carbon dioxide. Over time, a serious RSV infection can lead to hypoxemia which is a decreased oxygen content in the blood.
有时在肺部的不同区域可以同时出现肺不张和气体潴留，就像图中的这个胸部X片一样。肺不张和气体滞留都会降低肺部吸入氧气和排出二氧化碳的能力。随着时间推移，严重的RSV感染可导致低氧血症，即血液中氧气含量较低。
病因
Although the main cause of bronchiolitis is respiratory syncytial virus, it can be caused by other viruses like adenovirus, human bocavirus, and human metapneumovirus. It can also be caused by other pathogens or viruses, like the bacteria Mycoplasma pneumoniae. Sometimes a severe bout of bronchiolitis may be due to more than one of these invaders attacking at the same time.
虽然细支气管炎的主要原因是呼吸道合胞病毒感染，但其他病毒感染也会导致细支气管炎，如腺病毒，人博卡病毒和人偏肺病毒。其他病原体或病毒也可以引起细支气管炎，如肺炎支原体（Mycoplasma pneumoniae）。有时严重的细支气管炎可能是因为感染了不止一种病原体。
症状
Initially, bronchiolitis symptoms are similar to the common cold - congestion, pharyngitis, sore throat, and cough. If the infection becomes more severe, it can lead to symptoms like difficulty breathing, wheezing, and fever. If there’s hypoxia it can be especially dangerous for a child’s developing brain, and the body’s natural response is to increase heart rate and breathing in an attempt to deliver oxygen to the brain more quickly. Over time, this can lead to exhaustion, and require hospitalization. Young infants with bronchiolitis can also experience central apnea which is where they have short periods of time where they stop breathing altogether.
细支气管炎一开始的症状和普通感冒相似：鼻塞、咽部发炎、喉咙痛、咳嗽等。如果感染加重，会产生呼吸困难、气喘、发热等症状。缺氧尤其会影响儿童的大脑发育，此时身体会产生自然反应，加快心率和呼吸频率，以便向大脑更快地输送氧气。时间一长会导致疲惫并需要进行住院治疗。患有细支气管炎的较小的婴儿也可能会产生中枢性呼吸暂停，即在较短时间内呼吸完全停止。
诊断
The diagnosis of bronchiolitis is largely a clinical diagnosis based on whether RSV is known to be circulating at a given time of the year, the child’s age, and the presence of classic signs and symptoms. Children at risk for bronchiolitis include those who weren’t breastfed, those born prematurely, and those with neuromuscular disorders that cannot easily clear their airways. Although it’s not always needed, diagnostic testing for RSV can be done by swabbing epithelial cells in the nasopharynx and looking for the presence of viral antigens.
细支气管炎的诊断主要是通过临床诊断，诊断依据包括RSV在一年中的流行时段、儿童的年龄和典型体征和症状。儿童易患细支气管炎的风险因素包括未经母乳喂养、早产或患有神经肌肉型疾病难以清除气管杂物。可以通过擦拭鼻咽部上皮细胞，检查是否存在病毒抗原，但这一检查并不是人人都必要的。
治疗
There’s no proven antiviral therapy for bronchiolitis, so treatment usually consists of supplemental oxygen and giving fluids to prevent dehydration. For some kids at high risk of serious complications like those born very premature, with significant pulmonary disease like bronchopulmonary dysplasia or with congenital heart disease, monthly injections of a premade antibody against RSV called palivizumab has been shown to be beneficial.
目前针对细支气管炎没有可靠的抗病毒治疗，因此治疗通常包括补氧和补液以防止脱水。对于具有高危并发症风险的儿童，如出生时异常早产、具有严重肺部疾病如支气管肺发育不良或先天性心脏病等，每月注射RSV抗体帕利珠单抗（Palivizumab）可以有效预防。
小结
Alright, as a quick recap, bronchiolitis is inflammation of the small airways that typically affects infants and young children. Inflamed airways along with atelectasis and air trapping due to mucus plugs can lead to difficulty breathing and hypoxia. Bronchiolitis is typically diagnosed clinically, and the treatment is supportive with supplemental oxygen and hydration.
最后做一个快速回顾，细支气管炎指细小气管产生炎症，通常影响婴儿和年幼的儿童。气管产生炎症，以及黏液栓导致的肺不张以及气体潴留会导致呼吸困难和缺氧症。细支气管炎通常通过临床诊断确诊，辅助治疗包括补充氧气和水分。
Meducal～本期医理闪充完结撒花～～转载的小伙伴注明出处哟喂～～
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