How Chronic Bronchitis Affects the Lungs
Chronic bronchitis is a lung disease that causes a cough with increased mucus production for at least three months in two consecutive years.
It generally falls under the category of chronic obstructive pulmonary disease, or COPD.
The most common cause is cigarette smoking, although the inhalation of irritants at work, air pollution and lung infections may also cause it.
Considering most people develop this disease due to exposure to cigarette smoke, one might wonder: Why does smoking cause chronic bronchitis?
To best answer this question it's helpful to understand the basics of airway anatomy, which is covered in the pithy post "Your Journey Down the Respiratory Tract." Knowledge of lung anatomy is helpful because long-term exposure to inhaled cigarette smoke may cause changes inside the airways.
These changes may include:
1.
支气管粘液腺变大:
This causes increased mucus or secretion production inside the lungs.
2.
Goblet cells increase in number:
这也会导致粘液分泌增加。
3.
Bronchial walls become inflamed:
这是由于反复接触香烟烟雾中的有害化学物质。
这些化学物质会损伤细胞壁，而人体试图修复它们会导致细胞壁发炎或肿胀。
Common treatments for this are inhaled corticosteroids such as Qvar, Pulmicort, Advair, and Symbicort. Systemic corticosteroids are also sometimes needed.
4.
Bronchial walls become thick and scarred:
This is often referred to as airway remodeling.
It occurs when inflammation lasts for such a long time that the body tries to fix it.
这会导致疤痕组织，导致气道纤维化或僵硬。这种损伤是永久性的，没有治疗方法。
5.
支气管壁上的纤毛消失了：纤毛是细小的毛发状结构，起着自动扶梯的作用，将粘液带到上呼吸道，在那里粘液可能被吞咽、咳嗽或吐出。
由于缺乏纤毛，呼吸道很难将粘液转移到上呼吸道，导致粘液在肺部积聚。
6.
Mucus plugging in the smaller airways: This means that dried up secretions block air passages.
7.
支气管痉挛:
Inflamed airways are extra sensitive to certain triggers (such as inhaled irritants, allergens, and strong smells) that may cause flare-ups.
这可能会导致环绕呼吸道的肌肉痉挛。
在我最近的帖子“COPD发作原因”中讨论了发作
Treatment for this include albuterol (ventolin), levalbuterol (xopenex), ipatropium bromide (Atrovent), Duoneb, Combivent, theophylline, serevent, formoterol, Advair, and Symbicort.
8.
气道阻塞/狭窄: The combination of increased mucus, mucus plugging, scarring, inflammation, and bronchospasm cause air passages to become permanently narrowed and frequently obstructed.
Air traveling through narrowed or obstructed airways may cause a wheeze.
9.Air Trapping:
Air can get past an obstruction in the airway, but has a hard time getting out.
换句话说，患有这种疾病的人可能会觉得他们无法吸入空气，但事实是他们无法排出空气。这会导致呼气时间延长。
A good treatment technique for this is to exhale through pursed lips, thus allowing more time for trapped air to get out.
10.
肺气肿: Most people with chronic bronchitis also suffer from emphysema, which is the breakdown or destruction of lung tissue, which is probably also caused by inflammation. More specifically, it is the breakdown of the walls of the air sacs, or alveoli. This makes it so the lungs lose their ability to expand.
由于破裂，肺泡囊也可能与小气道分离，减少可进行气体交换的区域。
The treatment for emphysema is usually supportive, and often includes wearing oxygen.
11.
气流限制:
狭窄和阻塞的气道会增加气流阻力，从而减慢气流速度。这可能会导致呼吸困难或呼吸急促。
慢性支气管炎的气流受限是部分可逆的，这取决于病因：
Reversible:
Obstruction caused by increased mucus, inflammation and bronchospasmIrreversible: Obstruction caused by airway remodelling and emphysema
气流限制is best measured during pulmonary function testing, a test that can determine how severe your airflow limitation is, or how severe our COPD is.
12.
低氧血症:
由于上述疾病过程的结合，肺部会有氧气无法进入血液的区域。
这可能会导致血液中的低氧水平。
This makes it so the blood has less available oxygen to take to tissues, and so it takes it to vital organs before less vital areas of the body like fingertips and lips.
Common symptoms of this are dyspnea and cyanosis, or a blue tinge around the fingertips and lips. Treatment for this is wearing oxygen.
13.
高碳酸血症:
随着氧气进入血液的减少，离开血液进入肺部呼出的二氧化碳（CO2）也将减少。二氧化碳是肺部呼出的细胞代谢废物。如果不能到达肺部，二氧化碳就会在血液中积聚。
症状包括感到困倦和困惑。
It's important to note that not all of the above occur in every person with chronic bronchitis, which is kind of what makes this disease so complicated for physicians to understand and treat. Also, the progression of these disease processes are often so gradual that a person may not even notice them happening, especially in the early stages of the disease.
A neat thing about this disease, however, is that, while damage already done cannot be undone, quitting smoking will almost immediately slow down its progression.
It is for this reason most physicians recommend people diagnosed with it quit smoking immediately.
For tips on how to quit smoking check out "6 tips to help you quit smoking."
所以，现在你应该大致了解人们是如何发展成慢性支气管炎的，症状是什么，支气管炎是如何影响肺部的。
参考资料：
罗伯特·L·威尔金斯，詹姆斯·R·德克斯特，“呼吸系统疾病：原理与实践”，1993年，费城F.A.戴维斯公司
"Understanding Chronic Bronchitis," American Lung Association,http://www.lung.org/lung-disease/bronchitis-chronic/understanding-chronic-bronchitis.html, accessed 4/9/14
“什么是COPD？”国家心肺和血液研究所，https://www.nhlbi.nih.gov/health/health-topics/topics/copd/, accessed 4/9/14
Hanania，Nicola A.，Amir Sharafkhaneh，编辑，“COPD：诊断和临床管理指南”，2011年，纽约，伦敦，海德堡多德雷赫特斯普林格，
pages 2-5全球慢性阻塞性肺疾病倡议（GOLD），“慢性阻塞性肺疾病诊断、管理和预防全球战略”，2014年更新
