ICL 3.1: Pathology of Obstructive Lung Diseases Flashcards
how many lobes do the lungs have?
right = 3
left = 2
describe the left and right bronchus?
right bronchus is slight shorter than the left
right bronchus arises a little proximally and at a steeper angle than the left
what type of cells are in the trachea/bronchi?
pseudostratified columnar, ciliated epithelial cells
there’s submuscoasl glands and cartilage too
bronchioles lack cartilage and submucosal glands; the smaller bronchioles are lined by conciliated clara cells
what is the conducting portion of the respiratory system?
conducting = trachea –> terminal bronchiole
respiratory = acinus
what is the acinus?
the terminal respiratory unit that consists of the respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli
a lobule consists of 3-5 terminal bronchioles with associated acini
in emphysema, this is what’s effected!
what is the structure of an alveolus?
- capillaries lined by endothelial cells
- in the alveolus itself, there’s type i and II pneumocytes
type I cover 95% of the alveolus and the function for gas exchange
type II are only 5% but they synthesize surfactant and they can divide and become type I pneumocytes if there’s injury
- alveolar macrophages = dust cells –> can become heart failure cells when they phagocytose hemocydrin
- supporting tissue rich in elastin
what are obstructive pulmonary diseases?
a group of diseases characterized by an increase in the resistance to airflow due to partial or complete obstruction at any level of the tracheobronchial tree
there’s a blockage of air going in and out!
what are the common features of obstructive pulmonary diseases?
- dyspnea
- chronic or recurrent obstruction to airflow within the lung
- limitation of maximal airflow rates during forced expiration (FEV1/FVC < 0.8)
which diseases are entailed when you’re talking about COPD?
- emphysema
- bronchitis
COPD is the 4th major cause of morbidity and mortally in the USA
asthma may also be a component of COPD but it’s only transient; emphysema and bronchitis are irreversible
what is the anatomic site, major pathologic changes, etiology and signs/symptoms of chronic bronchitis?
anatomic site = bronchus
pathologic changes = submucousal gland hyperplasia and hyper-secretion
etiology = tobacco smoke, air pollutants
symptoms = productive cough, sputum production
what is the anatomic site, major pathologic changes, etiology and signs/symptoms of bronchiectasis?
anatomic site = bronchus
pathologic changes = airway dilation and scarring
etiology = persistent or severe infections
symptoms = productive cough with purulent sputum, fever
what is the anatomic site, major pathologic changes, etiology and signs/symptoms of asthma?
anatomic site = bronchus
pathologic changes = smooth muscle hyperplasia, excess mucus, goblet cell hyperplasia, inflammation
etiology = immunological or undefined causes
symptoms = episodic wheezing, cough, dyspnea
what does wheezing vs crackles signify?
if you hear wheezing, think of bronchiole diseases
if you hear crackles/bubble sounds, think of alveolar problems
what is the anatomic site, major pathologic changes, etiology and signs/symptoms of emphysema?
anatomic site = acinus
pathologic changes = airspace enlargement, wall destruction*
etiology = tobacco smoke
symptoms = dyspnea
what is the anatomic site, major pathologic changes, etiology and signs/symptoms of small-airway disease/bronchiolitis?
anatomic site = bronchiole
pathologic changes = inflammatory scarring/obliteration
etiology = tobacco smoke, air pollutants, miscellaneous
symptoms = cough, dyspnea
what is asthma?
bronchial hyper-responsiveness triggered by allergens, infection, etc.
reversible obstruction that’s type I hypersensitivity mediated
54 year old male present with productive cough for 5 months and has been a smoker since 14. his cough is associated with SOB and a year ago he was treated for pneumonia even though cultures were negative. PE shows bilateral wheezes in the chest
diagnosis?
chronic bronchitis caused by chronic irritation from smoking
dyspnea + productive cough that lasts 5 months = chronic bronchitis
mucous caused superimposed pneumonia infection
wheezes = bronchiole disease
what is the required clinical criteria to diagnose chronic bronchitis?
- persistent cough with sputum production
- present for at least 3 months per year
- present for at least 2 consecutive years
- in the absence of any other identifiable cause
what is the pathogenesis of chronic bronchitis?
chronic irritation by inhaled substances (smoking)
microbiologic infections trigger acute exacerbation and maintain chronic bronchitis
most frequent in middle-aged male smokers
what are the morphologic changes in chronic bronchitis?
- mucous hypersecretion in large airways
- hypertrophy and hyperplasia of submucosal glands
this results in extra mucous produced in cough which is reported via the Reid index
- hyperplasia of goblet cells in bronchi and bronchioles
- variable degree of chronic inflammation and fibrosis – bronchiolitis obliterans
- squamous metaplasia and dysplasia
what is the Reid index?
thickness of submucous gland layer/thickness of the wall between epithelium and cartilage
normally the Reid index is 0.4 but with chronic bronchitis there’s an increase in the Reid index because there’s metaplasia of the submucosal goblet cells
what are the clinical features of chronic bronchitis?
- initial cough with productive sputum
- later dyspnea on exertion
- hypoxemia, mild cyanosis
- cor pulmonale with heart failure = JVD, peripheral edema, ascites, hepatomegaly
what is the hallmark name for patients with chronic bronchitis?
low pO2 = cyanosis = blue bloaters!
65 year old male with severe SOB for the last several months. smoker for 50 years. PE reveals a barrel chest. CXR reveals a flat diaphragm.
diagnosis?
emphysema
no mucous or cough, just SOB
flat diaphragm and barrel chest = lungs are over-inflated
what is the required morphologic criteria needed to diagnose emphysema?
- abnormal permanent airspace enlargement
- involvement distal to terminal bronchiole
- airspace wall destruction**
- lack of significant interstitial fibrosis
what is the incidence of emphysema?
more common and severe in males
clear association with cigarette smoking
generally does not become disabling until the 4th-7th decades but ventilatory deficits may make their first appearance decades earlier
how is emphysema classified?
it’s based on the anatomic distribution of the damage in the lobule
- centriacinar = proximal acinar is involved
- panacinar = the whole acinar is involved
- paraseptal = subpleural and upper half of the lungs is involved
which types of emphysema are the most common?
centrilobular accounts for > 95% of the cases
clinically significant airway obstruction is seen in both centriacinar and panacinar emphysema
what is centriacinar emphysema?
it starts in the respiratory bronchioles and destroys the central (proximal) parts of the acinus
both emphysematous and normal areas exist in the same acinus and lobule
predominately involves the upper lobes; especially apical segments
it’s more frequent in heavy smokers so it’s often seen in associated with chronic bronchitis
what is paniacinar emphysema?
associated with alpha-antitrypsin deficiency which normally inhibits proteases that break down elastin in the walls of the alveoli
more common in lower lobes and in the anterior margins of the lungs so it’s most severe in the lung bases –> it’s most common in the bases because that’s where there’s the most blood flow and the blood is what brings in all the inflammatory cells and neutrophils are sequestered in the lungs in the lower lobes and they release elastase!
it affects the ENTIRE acinus but there’s initial involvement of the peripheral alveoli and alveolar ducts
compare and contract centriacinar and panacinar emphysema
centiracinar
1. upper lobes
- cigarette smoking
- involves the central portion of the acinus
panacinar
1. lower lobes
- alpha antitrypsin deficiency
- involves the entire acinus
what is the pathogenesis of emphysema?
protease-antiprotenase theory
proteases are enzymes that digest proteins
alveolar wall destruction results from an imbalance of elastase, a protease, and alpha-antitrypsin, an antiprotenase
how does centriacinar emphysema happen?
smoke particles impact in small bronchi and bronchioles and form ROS that inactivate antiproteases while increasing inflammatory cytokines
then an influx of neutrophils and macrophages which leads to increased elastase
more common in the upper lobe because it’s less perfusion and there’s less α1-AT and smoke rises
how does panacinar emphysema happen?
α1-AT deficiency throughout acinus
neutrophils are normally sequestered in lungs, more in lower than upper lobe – neutrophils release elastase! so that’s why there’s more damage in the lower lobes with apnacinar emphysema
more common in the lower lobe – more perfusion
what are the clinical features of emphysema?
dyspnea is the initial symptom –> symptoms appear when at least 1/3 of the parenchyma is effected
not too much cough or sputum; you’ll only see it if there’s accompanying chronic bronchitis
when there’s severe emphysema, you’ll see marked inflation of the lungs, barrel chest, and flattened diaphragm
you’ll also see weight loss because of how hard it is to breath and enlargement of accessory muscles of respiration
what causes death in emphysema?
- respiratory acidosis and coma
- right sided heart failure
- massive lung collapse second to pneumothorax
some of the expanded alveoli can rupture and release air into the pleura
what is the hallmark name for people with emphysema? what are the hallmark signs of emphysema?
pink puffers
they have dyspnea because of the low pressure during expiration that will cause their lungs to collapse without elastin; so they pinch their nose and purse their lips and sit forward to try and increase the pressure in their lungs so that their bronchioles don’t collapse as much and this is where they get the name pink puffers!
they have to use accessory muscles of respiration to do this (so check for their enlargement) and they have prolonged, forced expiration so they lose a ton of weight because of how hard it is to breathe
oxygen saturation is maintained at near normal levels from over inflation of the lungs so they’re not cyanotic, they remain pink
36 year old female with jaundice and SOB for 6 months. her material aunt died at the age of 45 from hepatic failure.
diagnosis?
alpha1-antitrypsin deficiency
the alpha1 produced in the liver can’t leave the liver so it destroys hepatocytes and you get cirrhosis on top of the emphysema