Post on 05-Apr-2018
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OBSTRUCTIVE
LUNG DISEASESROSHNI SANKARA
SUBRAMANIAN
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OBSTRUCTIVE DISEASES
Obstructive lung disease is a category ofrespiratory disease characterized byairwayobstruction
inflamed and easily collapsible airways
obstruction to airflow
problems exhaling
http://en.wikipedia.org/wiki/Respiratory_diseasehttp://en.wikipedia.org/wiki/Airway_obstructionhttp://en.wikipedia.org/wiki/Airway_obstructionhttp://en.wikipedia.org/wiki/Airway_obstructionhttp://en.wikipedia.org/wiki/Airway_obstructionhttp://en.wikipedia.org/wiki/Respiratory_disease7/31/2019 Rosh- Obstructive LD
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OBSTRUCTIVE DISEASES
In these diseases:
TLC and FVC are normal or slightly increased
Marked by decreased expiratory flow (FEV1) Ratio of FEV1 to FVC is decreased
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OBSTRUCTIVE CONDITIONS
Asthma
Emphysema
Chronic bronchitis Bronchiectasis
Bronchiolitis
COPD
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ASTHMA
Characterized by episodic, reversible
bronchospasm resulting from broncho
constriction in response to various stimuli
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ASTHMA
Triggers
Allergens
Exercise
Respiratory infections
Drugs and food additives
Nose and sinus problems
GERD
Emotional stress
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Inflammation causes obstruction of airways
by:
Acute bronchoconstriction
Swelling of bronchial wall
Chronic production of mucous
Remodeling of airways walls
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Two main processes are seen in thepathophysiology of asthma in the airways.
1. Inflammatory reaction
2. Remodeling
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Cells involved in chronic allergic
inflammation
1. Eosinophils
2. Mast cells
3. T-lymphocytes
4. Neutrophils 5. Basophils
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ASTHAMA- pathology
Early phase response: 30 60 minutes
Allergen or irritant activates mast cells
Inflammatory mediators are released
histamine, bradykinin, leukotrienes, prostaglandins, platelet-activating-factor, chemotactic factors, cytokines
Intense inflammation occurs
Bronchial smooth muscle constricts
Increased vasodilation and permeability Epithelial damage
Bronchospasm
Increased mucus secretion
Edema
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ASTHAMA- pathology
Late phase response: 5 6 hours
Characterized by inflammation
Eosinophils and neutrophils infiltrate
Mediators are released mast cells releasehistamine and additional mediators
Self-perpetuating cycle
Lymphocytes and monocytes invade as well
Future attacks may be worse because of increasedairway reactivity that results from late phase response Individual becomes hyperresponsive to specific allergens and
non-specific irritants such as cold air and dust
Specific triggers can be difficult to identify and less
stimulation is required to produce a reaction
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Airway remodeling
thickening of basement membrane
edema
size of submucosal glands
muscular hypertrophy
inflammatory infiltrate in bronchial walls
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Asthma: Early Clinical
Manifestations
Expiratory & inspiratory wheezing
Dry or moist non-productive cough
Chest tightness Dyspnea
Anxious &Agitated
Prolonged expiratory phase Increased respiratory & heart rate
Decreased PEFR
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Asthma: Early Clinical
Manifestations
Wheezing
Chest tightness
Dyspnea Cough
Prolonged expiratory phase [1:3 or 1:4]
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Asthma: Severe Clinical
Manifestations Hypoxia
Confusion
Increased heart rate & blood pressure
Respiratory rate up to 40/minute & pursed lipbreathing
Use of accessory muscles
Diaphoresis(excessive sweating) & pallor
Cyanotic nail beds
Flaring nostrils
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COPD
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Chronic Obstructive Pulmonary
Disease: COPD
Disease of airflow obstruction that is
not totally reversible
Chronic Bronchitis
Emphysema
Ch i B hi i
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Chronic Bronchitis Common in smokers (> 90%), passive
inhalation of smoke and smog-ridden cities
Definition: Based on clinical grounds.persistent productive cough for at least 3consecutive months and at least 2 consecutive
years Occurrence: (Increased mucus production)
a) simple chronic bronchitis
i) raises mucoid sputumii) airflow not obstructedb) chronic mucopurulent bronchitis
i) mucus and pusii from secondar infection
) h i th ti b hiti
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c) chronic asthmatic bronchitisi) bronchitis with intermittent
hypersensitivity and asthmatic
constriction (difficult to diagnosefrom atopic asthma)
d) chronic obstructive bronchitis
i) difficult outflow as measured bypulmonary function test
P th i
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Pathogenesis Hypersecretion of mucus
a) beginning in large airways
b) smoking single most important causativefactor
Increased transcription of mucin gene
(MUC5AC) by cigarette smokea) enlargement of mucus secreting glands
(major consequence)
b) hyperplasia and hypertrophy of mucussecreting cells and increase proportion ofmucus to serous secretions.
i) Reid index size of mucus glands
C h ith t l t i d fi it l
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Cough with sputum may last indefinitelywithout respiratory obstruction
usually accompanies emphysema
Some patients develop COPD withoutflow obstruction
a) hypercapnia
b) hypoxemiac) exertional dyspnead) cyanosisblue-bloaters
Progression of diseasea) pulmonary hypertension (Cor Pulmonale)b) cardiac failure
Metaplasia of bronchial epithelium
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2 E h
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2. Emphysema Permanent enlargement of airspaces
distal to terminal bronchioles and is
accompanied by destruction of theirwalls
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T f h
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Types of emphysemaa) Panacinar (panlobular) emphysema
i) uniformly enlarged acini
ii) lower lung zonesiii)1-antitrypsin definciency
b) Centrilacinar emphysemai) dilation upstream with normal distal
portions
ii) more common than panacinar (~95% of cases)iii) seen in heavy smokers, often in
association with chronic bronchitis
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c) Distal Acinar (paraseptal) emphysema
i) proximal acini normal and distal
part most involvedii) upper half of lungs/near pleura
d) irregular
i) acini irregularly involvedii) airspace enlargement with fibrosisiii) most are asymptomatic and not
clinically significant
Centriacinar and panacinar are the onesthat cause clinical airflow obstruction
Incidence
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IncidenceCentrilobular most common and severe in
men
Clear association with cigarette smoking2 Theories
i) protease-antiprotease imbalance
ii) oxidant-antioxidant imbalance
Protease antiprotease Hypothesis
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Protease-antiprotease Hypothesisa) patients with deficiency of antiprotease,1-antitrypsin (AAT) have increased
tendency to develop emphysemab) about 1% of all patients have this defectc)1-antitrypsin major inhibitor of
proteases, particularly elastased) homozygous patients with genetic AAT
deficiency develop emphysema
Sequence:
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Sequence:a) neutrophils (primary source of proteases)
sequestered in pulmonary capillaries
(lower zones primarily)i) smoking neutrophils &
macrophages
ii) CD8+ T cells cause directdamage and/or recruit macrophages
b) few gain access to alveolar space
c) release of proteolytic enzymes + ROS(reactive oxygen species)d) low levels of1-antitrypsin damage to
elastin (via elastase)e em h sema ensues
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Oxidant-antioxidant hypothesisLung has antioxidants
a) superoxide dismutaseb) glutathione
Smoke has many oxidant species which
deplete these normal scavengersa) activated neutrophils also has ROS Oxidative injury depletes or destroys
native antiproteasesa)Functional1- antitrypsin definciency
even though blood enzyme is notdeficient
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Signs:a)Barrelchested and dyspneicb) Hyperventilation
c) Normal blood gases (-pink puffers) Some patients have other pulmonary disease
a) do not hyperventilate and becomecyanotici)blue-bloaters (chronic bronchitis)
b) death from Right CHF, coma, acidosis,pulmonary fatigue
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Bronchiectasis
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Bronchiectasis Permanent dilation of bronchi and
bronchioles caused by destruction of the
muscle and elastic supporting tissueresulting or associated withchronic necrotizing infection.
Is not primary disease but secondary topersisting infection or obstruction causedby variety of conditions.
Cough and purulent sputum Irreversible Bronchial dilation
Most often caused by:
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Most often caused by:a) bronchial obstruction
i) tumors
ii) foreign bodiesiii) localized to obstructed lung
segment
b) congenital or hereditary conditioni) cystic fibrosisii) immunodeficiency states (IgE
deficiency) repeated infectionsiii) Kartagener syndrome (Structuralabnormalities of cilia (decreasedmucocilliary clearance)
- Sterilit in males/females
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c) necrotizing pneumonia (S. aureus, K.pneumoniae)
i) post tubercular bronchiectasissignificant cause of morbidity
B hi li i
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Bronchiolitis
Bronchiolitis is an acute inflammatory injury ofthe bronchioles that is usually caused by a viralinfection.
severe symptoms are usually only evident in
young infants
Bronchiolitis usually affects children youngerthan 2 years, with a peak in infants aged 3-6
months
Bronchioles are small airways, less than 2 mm indiameter, and lack cartilage and submucosal
glands
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Bronchiolitis is very contagious. The virus thatcauses it is spread from person to person bydirect contact with nasal secretions, airborne
droplets, and fomites.The effects of bronchiolar injury include the
following:
Increased mucus secretion Bronchial obstruction and constriction
Alveolar cell death, mucus debris, viral invasion
Bronchiolitis - Pathophysiology
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Air trapping
Atelectasis
Reduced ventilation that leads toventilation/perfusion mismatch
Labored breathing
Ninety percent of cases are caused by respiratorysyncytial virus (RSV)
Bronchiolitis - Pathophysiology
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Cough
Dyspnea
Wheezing Poor feeding
Hypothermia or hyperthermia
Wheezing Hypoxia
Nasal flaring
Bronchiolitis- signs & symptoms
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