1. Diseases of Respiratory System
Dr. Faten Ghazal
Prof. of Pathology, Ain Shams University
Lecture 4
Emphysema
Lung Collapse

2. By the end of this lecture you will able to :
Define emphysema and describe its different types.
Explain the pathogenesis of emphysema.
Describe the pathologic features of emphysema, recognize its clinical picture & list its complications .
Describe the conditions that mimic emphysema.
Define lung collapse & describe its different types.
List the main characteristics of obstruction collapse
Give reasons :1.The centriacinar emphysema occurring in smokers is more common in the upper lobe , while the panacinar emphysema occurring in alpha1 deficient individuals is more common in lower lobe Early treatment of lung collapse is essential.

3. Pulmonary Emphysema

4. LUNG DISEASES
To remind you, emphysema is one of the major diffuse obstructive diseases, which include as well chronic bronchitis, bronchial asthma, & bronchiectasis. In these patients there is limitation of maximal airflow rates during forced expiration (increased resistance to airflow).
Expiratory airflow obstruction may result from airway narrowing as in asthma or from loss of elastic recoil which characteristically occurs in emphysema.

5. Diffuse pulmonary diseases can be classified into 2 categories
LUNG DISEASES
Diffuse pulmonary diseases can be classified into 2 categories
Obstructive Disease
It is ch.ch. by increased resistance to airflow due to partial or complete obstruction .
The major obstructive diseases after excluding tumors & inhalation of foreign body are:
Bronchial Asthma (anatomic airway narrowing)
Emphysema (loss of elastic recoil)
Chronic bronchitis (both 2&3 are called COPD)
Bronchiectasis
Cystitis fibrosis
Bronchiolitis
Restrictive Disease
It is ch.ch. by reduced expansion of lung parenchyma with decreased total lung capacity.
The restrictive diseases occur in 2 conditions:
Acute and chronic interstitial lung diseases e.g. acute respiratory distress syndrome and chronic diseases as pneumoconiosis, sarcoidosis & idiopathic pulmonary fibrosis.
Extra pulmonary disorders e.g. obesity, poliomyelitis, pleural diseases and kyphoscoliosis.

6. containing 3-5 terminal bronchioles & 3-5 respiratory acini
Pulmonary Emphysema
Normal Anatomy
The cut surface of a normally distended lung shows hexagonal areas of parenchyma, each 1-2cm. in diameter, outlined by thin fibrous septa. Each hexagonal area is called a lung lobule containing lung tissue supplied by 3-5 terminal bronchioles followed by 3-5 respiratory acini (including respiratory bronchioles, alveolar ducts & alveolar sacs).
Normal Lung
Lung Lobule
containing 3-5 terminal bronchioles & 3-5 respiratory acini

7. Lung Lobule =3 - 5 Respiratory Acini Terminal bronchiole
Respiratory bronchiole
Alveolar duct
Alveoli
Respiratory Acinus

8. Pulmonary Emphysema
Microanatomy: The acinus is the part of the lung distal to the terminal bronchiole and includes respiratory bronchiole, alveolar ducts and alveoli.

9. Pulmonary Emphysema

10. Pulmonary Emphysema
Definition: It is characterized by permanent enlargement of airspaces distal to the terminal bronchiole (respiratory bronchioles, alveolar ducts & alveoli) accompanied by destruction of their walls.
N.B. There are several conditions in which enlargement of air spaces is
not accompanied by destruction; this is more correctly termed as over inflation.

11. Classification of Emphysema
Emphysema is classified according to its anatomic classification within the lobule (cluster of acini , the alveolated respiratory units).
There are 4 major types: centriacinar, 2.panacinar, 3.paraseptal , and 4. irregular. Of these, only the first two cause clinically significant obstruction. N.B. Centriacinar is far more common than panacinar form, constituting more than 95% of cases

12. 1.Centrilobular (Centriacinar) Emphysema
Types of Emphysema
1.Centrilobular (Centriacinar) Emphysema
There is enlargement of the respiratory bronchiole (central or proximal part) while the distal alveoli are spared (normal). Thus both emphysematous & normal airspaces exist in the same acinus and lobule. It is common in the upper lobes & associated with smoking.

13. 1.Centrilobular (Centriacinar) Emphysema Respiratory bronchiole
Alveolar duct
Respiratory bronchiole
Alveoli

14. 2.Panlobular (Panacinar) Emphysema
There is enlargement of all the acinus including respiratory bronchiole, alveolar ducts, and alveoli.
It is more common in the lower lobes and in the anterior margins of the lung, & usually more severe in the base.
It is associated with alpha 1 antitrypsin deficiency.
The prefix pan refers to the entire acinus & not the entire lung.

15. 2.Panlobular (Panacinar) Emphysema

16. In severe cases of centriacinar emphysema the distal acinus becomes involved thus the distinction from panacinar emphysema becomes difficult.

17. 3.Distal Acinar (paraseptal) Emphysema
The proximal portion of the acinus (respiratory bronchiole) is normal but the distal part is enlarged (alveolar duct & alveoli). The emphysema is more striking adjacent to the pleura (can produce spontaneous pneumothorax in young adults), along the lobular connective tissue septa, at the margins of the lobules. It occurs in the upper half, near areas of fibrosis , scarring or atelectasis.

18. 3.Distal Acinar (paraseptal) Emphysema Alveolar ducts & alveoli

19. 4. Irregular Emphysema (Airspace Enlargement with Fibrosis)
Irregular emphysema is so named because the acinus is irregularly involved. It is associated with scarring & fibrosis from a healed inflammatory process.
In most instances these foci of emphysema are asymptomatic (apparently healthy individuals) and clinically insignificant.

20. What is the pathogenesis of emphysema?

21. Pathogenesis of Emphysema
2 critical imbalances:
A. protease – antiprotease) B. (Oxidant – antioxidant)
Alpha 1 antitrypsin is synthesized by liver, present in serum, tissue fluid & macrophages) has antiprotease activity (inhibits elastolytic activity)
Protease is secreted by neutrophils and macrophages ( it has elastolytic activity)
O free radical inhibits the function of the alpha 1 antitrypsin ( it is present in smoke & can be secreted by activated neutrophils)

22. Pathogenesis of Emphysema
If alpha 1 antitrypsin is decreased (deficiency or functional deficiency by O free radical) or
If protease is increased by inflammation (chronic bronchitis) or smoking (chemoattraction of N & M)
Imbalance results & destruction occurs

23. B. Oxidant – Antioxidant Imbalance
Normally the lung contains antioxidants.
Tobacco smoke contains abundant reactive oxygen species (free radical).
Activated neutrophils also secrete reactive O free radical which in addition to its oxidative damage results in inactivation of antiprotease, i.e. functional deficiency.
This results in oxidative damage.

24. Pathogenesis of Emphysema
Normally neutrophils are present in capillaries including those of lung and few pass into the alveoli (more in the lower zones than in the upper).
Any stimulus that increases the no. of neutrophils and macrophages in the lung
Increased protease (elastase) & as well O2 free radical (inhibit alpha 1 activity)
low levels of alpha 1 antitrypsin by deficiency or functional deficiency
with
Unchecked tissue destruction
Emphysema

25. Pathogenesis of Emphysema
In smokers: Tobacco
Pathogenesis of Emphysema
*Alveolar macrophage secretes macrophage elastase& other proteases
Tobacco
Nicotine
Reactive O2 free radical
Chemoattraction of neutrophils from the capillaries to the respiratory acinus
Inactivation of anti -protease (functional deficiency)=oxidative inactivation
Tissue destruction
Neutrophil elastase & other proteases
Increase no. of neutrophils

26. Pathogenesis of Emphysema
Smoke particles are impacted at respiratory bronchiole result in increased influx of neutrophils & macrophages both of which secrete proteases
Smoke-induced oxidative damage (O free radical) results in functional deficiency of alpha antitrypsin
This results in uncontrolled proteolysis & destruction of elastic tissue in centriacinar region.

27. Pathogenesis of Emphysema
In alpha 1 antitrypsin deficiency there is panacinar emphysema reflecting the decrease in alpha 1 antitrypsin through the whole acinus = panacinus This type of emphysema is present in lower lobes because more neutrophils are brought to the lower zones due to greater perfusion by gravity with increased proteases.
Finally, some consider the upper lobe distribution of centriacinar emphysema also reflects the relative lack of the normal serum alpha1antitrypsin delivery to this less perfused region in addition to increased N & M by smoke (nicotine, tobacco & O2 free radical) .

28. 1. Why emphysema in smokers is centriacinar & 2
1. Why emphysema in smokers is centriacinar & 2. why more in upper lobes?
1. Due to impaction of smoke particles at the respiratory bronchioles with subsequent attraction of neutrophils & macrophages thus more protease production & more destruction at this region in addition the O free radical causes functional inactivation of normal alpha 1 antitrypsin.
2. The upper lobes are less perfused by blood thus there is a relative lack of antitrypsin (antiprotease) brought to this area.

29. 1. Why emphysema in alpha 1 antitrypsin deficient patients is panacinar & 2. why more in lower lobes?
1. In alpha 1 antitrypsin deficiency there is panacinar emphysema reflecting the decrease in alpha 1 antitrypsin through the whole acinus = panacinus This type of emphysema is present in lower lobes because more neutrophils are brought to the lower zones due to greater perfusion by gravity which results in increased proteases.

30. What are the pathological features of emphysema?

31. Emphysema

32. Emphysema
Microscopically: There is thinning and destruction of alveolar walls.
The adjacent alveoli become confluent creating large air spaces.
Fibrosis and chronic inflammation around bronchioles occur with the loss of elastic tissue in the surrounding alveolar septa in cases associated with chronic bronchitis.

33. Emphysema & Chronic Bronchitis

34. What is the clinical picture?

35. Emphysema (Pink Puffer) Chronic Bronchitis (Blue Bloater)
The clinical manifestations do not appear until at least one third of the lung parenchyma is damaged.
Progressive dyspnea but cough is often slight
Hyperventilation occurs with the result of well oxygenation
Hyperinflation of lung with small heart
Massive lung collapse due to rupture of emphysematous bullae leading to pneumothorax
Chronic Bronchitis (Blue Bloater)
Cough with expectoration of large amount of sputum
Cyanosis, hypercapnea (CO2) and hypoxemia (leading to polycythaemia)
Pulmonary hypertension and later corpulmonale

36. Clinical changes seen in emphysema:
Prominent sternoclavicular muscles due to increase use of accessory muscles of respiration.
Shoulders are held high.
Barrel shaped chest and ribs are almost horizontal.
Liver dullness is reduced due to downward displacement of diaphragm.
The heart is covered by lungs.

37. What are other conditions related to Emphysema?

38. Conditions related to Emphysema
Compensatory emphysema refers to compensatory dilatation of air spaces in response to loss of lung substance better to be called compensatory over inflation. e.g. after lobectomy
Senile Emphysema refers to over distended lungs of elders, resulting from age related changes (large alveolar ducts & small alveoli) but there is no tissue destruction/ Senile over inflation.

39. Conditions related to Emphysema
3. Obstructive Over inflation refers to expansion of the lung due to trapped air resulting from partial obstruction by a tumor or foreign body.
4. Mediastinal, interstitial, or subcutaneous Emphysema refers to air entering in connective tissue septa of the lung, mediastinum ,and subcutaneous tissue.
It may occur : 1. due to sudden increase in intra alveolar pressure e.g. with vomiting or violent coughing or 2. due to lung injury by fractured rib or perforating wound.

40. Mediastinal & subcutaneous (interstitial) Emphysema
Root of the neck
Mediastinal & subcutaneous (interstitial) Emphysema
Fractured clavicle
Interstitial subcutaneous emphysema (subcutaneous crepitation)

41. Lung Collapse (Atelectasis)

42. Lung Collapse (Atelectasis)
Atelectasis refers either to incomplete expansion of the lungs (neonatal atelectasis) or to the collapse of previously inflated lung, producing areas of relatively airless pulmonary parenchyma.

43. Lung Collapse (Atelectasis)
Definition: It is the loss of lung volume caused by inadequate expansion of air spaces.
It is associated with shunting of inadequately oxygenated blood from pulmonary arteries to veins, resulting in ventilation perfusion imbalance & hypoxia.
On the basis of underlying mechanism or the distribution of alveolar collapse it is divided into 3 categories: 1. compression collapse, absorption collapse & 3. contraction collapse.

44. Lung Collapse (Atelectasis)
1. Compression Collapse
It occurs as result of accumulation of air, fluid or blood in the pleural cavity, leading to pressure on the lung & collapse. The mediastinum shifts away of affected lung
Pathogenesis: Bronchial secretions will be drained since there is no obstruction. (infection is late-if untreated)
Fate :In pleural effusion or haemothorax, organization & fibrosis of the pleura prevents re expansion.
So drainage of the pleura is important to allow re expansion.

45. Lung Collapse (Atelectasis)
1. Compression Collapse

46. Left Pneumothorax & Lt. Lung Collapse
The mediastinum is shifted away from the affected lung (the air in the pleural cavity collapsed the lt. lung & pushed it & the mediastinum to the other side, i.e. normal rt side)

47. Rt is Normal, the mediastinum is shifted to the rt.
1. Compression Collapse
Left pleural effusion: The mediastinum is shifted away from the collapsed side (Left side)
Rt is Normal, the mediastinum is shifted to the rt.

48. 2.Resorption( Absorption )Collapse
It occurs when bronchial obstruction prevents air from reaching distal air spaces. The mediastinum is shifted toward the affected lung.
Acute complete obstruction by: 1.foreign body (children), mucus or mucopurulent plug (chronic bronchitis or bronchiectasis) or 3.blood clots during surgery.
Chronic obstruction by 1.tumors in bronchial wall or pressure on the wall 2.from outside by enlarged hilar L.N. or an aneurysm.
Pathogenesis: After obstruction collateral air ventilation may keep the obstructed segment for a time. Later air is replaced by secretions which may lead to infection.

49. 2. Right Resorption( Absorption )Collapse
The mediastinum is shifted towards the right diseased & collapsed lung

50. 2. Left Resorption( Absorption )Collapse
The mediastinum is shifted towards the left diseased & collapsed lung

51. Lt. tension pneumothorax caused lt. .lung compression collapse
Compare
Lt. tension pneumothorax caused lt. .lung compression collapse
Lt. lung absorption collapse due to obstruction of lt. bronchus
Compressed the same side of lung & shifted the mediastinum to the other side
The air is absorbed on the same side & shifted to diseased lung

52. Rt. pleural effusion Lt. lung collapse
Compare
Rt. pleural effusion
Lt. lung collapse
Compression Collapse
Absorption Collapse
© Vascular 2007

53. 3.Contraction Collapse (Atelectasis)
It occurs when either local or generalized fibrotic changes in the lung or pleura prevent lung expansion & increase elastic recoil during expiration.
N.B.
Significant collapse reduces oxygenation (hypoxemia) and predisposes to infection (bronchitis, bronchiolitis & bronchiectasis). Since lung collapse is a reversible disorder (except that caused by contraction), thus early treatment of the cause is essential to allow re expansion of the collapsed lung.

54. What are the pathologic features of lung collapse?

55. Lung Collapse (Atelectasis)
Gross
Pleural surfaces are wrinkled.
The affected lobe is airless, sinks in water & is purple in colour (bluish red) due to reduced haemoglobin.
Mcs
Slit like opening of the alveoli & pulmonary arterioles are constricted.
If not treated: proliferation of pneumocytes occur, progressive pulmonary fibrosis & intimal fibroelastosis of pulmonary arterioles

56. Acute Massive Lung Collapse
It affects one or both lungs
Causes:
Chest wall injuries due to extensive pneumothorax or haemopneumothorax
Surgical operations due to bronchial obstruction by mucus plug
Abnormal elevation of diaphragm as in severe peritonitis & subdiaphragmatic abscess
May follow the use of lipidol in bronchography

57. Complete the following statements by specifying the type of emphysema
………………… occurs in apparently healthy persons, in upper half , subpleural in position and is usually asymptomatic unless pneumothorax develops.
…………………occurs mainly in lower half & is associated with alpha 1 antitrypsin deficiency.
………………….occurs in residual lung after lobectomy.
……………….. may occur due to vigorous coughing in a child suffering of whooping cough.
…………………..occurs most commonly in smokers.
……………………is usually asymptomatic, discovered accidentally & is associated with scarring.
……………………occurs due to diminished elastic recoil in elderly persons.

58. By the end of this lecture you will able to :
Define emphysema and describe its different types.
Explain the pathogenesis of emphysema.
Describe the pathologic features of emphysema, recognize its clinical picture & list its complications .
Describe the conditions that mimic emphysema.
Define lung collapse & describe its different types.
List the main characteristics of obstruction collapse
Give reasons :1.The centriacinar emphysema occurring in smokers is more common in the upper lobe , while the panacinar emphysema occurring in alpha1 deficient individuals is more common in lower lobe Early treatment of lung collapse is essential.