1. Lecture 3

2. - At the other extreme of the clinical presentation in emphysema is a patient who also has pronounced chronic bronchitis
- Dyspnea usually is less prominent, with diminished respiratory drive, so the patient retains carbon dioxide, becomes hypoxic, and often is cyanotic.

3. - For reasons not entirely clear, such patients tend to be obese-hence the designation "blue bloaters.
- They seek medical help after the onset of CHF (cor pulmonale) and associated edema

4. Note :
- In all cases, secondary pulmonary hypertension develops arising from both hypoxia-induced pulmonary vascular spasm and loss of pulmonary capillaries
- Death from emphysema is related to either pulmonary failure, with respiratory acidosis, hypoxia, and coma, or right-sided heart failure (cor pulmonale).

5. Conditions Related to Emphysema
- Several conditions resemble emphysema only superficially but nevertheless are (inappropriately) referred to as such: I. Compensatory emphysema - Is a term used to designate the compensatory dilation of alveoli in response to loss of lung substance, such as occurs in residual lung parenchyma after surgical removal of a diseased lung or lobe.

6. - A common cause is subtotal obstruction by a tumor or foreign object.
II. Obstructive overinflation
- The condition in which the lung expands because air is trapped within it.
- A common cause is subtotal obstruction by a tumor or foreign object.
- Obstructive overinflation can be a life-threatening emergency if the affected portion extends sufficiently to compress the remaining normal lung.

7. III. Bullous emphysema - Refers to any form of emphysema that produces large subpleural blebs or bullae (spaces greater than 1 cm in diameter in the distended state).

8. and these blebs represent localized accentuations of any form of emphysema; most often the blebs are subpleural, and on occasion they may rupture, leading to pneumothorax

9. IV. Mediastinal (interstitial) emphysema
- Is the condition resulting when air enters the connective tissue stroma of the lung, mediastinum, and subcutaneous tissue.

10. Causes
1.Spontaneously with a sudden increase in intra-alveolar pressure (vomiting or violent coughing) in children with whooping cough
2. Occurs in patients on respirators who have partial bronchiolar obstruction
3. In persons who suffer a perforating injury (e.g., a fractured rib).

11. - When the interstitial air enters the subcutaneous tissue, the patient may blow up like a balloon, with marked swelling of the head and neck and crackling crepitation all over the chest. - In most instances, the air is resorbed spontaneously after the site of entry is sealed.

12. 2. Chronic Bronchitis
- Is common among cigarette smokers and urban dwellers - The diagnosis of chronic bronchitis is made on clinical grounds: - It is defined by the presence of a persistent productive cough for at least 3 consecutive months in at least 2 consecutive years.

13. Note
-In early stages of the disease, the productive cough raises mucoid sputum, but airflow is not obstructed.
- Some patients with chronic bronchitis may have hyper-responsive airways with intermittent bronchospasm and wheezing.

14. - A subset of bronchitic patients, especially heavy smokers, develop chronic outflow obstruction, usually with associated emphysema

15. PATHOGENESIS
- The distinctive feature of chronic bronchitis is hypersecretion of mucus, beginning in the large airways.
- Although the single most important cause is cigarette smoking, other air pollutants, such as sulfur dioxide and nitrogen dioxide, may contribute.

16. - These environmental irritants
a. Induce hypertrophy of mucous glands in the trachea and main bronchi,
b. Marked increase in mucin-secreting goblet cells in the surface epithelium of smaller bronchi and bronchioles.
C. Infiltration of CD8+ lymphocytes, neutrophils but no eosinophils

17. - It is postulated that many of the respiratory epithelial effects of environmental irritants (mucus hypersecretion) are mediated by local release of T- cell cytokines such as IL The transcription of the mucin gene MUC5AC in bronchial epithelium is a consequence of exposure to tobacco smoke.

18. Note
- The defining feature of chronic bronchitis (mucus hypersecretion) is primarily a reflection of large bronchial involvement
- The morphologic basis of airflow obstruction in chronic bronchitis is more peripheral and results from:

19. (1) Small airway disease –(chronic bronchiolitis) is induced by:
a. Goblet cell metaplasia with mucous plugging of the bronchiolar lumen,
b. Inflammation,
c. Bronchiolar wall fibrosis,
(2) Coexistent emphysema

20. .
Note
- Small airway disease ( chronic bronchiolitis) is an important component of early and relatively mild airflow obstruction,
- Significant airflow obstruction is almost always caused by emphysema - chronic bronchitis with

21. MORPHOLOGY Gross: - Hyperemia and swelling of the mucosal lining of the large airways. - The mucosa of bronchi is covered by a layer of mucinous or mucopurulent secretions

22. On histologic examination
- Enlargement of the mucus-secreting glands in trachea and large bronchi.
- The magnitude of the increase in size is assessed by the ratio of the thickness of the submucosal gland layer to that of the bronchial wall (the Reid index-normally 0.4).

23. - Inflammatory cells, largely mononuclear but sometimes admixed with neutrophils, are frequently present in variable density in the bronchial mucosa .

24. - Changes of emphysema often co-exist.
- It is the submucosal fibrosis that leads to luminal narrowing and airway obstruction.
- Changes of emphysema often co-exist

25. Clinical Features - In patients with chronic bronchitis, a prominent cough and the production of sputum may persist indefinitely without ventilatory dysfunction - Some patients develop significant COPD with outflow obstruction.

26. - This clinical syndrome is accompanied by hypercapnia, hypoxemia, and (in severe cases) cyanosis (hence the term "blue bloaters").
- With progression, chronic bronchitis is complicated by pulmonary hypertension and cardiac failure .
- Recurrent infections and respiratory failure are constant threats.