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Obstructive Lung Diseases

Is Irreversible Dilation of Bronchi Caused by Destruction of Bronchial Wall Muscle and Elastic Elements.
  1. Bronchiectasis may be obstructive or nonobstructive. Obstructive bronchiectasis is localized to a segment of the lung distal to a mechanical obstruction of a central bronchus by a variety of lesions, including tumors, inhaled foreign bodies, mucous plugs in asthma, and compressive lymphadenopathy. Q
  2. Nonobstructive bronchiectasis is usually a complication of respiratory infections.
  3. The acquired disorders that predispose to bronchiectasis include: Q
  1. Neurologic diseases that impair consciousness, swallowing, respiratory excursions, and the cough reflex;
  2. Incompetence of the lower esophageal sphincter;
  3. Nasogastric intubation; and
  4. Chronic bronchitis.
Kartagener Syndrome:
  1. It is one of the immotile cilia (ciliary dyskinesia) syndromes and comprises the triad of dextrocardia (with or without situs inversus), bronchiectasis, and sinusitis.
  2. Cilia are deficient throughout the body. Q
  3. Both men and women are sterile.
  4. Repeated upper and lower respiratory tract infections in the lung and, thus, to bronchiectasis.
  1. Generalized bronchiectasis is usually bilateral and is most common in the lower lobes, the left more commonly involved than the right.
  2. Bronchial lumens frequently contain thick, mucopurulent secretions.
  3. Microscopically, severe inflammation of bronchi and bronchioles results in destruction of all components of the bronchial wall.
Clinical features:
  1. Chronic productive cough
  2. Hemoptysis is common, Q
  3. Dyspnea and wheezing are variable.
  4. Pneumonia is a common complication.
  5. The definitive diagnosis is made by CT scans of the lung.  Q
Chronic bronchitis
  1. Primarily a disease of cigarette smokers, 90% of cases occur in smokers. Q
  2. The frequency and severity of acute respiratory tract infections are increased in patients with chronic bronchitis; conversely.
  1. Two types of cells line the mucous glands: pale mucous cells, (which are more common) and serous cells.
  2. Chronic bronchitis is characterized by hyperplasia and hypertrophy of the mucous cells and an increased ratio of mucous to serous cells. Q
  3. The Reid index is a measure of the increase in the size of the mucous glands. Q
  4. A normal Reid index is 0.4 or less; in chronic bronchitis it is more than 0.5.
Other morphologic changes in chronic bronchitis are variable and include:
  1. Thickening of the bronchial wall by mucous gland enlargement and edema
    An increase in the number of goblet cells (hyperplasia) in the bronchial epithelium.
  2. Increased smooth muscle
  3. Squamous metaplasia of the bronchial epithelium.
  1. Clinical features:
  1. Chronic bronchitis is often accompanied by emphysema.
  2. Patients with predominantly chronic bronchitis have had a productive cough for many years.
  3. Exertional dyspnea and cyanosis supervene, and cor pulmonale may ensue.
  4. Acute respiratory failure in patients with advanced chronic bronchitis,
  5. Increased risk for bacterial infections of the lung, particularly with Haemophilus influenzae and Streptococcus pneumoniae. Q
Emphysema is a chronic lung disease characterized by enlargement of airspaces distal to the terminal bronchioles, with destruction of their walls but without fibrosis.

Figure - Pathogenesis of emphysema. The protease-antiprotease imbalance and oxidant-antioxidant imbalance are additive in their effects and contribute to tissue damage. α1-antitrypsin (α1-AT) deficiency can be either congenital or "functional" as a result of oxidative inactivation.

  1. The major cause of emphysema is cigarette smoking.
  2. A balance exists between elastin synthesis and catabolism in the lung.  Q
  3. Emphysema results when elastolytic activity increases or antielastolytic activity is reduced.
  4. Increased numbers of neutrophils are found in the bronchoalveolar lavage fluid of smokers. Q
  5. Smoking also interferes with alpha 1 antitrypsin activity.
  6. Unopposed and increased elastolytic activity leads to destruction of elastic tissue in the walls of distal airspaces, thereby impairing elastic recoil. Q
Alpha 1 At Deficiency:
  1. More common in young persons with severe emphysema.
  2. A circulating glycoprotein produced in the liver, a major inhibitor of a variety of proteases, including elastase, trypsin, chymotrypsin, thrombin, and bacterial proteases.
  3. In the lung, its most important action to inhibit neutrophil elastase.
  4. The amount and type of alpha 1 AT is determined by a pair of codominant alleles, referred to as Pi (protease inhibitor). Q
  5. The most common genotype, PiM.
  6. The most serious abnormality is associated with the PiZ allele. PiZZ homozygotes have only 15% to 20% of the normal plasma concentration of alpha 1 AT. These persons are at risk for both cirrhosis of the liver and emphysema. Q
  1. Emphysema is morphologically classified according to the location of the lesions within the pulmonary acinus.
  2. The proximal part of the acinus (respiratory bronchiole) is selectively involved in centrilobular emphysema, whereas the entire acinus is destroyed in panacinar emphysema.
Centrilobular Emphysema:
  1. This form of emphysema is most frequent and is usually associated with cigarette smoking.
  2. Characterized by destruction of the cluster of terminal bronchioles near the end of the bronchiolar tree in the central part of the pulmonary lobule.
  3. Dilated respiratory bronchioles form enlarged airspaces that are separated from each other and from the lobular septa by normal alveolar ducts and alveoli. Q
  4. Centrilobular emphysema is most severe in the upper zones of the lung, the upper lobe, and the superior segment of the lower lobe.
Panacinar Emphysema
  1. The acinus is uniformly involved, with destruction of the alveolar septa from the center to the periphery of the acinus.
  2. It is typically associated with alpha 1 AT deficiency.
  3. The panacinar pattern tends to occur in the lower zones of the lung, whereas centrilobular emphysema is seen in the upper regions.
Localized Emphysema:
  1. This condition, previously known as paraseptal emphysema is characterized by destruction of alveoli and resulting emphysema in only one or at most a few locations. Q
  2. It is usually found at the apex of an upper lobe rupture of an area of localized emphysema produces spontaneous pneumothorax . Q
  3. Can result in a large area of destruction, termed a bulla.
Clinical Features
  1. Most patients are seen at age 60 years or older with a prolonged history of exertional dyspnea but a minimal, nonproductive cough.
  2. They have lost weight. Tachypnea and a prolonged expiratory phase are typical. Q
  3. The most prominent radiologic abnormality is overinflation of the lung.
  4. These patients have a higher respiratory rate, they can maintain arterial hemoglobin saturation at near-normal levels and so are called pink puffers. 

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