Pathophysiology 1 - Chapter 22/23

True or False: Obstructive lung diseases are manifested by increased resistance to airflow

True

What is asthma?

lung disease related to the wall of the lumen of airways

What is asthma characterized by?

• airway obstruction that is reversible (not completely in some patients)

• airway inflammation

• increased airway responsiveness to a variety of stimuli

*most common chronic disease of children, occurs in 7-14% of US population

Two types of asthma

• intrinsic

• extrinsic

Intrinsic asthma

non-allergic

• sometimes called adult-onset asthma

• develops in middle age with less favorable prognosis

• no history of allergies

• respiratory infections or psychological factors appear to be contibutory

• allergen-specific immunotherapy and environmental control are not helpful

Extrinsic asthma

allergic

• sometimes called pediatric-onset asthma

• 1/3 - ½ of asthma cases

• IgE-mediated response is common

• treated by pharmacologic therapy, allergen-specific immunotherapy, and environmental control

Other types of asthma

• exercise-induced asthma

• occupational asthma

• drug-induced asthma

• food additives can trigger asthma attacks

Immunohistopathologic features of asthma pathogenesis

• denudation of airway epithelium

• edema

• mast cell activation

• inflammatory cell infiltration by neutrophils, eosinophils, and lymphocytes

Inflammation of the airway for asthma

• acute bronchospasm

• mucosal edema, mucus plug formation

• airway wall remodeling: thickening of basement membrane

In asthma, normal respiratory epithelium is replaced by

goblet (mucus-producing) cells

Which immunoglobulin mediates extrinsic asthma most commonly?

IgE

Inflammatory mediators of asthma

• histamine

• leukotrienes (anaphylactic)

• cytokines (released by T cells)

Treatment of asthma

• avoid triggers

• environmental control

• preventive therapy

  • ex. stop smoking

• desensitization

  • allergen-specific immunotherapy

• medications

What is acute bronchitis?

Acute inflammation of the trachea and bronchi

Acute bronchitis etiology

• Viral (80% of cases)

  • ex. influenza A and B viruses, coronavirus

• non-viral (bacterial infections)

• heat

• smoke inhalation

• inhalation of irritant chemicals

• allergic reactions

Allergic bronchitis

Swelling of bronchial mucosa in children, associated with obstruction, respiratory distress, and wheezing

Distinct hallmark of bronchitis

recent onset of cough

Acute bronchitis can be distinguished from pneumonia by chest x-ray

bronchitis: normal chest x-ray

pneumonia: pulmonary infiltrates in chest x-ray

Pathogenesis of chronic bronchitis

chronic inflammation and swelling of the bronchial mucosa, resulting in scarring

• increased bronchial wall thickness

• pulmonary hypertension

Increased bronchial wall thickness in chronic bronchitis

• high airflow resistance increases work of breathing and O₂ demands

• alveoli fill more slowly resulting in a ventilation-perfusion mismatch which then causes hypoxemia and hypercarbia; increases pulmonary artery resistance

Pulmonary hypertension in chronic bronchitis

• inflammation in bronchial walls with vasoconstriction of pulmonary vessels and arteries

• right sided heart failure may occur due to high pulmonary resistance

Chronic Bronchitis medication

Inhaled short-acting B₂ agonists given to cause bronchodilation

Emphysema Etiology

• Destructive changes of the alveolar walls without fibrosis

• Abnormal enlargement of the distal air sacs

• Damage is irreversible

Emphysema lifestyle causes

• smoking

• pollution

• certain occupations

Emphysema pathogenesis

• release of proteolytic enzymes from neutrophils and macrophages leading to alveolar damage

• smoking causes alveolar damage

• reduction in pulmonary capillary bed

• loss of elastic tissue in lung

  • results in loss of radial traction

• air becomes trapped in distal alveoli

Bronciectasis

Obstruction of bronchi due to inflammation, infection, and dilation of the bronchial wall of medium sized bronchi and bronchioles

Bronchiectasis clinical manifestations

persistent, daily, chronic productive cough

• purulent, foul-smelling, green or yellow sputum

Bronchiolitis

Widespread inflammation of bronchioles as a result of infectious agents

Inflammation from bronchiolitis leads to

mucosal edema and excessive mucus production which can lead to airway obstruction

Cystic fibrosis

• autosomal recessive disorder of exocrine glands

• most common genetic lung disease

• abnormal, thick mucus obstructing exocrine glands and ducts

Croup syndrome etiology

a number of acute, viral, inflammatory diseases of larynx, trachea, and bronchi

• laryngotracheobronchitis (viral croup)

• bacterial tracheitis

Croup syndrome pathogenesis

• infectious agent causes inflammation along entire airway, leading to edema in subglottic area

Restrictive pulmonary diseases result from

decreased lung expansion

restrictive pulmonary disease classifications

• pulmonary

• extrapulmonary

Diffuse interstitial lung disease characterized by

thickening of alveolar intersitium

Diffuse interstitial lung disease pathogenesis

• begins as injury to alveolar epithelial or capillary endothelial cells

• persistant alveolitis leads to obliteration of alveolar capillaries, reorganization of lung parenchyma, irreversible fibrosis

diffuse interstitial lung disease other name

diffuse interstitial pulmonary fibrosis

diffuse interstitial pulmonary fibrosis three pathologic patterns

• inflammation

• fibrosis

• destruction

diffuse interstitial pulmonary fibrosis triggering events

• occupational exposure

• tobacco abuse

• drug ingestion

in diffuse interstitial pulmonary fibrosis, lung tissue becomes infiltrated by

lymphocytes, macrophages, and plasma B cells

Sarcoidosis

Restrictive disorder associated with abnormal protein deposits in the lung

Sarcoidosis etiology

• acute or chronic systemic disease of unknown cause

• immunologic basis is most likely cause

• First degree relative increases risk fivefold

Sarcoidosis pathogenesis

development of multiple, uniform, noncaseating epithelioid granulomas