Lung disease has huge implications. Respiratory tract infections are common, and smoking air pollution, and environmental chemicals have led to huge increases in COPD rates. Lung cancer is the biggest malignant killer. Lungs are also secondarily affected in almost every dying patient, through pulmonary edema, atelectasis, or pneumonia.
Obstructive diseases are characterized by airflow limitations on lung function tests. Obstructions can result from airway narrowing or loss of elastic recoil. Important obstructive diseases include:
Restrictive, or diffuse interstitial diseases, are characterized by diffuse and usually chronic involvement of alveolar connective tissue. Important restrictive diseases include:
secondary interstitial lung disease includes:
The array of restrictive pathologies all cause dyspnea, tachypnea, end-inspiratory crackles, and eventual cyanosis, without wheezing. Diffusing capacity, lung volume, and compliance all decrease.
Chest X rays show diffuse infiltration by small nodules, irregular lines, or ground glass shadows. Pulmonary hypertension and cor pulmonale may result. Advanced destruction leads to honeycomb lung.
Oxygen diffusion capacity and compliance decrease.
Alveolitis appears to be the earliest manifestation of all restrictive diseases, with most types of leukocytes accumulating in the interstitial and alveolar spaces. Interstitial or granulomatous inflammation can occur.
Pulmonary function tests can be used to distinguish these patterns.
Infections are important causes and complications of respiratory disease. 100 million respiratory infections/year (Glass R, JAMA 2003) Coughs, colds, and antibiotics
upper airway tract infections |
lower airway tract infections |
Defense against respiratory infections include:
Particulate trapping occurs throughout the respiratory system. Particles of various sizes are trapped in various locales:
Common bacterial pathogens:
Common viral pathogens:
lung cancer
agenesis or hypoplasia
trachial or bronchial malformations
vascular anomalies