Chronic Bronchitis – Top USMLE Diseases

Pneumonia is the infection of the lung parenchyma, resulting from the spread of pathogens and accompanied by the host inflammatory response. This condition is the most common infectious cause of death. Multiple organisms cause pneumonia, including bacteria (of which Streptococcus pneumoniae is the most common), viruses, and fungi. The infection can be acquired while hospitalized (hospital-acquired) or outside the hospital setting (community-acquired). Common symptoms include fever, chills, cough, chest pain, and dyspnea. Chest X-ray usually shows consolidation and/or infiltrates. Diagnosis can be made with clinical presentation and imaging, but in severe cases, microbiological testing (sputum and cultures, molecular testing) and routine blood tests are needed. Empiric treatment with antibiotics is recommended, with regimen depending on the setting, risk factors for multidrug-resistant organisms, and individual comorbidities. Identification of the causative pathogen helps narrow down the antibiotics. Preventive measures include vaccinations (pneumococcal and influenza) and smoking cessation.

Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in individuals over age 40 with a history of more than 40 pack-years of cigarette smoking. Symptoms include progressive dyspnea and chronic cough. Prolonged expiration, wheezing, and/or diminished breath sounds may be noted on physical exam. The diagnosis is confirmed with a pulmonary function test. Management includes smoking cessation, pulmonary rehabilitation, and pharmacotherapy.

Acute bronchitis is a common lower respiratory tract infection of the bronchi that accounts for many health care visits annually. It is most often due to viral causes in patients without chronic lung disease. Presenting symptoms include cough, with or without sputum, typically resolving within 1–3 weeks. Acute bronchitis is diagnosed clinically, although a chest X-ray helps clarify the diagnosis if pneumonia is suspected. Management is supportive, and antibiotics are not indicated in otherwise healthy adults.

Diagnostic modalities such as chest X-rays provide static images of the thoracic cavity, including the lungs and airways. While providing a wealth of anatomical information necessary for the diagnosis of pulmonary disease, chest X-rays do not give much information about the individual's respiratory function. Pulmonary function tests are a group of diagnostic procedures yielding useful, quantifiable information about the rate of the flow of air through the individual's airways, lung capacity, and the efficiency of gas exchange in relation to time. The most commonly utilized tests include spirometry (before and after bronchodilator use), lung volumes, and quantitation of diffusing capacity for carbon monoxide (CO). The tests can be influenced by the individual's effort/fatigue, disease state, or anatomical malformation.

Acute bronchitis is an infection of the mucous membrane of the bronchi without evidence of pneumonia. Due to its pathogenesis, acute bronchitis is frequently accompanied by an upper respiratory tract infection. Cases in which the trachea is also involved are referred to as tracheobronchitis. Acute bronchitis is usually viral (approximately 95% of all cases), and bacterial infections are usually caused by atypical bacteria. Acute bronchitis is diagnosed clinically, although a chest X-ray may be useful in ruling out pneumonia. Management is supportive, and antibiotics are not indicated in otherwise healthy adults.

Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy.

Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Symptoms include progressive dyspnea and chronic cough. Prolonged expiration, wheezing, and/or diminished breath sounds may be noted on physical exam. The diagnosis is confirmed with a pulmonary function test. Management includes smoking cessation, pulmonary rehabilitation, and pharmacotherapy.