Diseases of the lower respiratory tract

Acute bronchitis is an inflammation of the large bronchi (medium-size airways) in the lungs that is usually caused by viruses or bacteria, generally self-limited and with complete healing and return of function in several days or weeks. Though commonly mild, bronchitis may be serious in debilitated patients and those with chronic lung or heart disease. Pneumonia is a critical complication.

Acute infectious bronchitis, most prevalent in winter, is often a part of an acute URI. It may develop after a common cold or other viral infection of the nasopharynx, throat, or tracheobronchial tree, often with secondary bacterial infection.

Acute infectious bronchitis is often preceded by symptoms of an URI: coryza, malaise, chilliness, slight fever, back and muscle pain, and sore throat. Onset of cough usually signals onset of bronchitis. The cough is initially dry and nonproductive, but small amounts of viscid sputum are raised after a few hours or days; it may later become more abundant and mucoid or mucopurulent. In a severe uncomplicated cases, fever to 38.3 or 38.8 C° (101 or 102° F) may be present for up to 3 to 5 days, following which acute symptoms subside though cough may continue for several weeks. Persistent fever suggests complicating pneumonia. Dyspnea may be noted secondary to the airways obstruction.

Diagnosis is usually based on the symptoms and signs, but a chest x-ray is indicated if symptoms are serious or prolonged.

Rest is indicated until fever subsides. Oral fluids (up to 3 or 4 L/day) are advised during the febrile course. An antipyretic analgesic (e.g, for adults aspirin 600 mg or acetaminophen 500 mg 4 to 6 h; for children acetaminophen 10 to 15 mg/kg 4 to 6 h) relieves malaise and reduces fever.

Antibiotics are indicated when there is concomitant chronic obstructive pulmonary disease, when purulent sputum is present, or when high fever persists and the patient is more than mildly ill.

Pneumonia is an acute infection of lung parenchyma including alveolar spaces and interstitial tissue. The most common causes in adults are bacteria.

Pneumococcal pneumonia is often preceded by an URI. The onset is often sudden with a single shaking chill; persistent chills suggest an alternative diagnosis. This is ordinarily followed by fever, pain with breathing on the involved side (pleurisy), cough, dyspnea, and sputum production. The temperature rises rapidly to 38 to 40.5° C (100.4 to 105° F); the pulse is usually 100 to 140/min; and respirations accelerate to 20 to 45/min. Additional common findings are nausea, vomiting, malaise, and myalgias. The cough may be dry initially, but usually becomes productive with purulent, blood-streaked or rusty sputum.

Serious, potentially lethal complications include overwhelming sepsis, sometimes associated with the adult respiratory distress syndrome and/or septic shock.

Laboratory studies usually show leukocytosis with a shift to the left. There may be blood gas abnormalities due to perfusion of poorly aerated lung resulting in hypoxemia and respiratory alkalosis.

Pneumococcal pneumonia should be suspected in anyone with an acute febrile illness associated with chest pain, dyspnea, and cough. A presumptive diagnosis can be based on the history, changes on chest x-ray, culture and Gram stains of appropriate specimens. Treatment depends on the kind of pneumonia.

Exercise 5. Answer the questions:

1. What is acute bronchitis often preceded by?

2. What is bronchitis?

3. What are the symptoms of bronchitis?

4. What is the most common cause of pneumonia?

5. What is pneumonia?

6. What are the symptoms of pneumonia?

7. What are the complications of pneumonia?