Pneumonia

Inflammation of the lungs, usually due to infection with bacteria, viruses, or other pathogenic organisms. Clinically, pneumonia indicates an infectious disease. Pulmonary inflammation due to other causes is called pneumonitis. In the U.S., about 4,500,000 people contract pneumonia each year, and pneumonia is the sixth most common cause of death in the U.S. and the most common cause of death due to infectious disease. Pneumonia occurs most commonly in weakened people (those with cancer, heart or lung disease, immunosuppressive illnesses, diabetes mellitus, cirrhosis, malnutrition, and renal failure), but virulent pathogens can cause pneumonia in the healthy, as well. Smoking, general anesthesia, and endotracheal intubation increase the risk for developing pneumonia by inhibiting airway defenses and helping disease-causing germs reach the alveoli of the lungs. aspiration; pleural effusion; empyema; pleurisy; pneumonitis; tuberculosis (and names of lung pathogens);

Etiology

Pneumonias are categorized by site and cause. Lobar pneumonia affects most of a single lobe; bronchopneumonia involves smaller lung areas in several lobes; interstitial pneumonia affects tissues surrounding the alveoli and bronchi of the lung. Atypical pneumonias diffusely affect lung tissues rather than anatomical lobes or lobules. Community-acquired pneumonia is a lung infection that occurs in noninstitutionalized people, typically involving organisms such as viruses, Streptococcus pneumoniae, Klebsiella pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, Chlamydia pneumoniae, Moraxella species, or Pneumocystis carinii. Nosocomial pneumonia develops in patients in the hospital or nursing home; this type is most likely to be caused by gram-negative rods or staphylococcal species. Aspiration pneumonias result from the inhalation of oropharyngeal microorganisms and often involve anaerobic organisms. Pneumonias in immunocompromised patients sometimes are caused by Pneumocystis jiroveci or by fungal species such as Aspergillus. or Candida. Some fungal pneumonias occur in specific geographical regions of the U.S. For example, histoplasmosis is common in the Ohio River Valley, and coccidioidomycosis is found in the San Joaquin River Valley of southern California. Viral pneumonias may be caused by influenza, varicella-zoster, herpes, or adenoviruses.

Symptoms

Most patients with pneumonia have cough, shortness of breath, and fever although these symptoms are not universal. Bacterial pneumonias are marked by abrupt onset, with high fevers, shaking chills, pleuritic chest pain, and prostration. Patients with atypical pneumonias usually have lower temperatures and nonproductive coughs and appear less ill.

Prevention

Pneumococcal vaccine effectively prevents many forms of streptococcal pneumonia. This vaccine is recommended for people over 65; those with chronic respiratory, cardiac, or neuromuscular diseases; and patients with diabetes mellitus or renal failure.

Treatment

Treatment is based on the clinical presentation (such as community-acquired versus nosocomial), results of the Gram stain of sputum specimens, the radiographical appearance of the pneumonia, the degree of respiratory impairment, and the results of cultures. Many patients hospitalized with pneumonia require supplemental oxygen and analgesics. Initial antibiotic treatments for pneumonia should be given without delay and typically involve powerful, broad-spectrum drugs. The antibiotic used for subsequent therapy is guided by the results of cultured specimens taken on presentation.

Patient care

A large percentage of patients with pneumonia are not admitted to hospitals but are treated with antibiotics given on an outpatient basis. However, older adults, people with serious chronic diseases, and those with evidence of organ dysfunction, poor oxygenation, or acute decompensation may need hospitalization to reduce the risk of injury or death. Supportive care is provided to the patient to remove secretions and improve gas exchange. Such care includes position changes, deep breathing and coughing exercises, incentive spirometry, active and passive limb exercises, and assistance with self-care. Respiratory status is monitored by listening to the chest for crackles and/or wheezing, performing oximetry on a regular basis, and, when patients are failing, performing arterial blood gas studies. Supplemental oxygen is usually prescribed to maintain an oxygen saturation of > 92%. The patient is assessed for signs and symptoms of respiratory failure, sepsis, and shock. Mechanical ventilation is required in patients with respiratory failure. Analgesics are provided as prescribed to manage pain and discomfort and encourage good pulmonary toilet. A large percentage of patients receive care to remove secretions and to improve gas exchange. Such care includes position changes, deep-breathing, and coughing exercises. The patient is encouraged to verbalize concerns; diagnostic studies and therapeutic measures are explained, and the patient is taught about the importance of follow-up care. Outpatient therapy of community-acquired pneumonia can be recommended for selected patients who are young, otherwise healthy, and not hypoxic, hypotensive, hypothermic, or in renal failure. Activities are scheduled to allow for plenty of rest. The patient is taught hand hygiene and encouraged to wash hands with soap and water or use an alcohol-based hand wipe entirely over both hands after blowing the nose, coughing, using the bathroom, or eating or drinking. Only disposable tissues are used for sneezing and coughing. Used tissues are deposited in a lined bag taped to the bedside and are disposed of frequently according to agency policy. Unless otherwise restricted, the patient should drink eight 12-ounce glasses of water daily to help thin and loosen mucous secretions. Each patient’s meal preferences and restrictions are discussed to plan a diet that ensures adequate high-caloric intake. Emotional support is provided, and all procedures and treatments are explained. The patient who smokes is taught the relationship between smoking and lung diseases (including the increased risk of respiratory infections) and referred for support group assistance with quitting as needed. Pneumonia prevention is aided by encouraging individuals to avoid indiscriminate antibiotic use, receive pneumonia and influenza vaccinations, perform deep-breathing and coughing exercises when confined to bed and after surgery, and ambulate early after surgery. Aspiration pneumonia is prevented in tube-fed patients by correct positioning and slow, low-volume feedings. The chronically ill and debilitated in nursing homes should have swallowing function assessed as necessary; caregivers should be taught correct feeding techniques to prevent aspiration.

An obsolete term for mild pneumonia with a brief course.

A pneumonia seen in stillborn infants; caused by congenital syphilis.

Pneumonia caused by inhalation of gastric contents, food, or other substances. A frequent cause is loss of the gag reflex in patients with central nervous system depression or damage or alcoholic intoxication with stupor and vomiting. This condition also occurs in newborns who inhale infected amniotic fluid, meconium, or vaginal secretions during delivery.

Pneumonia caused by a virus or Mycoplasma pneumoniae. The symptoms are low-grade fever, nonproductive cough, pharyngitis, myalgia, and minimal adventitious lung sounds.

Pneumonia caused by bacteria such as streptococcus, Staphylococcus aureus, Klebsiella, or coliforms.

An atypical pneumonia caused by Chlamydia species, characterized clinically by cough, low-grade fever, sore throat, and malaise. A chest x-ray taken during the illness is more likely to show diffuse lung involvement than a lobar pneumonia.

Pneumonia occurring in outpatients, often caused by infection with streptococcus, Haemophilus influenzae, Staphylococcus aureus, and atypical organisms such as Legionella species. Mortality is approximately 15% but depends on many host and pathogen features.

Pneumonia of unknown cause, accompanied by cellular infiltration or fibrosis in the pulmonary interstitium. Progressive dyspnea and a nonproductive cough are symptoms characterizing this disease. Clubbing of the fingers is a common finding. Diffusion of oxygen and carbon dioxide is abnormal. Diagnosis is made by lung biopsy. The condition is treated by corticosteroids.

Pneumonia that involves both lungs or two lobes.

Pneumonia following embolization of a pulmonary blood vessel.

Infiltration of the lung by eosinophils, typically found in patients with peripheral eosinophilia. The cause is usually unknown; occasionally, the condition responds to the administration of corticosteroids. In some cases, a specific underlying cause is found, such as the recent initiation of cigarette smoking or an allergic drug reaction. Infection with some parasites or fungi also can trigger the disease.

Pneumonia followed by formation of scar tissue.

Pulmonary gangrene.

An interstitial pneumonitis of infancy and childhood. The lung tissue contains multinucleated giant cells. The disease often occurs in connection with measles.

Pneumonia occurring in elderly or bed-ridden patients who remain constantly in the same position. Ventilation is greatest in dependent areas. Remaining in one position causes hypoventilation in many areas, causing alveolar collapse (atelectasis) and creating a pulmonary environment that supports the growth of bacteria or other organisms. Development of this condition is prevented by having the patient change positions and take deep breaths to inflate peripheral alveoli.

Patient care

Prevention is the most important factor, esp. in older and immobile persons. Patients should be moved and turned frequently at least every 1 to 2 hr. The nurse and respiratory therapist should monitor respiratory status by frequently auscultating for crackles, gurgles, and wheezes and encourage the patient to engage in active movement and to perform deep-breathing and coughing exercises frequently and regularly. Incentive spirometry may prove useful in patients who need added encouragement to deep breathe periodically.

Pneumonia contracted in utero.

Damage to lung tissue that results from aspiration of oils. It may occur repeatedly in patients with impaired swallowing mechanisms or in persons affected by esophageal disorders, such as esophageal carcinoma, achalasia, or scleroderma. Mineral oils and cooking oils often are responsible. Most cases resolve spontaneously, but corticosteroids sometimes are used as treatment to reduce inflammatory changes. Distinguishing lipoid pneumonia from bacterial pneumonia may require endoscopy.

Pneumonia infecting one or more lobes of the lung, usually caused by Streptococcus pneumoniae. The pathologic changes are, in order, congestion; redness and firmness due to exudate and red blood cells in the alveoli; and, finally, gray hepatization as the exudate degenerates and is absorbed. Synonym: acute lobar pneumonia See: illustration

Lung infection occurring in the first few days of life due to uterine exposure to infectious microorganisms or to infection during or immediately after birth. Common causes include viruses (such as herpes simplex) and bacteria (such as group B streptococcus, Chlamydia, Escherichia coli, Listeria).

Pneumonia occurring after 48 hours of confinement in a hospital, intensive care unit, or nursing home. It is often the result of infection with gram-negative pathogens or multiply drug-resistant bacteria and includes both ventilator-associated pneumonias and other lower respiratory tract infections. Synonym: healthcare-associated pneumonia

The most common form of pneumonia in the U.S., affecting about half a million people each year. It often begins with hard-shaking chills and may be fatal, esp. in the elderly or those with underlying diseases. It usually strikes smokers, people with underlying lung diseases, those recently infected with influenza or those with sickle-cell anemia, chronic or heavy alcohol use, or cirrhosis.

Symptoms

Fevers, body-shaking chills, productive cough, pleurisy, prostration, and sweating.

Treatment

Penicillin may be used when the pneumococcus is sensitive to this agent, but the incidence of penicillin resistance in pneumococci is rapidly growing. Third-generation cephalosporins, erythromycin, vancomycin, and linezolid, are alternative agents.

Patient care

Vaccination provides passive immunity against many serotypes of pneumococcal pneumonia. People over the age of 65 or those with heart, lung, liver, kidney, or immunosuppressive diseases should be immunized as should infants under the age of two.

A subacute opportunistic infection marked by fever, nonproductive cough, tachypnea, dyspnea, and hypoxemia. It is caused by Pneumocystis carinii, the former name of Pneumocystis jiroveci, an organism formerly thought to be a protozoan but now generally accepted as a fungus. The disease is seen principally in immunosuppressed patients, such as those with AIDS or who have received an organ transplant and immunosuppressant drugs. Without treatment, the progressive respiratory failure that the infection causes is ultimately fatal.

Diagnosis

The disease should be suspected in patients with human immunodeficiency virus infection or other risk factors for the disease who present with cough and shortness of breath. Chest x-ray examination may reveal diffuse interstitial infiltrates, upper lobe disease, spontaneous pneumothorax, or cystic lung disease. The diagnosis is confirmed with special stains of sputum, bronchial washings, or lung biopsy specimens. See: illustration

Treatment

Oral trimethoprim-sulfamethoxazole effectively protects against PCP, and is also the drug of choice for active infection. Other drugs that are active against PCP include pentamidine, trimethoprim in combination with dapsone, and atovaquone. Corticosteroids are used as adjunctive therapy when treating markedly hypoxic patients, e.g., those who present with an alveolar-arterial oxygen gradient of more than 35 mm Hg. The introduction of highly active antiretroviral drug cocktails for AIDS patients has markedly reduced the incidence of PCP.

Pneumonia that occurs in connection with a specific systemic disease such as typhoid, diphtheria, or plague.

Pneumonia caused by Mycobacterium tuberculosis. See: tuberculosis

Pneumonia caused by Francisella tularensis. It may be primary or associated with tularemia.

In patients receiving invasive mechanical ventilation, a new and persistent infiltrate seen on chest x-ray associated with fever, elevated or depressed white blood cell counts, and sputum that is either purulent or full of disease-causing bacteria. Synonym: artificial airway-associated pneumonia

Any infections of the lower respiratory tract (the lungs, bronchioles, and trachea) caused by viral species such as adenovirus, coronavirus, herpesviruses, influenza viruses, and respiratory syncytial viruses. Viral pneumonias may range from mild respiratory infections (with nonproductive cough and low-grade fevers) to life-threatening and highly contagious illnesses (such as SARS). See: bronchitis; bronchiolitis