Pneumonia
Pneumonia: Excerpt from Professional Guide to Diseases (Eighth Edition)
Pneumonia is an acute infection of the lung parenchyma that commonly impairs gas exchange. The prognosis is generally good for people who have normal lungs and adequate host defenses before the onset of pneumonia; however, pneumonia is the sixth leading cause of death in the United States.
Causes and incidence
Pneumonia can be classified in several ways:
❑ Microbiologic etiology — Pneumonia can be viral, bacterial, fungal, protozoan, mycobacterial, mycoplasmal, or rickettsial in origin. (See Types of pneumonia, pages 538 to 541.)
❑ Location — Bronchopneumonia involves distal airways and alveoli; lobular pneumonia, part of a lobe; and lobar pneumonia, an entire lobe.
❑ Type — Primary pneumonia results from inhalation or aspiration of a pathogen; it includes pneumococcal and viral pneumonia. Secondary pneumonia may follow initial lung damage from a noxious chemical or other insult (superinfection), or may result from hematogenous spread of bacteria from a distant focus.
Predisposing factors for bacterial and viral pneumonia include chronic illness and debilitation, cancer (particularly lung cancer), abdominal and thoracic surgery, atelectasis, common colds or other viral respiratory infections, such as acquired immunodeficiency syndrome, chronic respiratory disease (chronic obstructive pulmonary disease [COPD], asthma, bronchiectasis, and cystic fibrosis), influenza, smoking, malnutrition, alcoholism, sickle cell disease, tracheostomy, exposure to noxious gases, aspiration, and immunosuppressive therapy.
Predisposing factors for aspiration pneumonia include old age, debilitation, artificial airway use, nasogastric (NG) tube feedings, impaired gag reflex, poor oral hygiene, and decreased level of consciousness.
In elderly patients and patients who are debilitated, bacterial pneumonia may follow influenza or a common cold. Respiratory viruses are the most common cause of pneumonia in children ages 2 to 3. In school-age children, mycoplasma pneumonia is more common.
Signs and symptoms
The main symptoms of pneumonia are coughing, sputum production, pleuritic chest pain, shaking chills, shortness of breath, rapid shallow breathing, and fever. Physical signs vary widely, ranging from diffuse, fine crackles to signs of localized or extensive consolidation and pleural effusion. There may also be associated symptoms of headache, sweating, loss of appetite, excess fatigue, and confusion (in older people).
Complications include hypoxemia, respiratory failure, pleural effusion, empyema, lung abscess, and bacteremia, with spread of infection to other parts of the body, resulting in meningitis, endocarditis, and pericarditis.
Diagnosis
Clinical features, chest X-ray showing infiltrates, and sputum smear demonstrating acute inflammatory cells support the diagnosis. Gram stain and sputum culture may identify the organism. Positive blood cultures in the patient with pulmonary infiltrates strongly suggest pneumonia produced by the organisms isolated from the blood cultures. Pleural effusions, if present, should be tapped and fluid analyzed for evidence of infection in the pleural space. Occasionally, a transtracheal aspirate of tracheobronchial secretions or bronchoscopy with brushings or washings may be done to obtain material for smear and culture. The patient’s response to antimicrobial therapy also provides important evidence of the presence of pneumonia.
Treatment
Antimicrobial therapy varies with the causative agent. Therapy should be reevaluated early in the course of treatment. Supportive measures include humidified oxygen therapy for hypoxemia, mechanical ventilation for respiratory failure, a high-calorie diet and adequate fluid intake, bed rest, and an analgesic to relieve pleuritic chest pain. Patients with severe pneumonia on mechanical ventilation may require positive end-expiratory pressure to facilitate adequate oxygenation.
Special considerations
Correct supportive care can increase patient comfort, avoid complications, and speed recovery.
The following protocol should be observed throughout the illness:
❑ Maintain a patent airway and adequate oxygenation. Monitor pulse oximetry. Measure arterial blood gas levels, especially in hypoxemic patients. Administer supplemental oxygen if the partial pressure of arterial oxygen is less than 55 to 60 mm Hg. Patients with underlying chronic lung disease should be given oxygen cautiously.
❑ Teach the patient how to cough and perform deep-breathing exercises to clear secretions; encourage him to do so often. In severe pneumonia that requires endotracheal intubation or tracheostomy (with or without mechanical ventilation), provide thorough respiratory care. Suction often, using sterile technique, to remove secretions.
❑ Obtain sputum specimens as needed, by suction if the patient can’t produce specimens independently. Collect specimens in a sterile container and deliver them promptly to the microbiology laboratory.
❑ Administer antibiotics as ordered and pain medication as needed; record the patient’s response to medications. Fever and dehydration may require I.V. fluids and electrolyte replacement.
❑ Maintain adequate nutrition to offset hypermetabolic state secondary to infection. Ask the dietary department to provide a high-calorie, high-protein diet consisting of soft, easy-to-eat foods. Encourage the patient to eat. As necessary, supplement oral feedings with NG tube feedings or parenteral nutrition. Monitor fluid intake and output. Consider limiting the use of milk products as they may increase sputum production.
❑ Provide a quiet, calm environment for the patient, with frequent rest periods.
❑ Give emotional support by explaining all procedures (especially intubation and suctioning) to the patient and his family. Encourage family visits. Provide diversionary activities appropriate to the patient’s age.
❑ To control the spread of infection, dispose of secretions properly. Tell the patient to sneeze and cough into a disposable tissue; tape a lined bag to the side of the bed for used tissues.
Pneumonia can be prevented as follows:
❑ Advise the patient to avoid using antibiotics indiscriminately during minor viral infections because this may result in upper airway colonization with antibiotic-resistant bacteria. If the patient then develops pneumonia, the organisms producing the pneumonia may require treatment with more toxic antibiotics.
❑ Encourage pneumovax and annual influenza vaccination for high-risk patients, such as those with COPD, chronic heart disease, or sickle cell disease.
❑ Urge all bedridden and postoperative patients to perform deep-breathing and coughing exercises frequently. Reposition such patients often to promote full aeration and drainage of secretions. Encourage early ambulation in postoperative patients.
❑ To prevent aspiration during NG tube feedings, elevate the patient’s head, check the tube’s position, and administer the formula slowly. Don’t give large volumes at one time; this could cause vomiting. Keep the patient’s head elevated for at least 30 minutes after the feeding. Check for residual formula at 4- to 6-hour intervals.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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