Infectious Disorders of the Lower Respiratory Tract
Infectious disorders of the lower respiratory tract refers to diseases affecting the lungs. Pneumonia and pulmonary tuberculosis represent two major infectious disorders of the lower respiratory tract.
Pneumonia is an inflammation of the parenchyma of the lungs caused by any number of organisms that include bacteria, viruses, and fungi. Community-acquired pneumonias include streptococcal pneumonia, Haemophilus influenza, Legionnaires' disease, Mycoplasma pneumoniae, viral pneumonia, and chlamydial pneumonia. Hospital-acquired pneumonias include Pseudomonas pneumonia, staphylococcal pneumonia, Klebsiella pneumonia, Pneumocystis carinii pneumonia (PCP), and fungal pneumonia.
Presenting symptoms depend on the causative organism. The client with viral pneumonia tends to have milder symptoms, whereas the client with bacterial pneumonia might have chills and fever as high as 103°. Clients with cytomegalovirus, Pneumocystis carinii, or aspergillus will be acutely ill. General symptoms of pneumonia include
- Chest pain
- Confusion (particularly in the elderly)
Care of the client with pneumonia depends on the causative organism. The management of bacterial pneumonias includes antibiotics, antitussives, antipyretics, and oxygen. Antibiotics that might be ordered include penicillin G, tetracycline, gentamicin, and erythromycin. Viral pneumonias do not respond to antimicrobial therapy but are treated with antiviral therapy. Fungal pneumonias are treated with antifungal therapy. Tables 5.2 and 5.3 at the end of the chapter provide examples of community- and hospital-acquired pneumonias as well as drugs used to treat them.
Additional therapies for the client with pneumonia include providing for fluid and nutritional needs, obtaining frequent vital signs, and providing oral hygiene. Supplemental oxygen and chest percussion and drainage should be performed as ordered by the physician.
The goal of oxygen therapy is to provide adequate levels of oxygen to blood while decreasing the workload of the heart and lungs. As with other medications, a physician's order is required when administering oxygen, except in emergency situations when failure to do so would result in injury or death of the client.
Oxygen delivery systems are classified as low flow or high flow. Low-flow systems provide supplemental oxygen while the client continues to breathe some room air. Examples of low-flow systems are nasal cannula, simple mask, and rebreather masks. Nasal cannulas are capable of providing 1–6 liters of oxygen per minute. Masks are capable of providing 6–12 liters of oxygen per minute. Venturi and aerosol masks are examples of high-flow systems, which are capable of delivering 4–10 liters of oxygen per minute. Oxygen flow rates are prescribed by the physician according to the client's condition and oxygen requirements. Figure 5.2 illustrates a Venturi mask as well as nasal cannula.
Figure 5.2 Examples of oxygen delivery systems.
The nurse should observe the client's response to oxygen therapy as well as watching for signs of oxygen toxicity. Signs of oxygen toxicity include substernal discomfort, paresthesias, dyspnea, restlessness, fatigue, malaise, and progressive respiratory difficulty.
Chest physiotherapy that includes percussion, vibration, and postural drainage is used to remove bronchial secretions and improve oxygenation. The nurse should assess the client for any conditions, such as recent thoracic surgery, that would contraindicate the use of chest physiotherapy.
Auscultation of the chest before and after the procedure is carried out to determine the effectiveness of treatment. A towel placed over the client's chest will make the client more comfortable during percussion. Using cupped hands, the nurse strikes the client's chest in a rhythmical fashion for 3–5 minutes for each lung segment. As the client exhales, manual vibration or tremor might be used to help loosen secretions. Figure 5.3 illustrates chest percussion and drainage.
Figure 5.3 Chest percussion and postural drainage for sides (lower lobes) and back (upper lobes).
Tuberculosis (TB) is a highly contagious respiratory infection caused by the mycobacterium tuberculosis. The organism is transmitted by droplets from the respiratory tract. The incidence of TB has been steadily increasing in the United States and world wide for the past twenty years. Risk factors include living in overcrowded conditions, being immune compromised, and age. Duration of exposure affects transmission.
Symptoms of TB are varied. Some clients might have no symptoms; others might complain of fever (particularly in the afternoon), weight loss, anorexia, indigestion, cough that becomes productive, night sweats, shortness of breath, and changes in lung sounds. Sites most commonly affected by TB include the lungs, cervical lymph nodes, kidney, and spine.
Methods used for tuberculosis testing include the intradermal PPD (Mantoux) test and the multiple puncture (tine) test. The multiple puncture test is less accurate than the PPD test; therefore, it is used less often. The PPD (Mantoux) is performed by injecting 0.1 mL of PPD intradermally in the inner aspect of the forearm. The test is read within 48–72 hours with notation of induration, not redness. Indurations of 0 mm–4 mm are generally considered negative, whereas indurations of 5 mm–9 mm indicate questionable exposure. Indurations of 5 mm–9 mm are considered positive for those in close contact with a client with TB, those with HIV or who are immunocompromised, and in those who have an abnormal chest x-ray. Indurations of 10 mm–15 mm are considered positive for those born in a country where TB is prevalent; those who are intravenous drug users; residents of long-term care facilities, homeless shelters, or correctional facilities; and those with medical conditions such as malnutrition and diabetes.
Indurations greater than 15 mm are considered to be positive for all. Positive test results indicate exposure and infection, but not necessarily active disease. An induration of 5 mm is the cut-off for organ transplant recipients and other immunosuppressed clients treated with prednisone or TNF antagonists. (CDC, 2005) Persons who have had a positive skin test will always have a positive skin test, therefore they should be screened with a chest x-ray as needed to detect clinically active TB.
Positive skin tests can be measured accurately for up to seven days. Negative reactions can be measured accurately for only 72 hours. Factors that can cause false positive TB skin test include nontuberculous mycobacterium and inoculation with BCG vaccine. Factors that can cause false negative TB skin test include anergy (weakened immune system), recent TB infection, age, vaccination with live viruses, overwhelming TB, and poor testing technique.
TB is confirmed by positive sputum test. Automated radiometric culture systems (Bactec) yield results in one to three weeks. Blood tests that measure and compare the amount of interferon-gamma released by blood cells in response to antigens include the Quantiferon TB test and Quantiferon Gold. Two-step testing is used to establish a baseline skin test and for adults tested periodically such as healthcare workers:
- If the first TB skin test is read as positive, the client is considered infected.
- If the first TB skin test is read as negative, give second TB skin test one to three weeks later. If the second TB skin test is read as positive, the client is considered infected.
- If the second TB skin test is read as negative, the client is considered uninfected at the baseline.
Care of the client with TB includes the use of antimycobacterial drugs INH (isoniazid), Myambutol (ethambutol), Rifadin (rifampin), and streptomycin. Multiple drug therapy destroys organisms quickly and decreases the chance of developing drug-resistant organisms. Clients newly diagnosed with TB are typically treated with a regimen of four antituberulars: Rifadin(rifampin) and INH (isoniazid) are given throughout the course of treatment, and Tebrazid (pyrazinamide and Myambutol (ethambutol) are added for the first 2 months. The combination of medications reduces the treatment time to 6 months for most clients; however, clients with HIV infection are typically treated for 9 months.
Airborne precautions, which are used in the hospital setting, are not used if the client is convalescing home, however all household members need to be checked for infection. Sputum specimens are collected every 2–4 weeks. The client can return to work when he/she has three negative sputum specimens. Household contacts are generally treated with prophylactically with INH (isoniazid). Table 5.4, presented in the Key Concepts section later in the chapter, lists details about antitubercular drugs. Because of the length and intensity of treatment, the client should have the following lab studies performed before beginning therapy and on a regularly scheduled basis:
- Alanine transaminase (ALT)
- Aspartate transaminase (AST)
- Platelet count
- Serum creatinine
Adverse effects of ethambutol include changes in visual acuity and color vision; therefore, clients should have an eye exam before beginning therapy to detect any existing problems and should report visual changes to their physician. Adverse effects of streptomycin include ototoxicity, so audiometric testing should be performed before streptomycin therapy is begun to detect problems with hearing. Changes in hearing should also be reported to the physician.
Influenza is an acute highly contagious viral infection that affects primarily the upper respiratory tract and is sometimes complicated by the development of pneumonia. Influenza is caused by one of three types of Myxovirus influenzae. Infection with one strain produces immunity to only that strain; therefore, annual immunization is needed to protect against the strain projected to be prevalent that year.
Symptoms of influenza include chills, laryngitis, sore throat, runny nose, muscle aches, headache, and fever greater than 102°. Complications associated with influenza include pneumonia, exacerbations of COPD (chronic obstructive pulmonary disease), and myositis. More serious complications include pericarditis and encephalitis. The elderly, children, and those with chronic illness are more likely to develop severe complications; therefore, it is recommended that these clients receive annual influenza immunization. The vaccine is given in the fall, prior to the onset of annual outbreaks that occur in the winter months. The vaccine is produced in eggs, so it should not be given to anyone who is allergic to egg protein.
Treatment of influenza is aimed at controlling symptoms and preventing complications. Bed rest and increased fluid intake are important interventions during the acute phase. Decongestant nasal sprays, antitussives with codeine, and antipyretics help make the client more comfortable. Antibiotics are indicated if the client develops bacterial pneumonia. Clients with influenza as well as nonimmunized persons who have been exposed to influenza might receive chemoprophylaxis if an outbreak occurs. Antiviral medication such as Relenza (zanamivir) and Tamiflu (oseltamivir) are used in both the prevention and treatment of influenza A and B and can be used to reduce the duration and severity of symptoms.
Symmetrel (amantadine) or Flumadine (rimantadine) are also used to prevent or decrease symptoms of the flu.