6/11/2019 PDF.js viewer https://lms-ugrad.gcu.edu/learningPlatform/user/users.lc?operation=loggedIn&token=khLNAgNxucQ4jeqMmnIJ72ayBtOv6%2f4%2fqmGdmip8ZmMwuhTe%2fvN… 1/1 6/11/2019 PDF.js viewer https://lms-ugrad.gcu.edu/learningPlatform/user/users.lc?operation=loggedIn&token=khLNAgNxucQ4jeqMmnIJ72ayBtOv6%2f4%2fqmGdmip8ZmMwuhTe%2fvN… 1/1 FIFTH EDITION PATHOPHYSIOLOGY Lee-Ellen C. Copstead, PhD, RN Jacquelyn L. Banasik, PhD, ARNP Professor Department of Nursing College of Nursing and Health Sciences University of Wisconsin-Eau Claire Eau Claire, Wisconsin Associate Professor College of Nursing Washington State University Spokane, Washington ELSEVIER 512 UNIT VI Respiratory Function gastric volume and size has proved successful in some patients. These operations are intended to permanently curtail food intake. KEY POINTS • Neuromuscular diseases affect the muscles of respiration, leading to mus- cular weakness, increased risk of pulmonary infections, and respiratory failure. • Kyphoscoliosis is a deformity of the bony structure of the chest wall char- acterized by hunchback and lateral curvature of the spine. The abnormal shape of the chest interferes with the normal mechanics of breathing, resulting in small lung volumes, compression atelectasis, and hypoxemia. Compensatory tachypnea is usually present. • Ankylosing spondylitis is a progressive inflammatory disease affecting vertebrae and ribs. Chronic inflammation leads to chest wall fibrosis and immobility. Chest wall muscle atrophy and rib cage stiffening result in pul- monary dysfunction characteristic of restrictive disorders. Obesity may interfere with the normal mechanics of breathing because of excessive chest weight and abdominal impingement on the chest cavity. Pickwickian syndrome is a disorder of obesity associated with hypoventila- tion and upper airway obstruction during sleep. INFECTION OR INFLAMMATION OF THE LUNG Disorders of Obesity Etiology. Obesity is defined as excessive body fat, with a body mass index (BMI) greater than 30 kg/m² based on body weight and height. Overweight is defined as a BMI of 25 to 29.9 kg/m2.43 Obesity results from excessive caloric intake and/or reduced caloric expenditure. The National Health and Nutrition Exam survey reported that 59.4% of men and 49.9% of women are overweight. The findings for obesity were 19.9% of men and 25.1% of women 44,45 A higher prevalence of obesity was found in blacks than in whites and in persons with lower incomes than in those with higher incomes.43-45 Obese patients are at risk for a variety of disorders, the most common of which are diabetes mel- litus, coronary artery disease, degenerative joint disease, gallstones, cer- tain cancers (colon, rectum, and prostate in men; uterus, biliary tract, breast, and ovary in women), and pulmonary impairment. Persons with a BMI of 30 kg/m² have an all-cause increase in mortality of 50% to 100% compared to persons with a BMI between 20 and 25 kg/m2.43 Pathogenesis. Endocrine causes of obesity are rare. 10 Hypothy- roidism, the use of corticosteroids, and hypothalamic lesions all can lead to weight gain; however, the major cause of obesity is excess caloric intake in relation to caloric expenditure. Several hormones act on brain receptors to regulate appetite and metabolism. Leptin binds to brain receptors, causing the release of neuropeptides that promote satiety and increase metabolic rate. Ghrelin stimulates appe- tite. Genetic diseases such as familial partial lipodystrophy, Prader- Willi syndrome, Laurence-Moon syndrome, Bardet-Biedl syndrome, and Cohen syndrome are associated with obesity.43-46 Obesity may be associated with hypoventilation. The mechanisms of obesity hypoven- tilation are reduced ventilatory drive and increased work of breath- ing. Some patients are thought to have an abnormality in the central nervous system. In addition, the increased abdominal size can force the abdominal contents upward into the chest cavity, thus decreasing lung expansion and diaphragmatic shortening. Obesity hypoventila- tion is also called pickwickian syndrome, named after the obese boy in Pickwick Papers written by Charles Dickens. Pickwickian syndrome is associated with hypoventilation and airway obstruction. An addi- tional factor that contributes to the overall clinical picture in many obese patients is upper airway obstruction during sleep, the obstruc- tive form of sleep apnea syndrome. Soft-tissue deposits in the neck and tissues surrounding the upper airway predispose the person to episodes of complete upper airway obstruction during sleep. In a large percentage of cases, the daytime somnolence that occurs in patients who have the obesity hypoventilation syndrome is related to obstruc- tive sleep apnea.44 Clinical manifestations. Obesity hypoventilation is character- ized by decreased alveolar ventilation, somnolence, severe hypoxemia, polycythemia, and cor pulmonale. Patients complain of daytime som- nolence, impotence, shortness of breath, headache, and enuresis. Diagnosis. The diagnosis of obesity is self-evident on examination. Tests for hypothyroidism, Cushing syndrome, insulinoma, diabetes, and hyperlipidemia may be done to identify comorbid factors.43 For persons with hypoventilation, arterial blood gas analyses may reveal hypoxemia and hypercapnia. Chest wall compliance, vital capacity, total lung capacity, and expiratory reserve volume are all decreased. Patients may also have an increased red blood cell count and show signs and symptoms of cor pulmonale and pulmonary hypertension. Treatment. Primary treatment for obesity consists of a weight loss program that includes the family members. Caloric intake that pro- motes an energy deficit of 500 to 1000 kcal/day is recommended. Aerobic exercise preserves lean body mass and increases energy expen- diture.43,44 Oxygen delivery through a nasal cannula or mechanical ventilation may be necessary for patients with morbid obesity. Surgi- cal intervention with gastric stapling or gastric bypass to decrease the Pneumonia Etiology. The term pneumonia (from the Greek pneuma, which means "breath") refers to an inflammatory reaction in the alveoli and interstitium of the lung, usually caused by an infectious agent. Pneumonia can result from three different sources: (1) aspiration of oropharyngeal secretions composed of normal bacterial flora and/ or gastric contents (25% to 35% of all pneumonias); (2) inhalation of contaminants (virus, Mycoplasma); or (3) contamination from the systemic circulation.2,47-49 There are several ways to classify pneumonia. Pneumonias are typically classified as community acquired or hospital acquired. The incidence of community-acquired pneumonia is 1 in 100 persons. Approximately 15% to 20% of persons presenting with pneumonia require hospitilization.50 Pneumonia is further classified as bacterial, atypical, and viral. The bacterial pneumonias may be grouped as either gram-positive or gram-negative, based on the staining characteristics of the organism. Staphylococcus and Streptococcus (including pneumo- cocci) are the predominant gram-positive organisms. Gram-negative bacteria that may cause pneumonia include Haemophilus influenzae, Klebsiella species, Pseudomonas aeruginosa, Serratia marcescens, Esch- erichia coli, and Proteus species. Patients at risk of pneumonia include the elderly; those with a dimin- ished gag reflex; seriously ill, hospitalized patients; hypoxic patients; and immunocompromised patients.S0 Anaerobic bacteria may pres- ent clinically as a lung abscess, necrotizing pneumonia, or empyema. These diseases are usually caused by aspiration of normal oral bacteria (such as Bacteroides and Fusobacterium) into the lung. Mycoplasmal pneumonia is more commonly seen in the summer and fall in young adults. About half of the cases of pneumonia in persons between 5 and 20 years of age can be classified as mycoplasmal pneumonia. Other causes of pneumonia occur less frequently in the general population. Legionnaires disease, for example, is a severe systemic illness character- ized by fever, diarrhea, abdominal pain, liver and kidney failure, and pulmonary infiltrates. The causative organism for legionnaires disease lives in water and is transmitted by means of potable water, condensers, and cooling towers. The current treatment of choice is administration of a macrolide antibiotic. Patients whose immune systems have been CHAPTER 23 Restrictive Pulmonary Disorders 513 compromised by disease or by drug therapy may be susceptible to the development of opportunistic pneumonia. 50 For example, Pneumocys- tis (carinii) jiroveci pneumonia, an opportunistic fungal infection, is commonly found in patients with cancer or with human immunodefi- ciency virus (HIV). (See Chapter 12 for further discussion of acquired immunodeficiency syndrome (AIDS).) Aspergillus, an opportunistic fungus that is widespread in nature, may cause progressive pneumonia. Aspergillus is released from the walls of old buildings under reconstruction. Attention should be given when old hospitals are renovated and when susceptible patients are located in a reconstruction area.49 To assist the reader in differ- entiating among the various types of pneumonia, Table 23-7 presents the etiologic factors, common clinical features with age-related char- acteristics, radiologic findings, and antibiotic therapies for 11 forms of the disease. There are many other types of pneumonia that are not listed. Pathogenesis. Normally, pulmonary defense mechanisms (immune responses, cough reflex, sneezing, mucociliary clearance) protect individuals from pneumonia. Community-acquired pneumo- nia occurs when defense mechanisms are compromised.2,46 A highly virulent organism may also overwhelm a person's defense mecha- nisms. Community-acquired pneumonias are commonly bacterial in origin." After microbial agents enter the lung, they multiply and trig- ger pulmonary inflammation. Alveolar air spaces fill with an exudative fluid, and inflammatory cells invade the alveolar septa. Acute bacte- rial pneumonia may be associated with significant /Q mismatching and hypoxemia because inflammatory exudate collects in the alveolar spaces. Alveolar exudate tends to consolidate and becomes difficult to expectorate. Viral pneumonia does not produce exudative fluids. Figure 23-9 shows the histologic progression of acute bacterial pneu- monia. Patients with chronic illnesses and those who are immobile or immunosuppressed or have a decreased level of consciousness are at TABLE 23-7 DIFFERENTIATING FEATURES OF TYPES OF PNEUMONIA CHEST RADIOGRAPH ETIOLOGIC ORGANISM Staphylococcus aureus, gram- positive cocci in clumps COMMON CLINICAL FEATURES Follows upper respiratory tract infection; fever, chills, pleuritic chest pain, cough, yellow purulent sputum; seen in patients in chronic care facilities Consolidation, may have cavitation Patchy infiltrates Streptococcus pneumoniae (pneumococcus) gram-positive diplococci ANTIBIOTIC TREATMENT Methicillin-susceptible strains: nafcillin or oxacillin with or without rifampin; methicillin- resistant strains: vancomycin with or without rifampin; alternative choice: cephalosporins, clindamycin, vancomycin Procaine penicillin G or aqueous penicillin G, amoxicillin; alternative choice: macrolides, cephalosporins, doxycycline, quinolones; prophylactic vaccine available Cefotaxime, ceftriaxone, doxycycline, azithromycin, TMP-SMX; alternative choice: quinolones or clarithromycin Consolidation Haemophilus influenzae; pleomorphic gram-negative coccobacilli More common in alcoholics; also seen with chronic cardiopulmonary disease; fever, chills, pleuritic chest pain, cough, rust-colored sputum Upper respiratory tract symptoms, fever, vomiting, irritability, cough, purulent sputum, dyspnea, affects children and older adults; affects people with chronic cardiorespiratory problems Seen frequently in middle-aged men and associated with alcoholism and diabetes mellitus, rust-colored sputum Chronic obstructive pulmonary disease, cystic fibrosis, and mechanical ventila- tion; fever, chills, and copious greenish, foul-smelling sputum Complication of gastrointestinal surgery Consolidation Klebsiella pneumoniae, gram- negative encapsulated rods Pseudomonas aeruginosa, gram- negative rods Aminoglycoside plus third-generation cepha- losporin; alternative: aztreonam, imipenem, quinolone Aminoglycoside plus ticarcillin/Clavulanate or piperacillin/tazobactam or aztreonam or imipenem Infiltrates, small pleural effusion Escherichia coli gram-negative rods Infiltrates, may have pleural effusion Aminoglycoside plus third-generation cepha- losporin; alternative: aztreonam, imipenem, quinolone Amantadine, rimantadine Patchy infiltrates Consolidation Macrolides with or without rifampin; alterna- tive: TMP-SMX, quinolone Erythromycin, doxycycline; alternative: quino- lone or other macrolide Infiltrates Virus Fever, malaise, headache, nonproductive cough Legionella species; no bacteria Acute onset with fever, diarrhea, myalgia, and abdominal pain Mycoplasma pneumoniae (atypi- Ages 5-25 years, most common in young cal pneumonia); monocytes adults; associated with otitis media and and neutrophils; no bacteria myringitis, sore throat, headache, myal- gia, dry cough, fatigue, low-grade fever Pneumocystis (carinii) jiroveci Immunosuppressed patients infants, (fungus) children, and adults); 60% of patients have AIDS Anaerobic pneumonia (aspiration Predisposition to aspiration, fever, weight pneumonia); mixed flora loss, malaise; risk increases with de- creased level of consciousness, artificial airway, and sedation; seen in individuals with poor dental hygiene Diffuse infiltrates, or chest X-ray may appear normal TMP-SMX or pentamidine; isethionate plus prednisone; alternative: dapsone plus TMP- SMX, clindamycin plus primaquine Penicillin G; alternative choices: clindamycin, metronidazole, cefoxitin Infiltrates in dependent lung fields AIDS, Acquired immunodeficiency syndrome; TMP-SMX, trimethoprim-sulfamethoxazole.
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