Respiratory Function



Respiratory Function


Thomas J. Hendrix, PhD, RN




The respiratory system is responsible for gas exchange between the environment and the blood and involves two processes: ventilation and oxygenation. Ventilation is the movement of air into and out of the lungs and consists of inhalation and exhalation. During inhalation, oxygen-rich air is moved into the lungs, then during exhalation carbon dioxide (CO2)-rich air is moved out. During oxygenation, CO2 is transferred from the vasculature to the pulmonary side of the lungs and oxygen is transferred from the pulmonary side to the vasculture, where it is loaded on to hemoglobin. The process of respiration, including rate and depth, are controlled by chemoreceptors in the medulla oblongata, the arch of the aorta, and in the carotid artery and are sensitive to oxygen levels and pH. Respiration depends on adequate structures for moving air during ventilation, an environment where oxygen and CO2 can transfer, and chemoreceptors sensitive to the maintenance of oxygenation and pH levels.



Age-Related Changes in Structure and Function


Normal aging results in changes to the ribs and vertebrae. The ribs become less mobile and chest wall compliance decreases. Osteoporosis and calcification of the costal cartilage lead to increased rigidity and stiffness of the thoracic cage. If kyphosis or scoliosis is present, degeneration of the intervertebral disks occurs, resulting in a shorter thorax with an increased anteroposterior diameter. Advanced cases may result in marked limitation of thoracic movement because of the rib cage resting on the pelvic bones. There is also progressive loss of elastic recoil of the lung parenchyma and conducting airways and reduced elastic recoil of the lung and the opposing forces of the chest wall. The lung becomes less elastic as collagenic substances surrounding the alveoli and alveolar ducts stiffen and form cross-linkages that interfere with the elastic properties of the lungs. Any and all of these structural changes makes it more difficult for the older person to ventilate. It requires more energy. Table 24–1 summarizes various changes in the aging respiratory system.



TABLE 24–1


AGE-RELATED CHANGES IN THE RESPIRATORY SYSTEM





























































































RESPIRATORY FUNCTION PATHOPHYSIOLOGIC CHANGES CLINICAL PRESENTATION
Mechanics of breathing Increased chest wall compliance Decreased vital capacity
  Loss of elastic recoil Increased reserve volume
  Decreased respiratory muscle mass and strength Decreased expiratory flow rates
Oxygenation Increased ventilation/perfusion mismatch Decreased Pao2
  Decreased cardiac output Increased A–a oxygen gradient
  Decreased mixed venous oxygen  
  Increased physiologic dead space  
  Decreased alveolar surface area available for gas exchange  
  Reduced CO2 diffusion capacity  
Control of ventilation Decreased responsiveness of central and peripheral chemoreceptors to hypoxemia and hypercapnia
Lung defense mechanisms Decreased number of cilia Decreased ability to clear secretions
  Decreased effectiveness of mucociliary clearance Increased susceptibility to infection
  Decreased cough reflex Increased risk of aspiration
  Decreased humoral and cellular immunity  
  Decreased IgA production  
Sleep and breathing

Exercise capacity
Decreased maximum oxygen consumption
  Decreased efficiency of respiratory muscles Breathlessness at low exercise levels
  Decreased reserves  
Breathing pattern Decreased responsiveness to hypoxemia and hypercapnia
  Change in respiratory mechanics Increased minute ventilation


image


A–a, Alveolar–arterial; IgA, immunoglobulin A; Pao2, partial pressure of arterial oxygen; Vt; tidal volume.


Modified from Pierson DJ, Kacmarek RM, editors: Foundations of respiratory care, New York, 1992, Churchill Livingstone.


Muscle strength declines with age, and as respiratory muscles weaken, it becomes increasingly more difficult to exert inspiratory and expiratory forces. The combination of an increasingly stiffer skeletal structure and weaker muscles results in additional effort and energy to breathe. The diaphragm, a major respiratory muscle, flattens and becomes less efficient in clients with advancing chronic obstructive pulmonary disease (COPD). Because of this, older adults use the less efficient accessory muscles of respiration such as the abdominal, sternocleidomastoid, and trapezius muscles. As the abdominal muscles become more important to older adults, their breathing patterns can become much affected by positioning and increased abdominal pressure.


Respiratory rates generally are faster and shallower in older adults: a normal rate is 16 to 25 breaths/min. This combination results in a relatively unchanged arterial CO2 pressure (Paco2). However, shallow breathing patterns may result in hypoxemia and hypercapnia as the alveoli at the base of the lungs are underventilated, which, in turn, results in a decreased ventilation/perfusion ratio and less effective alveolar gas exchange. Age-related reductions in cardiac output and mixed venous oxygen content compound the effect of the ventilation/perfusion imbalance in older adults. In healthy older adults the number of alveoli remains relatively unchanged but their structure is altered. As a result, the number of functioning alveoli decreases. With age, alveolar supporting structures deteriorate, which leads to a progressive loss of the intraalveolar septum. As the alveolar septal walls become thinner, the alveoli enlarge because of dilation of the proximal bronchioles, but fewer capillaries are available for gas exchange. The increase in physiologic dead space is seen as the capillary structures surrounding the alveoli diminish. The result is a decrease in the surface area available for gas exchange from the normal 80 m2 at age 20 to about 65 to 70 m2 by age 70. As such, there is less surface area for gas exchange to take place, which contributes to the systemic reduction in partial pressure of arterial oxygen (Pao2).


Older adults have a decrease in the number and effectiveness of cilia in the tracheobronchial tree, which results in increasing difficulty clearing secretions. Older clients also have decreased immunoglobulin A (IgA), which is found in the nasal respiratory mucosal surface that neutralizes viruses. The combination of decreased IgA and an increase of pooling secretions makes infections more likely. With repeated respiratory tract infections or smoking, the effectiveness of the ciliary action and the number of cilia are significantly decreased, which results in an ineffective mucociliary escalator.


One of the primary functions of the respiratory system is gas exchange. For a healthy adult, the normal Pao2 is 80 to 100 mm Hg. However, after the age of 60, the Pao2 drops by 1 mm Hg per year. Therefore, a Pao2 of 70 mm Hg for a 70-year-old is relatively normal, which is how the phrase “70 at 70” originated. The expected decrease in Pao2 is most likely caused by some of the factors previously discussed, such as reduced tidal volume, less alveolar surface area, and increased residual volume.


The oxygen-carrying capacity of the blood is reduced with age. Hemoglobin is the molecule most responsible for oxygen transport to peripheral tissues, but its levels are diminished in older adults. The alveolar–arterial (A-a) oxygen gradient, a measure of the efficiency of oxygen transfer from lungs to the blood, compares the partial pressure of oxygen in alveolar air (PAo2) with the partial pressure of oxygen in arterial blood (Pao2). With rapid diffusion in a healthy adult the net difference is close to zero. This gradient normally increases in older adults, most likely because of ventilation/perfusion mismatching.


The arterial pH of the older person remains within the normal adult range of 7.35 to 7.45 unless influenced by an acute illness or comorbidity. Despite an increase in residual volume, Paco2 does not normally rise, primarily because of increased ventilation. However, older adults do not react as quickly to changes in either hypoxemia or hypercapnia. The normal clinical response to hypoxemia is an increase in the rate and depth of respiration, as well as an increase in heart rate and blood pressure. Older clients show less increase in heart rate and a lower response to increasing CO2. In fact, their ventilatory responses to hypoxia and hypercapnia may be diminished by as much as 50% in comparison with adults in their 20s largely as a result of a reduced sympathetic nervous system response. Therefore, careful assessment is crucial. The most sensitive clinical indicator for hypoxia and hypercapnia in older adults is mental status changes and complaints of occipital headaches or forgetfulness that are not otherwise explained. Finally, dyspnea on exertion is an increasing problem because any increased oxygen demand can lead quickly to symptomatic hypoxia.


As previously described, many of the changes in pulmonary functions in older adults are related to the changes in elastic recoil and musculoskeletal changes of the chest wall. Table 24–2 lists the lung volumes measured, the normal findings, and alterations related to aging. The ability to determine accurate pulmonary function by testing requires patience on the part of the health care provider as an older client may not be able to perform quickly. Ensure adequate time for this assessment of the older adult client.



Although the total lung capacity (TLC) remains relatively unchanged, the individual volumes that comprise TLC change dramatically. Tidal volume (Vt) is decreased in older adults. Vital capacity (VC) is also decreased as a result of decreased mobility of the chest wall and altered inspiratory and expiratory capabilities. The rate of reduction of VC is greater in older men than in older women. The inspiratory capacity of older adults is affected by the decreased ability to take deep breaths. Decreased compliance of the thorax accounts for the increase in residual volume (RV) and expiratory reserve volume (ERV). RV is also reduced because of decreased muscle strength and a shallow breathing pattern. As a result, functional dead space ventilation is increased from one third to as much as one half of each breath, which results in a decrease in the volume of air that can participate in gas exchange.


Airflow in the tracheobronchial tree is affected by the size of the airway, resistance in the airway, muscle strength, and elastic recoil. When measured in the older client, all of these indices are decreased. Forced expiratory volume in 1 second (FEV1) is reported to drop between 25 and 30 mL per year after age 30. Changes in the airflow measures are related to the stiffness of the chest wall and the loss of elastic recoil of the lungs. The decrease in thoracic muscular strength contributes to the decreased force of the air moved, and there can be as much as a 50% reduction in the maximum voluntary ventilation and FEV between ages 30 and 90.


At low tidal volumes, small airways tend to close early because of the loss of elastic recoil and decreased flow rates caused by increased airway resistance, trapping air in the alveoli. Closing capacity (CC), the volume at which the smallest airways close, increases with age, and by age 65 it exceeds the functional residual capacity (FRC) when in the upright position. This contributes to early airway closure. Other factors contributing to early airway closure include increased time in a supine position and shallow breathing.


In younger adults, pulmonary vascular circulation is a relatively low pressure system with high distensibility and low resistance. As adults age, these vessels become less distensible and more fibrous, which results in increased pulmonary artery diameter and greater thickness of the vessel wall; in turn, these increases result in increased pulmonary vascular resistance and increased pulmonary artery pressure. The alveolar capillary membrane also thickens, which further reduces the surface area available for gas exchange. The number of functional capillaries declines, which results in decreased alveolar vascularity; this in combination with a diminished cardiac output causes a decrease in pulmonary capillary blood flow.



Factors Affecting Lung Function


Exercise and Immobility


Exercise has a positive effect on the respiratory and cardiovascular systems. However, the ability of older clients to perform exercise is affected by the changes in cardiac output, skeletal muscle function, joint function, and overall coordination.



Increased oxygen demands during exercise periods may well exceed the abilities of older clients, and for those with COPD, activity intolerance is exacerbated. In addition, older clients are more likely to have comorbidities involving the cardiovascular and respiratory systems. Strength and endurance may also be reduced, which leads to increased immobility and increased breathlessness when activity is attempted. Older clients with COPD and immobility may benefit from a program of regular exercise to increase strength and endurance and decrease breathlessness as the respiratory muscles become trained (see Health Promotion/Illness Prevention Box).



Smoking


Smoking damages lungs. Prolonged exposure to secondhand smoke has also been shown to damage the lungs of nonsmokers. Heavy smokers may demonstrate a ninefold increase in the reduction of FEV1 over normal expected reductions. Cilia, which are paralyzed by nicotine, are unable to protect and clean the lungs, and, when coupled with the increased mucus production of goblet cells that is induced by tobacco, respiratory infections become more likely. Cigarette smoke also causes bronchoconstriction, increased airway resistance, and increased closing volumes and interferes with gas exchange because the carbon monoxide byproduct of tobacco competes with oxygen for the hemoglobin molecule. Many medications are also affected by smoking, which decreases clearance and increases serum drug levels. Some drugs altered by smoking include antidepressants, propranolol, theophylline, aminophylline, insulin, erythromycin, and lidocaine.



Smoking Cessation


Smoking cessation is imperative. The five components (five As) of smoking cessation consist of asking, advising, assessing, assisting, and arranging. At each encounter the patient is asked about tobacco use. This gives the health care worker an opportunity to advise and discuss the health benefits and promote smoking cessation. When speaking to older adults, the nurse should use strong, clear, and personalized language. The nurse should assess older adults for their willingness to give up smoking and determine how soon they are ready to start the process. Then the nurse assists older adults with smoking cessation by encouraging them to set a quit date,



reviewing preparations for quitting (e.g., removing associated objects like ashtrays), recommending nicotine replacement therapy, providing advice on successful quitting (e.g., avoid constant exposure to other smokers), providing supplemental educational materials, and offering appropriate skills training and support. Finally, the nurse arranges for follow-up (Agency for Health Care Research and Quality [AHCRQ], 2000).


Many new treatments are available to assist older smokers in quitting. These include the use of bupropion hydrochloride, nicotine gum, nicotine patches, and nicotine inhalation systems. Bupropion hydrochloride is given for 3 days at 150 mg per day and then increased to 150 mg twice a day, with doses 8 hours apart and the first dose in the morning. Older clients are encouraged to smoke during the first week of treatment and to set a quit-smoking date before the end of the first 14 days of treatment. Nicotine inhalation systems, gums, and patches are used to replace the client’s need for nicotine. While using these nicotine substitutes, the older adult client should not smoke. Gradually over a 6- to 8-week period, the frequency of usage is decreased.




Sleep


Older adults typically have more problems falling asleep, spend less time in the deeper stages of sleep, have irregular and early morning wake ups, and spend less total time sleeping. Diminished cough and arousal reflexes increase the likelihood of aspiration during sleep.


Older adults are also more likely to have primary sleep disorders, take medications that interfere with sleep, and suffer from sleep apnea. Older males with pathologic conditions of the prostate have increased nocturia. In short, older adults are at increased risk of insomnia. Older adults are also more likely to have hypertension and to be overweight, both of which make sleep apnea more likely. If a primary sleep disorder is suspected or physical functioning becomes impaired, formal sleep studies may be appropriate.



Anesthesia and Surgery


An older client undergoing surgery has an increased risk of aspiration as a result of loss of laryngeal reflexes. If surgery is an emergency, this risk is increased because of the older client’s delayed gastric emptying and the potential for a full stomach. The normal healthy adult has a risk of postoperative atelectasis because of general anesthesia and an inability or unwillingness to cough and deep breathe because of incisions, pain, and drowsiness. In the older adult, these risks are amplified because of decreased muscle strength, a decreased cough reflex, and a greater likelihood of alterations in consciousness. Postoperative immobility decreases ventilation and increases the risk of airway clearance problems. The older adult has a reduced thirst sensation. A healthy adult patient tends to be slightly “dry” after surgery, but the reduced thirst sensation of the older adult increases the risks of hypovolemia and resultant thickened secretions that are difficult to clear. Promotion of deep breathing for effective pain management, adequate hydration, frequent position changes, and early mobility will decrease the risk of developing atelectasis.



Respiratory Symptoms Common in Older Clients


Respiratory symptoms common in older clients include alterations in breathing patterns, dyspnea, and coughing. Abnormal breathing patterns in older clients can also be indicative of other metabolic and respiratory illnesses. An early sign of respiratory problems is a change in mental status. Because the physiologic responses to hypoxemia and hypercapnia are blunted in older clients, compensatory changes in heart rate, respiratory rate, and blood pressure may be delayed and cerebral perfusion may suffer. Mental status changes may include subtle increases in forgetfulness and irritability. Older clients may also complain of an occipital headache or confusion when awakening from sleep. If these signs persist, a more in-depth evaluation of the older client’s respiratory status is indicated.


Complaints of dyspnea or breathlessness in older clients are often associated with underlying respiratory and cardiac disease. Dyspnea is a perception of breathlessness that is difficult for the older client to quantify; dyspnea may therefore be dismissed, especially when no clinical evidence can be attributed to the complaint. Older clients most often describe their breathlessness as a sensation of an inability to get enough air, difficulty taking a deep breath, breathing rapidly, or a choking or smothering feeling. Dyspnea at rest is most often associated



with an acute respiratory or cardiac illness, whereas dyspnea on exertion may be related to immobility and respiratory muscle deconditioning. Older clients with COPD may experience dyspnea on exertion initially and dyspnea at rest as the disease progresses (see Evidence-Based Practice: COPD and Dyspnea). Dyspnea is a common complaint in older clients with pulmonary disease. However, older clients usually do not complain of dyspnea until it begins to interfere with their activities of daily living (ADLs) and then only if those activities are important to them. For example, it may become difficult to use the stairs. An older client may simply choose the elevator or escalator and not consider reporting the shortness of breath associated with stair climbing. It is important to determine which ADLs an older client no longer participates in and why.


The cough mechanism in older clients is altered because of the loss of elastic recoil and decreased respiratory muscle strength. Causes of coughing in older clients include postnasal drip, chronic bronchitis, acute respiratory tract infections, aspiration, gastroesophageal reflux disease (GERD), congestive heart failure (CHF), interstitial lung disease, cancer, and angiotensin-converting enzyme inhibitor medications for hypertension and CHF. Because of the age-related changes that affect an older client’s coughing mechanism, it is important to recommend cough suppressants with caution. Suppression of the cough and depression of any respiratory function could lead to retention of pulmonary secretions, plugged airways, atelectasis, and aspiration.



Respiratory Alterations in Older Clients


Chronic respiratory disease affects not only older clients but also their families. Many clients with respiratory illness feel a loss of control over their lives because of breathlessness on exertion and



at rest. They may become demanding and controlling in dealing with their families and friends. The quality of older clients’ lives depends on their feelings about and control of the disease. Support groups sponsored by the American Lung Association and local hospitals are available to help clients and families deal with anger, loss of control, and hopelessness. The family or a significant other needs to be included in all aspects of planning and care for an older client with respiratory illness. The client’s success in complying with the medical recommendations may depend on the assistance he or she receives in getting to the physician’s office, getting to the pharmacy for medications, administering medications, and performing ADLs. Older clients with respiratory disease need a good family support system and a health care team to support both them and their families (see Evidence-Based Practice: COPD and Family Dynamics).


Respiratory disease is divided into two categories: (1) obstructive pulmonary disease and (2) restrictive pulmonary disease. Obstructive lung diseases are characterized by changes in expiratory airflow rates and obstruction of the airway. The lumen of the airway can be decreased by mucus, edema of the airway lining, or constriction of the muscles surrounding the airway, causing bronchoconstriction. Restrictive lung disease is characterized by a decreased ability to expand the chest, impaired inhalation, and decreased lung volumes. Changes in the chest wall, lung parenchyma, pleural space, and extrapulmonary factors such as body mass can result in restrictive lung disease. Examples of these diseases include bronchogenic carcinoma and tuberculosis. Other respiratory diseases seen in older clients include bronchopulmonary infections, pulmonary edema, and pulmonary emboli.



Obstructive Pulmonary Disease


Asthma


Asthma is a chronic inflammatory disease that affects the airways and is characterized by reversible airway obstruction, airway inflammation, and increased airway responsiveness to a variety of stimuli. Asthma has higher morbidity and mortality rates in older adults than in other age groups. Older patients diagnosed with asthma have lower expiratory flow rates and fewer symptom-free periods. Because of other comorbidities and the normal deterioration caused by aging, a diagnosis of asthma may be delayed by the provider. Airway inflammation contributes to airway hyperresponsiveness; airflow limitations, including acute bronchoconstriction, airway edema, and mucous plug formation; airway wall remodeling; respiratory symptoms; and disease chronicity (National Heart, Lung, and Blood Institute [NHLBI], 2007a. Inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, often at night or early in the morning. Recent evidence suggests that persistent abnormalities in lung function are associated with subbasement membrane fibrosis in some clients. Patients with asthma, especially older ones who may not have had this disease through most of their lives, require careful education to include self-management, how to adjust medications during exacerbations, and the correct way to prepare themselves for exposure to known triggers.


An asthma attack can be precipitated by exposure to allergens or irritants such as changes in weather, odors, or stress. In older clients asthma is often associated with viral respiratory infections. Signs and symptoms include dyspnea, audible wheezing, palpitations, tachypnea, tachycardia, use of accessory muscles of respiration, pulsus paradoxus, diaphoresis, and chest hyperinflation. Initially, a client may hyperventilate and effectively blow off increasing CO2. Falling Pao2 and pH with rising Paco2 are indicative of imminent respiratory failure. The increasing Paco2 is a result of the client’s exhaustion and inability to hyperventilate.




Treatment


The goals of asthma therapy are to control asthma by reduction of impairment and risk, which can be done by (1) preventing chronic and troublesome symptoms like coughing or breathlessness during the day, at night, or after exercise, (2) maintaining (near) normal pulmonary function, (3) maintaining normal activity levels including exercise and attendance at work or school, (4) requiring infrequent use (≤2 days a week) of short-acting inhaled beta2-agonists and satisfying the client’s and family’s expectations of asthma care, (5) preventing recurrent exacerbations and minimizing emergency department visits, and (6) providing optimal pharmacologic treatment with minimal or no adverse effects (NHLBI, 2007a). The NHLBI (2007a) recommends a stepwise approach to pharmacologic management. The specific drug, dose, and frequency are dictated by the severity of the asthma attack at the time that therapy is initiated, then the drug should be stepped down to maintain long-term control with the minimum medication necessary. Medications are classified into two categories: long-term-control medications and quick-relief medications.



Long-term control medications

Long-term control medications are taken on a daily basis and include antiinflammatory agents, long-acting bronchodilators, and leukotriene modifiers. Corticosteroids are the most potent and effective long-term-control medications in the treatment of mild, moderate, or severe persistent asthma. They are well tolerated and safe when used at the recommended dosage. Most of the benefit is achieved with relatively low doses, and the potential for side effects increases with the dose. However, for asthma not controlled with maintenance doses of corticosteroids, there are now two options. The first is to combine the corticosteroids with long-acting beta2-agonists, and the second, most recent recommendation is to increase the dose of corticosteroids (NHLBI 2007b). The clinical response to corticosteroids is a reduction in airway inflammation, improvement in peak expiratory flow rate (PEFR), diminished airway hyperresponsiveness, prevention of exacerbations, and possible prevention of airway wall remodeling. Corticosteroids are generally inhaled twice a day.


Long-acting beta2-agonists act by relaxing the smooth muscle of the airways and stimulating beta2-receptors to increase cyclic adenosine monophosphate. They are not recommended as a monotherapy for long-term control but rather are often prescribed in combination with corticosteroids. The duration of action is 12 hours for a single dose. These medications are also not indicated for acute exacerbation, although they may be used before to prevent exercise-induced exacerbations; however, when beta2-agonists are used on a long-term basis before exercise, their effects last only 5 hours. An example of these medications is inhaled salmeterol (Serevent Diskus).


The leukotriene modifiers are potent biochemical mediators that are released from mast cells, eosinophils, and basophils. They act on the lungs, causing airway smooth muscle contraction and increased mucous secretion; they also attract and activate inflammatory cells in the airways. Leukotriene antagonists improve lung function, diminish symptoms, and reduce the need for short-acting beta2-agonists. They are an alternative, though not preferred, therapy for the treatment of mild persistent asthma. They can also be used with corticosteroids, although the long-acting beta2-agonists are the preferred adjunct. An example of a leukotriene antagonist is montelukast (Singulair, Merek, Whitehouse Station, NJ).


Cromolyn and nedocromil stabilize mast cells. Although they are not the preferred method of treatment, they are also an alternative therapy for mild persistent asthma and can also be used before exercise or before a known exposure to a trigger.


The immunomodulators are monoclonal antibodies that prevent the binding of IgE to the receptors cells of the basophils and mast cells. They are used for the treatment of severe persistent asthma, especially if allergies are the primary trigger. The nurse should always be prepared and equipped to treat for anaphylaxis that may occur.



Quick-relief medications

Quick-relief medications are used to treat acute symptoms and exacerbations such as chest tightness, coughing, and wheezing. This group of medications includes short-acting beta2-agonists, anticholinergics, and systemic corticosteroids. Short-acting beta2-agonists are bronchodilators that provide smooth muscle relaxation within 30 minutes and are the drug of choice for treating acute asthma symptoms and preventing exercise-induced exacerbations (NHLBI, 2007). Older clients who use more than one canister per month do not have adequate control and need additional antiinflammatory therapy. Daily use of short-acting beta2-agonists is not recommended.


Anticholinergics, such as ipratropium bromide (Atrovent), may provide an additive benefit to inhaled beta2-agonists in the treatment of severe exacerbations. They may also be used as an alternative to short-acting beta2-agonists for patients who do not tolerate them well. Finally, systemic corticosteroids, although not short-acting, may be used in the treatment of moderate to severe asthma exacerbations as an adjunct to the short-acting beta2-agonists. Their onset of action is more than 4 hours, and they act by preventing progression of the exacerbation, speeding recovery, and preventing early relapse (NHLBI, 2007b).



Asthma medications administered through a stepwise approach



Step 1: No daily medication indicated. Short-acting beta2-agonists are used as required (prn). If they are used more than two times a week, consider long-term control therapy.


Step 2: Daily low-dose inhaled corticosteroid.


Step 3: Daily low-dose inhaled corticosteroid used in conjunction with a long-acting bronchodilator. An alternative is to increase the corticosteroid dose to a medium level without the addition of a long-acting bronchodilator. If ineffective, a leukotriene modifier may be added to a low-dose corticosteroid. Short-acting beta2-agonists are used prn. If they are used daily or if there is an increase in use, add additional long-term control therapy.


Step 4: Daily antiinflammatory: inhaled corticosteroid (medium dose) and a long-acting bronchodilator. If ineffective, a leukotriene modifier may substitute for the long-acting bronchodilator. Short-acting beta2-agonists are used prn. If they are used daily or if there is an increase in use, add additional long-term control therapy.


Step 5: Daily inhaled corticosteroid (high dose) plus a long-acting bronchodilator. Consider an immunomodulator for patients with allergies. Short-acting beta2-agonists are used prn. If they are used daily or if there is an increase in use, add additional long-term control therapy.


Step 6: Daily inhaled corticosteroid plus long-acting bronchodilator plus an oral corticosteroid. Consider an immunomodulator for patients with allergies.


Patient education, environmental control, and quick management of comorbidities is required at each step. An asthma specialist should be considered at step 3 and implemented at step 4.


Asthma management in older adults may coexist with management of chronic bronchitis or emphysema. A trial of systemic corticosteroids is useful in determining the presence of reversible airflow obstruction (NHLBI, 2007a). An older adult may have medical conditions such as cardiac disease and osteoporosis that are aggravated by asthma medications. Older adults with ischemic heart disease may be more sensitive to beta2-agonist side effects such as tremors and tachycardia; the dosage may need to be adjusted, or different medications may need to be added as an adjunct.


Corticosteroids may cause confusion, agitation, and changes in glucose metabolism in older adults. The use of inhaled corticosteroids in older adults may predispose them to a reduction in bone mineral content, especially if there is preexisting osteoporosis, changes in estrogen levels affecting calcium utilization, and a sedentary lifestyle. NHLBI (2007a) recommends calcium and vitamin D supplements, as well as estrogen replacement therapy when appropriate. There is also an increased risk for adverse drug and disease interactions: asthma may be exacerbated by the use of nonsteroidal antiinflammatory agents for arthritis, aspirin for circulation, nonselective beta-blockers for hypertension, or glaucoma eye drops that contain beta-blockers. Finally, it is imperative that older adults are carefully assessed for their ability to use prescribed medications appropriately and devices correctly as there is an increased risk of physical (arthritis, visual) or cognitive impairments that could be challenging for them (NHLBI, 2007b).



Nursing Management


image Assessment


Evaluation of respiratory symptoms includes effect on ADLs, quantity of breathlessness on a scale of 1 to 10 (Stupka & deShazo, 2009), presence of asthma triggers, and frequency of the need for bronchodilator therapy. Physical assessment includes inspection of the chest for shape and symmetry and determination of respiratory rate and pattern, body position, use of accessory muscles of respiration, and amount and color of sputum production. Palpation and percussion of the chest are indicated so that increased tactile fremitus, chest wall movement, and diaphragmatic excursion can be assessed. When the chest wall is auscultated, the older adult should be given enough time to take deep breaths comfortably without becoming dizzy. Determine the presence of any wheezing, the phase of respiration in which it occurs, and whether it is present during a forced expiratory maneuver. Determination of the peak expiratory flow rate (PEFR) with a peak expiratory flow meter (PEFM) is important in determining trends of airway resistance (Fig. 24–1).




image Diagnosis


Nursing diagnoses common for an older client with asthma include (Kaufman, 2007)



The diagnosis of asthma is based on episodic symptoms of airflow obstruction that are partially reversible. Key indicators for the diagnosis of asthma include (1) wheezing, (2) a history of a cough that is worse at night, (3) recurrent difficulty breathing and chest tightness,(4) variation in PEFR of 20% or more, and (5) symptoms that worsen during exercise, with viral infection, in the presence of environmental irritants such as animal fur, dust mites, mold, smoke, pollen, changes in weather, airborne chemicals, or dust, during menses, or with strong emotional expression (NHLBI, 2007a).


Pulmonary function tests (PFTs) are used to measure the presence and amount of airway obstruction. An FEV1/forced vital capacity (FVC) ratio of less than 65% indicates obstruction of airflow. Measurements of FEV1, FVC, and the FEV1/FVC ratio before and after inhaled short-acting bronchodilators are recommended. Other diagnostic procedures include methacholine, histamine or exercise challenge, chest x-ray studies, allergy testing, ear, nose, and throat evaluation for nasal polyps and sinus disease, evaluation for gastroesophageal reflux, a 1- to 2-week evaluation of diurnal variation in PEFR, and evaluation for vocal cord dysfunction (NHLBI, 2007a).


The diagnosis and management of asthma in older clients is more difficult than in younger clients. The symptoms of asthma mimic other conditions such as myocardial ischemia or pulmonary embolus (NHLBI, 2007a). Asthma may appear as late as the eighth or ninth decade of life. Older adults with asthma may not show allergic skin sensitivity; therefore serum IgE and eosinophil levels can be more predictive. Incomplete reversibility of airflow obstruction is increasingly common (NHLBI, 2007). Older adult clients with asthma may only achieve a 12% improvement in their FEV1, even with optimally prescribed inhaled bronchodilators (NHLBI, 2007a). In older clients with heartburn, coughing, nocturnal symptoms occurring early in the night, and resistance to routine therapy, gastroesophageal reflux disease should be considered (NHLBI, 2007a).


Asthma is classified into three categories according to the severity of symptoms, frequency of nighttime symptoms, and lung function (Table 24–3). Asthma also occurs as seasonal asthma, cough variant asthma, and exercise-induced asthma.



TABLE 24–3


CLASSIFICATION OF ASTHMA BY SEVERITY OF DISEASE BEFORE TREATMENT


















































CHARACTERISTIC MILD MODERATE SEVERE
Frequency of exacerbations ≤2 times/week; lasting less than 1 hour >2 times/week; may last days; not frequently severe Frequent exacerbations, often severe
Frequency of symptoms Minimal Often Continuous
Exercise tolerance Minimal Diminished Poor; activity limited
Frequency of nocturnal asthma ≤2 times/month >2 times/week almost nightly, chest tight in am
School or work attendance Good Fair Poor
Pulmonary function: peak expiratory flow rate (PEFR) >80% 60% to 80% <60%
PEFR variability <20% 20% to 30% >30%
Spirometry Minimal airway obstruction Airway obstruction evident with reduced expiratory flow at low lung volumes Substantial airway obstruction with increased lung volumes and marked unevenness of ventilation


image


After treatment, severity is measured by the minimum medications needed to maintain good health.


From National Heart, Lung, and Blood Institute, National Institutes of Health (NIH). (2007a). Clinical practice guidelines; guidelines for the diagnosis and management of asthma. Retrieved May 2009, from www.nhlbi.nih.gov/guidelines/asthma/index.htm.




image Intervention


Interventions for clients with asthma include health maintenance, lifestyle changes, administration of medications at designated time intervals, exercise, and promotion of hydration and good nutrition (McCloskey & Bulechek, 1996). Education is started at the time of diagnosis and is integrated into every aspect of care. Emphasis is placed on asthma self-management; basic facts about asthma; roles of medications; environmental control measures; the use of inhalers, spacers, and PEFMs; and a daily written action plan for management of exacerbations (NHLBI, 2007b). Additional topics include smoking cessation, weight gain or loss, exercise requirements, and breathing retraining.


In addition to the basic interventions already described, older clients may require special considerations. The nurse should be accommodating to any neurologic changes such as altered senses, decreased fine motor movements, and memory loss. These expected changes can be managed in various ways. Make treatment plans simple. Use short explanations and easily explained graphs. Make sure instructional materials are in large type, and use color-coded peak flow meter diaries. Increase lighting, and speak in a low pitched clear voice. Have the patient read and then repeat the instructions, and allow sufficient time for instruction, demonstration, and return demonstrations (NHLBI, 2007b).




Chronic Bronchitis


Chronic bronchitis is a clinical syndrome characterized by excessive mucous production with a chronic or recurrent cough on most days for a minimum of 3 months of the year for at least 2 consecutive years in a patient in whom other causes have been ruled out. There is hypertrophy of the bronchial mucous gland, an increase in the number of goblet cells, and a decrease in the effectiveness of the mucociliary escalator, usually as a result of repeated infections. Cigarette smoking is the single most important factor that exacerbates chronic bronchitis. Chronic bronchitis is associated with right-sided heart failure, cor pulmonale, polycythemia, hypoxemia, and respiratory insufficiency. Clinical symptoms include a persistent cough, dyspnea on exertion, purulent sputum, cyanosis, crackles on auscultation, tachycardia, pedal edema, unexplained weight gain, and a decreased Pao2 with a normal or elevated Paco2.



Emphysema


Emphysema usually occurs between ages 60 and 70 and is characterized by progressive destruction of the alveoli and their supporting structures. The alveoli distal to the terminal bronchioles become enlarged. Loss of connective tissue supporting the alveoli leads to permanent obliteration of the peripheral airways. Physical signs include the classic barrel chest appearance and the use of accessory muscles of respiration. Emphysema is often associated with clients who have a history of smoking. The clinical presentation includes dyspnea on exertion or at rest, decreased weight, a chronic cough with little sputum production, digital clubbing, hyperresonance of the chest on percussion, an elevated hemoglobin level, crackles and wheezes on auscultation, and abnormal PFTs with decreased VC, increased TLC, increased FRC, and decreased FEV1.



Chronic Obstructive Pulmonary Disease


COPD is characterized by progressive airflow limitation that is not fully reversible and, during the course of the disease, lung tissue that becomes abnormally inflamed. The changes manifested include peripheral airway inflammation, airway fibrosis, hypertrophy of smooth muscles, hyperplasia of goblet cells and resultant mucus hypersecretion, and eventually, the destruction of the lung parenchyma (Barnett, 2009). The two reversible components in COPD are airway diameter and expiratory flow rate. COPD is a broad term that describes two obstructive airway diseases: chronic bronchitis and emphysema. Asthma may also be included in COPD, especially if there is a component of airway hyperreactivity; however, it may be difficult to differentiate between the two, especially if a history of cigarette smoking is present (Kaufman, 2007).


COPD is a progressive and ultimately fatal disease. The fatality rate for COPD is more than two times as high in men as in women between the ages of 65 and 74 and three times as high between the ages of 75 and 84. There has been an increase in the number of women with COPD since 1991 (Rabe, 2007). This is most likely a result of the increased number of women who smoke. Risk factors for COPD include age, male gender, reduced lung function, air pollution, exposure to secondhand smoke, familial allergies, poor nutrition, and alcohol intake. COPD is often a comorbid factor in deaths from pneumonia and influenza, it accounts for increased physician visits (Mannino, 2002), and it is preventable and treatable.




Diagnostic Tests and Procedures


A diagnosis of COPD should be considered based on a history of exposure to tobacco smoke or other occupational irritants and progressive dyspnea, a chronic cough, and chronic sputum production; the diagnosis should then be confirmed with spirometry testing. COPD is staged based on the percent of the predicted value of FEV1 (Table 24–4).



Most patients seek medical treatment because of progressive dyspnea leading to breathlessness and anxiety. Chronic coughing is often the first sign of COPD, but lack of a cough does not rule it out. Initially, chronic coughing is intermittent, and patients may describe “good days and bad days.” As the disease progresses, the cough is present every day. Wheezing and “chest tightness” may vary from day to day and may vary throughout a single day. Once again, an absence of tightness or wheezing does not rule out COPD. Weight loss, anorexia, depression, and anxiety often accompany the pulmonary signs of COPD (Rabe, 2007).



Treatment


Managing COPD focuses on increasing treatment depending on the disease severity; the clinical status of the patient with airflow limitations provides a general guide. Treatment is focused on symptom management through education about the disease and active engagement of the older client in care management. Aspects of management include smoking cessation, a stepwise approach to pharmacotherapy, limited occupational exposure to toxins and air pollution, and a healthy lifestyle, including regular exercise and weight control. Proper nutrition is essential for promoting efficient respiratory muscle work. Pneumococcal and annual influenza vaccinations are recommended for older clients. During peak influenza season, older clients with COPD should avoid crowds to decrease the risk of contracting influenza.


The single most important and cost-effective intervention is smoking cessation. Smoking cessation improves FEV1 and helps relieve symptoms. Benefits to smoking cessation include reduction in the number of respiratory infections, improvement in the function of the mucociliary clearance of the lungs, decreased coughing and dyspnea, increased appetite, and decreased sputum production. Older clients with COPD should also avoid secondhand smoke as it can also cause bronchospasm and coughing. There are now many pharmacotherapies available to help the older client quit smoking. Nicotine replacement drugs and some antidepressants (bupropion and nortriptyline) can increase smoking abstinence rates but should be used as part of an overall program of abstinence (Rabe, 2007).


Pulmonary pharmacotherapy is recommended in a stepwise approach based on the severity of airway obstruction and client symptoms. None of the medications modify the long-term decline of the client and thus are only used to reduce symptoms and complications. Bronchodilators are key in managing the symptoms of COPD and are given for both long-term therapy and during acute exacerbations; they include beta-adrenergic drugs, anticholinergics, and methylxanthines. Once a client reaches stage 3, the addition of inhaled glucocorticosteroids is appropriate. However, chronic treatment with systemic glucocorticosteroids is not recommended.



Bronchodilators

Bronchodilators are the central pharmacologic tool used in managing the symptoms of COPD. They can be prescribed for long-term maintenance or short-term exacerbations. Inhaled medications are preferred because the systemic complications they cause are both less severe and more rapidly reversed. However, with inhalation therapy, proper training is essential. The primary bronchodilators used are the beta2-agonists, anticholinergics, and the methylxanthines. The choice of drug will depend on the patient’s response.







Oxygen therapy

Long-term oxygen therapy increases survival rates and improves hemodynamics, exercise and lung capacity, and mental status. Supplemental oxygen therapy is indicated for clients with a resting Pao2 ≤ 55 mm Hg or a Sao2 ≤ 88% with or without hypercapnia (Fig. 24–3). Oxygen therapy may also be indicated if the client’s Pao2 is between 55 and 60 mm Hg, the Sao2 is 88% or less, or if there is evidence of pulmonary hypertension, peripheral edema, or polycythemia (hematocrit level > 55%). The primary goal of oxygen therapy is to increase the baseline Pao2 to at least 80 mm Hg and the Sao2 to at least 90%.


Nov 26, 2016 | Posted by in NURSING | Comments Off on Respiratory Function
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