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Find out about this common but lesser-known respiratory condition and how to help your patient.
YOU'RE PROBABLY FAMILIAR with chronic obstructive pulmonary disease (COPD) and asthma, diseases that also are known to the general public. Although not uncommon, restrictive lung disease (RLD) isn't as well known to health care providers and is almost unknown to the public.
In RLD, lung volumes are reduced and the patient has difficulty inhaling. In contrast, patients with COPD or asthma have problems getting air out of their lungs. In this article, I'll describe the five basic RLD groups-pulmonary (interstitial), chest wall/thorax, neurologic or neuromuscular, cardiac, and abdominal-and what you need to know if you're caring for a patient with one of these conditions. Note that RLD often is divided into two groups anatomically: intrinsic, involving the lung parenchyma, and extrinsic, involving problems in the chest wall, pleurae, and respiratory muscles. Under this approach, intrinsic RLD is synonymous with pulmonary RLD, and extrinsic RLD includes the other four groups (chest wall/thorax, neurologic or neuromuscular, cardiac, and abdominal).
In this type of RLD, the lung interstitium (tissue between the alveoli and capillaries) becomes inflamed and fibrotic. The fibrotic changes apparently start with activation of the inflammatory cells and subsequent release of cytokines, chemokines, and tissue growth factors into the interstitium. These mediators cause cells to proliferate and form fibroblasts and myofibroblasts, leading to an increase in the extracellular matrix. Agents involved in matrix remodeling and the fibrotic process include interleukin-1, interleukin-6, type I collagen, type III collagen, elastin, tumor necrosis factor alpha, and transforming growth factor beta. The normal architecture of the lung is disrupted and honeycomb scarring appears.1,2
This process resembles wound repair gone haywire. The fibrotic changes form extra collagen tissue and scarring in the interstitium, and alveoli are disrupted or destroyed. The fibrosis makes the lungs stiff by increasing the elastic recoil (the tendency to contract after being stretched) that occurs during expiration. Fibrosis also makes the lungs less compliant, defined as a decreased tendency to be stretched or distended during inspiration. Both of these effects (increased elastic recoil and decreased compliance) work together to decrease lung volumes. Also, fibrosis and scarring causes the alveolar-capillary membrane to become thicker, reducing gas diffusion from alveoli to capillaries and vice versa.
This type of RLD has four general subdivisions:
* Idiopathic pulmonary fibrosis has no known cause but has been associated with the use of bleomycin, amiodarone, methotrexate, or cyclophosphamide.3,4 This is the most common form of pulmonary RLD, with an incidence of some 27 to 29 cases per 100,000 Americans.4
* Pneumoconiosis is also called occupational lung disease because this form of pulmonary RLD is caused by inhaling particulate dust while on the job. The most common particles that cause pneumoconiosis (and the related disease) are silica (silicosis), iron (siderosis), asbestos (asbestosis), coal (coal worker's pneumoconiosis), and organic dust (farmer's lung, mushroom worker's lung).5
* Collagen vascular diseases include scleroderma, dermatomyositis, systemic lupus erythematosus, rheumatoid arthritis, and ankylosing spondylitis.
* Other causes include sarcoidosis, lymphangioleiomyomatosis, pulmonary histiocytosis X, pulmonary vasculitis, pulmonary alveolar proteinosis, eosinophilic pneumonia, and bronchiolitis obliterans organizing pneumonia.6
Restrictive lung disease caused from problems with the chest wall/thorax fall into four subdivisions: scoliosis, kyphosis, kyphoscoliosis, and disorders of the pleurae. In each of the first three, the chest wall is deformed and movement of the chest is limited, reducing lung volumes.
Scoliosis is a lateral deviation in the normally straight vertical line of the spine. Kyphosis is an abnormally increased convexity in the curvature of the thoracic spine as seen from the side. (See Some causes of chest wall/thorax RLD.) Kyphoscoliosis is a backward and lateral curvature of the spinal column that can lead to severe cardiopulmonary disability.
Abnormalities in the pleural space, such as massive pleural effusion or pneumothorax, also result in a restrictive loss of lung volume.7
Restrictive lung diseases due to neurologic or neuromuscular problems are typically caused by myasthenia gravis, Guillain-Barre syndrome, and spinal cord diseases or trauma.
Myasthenia gravis affects the facial, skeletal, and respiratory muscles and causes weakness and fatigue. The underlying cause of myasthenia gravis isn't known, but it appears to involve an autoimmune attack on receptors on the muscle end plates, where antibodies inactivate the receptor and block nerve impulse transmission to the muscle. Flare-ups of the disease can restrict ventilation and decrease lung volumes.8
Guillain-Barre syndrome is a peripheral nerve problem causing a self-limiting paralysis. Again, the cause is believed to be an autoimmune response involving an antibody attack on the myelin sheath covering nerves. This disrupts nerve impulse transmission, resulting in paralysis. About one-third of patients with Guillain-Barre syndrome have problems with adequate ventilation and decreased lung volumes.8
Spinal cord diseases or trauma include amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), a progressive, fatal disease involving motor neuron degeneration. The cause is unknown. Within 5 years of onset for this disease, about 80% of the patients will have died, generally from pulmonary complications and respiratory failure. Spinal cord trauma at the level of C3 to C5 causes major reductions in ventilation because the diaphragm is innervated at this level of the spine. Some paraplegic and most quadriplegic patients have decreased ventilation and some degree of RLD.8
Other causes of neurologic RLD are poliomyelitis, tetanus, muscular dystrophy, and tick bite paralysis.7
Cardiac diagnoses linked to RLD include heart failure, cardiomyopathy, congenital heart defects, aortic stenosis, and aortic insufficiency (regurgitation). In these cardiac problems, when the left side of the heart can't maintain adequate output, blood backs up into the pulmonary system and encroaches on lung volume. If the backup is severe enough, the patient develops pulmonary edema and the alveolar spaces become flooded.3
Conditions that increase the size of the abdomen or limit movement of the diaphragm can restrict lung volume. These conditions include obesity, abdominal tumors, third-trimester pregnancy, diaphragmatic hernias, ascites (typically from liver disease), and abdominal compartment syndrome.
Dyspnea, the primary symptom of RLD, is usually progressive and becomes more pronounced with exertion. With pulmonary RLD, the patient may have a dry cough and crackles. About half of patients diagnosed with interstitial pulmonary fibrosis have digital clubbing.
Most patients don't experience cyanosis until the restrictive process is well advanced. Wheezing and chest pain aren't usual findings unless some other condition is present, such as cancer, heart disease, or asthma. Patients with the neurologic or neuromuscular form of RLD may report fatigue, problems with secretions (oral and pulmonary), aspiration, and a tendency for lower respiratory infections.6 On physical exam, you'll note decreased chest wall movement, increased use of accessory muscles of ventilation, and rapid, shallow breathing.7
Because of the work of breathing and increased respiratory effort, patients may not eat enough, leading to unintended weight loss. Malnutrition and weight loss also can be the result of muscle weakness and loss of coordination for chewing and swallowing. Regardless of the cause, consult a nutritionist or registered dietitian to help manage a patient with RLD. Dietary supplements that give protein and calories are helpful; however, too many carbohydrates may cause increased carbon dioxide production. The patient may need full nutritional support via enteral tube feeding.8
For details on diagnostic testing for RLD, see Reaching a diagnosis.
Although RLD can have many causes, treatment often depends on the severity of the disease, not its cause. Respiratory treatment options include oxygen therapy, positive airway pressure, and ventilatory support.
* Oxygen therapy may be needed for patients with dyspnea or hypoxemia on exertion. Patients also may need supplemental oxygen because of pathologic changes in the alveoli, the thickened alveolar-capillary membrane, and ventilation/perfusion mismatch. However, these justifying conditions also make hypoxemia relatively refractory to oxygen therapy (meaning that despite oxygen therapy, the patient still suffers from hypoxemia and dyspnea).
* Continuous positive airway pressure can improve oxygenation in a patient whose hypoxemia is refractory to oxygen therapy.
* Ventilatory support, indicated for patients moving toward or in respiratory failure, can be accomplished by noninvasive positive pressure ventilation (NPPV) or by endotracheal intubation and mechanical ventilation. Noninvasive positive pressure ventilation can support a patient until the reason for respiratory failure is resolved and avoids the risks associated with intubation, including pneumonia, vocal cord trauma, loss of ability to speak, and loss of ability to eat and take oral medications. Used at night, NPPV may also help the patient sleep better.9
Other treatments are specific to the patient's type of RLD and its underlying causes. For example, corticosteroids may be prescribed to reduce inflammation in a patient with pulmonary RLD. However, because of adverse reactions and variability in patient response, systemic corticosteroid use often is on a trial basis and may be continued long-term if the benefits outweigh the adverse effects.
Many patients with RLD use inhaled corticosteroids and may also be on either a periodic short course of systemic corticosteroid therapy to reduce acute symptoms or on long-term systemic corticosteroid therapy to fight inflammation and fibrosis. Adverse reactions to systemic steroid therapy include suppression of the hypothalamus, pituitary, and adrenal glands; immunosuppression; osteoporosis; fluid retention; and change in the appearance (central obesity, moon face, and humpback).
Immunosuppressive therapy with drugs such as azathioprine or cyclophosphamide may also be used to reduce the inflammatory response.
For some patients, lung or heart/lung transplant may be considered. However, the long-term success and survival after transplant is only fair because of many potential problems, including rejection and infection. Poor patient adherence to long-term medication regimens increases the risks.7
For a patient whose RLD is caused by chest wall or thoracic problems, surgical correction of spinal deformities may be indicated.10
A patient with RLD related to neurologic or neuromuscular causes may benefit from aggressive and innovative secretion clearance techniques, which can reduce work of breathing, decrease the risk of infection, and improve arterial blood gases. Some of these patients may need mechanical support (at night only or full-time) and tracheotomy to avoid respiratory failure.
Treatment for cardiac causes of RLD focuses on reducing fluid buildup in the lungs. Depending on the underlying cause, treatment may include diuretics, antiarrhythmics, coronary revascularization procedures, heart valve repair or replacement, temporary support using the intra-aortic balloon pump, or surgical correction of congenital defects.
For RLD related to abdominal problems, surgery may be used to correct obesity, remove abdominal tumors, and repair diaphragmatic hernias. For pregnant patients, the health care provider may decide to induce labor or perform a cesarean section.
Your interventions will fall into the following broad areas:
* Pain management. The patient with RLD may need pain management for acute postsurgical pain or chronic neuropathic pain. Opioids such as hydrocodone, oxycodone, and morphine are effective for these patients. Respiratory drive depression is rare, but can be treated with naloxone.11
* Airway management. If your patient has problems clearing secretions, teach him good coughing technique. Perform suctioning and chest physiotherapy as appropriate.11
* Medication administration. Patients with neuromuscular disease may need help with medication administration if they can't self-administer medications or they have difficulty keeping track of their medication schedule.
* Addressing disease-specific concerns. Patients with neuromuscular diseases such as myasthenia gravis and Guillain-Barre syndrome may have problems with fatigue, impaired communication and swallowing, muscle weakness, impaired mobility, and inability to perform self-care. Assess a patient with ALS for fatigue, muscle atrophy, and weakness. As the disease progresses, he'll have difficulty speaking and swallowing, become easily fatigued, and develop increasing weakness of the hands, arms, and legs. He'll need mechanical ventilation when the respiratory muscles can no longer carry the workload. For more on ALS, see "Take Aim at Amyotrophic Lateral Sclerosis" in the November issue of Nursing2005.*
* Providing emotional support and education. Teach your patient and his family about RLD and educate them about his treatments and when to report adverse reactions to the health care provider.
If your patient is taking inhaled corticosteroids, teach him how to use the inhaler and remind him to rinse his mouth after use to reduce the risk of oropharyngeal fungal infection.12
Your patient may feel depressed, fearful, and anxious because of the debilitating effects of the lung restriction and ever-present dyspnea. Encourage him to talk about his feelings and seek spiritual counsel if he wishes, coach him in coping skills, and refer him to support groups and Web sites for more information.
Because RLD is usually a chronic condition, patients need major commitments of time, resources, caring, and compassion from their caregivers. By learning about the underlying causes and recommended treatments, you'll be prepared to provide the extra support they need.
To help diagnose RLD and rule out other problems, the health care provider will order various tests.
* Pulmonary function tests include measurements of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1/FVC ratio. A patient with RLD will show a decreased FVC and may have a normal FEV1 and a normal or increased FEV1/FVC.
* The flow-volume loop, a graphic representation of the rate of airflow and the total volume inspired or expired, will show a decreased FVC and may look abnormally narrowed.
* Lung volume measurements are the most helpful tests for diagnosing and managing RLD-specifically total lung capacity (TLC), functional residual capacity, and residual volume (RV). In restrictive lung diseases, the normal proportions of these measurements (RV to TLC, for example) will usually be preserved, but the absolute volumes of each measurement will be reduced at about the same percentage.
Lung volumes are measured in the pulmonary function lab by using nitrogen washout, helium dilution, or body plethysmography. Another test that may be useful in diagnosis or management of RLD uses a small amount of inhaled carbon monoxide to measure diffusion capacity. This test, most often referred to as DLCO, is used to measure the transfer of gas across the alveolar-capillary membrane. Patients with RLD will have a reduced DLCO measurement.
* Resting arterial blood gas (ABG) results often are normal in a patient with RLD. But if the blood sample is taken during or just after exercise, ABG results will reflect hypoxemia (a Pao2 below 80 mm Hg and Sao2 below 95%). Hypercapnia (Paco2 above 45 mm Hg) usually doesn't occur unless the patient is approaching or is in respiratory failure. The patient's pH usually will be normal (between 7.35 and 7.45).2
* Imaging studies such as X-rays and computed tomography (CT) scans may show infiltrates or signs of an inflammatory response in patients with interstitial lung disease. However, the chest X-ray is normal in 10% to 15% of patients with interstitial lung disease.6 An X-ray will show abnormalities in the chest wall and thorax and may show the change in lung volume and possible cardiac effects (depending on the extent of the deformity).
Trauma to the brain or spinal cord, which can lead to neurologic RLD, may be assessed by X-ray and CT scan. Abdominal X-ray and abdominal CT scan can help evaluate whether an enlarged abdomen is a factor in RLD.
* Lung biopsy often is used to confirm a diagnosis of interstitial RLD.2,6
* Fiberoptic bronchoscopy and transbronchial biopsy may be used to diagnose RLD caused by sarcoidosis or histiocytosis X or RLD related to pneumonitis or cancer. During a bronchoscopic procedure, the health care provider may perform bronchoalveolar lavage to assess for malignancy, asbestos, or other agents that cause pneumoconiosis.6
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