Interstitial Lung Diseases

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Interstitial Lung Diseases

Chapter Objectives

After reading this chapter, you will be able to:

• List the anatomic alterations of the lungs associated with chronic interstitial lung disease.

• Describe the causes of chronic interstitial lung disease.

• List the cardiopulmonary clinical manifestations associated with chronic interstitial lung disease.

• Describe the general management of chronic interstitial lung disease.

• Describe the clinical strategies and rationales of the SOAPs presented in the case study.

• Define key terms and complete self-assessment questions at the end of the chapter and on Evolve.

Key Terms

Anatomic Alterations of the Lungs

The anatomic alterations of ILD may involve the bronchi, alveolar walls, and adjacent alveolar spaces. In severe cases the extensive inflammation leads to pulmonary fibrosis, granulomas, honeycombing, and cavitation. During the acute stage of any ILD, the general inflammatory condition is characterized by edema and the infiltration of a variety of white blood cells (e.g., neutrophils, eosinophils, basophils, monocytes, macrophages, and lymphocytes) in the alveolar walls and interstitial spaces (see Figure 25-1, A). Bronchial inflammation and thickening and increasing airway secretions may be also present.

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FIGURE 25-1 A, Interstitial lung disease. Cross-sectional microscopic view of alveolar-capillary unit. B, Basophil; E, eosinophil; FIB, fibroblast (fibrosis); L, lymphocyte; M, monocyte; MAC, macrophage; N, neutrophil; PC, pulmonary capillary; RBC, red blood cell; TI, type I alveolar cell; TII, type II alveolar cell.B, Asbestosis (close-up of one alveolar unit). AF, Asbestos fiber; FIB, fibrosis; M, macrophage.

During the chronic stage the general inflammatory response is characterized by the infiltration of numerous white blood cells (especially monocytes, macrophages, and lymphocytes), and some fibroblasts may also be present in the alveolar walls and interstitial spaces. This stage may be followed by further interstitial thickening, fibrosis, granulomas, and, in some cases, honeycombing and cavity formation. Pleural effusion also may be present. In the chronic stages the basic pathologic features of interstitial fibrosis are identical in any interstitial lung disorder (so-called end-stage pulmonary fibrosis).

As a general rule, the interstitial lung disorders produce a restrictive lung disease. However, because bronchial inflammation and excessive airway secretions also can develop in the small airways, the clinical manifestations associated with an obstructive lung disorder may also be seen. Therefore the patient with ILD may demonstrate a restrictive disorder, an obstructive disorder, or a combination of both.

The major pathologic or structural changes associated with chronic ILDs are as follows:

Etiology and Epidemiology

Because there are over 180 different pulmonary disorders classified as ILD, it is helpful to group them according to their occupational or environmental exposure, disease associations, and specific pathology. Table 25-1 provides an overview of common ILD groups. A discussion of the more common ILDs follows.

Radiation Therapy Irritant Gases

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Interstitial Lung Diseases of Known Causes or Associations

Occupational, Environmental and Therapeutic Exposures

Inorganic particulate (dust) exposure

Asbestos

Exposure to asbestos may cause asbestosis—a common form of ILD. Asbestos fibers are a mixture of fibrous minerals composed of hydrous silicates of magnesium, sodium, and iron in various proportions. There are two primary types: the amphiboles (crocidolite, amosite, and anthophyllite) and chrysotile (most commonly used in industry). Asbestos fibers typically range from 50 to 100 µm in length and are about 0.5 µm in diameter. The chrysotiles have the longest and strongest fibers. Box 25-1 lists common sources associated with asbestos fibers.

Box 25-1   Common Sources Associated with Asbestos Fibers

As shown in Figure 25-1, B, asbestos fibers can be seen by microscope within the thickened septa as brown or orange baton-like structures. The fibers characteristically stain for iron with Perls’ stain. The pathologic process may affect only one lung, a lobe, or a segment of a lobe. The lower lobes are most commonly affected. Pleural calcification is common and diagnostic in patients with an asbestos exposure history.

Coal dust

The pulmonary deposition and accumulation of large amounts of coal dust causes what is known as coal worker’s pneumoconiosis (CWP). CWP also is known as coal miner’s lung and black lung. Miners who use cutting machines at the coal face have the greatest exposure, but even relatively minor exposures may result in the disease. Indeed, cases have been reported in which coal miners’ wives developed the disease, presumably from shaking the dust from their husbands’ work clothes.

Simple CWP is characterized by the presence of pinpoint nodules called coal macules (black spots) throughout the lungs. The coal macules often develop around the first- and second-generation respiratory bronchioles and cause the adjacent alveoli to retract. This condition is called focal emphysema.

Complicated CWP or progressive massive fibrosis (PMF) is characterized by areas of fibrotic nodules greater than 1 cm in diameter. The fibrotic nodules generally appear in the peripheral regions of upper lobes and extend toward the hilum with growth. The nodules are composed of dense collagenous tissue with black pigmentation. Coal dust by itself is chemically inert. The fibrotic changes in CWP are usually caused by silica.

Silica

Silicosis (also called grinder’s disease or quartz silicosis) is caused by the chronic inhalation of crystalline, free silica, or silicon dioxide particles. Silica is the main component of more than 95% of the rocks of the earth. It is found in sandstone, quartz (beach sand is mostly quartz), flint, granite, many hard rocks, and some clays.

Simple silicosis is characterized by small rounded nodules scattered throughout the lungs. No single nodule is greater than 9 mm in diameter. Patients with simple silicosis are usually symptom-free.

Complicated silicosis is characterized by nodules that coalesce and form large masses of fibrous tissue, usually in the upper lobes and perihilar regions. In severe cases the fibrotic regions may undergo tissue necrosis and cavitate. Box 25-2 lists common occupations associated with silica exposure.

Box 25-2   Common Occupations Associated with Silica Exposure

Organic materials exposure

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (also called allergic alveolitis or extrinsic allergic alveolitis) is a cell-mediated immune response of the lungs caused by the inhalation of a variety of offending agents or antigens. Such antigens include grains, silage, bird droppings or feathers, wood dust (especially redwood and maple), cork dust, animal pelts, coffee beans, fish meal, mushroom compost, and molds that grow on sugar cane, barley, and straw. The immune response to these allergens causes production of antibody and an inflammatory response. The lung inflammation, or pneumonitis, develops after repeated and prolonged exposure to the allergen. The term hypersensitivity pneumonitis (or allergic alveolitis) is often renamed according to the type of exposure that caused the lung disorder. For example, the hypersensitivity pneumonitis caused by the inhalation of moldy hay is called farmer’s lung. Table 25-2 provides common causes, exposure sources, and disease syndromes associated with hypersensitivity pneumonitis.

Table 25-2

Causes of Hypersensitivity Pneumonitis

Antigen Exposure Source Disease (Syndrome)
Bacteria, Thermophilic
Saccharopolyspora rectivirgula Moldy hay, silage Farmer’s lung
Thermoactinomyces vulgaris Moldy sugarcane Bagassosis
Thermoactinomyces sacchari Mushroom compost Mushroom worker’s lung
Thermoactinomyces candidus Heated water reservoirs Air conditioner lung
Bacteria, Nonthermophilic
Bacillus subtilis, Bacillus cereus Water, detergent Humidifier lung, washing powder lung
Fungi
Aspergillus species Moldy hay Farmer’s lung
  Water Ventilation pneumonitis
Aspergillus clavatus Barley Malt worker’s lung
Penicillium casei, Cheese Cheese washer’s lung
Penicillium roqueforti    
Alternaria species Wood pulp Woodworker’s lung
Cryptostroma corticale Wood bark Maple bark stripper’s lung
Graphium, Aureobasidium pullulans Wood dust Sequoiosis
Merulius lacrymans Rotten wood Dry root lung
Penicillium frequentans Cork dust Suberosis
Aureobasidium pullulans Water Humidifier lung
Cladosporium species Hot tub mist Hot tub HP*
Trichosporon cutaneum Damp wood and mats Japanese summer-type HP*
Amebae
Naegleria gruberi Contaminated water Humidifier lung
Acanthamoeba polyphaga Contaminated water Humidifier lung
Acanthamoeba castellani Contaminated water Humidifier lung
Animal Protein
Avian proteins Bird droppings, feathers Bird-breeder’s lung
Urine, serum, pelts Rates, gerbils Animal handler’s lung
Chemicals
Isocyanates, trimellitic anhydride Paints, resins, plastics Chemical worker’s lung
Copper sulfate Bordeaux mixture Vineyard sprayer’s lung
Phthalic anhydride Heated epoxy resin Epoxy resin lung
Sodium diazobenzene sulfate Chromatography reagent Pauli’s reagent alveolitis
Pyrethrum Pesticide Pyrethrum HP*

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*HP, Hypersensitivity pneumonitis.

From Selman M: Hypersensitivity pneumonitis. In Schwarz MI, Kin TE, eds: Interstitial lung disease, ed 4, Hamilton, 2003, BC Decker.

Medications and illicit drugs

As the list of medications and illicit drugs continues to grow, so does the list of possible side effects (Box 25-4). Unfortunately, the lungs are major target organs affected by these side effects. Although it is impossible to discuss in detail the various lung-related side effects of every drug, it is possible to describe some of the general concerns related to drug-induced lung disease and to list some of the pharmacologic agents that may be responsible.

Box 25-4   Medications and Illicit Drugs Associated with the Development of Interstitial Lung Disease

Antibiotics

Antiinflammatory agents

Cardiovascular agents

Drugs associated with drug-induced systemic lupus erythematosus

Illicit drugs

Miscellaneous agents

From Camus P: Drug induced infiltrative lung diseases. In Schwarz MI, Kin TE, eds: Interstitial lung disease, ed 4, Hamilton, 2003, BC Decker.

The chemotherapeutic (anticancer agents) are by far the largest group of agents associated with ILD. Bleomycin, mitomycin, busulfan, cyclophosphamide, methotrexate, and carmustine (BCNU) are the major offenders. Nitrofurantoin (an antibacterial drug used in the treatment of urinary tract infections) is also associated with ILD. Gold and penicillamine for the treatment of rheumatoid arthritis also have been shown to cause ILD. The excessive long-term administration of oxygen (oxygen toxicity) also is known to cause diffuse pulmonary injury and fibrosis (see Chapter 27). As a general rule, the risk of these drugs causing an interstitial lung disorder is directly related to the cumulative dosage. However, drug-induced interstitial disease may be seen as early as 1 month to as late as several years after exposure to these agents.

The precise cause of drug-induced ILD is not known. Diagnosis is confirmed by an open lung biopsy. When interstitial fibrosis is found with no infectious organisms, a drug-induced interstitial process must be suspected.

Radiation therapy

Radiation therapy in the management of cancer may cause ILD. Radiation-induced lung disease is commonly divided into the following two major phases: the acute pneumonitic phase and the late fibrotic phase. Acute pneumonitis rarely is seen in patients who receive a total radiation dose of less than 3500 rad. On the other hand, doses in excess of 6000 rad over 6 weeks almost always cause ILD in and near the radiated areas. The acute pneumonitic phase develops approximately 2 to 3 months after exposure. Chronic radiation fibrosis is seen in all patients who develop acute pneumonitis.

The late phase of fibrosis may develop (1) immediately after the development of acute pneumonitis, (2) without an acute pneumonitic period, or (3) after a symptom-free latent period. When fibrosis does develop, it generally does so 6 to 12 months after radiation exposure. Pleural effusion often is associated with the late fibrotic phase.

The precise cause of radiation-induced lung disease is not known. The establishment of a diagnosis is similar to that for drug-induced interstitial disease (i.e., by obtaining a history of recent radiation therapy and confirming the diagnosis with an open lung biopsy).

Irritant gases

The inhalation of irritant gases may cause an acute chemical pneumonitis and, in severe cases, ILD. Most exposures occur in an industrial setting. Table 25-3 lists some of the more common irritant gases and the industrial settings where they may be found.

Table 25-3

Common Irritant Gases Associated with Interstitial Lung Disease

Gas Industrial Setting
Chlorine Chemical and plastic industries; water disinfection
Ammonia Commercial refrigeration; smelting of sulfide ores
Ozone Welding
Nitrogen dioxide May be liberated after exposure of nitric acid to air
Phosgene Used in the production of aniline dyes

Systemic Diseases

Connective Tissue (Collagen Vascular) Diseases

Scleroderma

Scleroderma is characterized by chronic hardening and thickening of the skin caused by new collagen formation. It may occur in a localized form or as a systemic disorder (called systemic sclerosis). Progressive systemic sclerosis (PSS) is a relatively rare autoimmune disorder that affects the blood vessels and connective tissue. It causes fibrous degeneration of the connective tissue of the skin, lungs, and internal organs, especially the esophagus, digestive tract, and kidney.

Scleroderma of the lung appears in the form of ILD and fibrosis. Of all the collagen vascular disorders, scleroderma is the one in which pulmonary involvement is most severe and most likely to cause significant scarring of the lung parenchyma. The pulmonary complications include diffuse interstitial fibrosis, severe pulmonary hypertension, pleural disease, and aspiration pneumonitis (secondary to esophageal involvement). Scleroderma also may involve the small pulmonary blood vessels and appears to be independent of the fibrotic process involving the alveolar walls. The disease most commonly is seen in women 30 to 50 years of age.

Rheumatoid arthritis

Rheumatoid arthritis primarily is an inflammatory joint disease. It may, however, involve the lungs in the form of (1) pleurisy, with or without effusion; (2) interstitial pneumonitis; (3) necrobiotic nodules, with or without cavities; (4) Caplan’s syndrome; and (5) pulmonary hypertension secondary to pulmonary vasculitis.

Pleurisy with or without effusion is the most common pulmonary complication associated with rheumatoid arthritis. When present, the effusion is generally unilateral (often on the right side). Men appear to develop rheumatoid pleural complications more often than women. Rheumatoid interstitial pneumonitis is characterized by alveolar wall fibrosis, interstitial and intraalveolar mononuclear cell infiltration, and lymphoid nodules. In severe cases, extensive fibrosing alveolitis and honeycombing may develop. Rheumatoid interstitial pneumonitis is also more common in male patients. Necrobiotic nodules are characterized by the gradual degeneration and swelling of lung tissue.

The pulmonary nodules generally appear as well-circumscribed masses that often progress to cavitation. The nodules usually develop in the periphery of the lungs and are more common in men. Histologically, the pulmonary nodules are identical to the subcutaneous nodules that develop in rheumatoid arthritis.

Caplan’s syndrome (also called rheumatoid pneumoconiosis) is a progressive pulmonary fibrosis of the lung commonly seen in coal miners. Caplan’s syndrome is characterized by rounded densities in the lung periphery that often undergo cavity formation and, in some cases, calcification. Pulmonary hypertension is a common secondary complication caused by the progression of fibrosing alveolitis and pulmonary vasculitis.

Polymyositis-dermatomyositis

Polymyositis is a diffuse inflammatory disorder of the striated muscles that primarily weakens the limbs, neck, and pharynx. Dermatomyositis is the term used when an erythematous skin rash accompanies the muscle weakness. Pulmonary involvement develops in response to (1) recurrent episodes of aspiration pneumonia caused by esophageal weakness and atrophy, (2) hypostatic pneumonia secondary to a weakened diaphragm, and (3) drug-induced interstitial pneumonitis.

Polymyositis-dermatomyositis is seen more often in women than men, at about a 2 : 1 ratio. The disease occurs primarily in two age groups: before the age of 10 and from 40 to 50 years of age. In about 40% of the patients, the pulmonary manifestations are seen 1 to 24 months before the striated muscle or skin shows signs or symptoms.

Systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystem disorder that mainly involves the joints and skin. It also may cause serious problems in numerous other organs, including the kidneys, lungs, nervous system, and heart. Involvement of the lungs appears in about 50% to 70% of the cases. Pulmonary manifestations are characterized by (1) pleurisy with or without effusion, (2) atelectasis, (3) diffuse infiltrates and pneumonitis, (4) diffuse ILD, (5) uremic pulmonary edema, (6) diaphragmatic dysfunction, and (7) infections.

Pleurisy with or without effusion is the most common pulmonary complication of SLE. The effusions usually are exudates with high protein concentration and are frequently bilateral. Atelectasis commonly develops in response to the pleurisy, effusion, and diaphragmatic elevation associated with SLE. Diffuse noninfectious pulmonary infiltrates and pneumonitis are common. In severe cases, chronic interstitial pneumonitis may develop. Because SLE frequently impairs the renal system, uremic pulmonary edema may occur. SLE has also been found to be associated with diaphragmatic dysfunction and reduced lung volumes. Some research suggests that a diffuse myopathy affecting the diaphragm is the source of this problem. Approximately 50% of the cases have a complicating pulmonary infection.

Sarcoidosis

Sarcoidosis is a chronic disorder of unknown origin characterized by the formation of tubercles of nonnecrotizing epithelioid tissue (noncaseating granulomas). Common sites are the lungs, spleen, liver, skin, mucous membranes, and lacrimal and salivary glands, usually with the involvement of the lymph glands. The lung is the most frequently affected organ, with manifestations generally including ILD, enlargement of the mediastinal lymph nodes, or a combination of both. One of the clinical hallmarks of sarcoidosis is an increase in all three major immunoglobulins (IgM, IgG, and IgA). The disease is more common among African-Americans and appears most frequently in patients 10 to 40 years of age, with the highest incidence at 20 to 30 years of age. Women are affected more often than men, especially among African-Americans.

Idiopathic Interstitial Pneumonias

Many patients with ILD do not have a readily identified specific exposure, a systemic disorder, or an underlying genetic cause. Such instances of ILD are commonly placed in the idiopathic interstitial pneumonia (IIP) group or the group with specific pathology.

Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive inflammatory disease with varying degrees of fibrosis and, in severe cases, honeycombing. The precise cause is unknown. Although idiopathic pulmonary fibrosis is the term most frequently used for this disorder, numerous other names appear in the literature, such as acute interstitial fibrosis of the lung, cryptogenic fibrosing alveolitis, Hamman-Rich syndrome, honeycomb lung, interstitial fibrosis, and interstitial pneumonitis.

IPF commonly is separated into the following two major disease entities according to the predominant histologic appearance: desquamative interstitial pneumonia (DIP) and usual interstitial pneumonia (UIP). In DIP the most prominent features are hyperplasia and desquamation of the alveolar type II cells. The alveolar spaces are packed with macrophages, and there is an even distribution of the interstitial mononuclear infiltrate.

In UIP the most prominent features are interstitial and alveolar wall thickening caused by chronic inflammatory cells and fibrosis. In severe cases, fibrotic connective tissue replaces the alveolar walls, the alveolar architecture becomes distorted, and eventually honeycombing develops. When honeycombing is present, the inflammatory infiltrate is significantly reduced. The prognosis for patients with DIP is significantly better than that for patients with UIP.

Some experts believe that DIP and UIP are two distinct ILD entities. Others, however, believe that DIP and UIP are different stages of the same disease process. IPF most commonly seen is seen in men 40 to 70 years of age. Diagnosis generally is confirmed by an open lung biopsy. Most patients diagnosed with IPF have a more chronic progressive course, and death usually occurs in 4 to 10 years. Death usually is the result of progressive acute ventilatory failure, complicated by pulmonary infection.

Cryptogenic Organizing Pneumonia

Cryptogenic organizing pneumonia (COP) (also known as bronchiolitis obliterans organizing pneumonia [BOOP]) is characterized by connective tissue plugs in the small airways (hence the term bronchiolitis obliterans) and mononuclear cell infiltration of the surrounding parenchyma (hence the term organizing pneumonia). Although the most of the cases have no identifiable cause and therefore are considered idiopathic, COP has been associated with connective tissue disease, toxic gas inhalation, and infection. The chest radiograph commonly shows patchy infiltrates of alveolar rather than interstitial involvement. Diagnosis may require a surgical biopsy when the clinical and radiographic data are uncertain. COP is one of the ILDs in which both restrictive and obstructive pathologic lesions are present.

Specific Pathology

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare lung disease involving the smooth muscles of the airways and affects women of childbearing age. It is characterized by the proliferation of disorderly smooth muscle proliferation throughout the bronchioles, alveolar septa, perivascular spaces, and lymphatics. LAM causes the obstruction of small airways and lymphatics. Common clinical features associated with LAM are recurrent pneumothorax and chylous pleural effusion. The diagnosis of LAM is confirmed with an open lung biopsy. The prognosis is poor; the disease slowly progresses over 2 to 10 years, ending in death resulting from ventilatory failure.

Pulmonary Vasculitides

The pulmonary vasculitides (also called granulomatous vasculitides) consist of a heterogeneous group of pulmonary disorders characterized by inflammation and destruction of the pulmonary vessels. The major disorders in this category include Wegener’s granulomatosis, Churg-Strauss syndrome, and lymphomatoid granulomatosis.

Wegener’s granulomatosis

Wegener’s granulomatosis is a multisystem disorder characterized by (1) a necrotizing, granulomatous vasculitis; (2) focal and segmental glomerulonephritis; and (3) variable degrees of systemic vasculitis of the small veins and arteries. In the lungs, numerous 1- to 9-cm-diameter nodules are commonly seen in the upper lobes, and cavity formation is often associated with the larger lesions.

Wegener’s granulomatosis is considered an aggressive and fatal disorder, although the prognosis has significantly improved with the use of cytotoxic agents (e.g., cyclophosphamide). This disorder most commonly is seen in men older than 50 years of age. Diagnosis is confirmed by an open lung biopsy. Histologic examination reveals lesions with marked central necrosis. The area surrounding the necrotizing lesion consists of inflammatory white blood cells (WBCs) with some fibroblasts. Inflammatory cell infiltrate and necrotizing vasculitis are seen in the adjacent blood vessels.

Churg-Strauss syndrome

Churg-Strauss syndrome is a necrotizing vasculitis that predominantly involves the small vessels of the lungs. The granulomatous lesions are characterized by a heavy infiltrate of eosinophils, central necrosis, and peripheral eosinophilia. Cavity formation is rare in this disorder. Clinically, symptoms of asthma usually precede the onset of vasculitis. In recent years, rapid tapering of oral steroids with substitution of leukotriene inhibitors such as montelukast (Singulair) and zafirlukast (Accolate) has been associated with deaths from fulminant Churg-Strauss syndrome reactions. Neurologic disorders such as mononeuritis multiplex, a simultaneous disease of several peripheral nerves, are frequently associated with this disorder. Diagnosis is usually confirmed with an open lung biopsy, and the disease is often rapidly fatal.

Miscellaneous Diffuse Interstitial Lung Diseases

Goodpasture’s Syndrome

Goodpasture’s syndrome is a disease of unknown cause that involves two organ systems—the lungs and the kidneys. In the lungs there are recurrent episodes of pulmonary hemorrhage and in some cases pulmonary fibrosis, presumably as a consequence of the bleeding episodes. In the kidneys there is a glomerulonephritis characterized by the infiltration of antibodies within the glomerular basement membrane (GBM). These circulating antibodies function against the patient’s own GBM. They are commonly abbreviated as anti-GBM antibodies. It is believed that the anti-GBM antibodies cross-react with the basement membrane of the alveolar wall and that their deposition in the kidneys and lungs is responsible for producing the pathophysiologic processes of the disease.

Goodpasture’s syndrome usually is seen in young adults. The average survival period after diagnosis is about 15 weeks. About 50% of the patients die from massive pulmonary hemorrhage, and about 50% die from chronic renal failure. An interesting feature of Goodpasture’s syndrome is that the patient frequently demonstrates an increased Dlco, which is in direct contrast to most interstitial lung disorders. The increased carbon monoxide uptake commonly seen in this disorder is thought to be caused by the increased amount of retained blood in the pulmonary tissue.

Idiopathic Pulmonary Hemosiderosis

Idiopathic pulmonary hemosiderosis is a disease entity of unknown cause that is characterized by recurrent episodes of pulmonary hemorrhage similar to that seen in Goodpasture’s syndrome. Histologic examination reveals an alveolar hemorrhage with hemosiderin-laden macrophages and hyperplasia of the alveolar epithelium. Unlike in Goodpasture’s syndrome, however, there is no evidence of circulating anti-GBM antibodies attacking the alveoli or GBMs, and this disorder is not associated with renal disease.

Idiopathic pulmonary hemosiderosis most often is seen in children. As in Goodpasture’s syndrome, patients commonly demonstrate an increased Dlco, which is in direct contrast to most interstitial lung disorders. Again, the increased uptake of carbon monoxide is thought to be caused by the increased amount of blood retained in the lungs.

Chronic Eosinophilic Pneumonia

Chronic eosinophilic pneumonia is characterized by infiltration of eosinophils and, to a lesser extent, macrophages into the alveolar and interstitial spaces. Clinically, a unique feature of this disorder often is seen on the chest radiograph, consisting of a peripheral distribution of pulmonary infiltrates. This radiographic pattern is commonly referred to as a photographic negative of pulmonary edema. This is because of the dense peripheral infiltration, with the sparing of the perihilar areas, seen in chronic eosinophilic pneumonia, compared with the central pulmonary infiltration with the sparing of the lung periphery seen in pulmonary edema. An increased number of eosinophils also is commonly seen in the peripheral blood. Histologic diagnosis is made by means of an open lung biopsy.

image OVERVIEW of the Cardiopulmonary Clinical Manifestations Associated with Chronic Interstitial Lung Diseases

The following clinical manifestations result from the pathophysiologic mechanisms caused (or activated) by an Increased Alveolar-Capillary Membrane Thickness (see Figure 9-10) and Excessive Bronchial Secretions (see Figure 9-12)—the major anatomic alterations of the lungs associated with chronic interstitial lung disease (see Figure 28-1).

CLINICAL DATA OBTAINED AT THE PATIENT’S BEDSIDE

The Physical Examination

CLINICAL DATA OBTAINED FROM LABORATORY TESTS AND SPECIAL PROCEDURES

Pulmonary Function Test Findings Moderate to Severe Interstitial Lung Disease (Restrictive Lung Pathology)

FORCED EXPIRATORY FLOW RATE FINDINGS

FVC FEVT FEV1/FVC ratio FEF25%-75%
↓ N or ↓ N or ↑ N or ↓
FEF50% FEF200-1200 PEFR MVV
N or ↓ N or ↓ N or ↓ N or ↓

image

LUNG VOLUME AND CAPACITY FINDINGS

VT IRV ERV RV  
N or ↓ ↓ ↓ ↓  
VC IC FRC TLC RV/TLC ratio
↓ ↓ ↓ ↓ N

image

Arterial Blood Gases

MILD TO MODERATE INTERSTITIAL LUNG DISEASE

Oxygenation Indices*

Moderate to Severe Stage Interstitial Lung Disease

*image, Arterial-venous oxygen difference; DO2, total oxygen delivery; O2ER, oxygen extraction ratio; image, pulmonary shunt fraction; image, mixed venous oxygen saturation; image, oxygen consumption.

Hemodynamic Indices*

Severe Interstitial Lung Disease

CVP RAP image PCWP CO SV
↑ ↑ ↑ N N N
SVI CI RVSWI LVSWI PVR SVR
N N ↑ N ↑ N

image

*CO, Cardiac output; CVP, central venous pressure; LVSWI, left ventricular stroke work index; image, mean pulmonary artery pressure; PCWP, pulmonary capillary wedge pressure; PVR, pulmonary vascular resistance; RAP, right atrial pressure; RVSWI, right ventricular stroke work index; SV, stroke volume; SVI, stroke volume index; SVR, systemic vascular resistance.

RADIOLOGIC FINDINGS

Radiologic findings vary according to the cause.

Chest Radiograph

As shown in Figure 25-2, a patient with severe scleroderma, a bilateral reticulonodular pattern is commonly seen on the radiographs. In patients with asbestosis the opacity is often described as cloudy in appearance or as having a “ground-glass” appearance and is especially apparent in the lower lobes (Figure 25-3). Calcified pleural plaques may be seen on the superior border of the diaphragm or along the chest wall (Figure 25-4). The inflammatory response elicited by the asbestos fibers also may produce a fuzziness and irregularity of the cardiac and diaphragmatic borders.

image
FIGURE 25-2 Reticulonodular pattern of interstitial pulmonary fibrosis in a patient with scleroderma. (From Hansell DM, Armstrong P, Lynch DA, McAdams HP, eds: Imaging of diseases of the chest, ed 4, Philadelphia, 2005, Elsevier.)
image
FIGURE 25-3 Chest x-ray film of a patient with asbestosis.
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FIGURE 25-4 Calcified pleural plaques on the superior border of the diaphragm (arrows) in a patient with asbestosis. Thickening of the pleural margins also is seen along the lower lateral borders of the chest. A, Anteroposterior view. B, Lateral view.

Figure 25-5 shows a diffuse parenchymal ground-glass pattern with some areas of consolidation in a patient with acute farmer’s lung. The severity of parenchymal opacification in this case is rare.

image
FIGURE 25-5 Acute farmer’s lung. Chest radiograph shows diffuse parenchymal ground-glass pattern with some areas of consolidation. The severity of parenchymal opacification in this case is unusual. (From Hansell DM, Armstrong P, Lynch DA, McAdams HP, eds: Imaging of diseases of the chest, ed 4, Philadelphia, 2005, Elsevier.)

In Figure 25-6, the honeycomb appearance is nicely illustrated in a computed tomography (CT) scan of a patient with sarcoidosis. Figure 25-7 shows a patient with Wegener’s granulomatosis with numerous nodules with a large cavity lesion adjacent to the right hilus. Figure 25-8 shows a pleural effusion in a patient with rheumatoid disease.

image
FIGURE 25-6 Honeycomb cysts in sarcoidosis. HRCT through the right midlung shows perfuse clustered honeycomb cysts. The cysts are larger than the typical honeycomb cysts seen in usual interstitial pneumonia. Cysts are much less extensive in the left lung. (From Hansell DM, Armstrong P, Lynch DA, McAdams HP, eds: Imaging of diseases of the chest, ed 4, Philadelphia, 2005, Elsevier.)
image
FIGURE 25-7 Wegener’s granulomatosis. Numerous nodules with a large (6-cm) cavitary lesion adjacent to the right hilus. Its walls are thick and irregular. (From Hansell DM, Armstrong P, Lynch DA, McAdams HP, eds: Imaging of diseases of the chest, ed 4, Philadelphia, 2005, Elsevier.)
image
FIGURE 25-8 Pleural effusion in rheumatoid disease. Bilateral pleural effusions are present with mild changes of fibrosing alveolitis. The effusions were painless, and the one on the right had been present, more or less unchanged, for 5 months. Note the bilateral “meniscus signs.” (From Hansell DM, Armstrong P, Lynch DA, McAdams HP, eds: Imaging of diseases of the chest, ed 4, Philadelphia, 2005, Elsevier.)

General Management of Interstitial Lung Disease

Medications and Procedures Commonly Prescribed by the Physician

The management of interstitial lung disorders is directed at the inflammation associated with the various disorders.

Respiratory Care Treatment Protocols

Oxygen Therapy Protocol

Oxygen therapy is used to treat hypoxemia, decrease the work of breathing, and decrease myocardial work. Because of the hypoxemia associated with ILDs, supplemental oxygen often is required. The hypoxemia that develops in an interstitial lung disorder most commonly is caused by the alveolar thickening, fibrosis, and capillary shunting associated with the disorder. In addition, because the patient may demonstrate chronic ventilatory failure during the advanced stages of an ILD, caution must be taken not to overoxygenate the patient (see Oxygen Therapy Protocol, Protocol 9-1).

CASE STUDY

Interstitial Lung Disease

Admitting History

A 72-year-old man is well known to the treating-hospital staff members, having received care there for more than 12 years. While in the U.S. Navy during World War II, he worked on the East Coast in the ship construction industry. After his discharge in 1945, he returned to his home in Mississippi for about 6 months; he then moved to Detroit, Michigan, and worked for an automobile manufacturer. His primary job for the next 20 years was undercoating automobiles.

In the early 1970s the man was transferred to a nearby automotive plant, where he worked on an assembly line fastening bumpers and chrome trim to cars. He was popular with his fellow workers and considered a hard worker by the management. When he retired in 1980, he was one of four supervisors in charge of the chrome trim assembly line.

Although the man smoked two packs a day for more than 40 years, his health was essentially unremarkable until about 4 years before he retired. At that time he started to experience periods of coughing, dyspnea, and weakness. A complete examination provided by the company concluded that the man had moderate interstitial lung disease (ILD).

On the basis of the man’s work history, the doctor speculated that the ILD was caused by asbestos fibers. This theory was confirmed later with the finding of asbestos fibers in a Perls’ stain of sputum, and the diagnosis of asbestosis was noted in the patient’s chart. Just before the man retired, his pulmonary function test results (PFTs) showed a mild-to-moderate combined restrictive and obstructive disorder.

Although the man was able to enjoy a couple of relatively good years of retirement with his wife, his health declined rapidly. His cough and dyspnea quickly became a daily problem. Despite his deteriorating health, the man continued to smoke. When he was 68 years old, he was hospitalized for 8 days for treatment of pneumonia and severe respiratory distress. When he was discharged at that time, his PFTs still showed a moderate-to-severe restrictive disorder. He started using oxygen at home regularly.

Approximately 10 months before the current admission, the man was hospitalized because of congestive heart failure. He was treated aggressively and sent home within 5 days. At the time of discharge, his PFTs showed that he had a worsening restrictive respiratory disorder. His arterial blood gas values (ABGs) on 2 L/min oxygen by nasal cannula were as follows: pH 7.38, Paco2 86, image 46, and Pao2 63.

Approximately 3 hours before the current admission, the man awoke from an afternoon nap extremely short of breath. His wife stated that he coughed almost continuously and had difficulty speaking. She measured his oral temperature, which read 38° C (100° F). Concerned, she drove her husband to the hospital emergency room.

Physical Examination

As the man was wheeled into the emergency room, he appeared nervous, weak, and in obvious respiratory distress. He was on 1.5 L/min oxygen by nasal cannula, which was connected to an E-tank that was attached to the wheelchair. His skin felt damp and clammy to the touch. He appeared pale and cyanotic. His neck veins were distended, and his fingers and toes were clubbed. He demonstrated a frequent but weak cough productive of a moderate amount of thick, whitish-yellow secretions. He had 3+ peripheral edema of the ankles and feet. He said this was the worst his breathing had ever been.

The patient’s vital signs were as follows: blood pressure 180/96, heart rate 108 bpm, respiratory rate 32/min, and oral temperature 38.3° C (100.8° F). Palpation of the chest was negative. Percussion produced bilateral dull notes in the lung bases. Rhonchi and crackles were auscultated throughout both lungs. A pleural friction rub could be heard over the right middle lobe between the sixth and seventh ribs, between the anterior axillary line and midaxillary line.

The patient’s lower lobes had a diffuse, “ground-glass” appearance on the chest x-ray film. Irregularly shaped opacities in the right and left lower pleural spaces were identified by the radiologist as calcified pleural plaques. A possible infiltrate consistent with pneumonia also was visible in the right middle lobe. In addition, the chest x-ray suggested that the right side of the heart was moderately enlarged. His ABGs on a 1.5 L/min oxygen nasal cannula were as follows: pH 7.56, Paco2 51, image 42, and Pao2 47.

The physician started the patient on intravenous furosemide (Lasix) to treat the man’s cor pulmonale and began administering an antibiotic to treat suspected pneumonia. A respiratory care practitioner was called to obtain a sputum culture, perform a respiratory care evaluation, and outline further respiratory therapy. The physician said that she did not want to commit the patient to a ventilator unless absolutely necessary. On the basis of this information, the following SOAP was recorded.

Respiratory Assessment and Plan

S “This is the worst my breathing has ever been.”

O Vital signs: BP 180/96, HR 108, RR 32, T 38.3° C (100.8° F); weak appearance; skin: cyanotic, damp, and clammy; distended neck veins and digital clubbing; cough: frequent, weak, moderate amount of thick, whitish yellow secretions; peripheral edema 3+ of ankles and feet. Bilateral dull percussion notes in lung bases. Over both lungs: rhonchi and crackles; pleural friction rub over right middle lobe between sixth and seventh ribs, between anterior axillary line and midaxillary line; CXR: ground-glass appearance in lower lobes; calcified pleural plaques in right and left lower pleural spaces; consolidation in right middle lung lobe; right heart enlargement; ABGs (1.5 L/min O2 by nasal cannula): pH 7.56, Paco2 51, image 42, Pao2 47.

A

P Begin Oxygen Therapy Protocol (HAFOE at Fio2 0.28). Bronchopulmonary Hygiene Therapy Protocol (C&DB q4h; obtaining sputum for Gram stain and culture). Initiate Lung Expansion Therapy Protocol (incentive spirometry followed by C&DB). Monitor with alarming pulse oximeter set at 85% Spo2.

The Next Morning

Throughout the night the patient’s condition remained unstable. He continued to cough frequently but could not expectorate secretions adequately on his own. When the therapist assisted the patient during coughing episodes, a moderate amount of thick, white and yellow sputum was produced. Even though he was conscious, alert, and able to follow simple directions, he did not answer any of the respiratory care practitioner’s specific questions about his breathing.

His skin was cold and damp to the touch, and he appeared short of breath. His color was improved, but he still appeared pale and cyanotic. His neck veins were still distended, although not so severely as they had been on admission, and edema of his ankles and feet could still be seen. The patient’s vital signs were as follows: blood pressure 192/108, heart rate 113 bpm, respiratory rate 34/min, and oral temperature 38° C (100.4° F). Palpation of the chest was negative.

Dull percussion notes were elicited over the lung bases. Rhonchi and crackles continued to be auscultated throughout both lungs. A pleural friction rub could still be heard over the right middle lung between the sixth and seventh ribs, between the anterior axillary line and midaxillary line. No recent chest x-ray was available. His ABGs (Fio2 = 0.28) were as follows: pH 7.57, Paco2 47, image 36, and Pao2 40. His oxygen saturation measured by pulse oximetry (Spo2) was 77%. On the basis of these clinical data, the following SOAP was documented.

Respiratory Assessment and Plan

S N/A (patient too dyspneic to reply)

O Condition unstable; cough: frequent, weak, productive of thick, white and yellow secretions; skin: cyanotic, pale, cool, and damp; distended neck veins and peripheral edema, but improving; vital signs: BP 192/108, HR 113, RR 34, T 38° C (100.4° F); dull percussion notes over both lung bases; rhonchi and crackles throughout both lungs; pleural friction rub over right middle lobe between sixth and seventh ribs, between anterior axillary line and midaxillary line; ABGs (Fio2 = 0.28): pH 7.57, Paco2 47, image 36, Pao2 40; Spo2 77%

A

P Up-regulate Oxygen Therapy Protocol (HAFOE to Fio2 0.40). Bronchopulmonary Hygiene Therapy Protocol (adding intensive nasotracheal suctioning q2h). Start Aerosolized Medication Protocal (nebulize 2 mL acetylcysteine to the premix albuterol). Continue Lung Expansion Therapy Protocol (continuing to coach and monitor incentive spirometry; if FVC falls below 15 mL/kg, administer CPAP mask at +10 cm H2O for 20 minutes qid while patient is awake). Continue to monitor closely.

20 Hours Later

At 6:15 am the alarm on the patient’s cardiac monitor sounded. The electrocardiogram (ECG) strip showed frequent premature ventricular contractions followed by ventricular flutter and fibrillation. The head nurse called for a Code Blue. Cardiopulmonary resuscitation was started immediately. Because of the severe hypotension (blood pressure 80/50), epinephrine and dopamine were administered through the patient’s intravenous line. Approximately 12 minutes into the code, the patient exhibited a normal sinus rhythm and spontaneous respirations.

The patient was intubated, transferred to the intensive care unit (ICU), and placed on a mechanical ventilator. The initial ventilator settings were in assist control mode as follows: 12 breaths per minute, Fio2 1.0, pressure support 14 cm H2O, and 10 cm H2O positive end-expiratory pressure (PEEP). His cardiopulmonary status remained unstable. Premature ventricular contractions were frequently seen on the electrocardiographic monitor. A pulmonary artery catheter and arterial line were inserted.

The patient’s skin was pale, cyanotic, and clammy. His neck veins were still distended, and his ankles and feet were swollen. Vital signs were as follows: blood pressure 135/90, heart rate 84 bpm, and rectal temperature 38.3° C (100.8° F). Palpation of the chest wall was negative. Dull percussion notes were noted over the lung bases. Rhonchi and crackles continued to be auscultated throughout both lungs. Thick, greenish-yellow sputum was frequently suctioned from the patient’s endotracheal tube.

A pleural friction rub still could be heard over the right middle lung lobe between the sixth and seventh ribs, between the anterior axillary line and midaxillary line. A chest x-ray had been taken but had not yet been interpreted by the radiologist. The patient’s hemodynamic indices were as follows: elevated central venous pressure (CVP), right atrial pressure (RAP), mean pulmonary artery pressure (PA), right ventricular stroke work index (RVSWI), and pulmonary vascular resistance (PVR). All other hemodynamic values were normal. His ABGs on 1.0 oxygen were as follows: pH 7.53, Paco2 56, image 38, and Pao2 246. His Spo2 was 98%. At this time, the following SOAP note was charted.

Respiratory Assessment and Plan

S N/A (patient intubated on ventilator)

O Vital signs: BP 135/90 on vasopressors, HR 84, T 38.3° C (100.8° F); frequent premature ventricular contractions; skin: pale, cyanotic, and clammy; distended neck veins; peripheral edema of ankles and feet; dull percussion notes over lung bases; rhonchi and crackles throughout both lungs; thick, greenish-yellow sputum frequently suctioned; pleural friction rub over right middle lung lobe between sixth and seventh ribs and between anterior axillary line and midaxillary line; hemodynamic indices: elevated CVP, RAP, PA, RVSWI, and PVR; ABGs (Fio2 = 1.0): pH 7.53, Paco2 56, image 38, Pao2 246, Spo2 98%

A

P Down-regulate Oxygen Therapy Protocol (reduction of Fio2 to 0.50). Down-regulate Mechanical Ventilation Protocol (decreasing tidal volume to increase Paco2 to patient’s baseline—80 to 90 mm Hg). Continue Bronchopulmonary Hygiene Therapy Protocol and Aerosolized Medication Protocol. Continue Lung Expansion Therapy Protocol (depending on mean airway pressure). Continue to closely monitor and reevaluate.

Discussion

The admitting history revealed that the patient had been diagnosed with moderate pneumoconiosis (probable asbestosis) and that he had been a heavy smoker for more than 40 years. Not surprisingly, pulmonary function tests in the past had shown mild-to-moderate restrictive pulmonary disorders.

Significant new findings were the recent history suggesting congestive heart failure and the arterial blood gas values on his discharge from the hospital 10 months before the admission under discussion, which demonstrated chronic ventilatory failure. The patient’s recent fever and cough before his emergency room admission suggested an infectious cause for his symptoms. His cyanosis, neck-vein distention, and digital clubbing suggested chronic hypoxemia. The sputum purulence confirmed that infection may indeed have been present and that the assessing therapist’s desire to obtain a sputum culture was appropriate. The pleural rub demonstrated by this patient could have been related to his asbestosis or to a pneumonic infiltrate extending to the pleural surface.

In the initial assessment the patient’s severe hypertension and his fever were noted. Both deserved vigorous therapy if his pulmonary function were to improve at all. The patient’s severe hypoxemia reflected common clinical indicators caused by Alveolar-Capillary Membrane Thickening (see Figure 9-10) and Excessive Bronchial Secretions (see Figure 9-12). Although there is no therapy to reverse the increased alveolar membrane thickening, the excessive bronchial secretions can be effectively treated in most cases.

Note that the pulmonary capillary wedge pressure (PCWP) was not measured in the first assessment. Such measurements may have identified an element of left ventricular failure in this hypertensive patient as well. The patient was hyperventilating with respect to his earlier outpatient blood gases. During such an assessment the patient’s underlying pulmonary conditions (chronic pulmonary fibrosis, bronchitis, and congestive heart failure) should be recorded, but the assessment should really zero in on the treatable issues, specifically in this case the pulmonary infection, as suggested by the patient’s fever, sputum purulence, and chest x-ray film.

At the time of the second evaluation, the patient’s hypoxemia had worsened despite oxygen therapy. If not already being used, Venturi oxygen mask (HAFOE) therapy was indicated there, and additional mucolytics and endobronchial suctioning also could be indicated. The trial of Lung Expansion Therapy Protocol (Protocol 9-3) was appropriate to attempt to offset the pathologic effects of the alveolar consolidation and, possibly, atelectasis. The physician may have ordered a trial of diuretic therapy to reduce the fluid retention and a course of antibiotic therapy as well.

The last assessment revealed ventricular arrhythmias. The change in the patient’s sputum from thick and white to greenish-yellow suggests superinfection with another organism, and reculture of the sputum was appropriate. The respiratory practitioner responded quickly, and appropriately, to readjust the mechanical ventilator. The Fio2 was decreased to 0.5 to correct the patient’s overoxygenation (Pao2: 246), and the tidal volume was reduced to increase the Paco2 to the baseline—80 to 90 mm Hg according to the ABG history. Ventilator parameters should be adjusted to provide good pulmonary expansion while avoiding high mean airway pressures. A cautious trial of PEEP would have been in order.

Despite all that was done for this patient, he died 4 days later as a result of left-sided congestive heart failure and pneumonia complicating his pulmonary asbestosis.

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