Medical Care
Treatment is best determined by the specific diagnosis. Unfortunately, a specific etiology often is not determined. General supportive measures include the following:
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Smoking cessation should be counseled.
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Good pulmonary hygiene is important.
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Supplemental oxygen therapy may be useful for any patients who demonstrate significant hypoxemia (oxygen saturation [SaO2] less than or equal to 88% or PaO2< 55 mm Hg while breathing room air either at rest or upon exertion).
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If inhalational exposures are thought to be the etiology, as in HP and occupational forms of interstitial lung disease, removal from exposure is mandatory.
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If a toxic medication is suspected, its discontinuation is mandated.
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Respiratory infections should be promptly treated.
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Pulmonary rehabilitation may improve exercise tolerance and quality of life (see Pulmonary Rehabilitation).
Pharmacologic therapy with corticosteroids (eg, prednisone) and/or cytotoxic agents for their potential steroid-sparing effect (eg, cyclophosphamide, azathioprine, methotrexate) may be indicated for specific diagnoses.
Other immunosuppressive or antifibrotic agents such as colchicine, cyclosporine, and D-penicillamine may have a role in specific cases. Empiric use of these medications without a specific diagnosis should be discouraged because they have significant toxicities.
Interferon-gamma-1b, [12] pirfenidone, [13] and N-acetylcysteine [14] have been studied for the treatment of IPF. Interferon-gamma-1b initially appeared to have a favorable effect. This, however, was not supported in a larger follow-up study. Some evidence suggests that pirfenidone and acetylcysteine may have some benefit in IPF. Further investigation is still needed, particularly in other forms of DPLD. As much remains unknown regarding the optimal therapy for DPLD, eligible patients may benefit from enrollment in an experimental trial.
Pirfenidone and nintedanib are approved by the US Food and Drug Administration for IPF treatment. [15, 16, 17]
A 2008 multisystem, randomized, controlled study of bosentan, an endothelin-1 receptor antagonist, and potentially anti-fibrotic agent, did not show superiority over placebo. However, a trend toward delay in progression of disease and improvement in mortality was noted, which was more pronounced in patients with UIP documented by surgical biopsy. [18] Additional phase III trials are ongoing.
Other novel potential therapeutic agents, such as recombinant TNF-alpha antagonists and tyrosine kinase inhibitors, are currently under investigation. These agents are further described in a recently published comprehensive review. [19]
Most patients with DPLD can be treated in community settings. Transfer to a tertiary care center is indicated when the diagnosis is in doubt or when treatment is ineffective.
Surgical Care
Surgery in the form of either thoracoscopic (preferred) or open lung biopsy is often indicated to obtain tissue specimens for definitive diagnosis.
More recently, lung transplantation has become a treatment option for selected patients with advanced disease refractory to medical therapy. [20] It is the only interventional modality that has been shown to increase survival time in patients with UIP/IPF. [21, 22] Survival rates worldwide after single lung transplantation are approximately 74% at 1 year, 58% at 3 years, 47% at 5 years, and 24% at 10 years. Survival rates are lower for bilateral lung transplantation. Following transplantation, patients overall report improved quality of life with better physical, social, and general health functioning.
Consultations
Consider consultation with a pulmonary or occupational disease specialist for patients with suspected DPLD.
Diet
No specific dietary restrictions are warranted for affected patients.
Some suggest that antioxidants have a therapeutic benefit.
Activity
Encourage exercise and pulmonary rehabilitation because they may improve a patient's functional status. However, these activities generally have no effect on disease progression.
Long-Term Monitoring
See patients with diffuse interstitial lung disease every 3-6 months. Order pulmonary function testing every 3-6 months to assess disease progression and response to therapy. High-resolution CT scanning is becoming an increasingly important tool in making the initial diagnosis and subsequent assessments of disease progression and/or responses to therapy.
Patients with interstitial lung disease generally are treated in an outpatient setting. With advancing disease, progressive respiratory failure, pneumonia, pulmonary embolism, and cor pulmonale may all occur and require hospital admission. Bronchogenic cancer occurs with increased frequency. [23]
The prognosis is variable and depends on the specific diagnosis and clinical, physiologic, and pathologic severity.
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Frontal chest radiograph demonstrating bilateral reticular and nodular interstitial infiltrates with upper zone predominance.
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High-resolution chest CT scan of patient with bilateral reticular and nodular interstitial infiltrates with upper zone predominance.
