Farmer's Lung Follow-up

Updated: Dec 21, 2015
  • Author: Laurianne G Wild, MD, FAAAAI, FACAAI; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Follow-up

Further Outpatient Care

Outpatient care includes the following:

  • Routine spirometry with lung volumes and diffusion capacity.

  • Arterial PO2 and arterial-alveolar gradient: Recommend exercise (6-min walk or by ergometer) if the room air PO2 level is normal.

  • Monitor chest radiographs and consider high-resolution CT scans of the chest to seek resolution of infiltrates or presence of ground-glass opacities that may indicate a need for further treatment with corticosteroids and/or continued insult to the lungs by antigen exposure.

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Further Inpatient Care

Inpatient care includes the following:

  • Systemic corticosteroids

  • Serum precipitins

  • Flexible bronchoscopy to exclude other etiologies

  • Transbronchial biopsy may be of limited benefit in patients with acute farmer's lung.

  • Open lung biopsy may be indicated to confirm the diagnosis if other diagnostic criteria are not met

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Deterrence/Prevention

Complete avoidance of the antigen is indicated. Consider the following:

  • Protective devices (eg, masks) may reduce the amount of antigen; however, again, complete avoidance is recommended.

  • Maintaining humidity at less than 60% may discourage microbial growth.

  • Keeping hay on farms dry and well protected may discourage growth of bacteria and molds. However, salting of hay, a traditional empirical practice used to prevent molding in hay, does not significantly decrease the amount of actinomycetes, the organisms most commonly involved in farmer's lung disease. Salting of hay may provide a false sense of security that the farmer is protected from developing farmer's lung; this false notion should be dispelled. [18]

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Complications

Complications of farmer's lung include the following:

  • Cor pulmonale

  • Hypoxemic respiratory failure

  • Pulmonary fibrosis

  • Death

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Prognosis

The long-term prognosis of farmer's lung varies and depends on the extent of fibrosis and the amount of irreversible damage to the lung parenchyma. [19]  Consider the following:

  • In some patients, the disease may progress even after the antigen exposure has been eliminated.

  • If the diagnosis of farmer's lung is confirmed before irreversible changes have developed, most patients recover with minimal functional abnormalities and few become disabled.

  • In the acute stages, restriction with decreased static compliance and diffusing capacity that reverses over several weeks (with antigen avoidance) may occur.

  • In subacute disease, bronchiolitis and granuloma formation might be slower to resolve even with corticosteroid therapy.

  • Individuals with a ground-glass appearance on high-resolution CT scans of the chest have higher response rates to systemic corticosteroids.

  • Patients with honeycombing or pulmonary fibrosis may have less than a 20% response to corticosteroids and a mortality rate greater than 90% at 5 years after diagnosis.

  • Predictors of long-term decline in farmer's lung include recurrent acute episodes, allergy to mites, organic dust, and fungal elements, and smoking, which promotes deterioration of lung function in patients diagnosed with farmer's lung. [20]

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Patient Education

Environmental control and complete avoidance of the antigen should be the goal. Complete avoidance of the environment or farm may be required to ensure prevention of chronic disease and survival.

Many farmers have thought that salting the hay can prevent the growth of molds in the hay. However, salting does not prevent the growth of molds. The use of salt does not significantly decrease the amount of Saccharopolyspora rectivirgula (the actinomycetes most commonly involved in farmer's lung disease), or Absidia corymbifera, Eurotium amstelodami, and Wallemia sebi, 3 molds responsible for farmer's lung disease in Europe. Therefore, palatable hay is not safe hay.

For patient education information, see Bronchoscopy.

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