eMedicine Specialties > Pulmonology > Occupational Lung Diseases

Silo Filler's Disease: Follow-up

Author: Nader Kamangar, MD, FACP, FCCP, FAASM,, Associate Professor of Clinical Medicine, Director of Hospitalist/Intensivist Program, Division of Pulmonary, Critical Care and Sleep Medicine, David Geffen School of Medicine at University of California Los Angeles; Associate Director, Combined Pulmonary and Critical Care Fellowship Program, Cedars-Sinai/Olive View-UCLA/West Los Angeles Veterans Affairs Medical Center
Coauthor(s): Lex Chen, MD, Resident Physician, Department of Internal Medicine, University of California Los Angeles, Olive View Medical Center
Contributor Information and Disclosures

Updated: Sep 17, 2009

Follow-up

Further Inpatient Care

  • Admit silo filler's disease (SFD) patients for at least 24 hours if they have signs of dyspnea, altered mental status, hypoxemia, or a widened alveolar-arterial oxygen gradient.
  • If no initial symptoms are present, observe the patient for at least 12 hours for hypoxemia.
  • Pulmonary edema can take up to 48 hours to develop. Educate the silo filler's disease patient on the possible symptoms and instruct the patient to return if the symptoms develop.
  • Clinical improvement and resolution of hypoxemia and methemoglobinemia are helpful endpoints for discharge.

Further Outpatient Care

  • Conduct a follow-up examination at 1 week, 1 month, and 3 months after exposure, with serial pulmonary function testing and radiographs.

Inpatient & Outpatient Medications

  • When the silo filler's disease patient is discharged, prescribe corticosteroid taper for at least 8 weeks. A longer duration (ie, 6-12 mo) may be indicated if symptoms of bronchiolitis obliterans persist or recur after initial steroid taper.
  • Inhaled sympathomimetics (eg, albuterol), anticholinergics (eg, ipratropium bromide), and steroids (eg, fluticasone propionate) may also be indicated if the patient has additional symptoms of reactive airway disease. A typical asthma disease management plan can be used for these patients.

Transfer

  • Transferring the silo filler's disease patient to a tertiary care center for further diagnostic evaluation and ventilatory support may be necessary.

Deterrence/Prevention

  • Educate farm workers at risk for exposure and development of silo filler's disease.

Complications

  • Secondary infection: Infection (eg, pneumonia) is possible because of the mucosal injury caused by pulmonary edema and the inhibition of immune function by nitrogen dioxide.
  • Bronchiolitis obliterans: Fibrous granulation tissue develops within small airways and alveolar ducts, occurring weeks or months after the initial incident.

Prognosis

  • Pulmonary function may not improve (without permanent disability) for weeks or months; however, mild dysfunction likely due to bronchiolitis obliterans may occur. This manifests as mild hyperinflation; abnormal Vmax50, Vmax75, or FEF25-75; increased respiratory resistance; and airway obstruction.
  • The lungs clear quickly with steroid treatment, and the chest radiograph may reveal no evidence of residual lung damage.
  • Treat deconditioning by referring the patient to a pulmonary rehabilitation program.

Patient Education

  • Offer the following preventive advice to the patient:
    • Stay out of the silos during the 2-week danger period after the initial filling.
    • Close all doors before putting in the silage.
    • Go up the outside ladder to the level of silage.
    • If the silo is not completely full, remove the doors that lead down to the silage.
    • Enter the silo only with a complete oxygen support system (ie, air supply, self-contained breathing apparatus).
    • Ventilate the silo by opening the cover flaps and running the silo blower for 24-48 hours before entering.
    • Never enter the silo alone or without a lifeline for rescue during the danger period.
    • If entering a silo during filling is necessary, enter immediately after the last load.

Miscellaneous

Medicolegal Pitfalls

  • Failure to inform the patient about delayed symptoms, including life-threatening pulmonary edema and dyspnea due to bronchiolitis obliterans
  • Failure to consider the asymptomatic period and the delayed onset of symptoms associated with nitrogen dioxide toxicity
  • Discharging the patient too soon from the emergency department
  • Failure to consider nitrogen dioxide toxicity in patients who present with dyspnea and who have occupations allowing exposure
  • Failure to recognize early signs of significant respiratory distress and to document either a PO2, an Aa gradient, or oxygen saturation via pulse oximetry
  • Failure to monitor the patient in a setting where respiratory support is immediately available
  • Failure to monitor the patient for bronchiolitis obliterans or to prescribe the patient steroids when signs manifest
 
Acknowledgments

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors, Rebecca Bascom, MD, MPH, and Mark D Rasmussen, MD, to the development and writing of this article.



More on Silo Filler's Disease

Overview: Silo Filler's Disease
Differential Diagnoses & Workup: Silo Filler's Disease
Treatment & Medication: Silo Filler's Disease
Follow-up: Silo Filler's Disease
References
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References

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Further Reading

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Keywords

silo filler’s disease, silo filler disease, silo unloader disease, nitrogen dioxide poisoning, SFD, silo-filler's disease, proliferative pulmonary disease, pulmonary edema, bronchiolitis obliterans, asphyxiation, methemoglobinemia, chemical pneumonitis, acute respiratory distress syndrome, ARDS, acute lung injury, nitrogen oxides, bronchioles lung injury, alveoli lung injury, arterial blood gas, ABG, methemoglobin, MHb, methemoglobinemia

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Contributor Information and Disclosures

Author

Nader Kamangar, MD, FACP, FCCP, FAASM,, Associate Professor of Clinical Medicine, Director of Hospitalist/Intensivist Program, Division of Pulmonary, Critical Care and Sleep Medicine, David Geffen School of Medicine at University of California Los Angeles; Associate Director, Combined Pulmonary and Critical Care Fellowship Program, Cedars-Sinai/Olive View-UCLA/West Los Angeles Veterans Affairs Medical Center
Nader Kamangar, MD, FACP, FCCP, FAASM, is a member of the following medical societies: American Academy of Sleep Medicine, American Association of Bronchology, American College of Chest Physicians, American College of Physicians, American Lung Association, American Medical Association, American Thoracic Society, California Thoracic Society, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Lex Chen, MD, Resident Physician, Department of Internal Medicine, University of California Los Angeles, Olive View Medical Center
Lex Chen, MD is a member of the following medical societies: American College of Physicians
Disclosure: Nothing to disclose.

Medical Editor

Gregory Tino, MD, Director of Pulmonary Outpatient Practices, Associate Professor, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care, University of Pennsylvania Medical Center and Hospital
Gregory Tino, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and American Thoracic Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Gregg T Anders, DO, Medical Director, Great Plains Regional Medical Command , Brook Army Medical Center; Clinical Associate Professor, Department of Internal Medicine, Division of Pulmonary Disease, University of Texas Health Science Center at San Antonio
Gregg T Anders, DO is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and American Thoracic Society
Disclosure: Nothing to disclose.

CME Editor

Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, Saint Louis University School of Medicine
Timothy D Rice, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Physicians
Disclosure: Nothing to disclose.

Chief Editor

Zab Mosenifar, MD, Director, Division of Pulmonary and Critical Care Medicine, Director, Women's Guild Pulmonary Disease Institute, Executive Vice Chair, Department of Medicine, Cedars Sinai Medical Center; Professor of Medicine, David Geffen School of Medicine at UCLA
Zab Mosenifar, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Federation for Medical Research, and American Thoracic Society
Disclosure: Nothing to disclose.

 
 
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