eMedicine Specialties > Pulmonology > Occupational Lung Diseases

Silo Filler's Disease: Differential Diagnoses & Workup

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

Differential Diagnoses

Acute Respiratory Distress Syndrome
Myocardial Ischemia
Angina Pectoris
Pneumonia, Aspiration
Anxiety Disorders
Pneumonia, Bacterial
Chronic Obstructive Pulmonary Disease
Pneumonia, Fungal
Emphysema
Pneumonia, Viral
Farmer's Lung
Pulmonary Edema, Cardiogenic
Hantavirus Pulmonary Syndrome
Pulmonary Embolism
Metastatic Cancer, Unknown Primary Site
Toxicity, Cyanide
Methemoglobinemia
Toxicity, Organophosphate
Miliary Tuberculosis
Toxicity, Salicylate
Myocardial Infarction

Other Problems to Be Considered

Acute lung injury
Pneumonitis, other chemical
Pneumoconiosis 
Conjunctivitis 
Smoke inhalation 
Toxicity, carbon monoxide
Toxicity, chlorine gas
Toxicity, hydrogen sulfide
Toxicity, carbamate
Toxicity, phosgene
Toxicity, ozone
Toxic organic dust syndrome

Workup

Laboratory Studies

  • Silo filler's disease (SFD) cannot be diagnosed using any laboratory studies; however, the following studies can be helpful in excluding other causes of the symptoms.
  • Arterial blood gas level
    • Measuring arterial blood gas (ABG) levels establishes the presence and severity of gas exchange impairment. Initial blood gas levels are extremely important in the decision to intubate.
    • Some available literature supports obtaining serial ABG levels during follow-up visits to ascertain whether bronchiolitis obliterans is developing.
  • Lactate level: Metabolic acidosis can occur by dissolution of nitrous oxide in body fluids, resulting in tissue hypoxemia and subsequent lactic acid formation.
  • Methemoglobin level
    • Perform a methemoglobin (MHb) test to evaluate cyanosis that does not respond to oxygen administration. MHb is an inactive oxidized form of hemoglobin that does not contribute to oxygen transport. Cyanosis results from an MHb test result that is greater than 10-15%.
    • Methylene blue administration can affect this test result.
  • Complete blood cell count: Leukocytosis is often present in silo filler’s disease.

Imaging Studies

  • Chest radiography
    • Findings may be normal.
    • During acute injury, the chest radiograph shows ill-defined, alveolar opacities, which are characteristic of pulmonary edema or ARDS.
    • Subacute injury reveals small opacities or confluent woolly opacities. The small opacities can be mistaken for miliary tuberculosis.

Other Tests

  • Pulmonary function testing
    • As soon as the patient is able to undergo tests, conduct a pulmonary function test (PFT) to chart the progress and document the severity of disease.
    • A baseline PFT is helpful as the patient recovers.
    • Conduct PFTs at regular intervals toward the end of the inpatient stay and during follow-up visits.
  • Electrocardiography
    • Symptoms of silo filler’s disease can mimic cardiovascular events; ECG may help rule out such occurrences.
    • Serial ECGs are helpful for baseline and initial encounters; however, only abnormal findings are helpful.
  • Pulse oximetry monitoring: Pulse oximetry monitoring may be misleading in the presence of methemoglobinemia.
  • Pulmonary artery catheter: In patients who are critically ill, monitoring of mixed venous oxygenation and pulmonary vascular resistance may assist in the management of oxygenation requirements, fluids, ARDS, and physiologic variables.

Procedures

  • Intubation and mechanical ventilation may be necessary if gas exchange is severely impaired.

Histologic Findings

In patients who quickly die, hemorrhagic edema and patches of pneumonia are revealed in their airways. Small palpable nodules and hemorrhagic areas appear in those patients who survive for several weeks.

Microscopic evaluation of tissues from patients with acute silo filler’s disease shows edema and extensive damage of the respiratory epithelium, which may be completely shed in the small bronchi and bronchioles. In patients who survive for longer periods, generalized infiltration of the alveolar walls with lymphocytes (ie, numerous macrophages in alveolar spaces) occurs. Bronchiolitis obliterans occurs in various stages of organization and is responsible for the palpable nodules.

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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  2. Belanger K, Gent JF, Triche EW, Bracken MB, Leaderer BP. Association of indoor nitrogen dioxide exposure with respiratory symptoms in children with asthma. Am J Respir Crit Care Med. Feb 1 2006;173(3):297-303. [Medline].

  3. Stieb DM, Szyszkowicz M, Rowe BH, Leech JA. Air pollution and emergency department visits for cardiac and respiratory conditions: a multi-city time-series analysis. Environ Health. Jun 10 2009;8:25. [Medline].

  4. MMWR. Silo-Filler's disease in rural New York. MMWR Morb Mortal Wkly Rep. Jul 23 1982;31(28):389-91. [Medline].

  5. Zwemer FL Jr, Pratt DS, May JJ. Silo filler's disease in New York State. Am Rev Respir Dis. Sep 1992;146(3):650-3. [Medline].

  6. Ichinose F, Roberts JD Jr, Zapol WM. Inhaled nitric oxide: a selective pulmonary vasodilator: current uses and therapeutic potential. Circulation. Jun 29 2004;109(25):3106-11. [Medline].

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  8. Douglas WW, Hepper NG, Colby TV. Silo-filler's disease. Mayo Clin Proc. Mar 1989;64(3):291-304. [Medline].

  9. Goldstein E, Peek NF, Parks NJ, Hines HH, Steffey EP, Tarkington B. Fate and distribution of inhaled nitrogen dioxide in rhesus monkeys. Am Rev Respir Dis. Mar 1977;115(3):403-12. [Medline].

  10. Gurney JW, Unger JM, Dorby CA, Mitby JK, Von Essen SG. Agricultural disorders of the lung. Radiographics. Jul 1991;11(4):625-34. [Medline].

  11. Leavey JF, Dubin RL, Singh N, Kaminsky DA. Silo-Filler's disease, the acute respiratory distress syndrome, and oxides of nitrogen. Ann Intern Med. Sep 7 2004;141(5):410-1. [Medline].

  12. Maurer WJ. Silo-filler's disease. A historical perspective and report of a case. Wis Med J. Aug 1985;84(8):13-6. [Medline].

  13. Ramirez J, Dowell AR. Silo-filler's disease: nitrogen dioxide-induced lung injury. Long-term follow-up and review of the literature. Ann Intern Med. Apr 1971;74(4):569-76. [Medline].

  14. Robinson DM, Yu ML, Prakash UB. 60-year-old man with respiratory distress and confusion. Mayo Clin Proc. Aug 1996;71(8):813-6. [Medline].

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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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