title: Secondary spontaneous pneumothorax in rapidly progressive forms of silicosis: characterization of pulmonary function measurements and clinical patterns.
abstract: BACKGROUND
  A secondary spontaneous pneumothorax is a complication of an underlying pulmonary disease. In recent years, there have been only a few scattered reports of patients with silicosis also having a pneumothorax. Silicosis, a form of disabling pulmonary fibrosis, is a well-known occupational disease resulting from high-level exposure to silica or silica-containing dusts. The objective of the present study was to elucidate any associations between the occurrence of a pneumothorax, and pulmonary function tests and clinical observations performed prior to the pneumothorax; these two factors may be predictors for a pneumothorax among workers exposed primarily to silica-containing respirable dust.
  
  
  METHODS
  A diagnosis of silicosis was made on several factors: silica dust exposure, appropriate interval of time after exposure, clinical findings, pulmonary function tests and chest radiological findings. A checklist was designed for collecting data of occupational history, respiratory signs, and symptoms from onset of dust exposure to the occurrence of a pneumothorax. Spirometery was conducted in accordance to the recommendations of standard protocols and guidelines posited by the American Thoracic Society. Autopsies were performed in three cases where the patient had suffered a pneumothorax due to silicosis. Mann-Whitney U-tests and Fisher's exact tests were used to determine any associations between pneumothorax and predictor factors.
  
  
  RESULTS
  An association between a progressive decrease in pulmonary function test values and a pneumothorax was observed. The occurrence of a pneumothorax was associated with complaints of pleuretic chest pain, resting dyspnea, respiratory distress, paroxysmal nocturnal dyspnea, orthopnea and crackle.
  
  
  CONCLUSIONS
  A characteristic decline in pulmonary function test values and the severity of respiratory impairment may facilitate the occurrence of a pneumothorax in silicosis.
authors.affiliation: Department of Occupational Medicine, Urmia Medical Sciences University, Urmia, Iran. irajmohebbi@umsu.ac.ir
authors.forename: Iraj
authors.initials: I
authors.lastname: Mohebbi
authors.forename: Isa Abdi
authors.initials: IA
authors.lastname: Rad
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects; D011030:Pneumothorax / Q000209:etiology*; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors; D012822:Silicon Dioxide / Q000633:toxicity; D012829:Silicosis / Q000150:complications*; D013997:Time Factors
chemical_list: D012822:Silicon Dioxide