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This Article Full Text (PDF) All Versions of this Article: chest.07-0913v1 132/4/1275    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Article Archive Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Oppenheimer, B. W. Articles by Berger, K. I. Search for Related Content PubMed PubMed Citation Articles by Oppenheimer, B. W. Articles by Berger, K. I.

DISTAL AIRWAY FUNCTION IN SYMPTOMATIC SUBJECTS WITH NORMAL SPIRO METRY FOLLOWING WORLD TRADE CENTER DUST EXPOSURE

¹Division of Pulmonary and Critical Care Medicine, Department of Medicine, New York University School of Medicine, New York, NY

Kenneth.berger{at}med.nyu.edu

Abstract

Rationale: Following collapse of the World Trade Center, individuals reported new onset respiratory symptoms. Despite symptoms, spirometry often revealed normal airway function. However, bronchial wall thickening and air trapping were seen radiographically in some subjects. We hypothesized that symptomatic individuals following exposure to World Trade Center dust may have functional abnormalities in distal airways not detectable with routine spirometry.

Methods: 174 subjects with respiratory symptoms and normal spirometry were evaluated. Impedance oscillometry was performed to determine resistance at 5Hz, 5-20Hz and reactance area. 43 subjects were also tested for frequency dependence of compliance (FDC). Testing was repeated post bronchodilator.

Results: Predominant symptoms included cough (67%) and dyspnea (65%). Despite normal spirometry, mean resistance at 5Hz, 5-20Hz and reactance area were elevated (4.36±0.12 cmH₂O/l/s, 0.86±0.05 cmH₂O/l/s, and 6.12±0.50cmH₂O/l respectively). Resistance and reactance normalized after bronchodilator. Frequency dependence of compliance was present in 37/43 individuals with improvement post bronchodilator.

Conclusions: Symptomatic individuals with presumed WTC dust/fume exposure and normal spirometry displayed airway dysfunction based on: 1) elevated airway resistance and frequency dependence of resistance determined by IOS; 2) heterogeneity of distal airway function demonstrated by elevated reactance area on oscillometry and FDC; and 3) reversibility of these functional abnormalities to or towards normal following administration of bronchodilator. Since spirometric evaluation was normal in all subjects, these abnormalities likely reflect dysfunction in airways more distal to those evaluated by spirometry. Examination of distal airway function when spirometry is normal may be important in the evaluation of subjects exposed to occupational and environmental hazards.

Key Words: Respiratory Function Tests • Oscillometry • World Trade Center Disaster • Environmental Exposure • Distal Airways