This Article Full Text Free Full Text (PDF) Free 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 Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 Spirometry Following World Trade Center Dust Exposure^*

^* From the Division of Pulmonary and Critical Care Medicine, Department of Medicine, New York University School of Medicine, New York, NY.

Correspondence to: Kenneth I. Berger, MD, FCCP, New York University School of Medicine, 550 First Ave, Room RR 108, New York, NY 10016; e-mail: Kenneth.berger{at}med.nyu.edu

Abstract

Rationale: Following collapse of the World Trade Center (WTC), 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 WTC dust may have functional abnormalities in distal airways not detectable with routine spirometry.

Methods: One hundred seventy-four subjects with respiratory symptoms and normal spirometry results were evaluated. Impedance oscillometry (IOS) was performed to determine resistance at 5 Hz, 5 to 20 Hz, and reactance area. Forty-three subjects were also tested for frequency dependence of compliance (FDC). Testing was repeated after bronchodilation.

Results: Predominant symptoms included cough (67%) and dyspnea (65%). Despite normal spirometry results, mean resistance at 5 Hz, 5 to 20 Hz, and reactance area were elevated (4.36 ± 0.12 cm H₂O/L/s, 0.86 ± 0.05 cm H₂O/L/s, and 6.12 ± 0.50 cm H₂O/L, respectively) [mean ± SE]. Resistance and reactance normalized after bronchodilation. FDC was present in 37 of 43 individuals with improvement after bronchodilation.

Conclusions: Symptomatic individuals with presumed WTC dust/fume exposure and normal spirometry results displayed airway dysfunction based on the following: (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 toward normal following administration of a bronchodilator. Since spirometry results were 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 results are normal may be important in the evaluation of subjects exposed to occupational and environmental hazards.

Clinical trials registration number: NCT00395330. http://www.clinicaltrials.gov.

Key Words: distal airways • environmental exposure • oscillometry • respiratory function tests • World Trade Center disaster