A group of 38 soldiers deployed to the Middle East have been diagnosed with constrictive bronchiolitis, a condition that is very rare in otherwise healthy young people, investigators reported.
Mean maximal oxygen consumption was significantly decreased in these soldiers compared with a group of historical controls (85.1% versus 105.4% of predicted value, P<0.001), according to Robert F. Miller, MD, of Vanderbilt University in Nashville, and colleagues.
Their anaerobic threshold also was low, at 45% of predicted value, compared with 78.2% in controls (P<0.001), the researchers reported in the July 21 New England Journal of Medicine.
Between 2004 and 2009, Miller and colleagues evaluated 80 soldiers who had been referred because of exertional dyspnea after returning from Iraq or Afghanistan.
A total of 49 of the soldiers underwent video-assisted thoracoscopic lung biopsy, as well as pulmonary and cardiac function testing and high-resolution CT imaging.
Constrictive bronchiolitis was defined as narrowing of the luminal wall associated with subepithelial fibrosis and/or hypertrophy of the bronchiolar smooth muscle.
The condition can be difficult to diagnose, Miller's group explained, with nonspecific symptoms and exercise limitations beyond what would be expected from pulmonary function tests.
Biopsy specimens of 38 of the soldiers showed evidence of this type of bronchiolitis.
Findings included black pigment containing polarizable material on the surface of the pleura, which is typical following the inhalation of particulate substances, and membranous bronchioles showing mural thickening and luminal narrowing.
The median age of the soldiers with constrictive bronchiolitis was 33, and 35 were men.
All had previously met the military fitness requirements, being able to complete a two-mile run within the time expected according to age.
A total of 25 had never smoked, and only seven were current smokers.
In this group, 28 had been exposed to smoke from a fire in a sulfur mine in northern Iraq, and the smoke contained levels up to 125 parts per million of toxic sulfur dioxide.
Chest x-rays were normal in all but one, and CT results also were normal in 68%, with only a few cases showing the typical nodularity and air trapping.
But compared with controls, soldiers with constrictive bronchiolitis had these abnormalities on pulmonary function testing:
- Forced expiratory volume in one second (FEV1), 86.7% versus 99.1% of predicted value, P<0.001
- Forced vital capacity (FVC), 90.7% versus 101.6% of predicted value, P<0.001
- Ratio of FEV1 to FVC, 79.1 versus 97.4, P<0.001
- Carbon monoxide diffusing capacity, 73.4% versus 90.6% of predicted value, P<0.001
On exercise testing, significant abnormalities also were found on maximal heart rate, respiratory rate, and ratio of minute ventilation to carbon dioxide production.
Miller and colleagues subsequently conducted a follow-up survey in 2010 to which 50 of the original 80 soldiers responded.
Among the 38 diagnosed with constrictive bronchiolitis, 50% were no longer in the military, having been given a disability rating; 21% were still serving although they were unable to do the two-mile run as required; and the remainder had been lost to follow up.
More than half were short of breath when climbing a flight of stairs and had few occupational opportunities because of their symptoms.
The researchers noted that, since they analyzed the 38 initial cases of constrictive bronchiolitis, nine more had been diagnosed.
They also explained that the soldiers they saw initially all had been exposed to the sulfur dioxide during the fire at the mine. They said they expected that the condition was limited to that unusual exposure.
That was not the case, however, and the diagnosis later was extended to soldiers with other types of exposures such as to waste incineration pits and severe dust storms.
"This group causes particular concern, since their potential toxic exposures are shared by most personnel who were deployed to Iraq and Afghanistan," cautioned Miller and colleagues.
They called for further studies to analyze the particulate matter found in the biopsy specimens, and to identify specific sources and exposures, with the goal of increasing protection for soldiers in the future.
One co-author disclosed receiving a grant from Actelion Pharmaceutical, a second has received royalties from Springer for a textbook, and a third is employed by the Veterans Administration.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
New England Journal of MedicineSource Reference: King M, et al "Constrictive bronchiolitis in soldiers returning from Iraq and Afghanistan" N Engl J Med 2011; 365: 222-230.