Graduation Year

2004

Document Type

Thesis

Degree

M.S.P.H.

Degree Granting Department

Public Health

Major Professor

Stuart M. Brooks

Keywords

chemiluminescence, aging, nitric oxide synthase, pulmonary infection, noninvasive markers of airway inflammation

Abstract

BACKGROUND: Older individuals suffer from higher rates of pulmonary infections than younger individuals. In addition, older individuals have increased morbidity and mortality due to pulmonary infections when compared to younger individuals. The physiological and immunological reasons for these aforementioned differences are not clear. Recently, non-invasive markers of the lung's physiologic and immunologic status have been recognized. This study employs one of these non-invasive markers, exhaled nitric oxide, in an attempt to determine how the airways may change with age, predisposing older individuals to pulmonary diseases and poorer outcomes as compared to younger individuals.

METHODS: Exhaled nitric oxide measurements were obtained from a group of 25 older subjects (61 to 79 years old, median 72 years old) and a group of 23 younger subjects (21 to 30 years old, median 24 years old) that were non-smokers with no history of pulmonary disease, no recent respiratory infections, and no history of environmental allergies. A focused history and physical exam along with spirometry were used to confirm the normal pulmonary status of each subject. Exhaled nitric oxide was measured following the American Thoracic Society recommendations using the Sievers Nitric Oxide Analyzer 280i. The exhaled nitric oxide values for the old and young groups were compared using the Wilcoxon Rank Sum test. RESULTS: For the older subjects, the median exhaled NO concentration was 36.9 ppb. For the younger subjects, the median exhaled NO concentration was 18.7 ppb. These exhaled NO concentrations are significantly different (p = 0.0011).

CONCLUSIONS: The exhaled NO concentrations are significantly higher in older individuals than in younger individuals. The reasons for this difference along with the significance are unclear and further studies will be necessary to further evaluate these issues.

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