Centers for Disease Control and Prevention

National Health and Nutrition Examination Survey (Nhanes): Respiratory Health Eno Procedures Manual Centers for Disease Control and Prevention

Exhaled nitric oxide (ENO) provides a measure of airway inflammation, a factor in the causal pathway of asthma and possibly other lung diseases. A current estimate of the prevalence of asthma in the United States varies between 4-10 percent.[1] Starting in 2007, NHANES will collect pulmonary function examination data to determine the prevalence of obstructive airway diseases in older children and adults. The new component, Respiratory Health (RH), will include an assessment of lung function testing, or spirometry, and a measurement of ENO. ENO is always performed before spirometry because spirometric maneuvers have been shown to transiently reduce exhaled NO (nitric oxide) levels. The motivation for spirometry with bronchodilator and supplemental ENO testing is to evaluate airway inflammation among children and to help explain the unanticipated excess prevalence of undiagnosed pulmonary obstruction in the adult population that was previously identified in the NHANES III sample. Bronchodilator and ENO tests will allow improved estimation of asthma prevalence based on objective measurements and help analysts to discriminate asthmatics from otherwise healthy individuals who have episodes of wheezing. Currently, there are no U. S. population-based estimates of ENO baseline levels for normal subjects or for those persons with asthma and chronic obstructive pulmonary disease (COPD). The goals of this study are to: (1) provide the first U. S. population-based estimates of ENO baseline levels for normal subjects as well as those with asthma and COPD; (2) allow estimation of the association of a marker for airway inflammation with other physical measurements of lung capacity and biologic correlates; (3) define the prevalence of undiagnosed airway inflammation; and (4) permit retrospective selection of a panel of questions and measures that would provide efficient screening for potentially treatable airflow limitation and obstruction in the general population. All participants aged 6-79 years will be eligible to participate in the ENO component. There are safety exclusions for this test. ENO will be part of the Respiratory Health (RH), which will include Spirometry. Please refer to the Spirometry Procedures Manual for further details.