Exhaled Nitric Oxide Levels Are Elevated in Persons with Tetraplegia and Comparable to that in Mild Asthmatics

The role of airway inflammation in mediating airflow obstruction in persons with chronic traumatic tetraplegia is unknown. Measurement of the fraction of exhaled nitric oxide (FeNO) affords a validated noninvasive technique for gauging the airway inflammatory response in asthma, although it has never been assessed in persons with tetraplegia. This study was designed to determine the FeNO in individuals with chronic tetraplegia compared with that in patients with mild asthma and healthy able-bodied individuals. Nine subjects with chronic tetraplegia, seven subjects with mild asthma, and seven matched healthy able-bodied controls were included in this prospective, observational, pilot study. All subjects were nonsmokers and clinically stable at the time of study. Spirometry was performed on all participants at baseline. FENO was determined online by a commercially available closed circuit, chemiluminescence method, using a single-breath technique. Subjects with tetraplegia had significantly higher values of FeNO than controls (17.72 ± 3.9 ppb vs. 10.37 ± 4.9 ppb; P ≤ 0.01), as did subjects with asthma (20.23 ± 4.64 ppb vs. 10.37 ± 4.9 ppb, P ≤ 0.001). There was no significant difference in FeNO between subjects with tetraplegia and those with asthma (17.72 ± 3.9 ppb vs. 20.23 ± 4.64 ppb, P ≤ 0.27). Individuals with chronic tetraplegia have FeNO levels that are comparable to that seen in mild asthmatics and higher than that in healthy able-bodied controls. The clinical relevance of this observation has yet to be determined.