The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

COMPARISON OF EXHALED NITRIC OXIDE (ENO) BEFORE AND AFTER DRINKING WATER.

Carl D. Mottram, James A. Dogo, Mohamed Y. Gamadid, Cassandra N. Haddad, Mohamed A. Saeed, Paul D. Scanlon, Mary K. Witt; Pulmonary and Critical Care, Mayo Clinic, Rochester, MN

Introduction: Exhaled nitric oxide (ENO) is a biomarker of airway inflammation. ENO is measured by having the subject inhale maximally and then exhale their breath through a mouthpiece into the ENO analyzer at a specific flow rate. The American Thoracic Society (ATS) and European Respiratory Society (ERS) have published testing guidelines1. They recommend that the subject not eat or drink one hour prior to testing. This includes no consumption of water. The data for this recommendation is based on a single study that also evaluated other conditions, which may have affected their outcome. However in clinical practice it has been our experience in the laboratory that the consumption of water prior to testing has little or no effect on the measurement. Hypothesis: The consumption of water has no effect on the exhaled nitric oxide measurement. Methods: 40 subjects (age 25-78; M/F 10/30)) for whom ENO was ordered as a clinical test were studied in the comparison. Subjects were tested using the Apieron ENO system which was calibrated according to manufacturer’s recommendations. They were asked prior to testing if they followed the laboratory’s pre-test instructions which currently state that no eating or drinking is permitted two hours prior to testing. After completing the initial measurement, the subject will be asked to drink twelve ounces of water. Ten minutes following consumption, a second measurement was obtained. The initial test was the reported clinical results. Data were analyzed using linear regression and Student paired t-test. Results: The pre-water consumption data ranged from 9-84 ppb (mean 25.1). The post-water data ranged from 9-82 ppb (mean 25.1). The linear regression yielded an R2 0.99 with a p<0.99. Conclusion: There was no statistical or clinical difference between the measured exhaled nitric oxide values results before or after the consumption of water. Our findings indicate that a subject may consume water prior to ENO testing. 1. ATS/ERS Recommendations for Standardized Procedures for the Online and Offline Measurement of Exhaled Lower Respiratory Nitric Oxide and Nasal Nitric Oxide. Am J Respir Crit Care Med 2005 Vol 171. pp 912–930. Sponsored Research - None