TY - JOUR T1 - Longitudinal variability of nasal nitric oxide measurements during winter JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.congress-2015.PA4002 VL - 46 IS - suppl 59 SP - PA4002 AU - Fabio Barresi AU - David Imo AU - Marion Maggi AU - Holger Dressel Y1 - 2015/09/01 UR - http://erj.ersjournals.com/content/46/suppl_59/PA4002.abstract N2 - The role of nasal nitric oxide (nNO) for clinical medicine is still largely unclear. This is partially due to methodological questions and insufficient standardization. Information about longitudinal intraindividual variability and its potentially influencing factors is scarce.Three non-smoking adults (one female, two males) without respiratory tract infections performed repeated nNO-measurements during a three-month period in winter. Two subjects (1 and 2) were assessed shortly after arriving from the cold outdoor environment, subject 3 was assessed after a longer indoor period. Assessments were done between 9:30 am and 12:00 am. Levels of nNO were determined by chemiluminescence technique (CLD 88sp, EcoMedics, Duernten, Switzerland) using aspiration at a constant airflow rate of 300 ml/min through one nostril with the velum closed by oral exalation against a resistance. Results from both nostrils were compared and coefficients of variation of consecutive measurements were calculated.Subjects performed measurments at 10 or 11 timepoints. Results from both nostrils differed in one subject (p<0.05). Coefficients of variation for consecutive means of both nostrils for subject 1 were 13%, for subject 2 13% and 6% for subject 3. The mean nNO-values over time ranged from 631 to 909 ppb for subject 1, from 692 to 1126 ppb for subject 2 and from 1039 to 1223 ppb for subject 3.Longitudinal variation of nNO was considerably higher in the 2 out of 3 subjects, who had measurements shortly after arriving from exposure to cold outdoor air. This may indicate that in winter a certain time period of nasal adaption to indoor environments (e.g. outpatient clinics) should elapse before performing the nNO-measurements. ER -