TY - JOUR T1 - Nasal nitric oxide measurement variability to establish a standard for reliable results JF - ERJ Open Research JO - erjor DO - 10.1183/23120541.00028-2022 VL - 8 IS - 2 SP - 00028-2022 AU - Nicole Beydon Y1 - 2022/04/01 UR - http://openres.ersjournals.com/content/8/2/00028-2022.abstract N2 - Nasal nitric oxide (nNO) measurement is a first-line test used to increase the post-measurement probability of primary ciliary dyskinesia (PCD) in subjects with symptoms consistent with this diagnosis [1]. The accuracy of nNO measurement is essential since it will orientate the work-up towards tests that are usually highly specialised and sometimes invasive. Accuracy of biological measurements relies on the technical and on the biological variability. While the accuracy of NO analysers is known better for chemiluminescence devices (e.g. <1 ppb with 1% linearity from 0.1 to 5000 ppb for CLD 88 (Eco Medics, Duernten, Switzerland)) than for widely used electrochemical devices (e.g. ±5 ppb for values <50 ppb and 10% for values >50 ppb for Niox Vero (Circassia, Oxford, UK)) [2], little is known on the biological variability of nNO measurements, except for increased nNO output variability in adults with rhinitis compared with healthy subjects and the positive effect of training on the level of nNO taken during expiration against a resistance (nNO-ER) in children [3, 4].A repeatability of 10% for NO measurements obtained with the velum closed in the same or both nostrils is relevant, while measurements taken during tidal breathing should aim for a repeatability of 20% and 30%, respectively https://bit.ly/3sMnug6The author is grateful to Jessica Assouline, Michèle Boulé, Houda Guillo, Marie-Claude La Rocca, Marc Koskas, Fatma Lacin, Lucia Maingot and Noria Medjahdi for their help in supervising the children's nasal nitric oxide measurements, and to Claire Goaguen, Pascale Jacquemart, Fanny Koëth, Valérie Le Bail, Isabelle Schmitt, and Françoise Vallée for their technical assistance, all working in Unité d'Exploration Fonctionnelle Respiratoire, Hôpital Armand Trousseau, Paris, France. ER -