Higher alveolar nitric oxide in COPD is related to poorer physical capacity and lower oxygen saturation after physical testing

Exhaled nitric oxide (FENO) is an inflammatory marker used in asthma management, but its clinical role in chronic obstructive pulmonary disease (COPD) is less defined. FENO represents the NO production in the airways. To gain information regarding peripheral NO from the lung, different mathematical models have been used [1]. NO from the gas-exchange area is referred to as alveolar NO (CANO). In symptomatic asthmatic subjects the CANO has been shown to be increased [2]. In COPD there is an alveolar destruction with emphysema and higher values of CANO have been reported [3–5]. However, in subjects with severe emphysema there was no increase in CANO, and therefore the clinical value of CANO is not clear [6]. CANO has been found to negatively correlate to the distance travelled in 6-minute walking tests [5]. Of interest, is that in athletes hypoxemia develops due to prolonged exercise [7], and in marathon runners who are regularly exposed to hypoxemia during strenuous training, CANO values have been reported to be increased [8]. COPD patients frequently report dyspnoea with exertion, and our hypothesis was that repeated hypoxemia could lead to an increase in CANO. We therefore investigated CANO in a Swedish study [9]. Footnotes This manuscript has recently been accepted for publication in the European Respiratory Journal . It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article. Conflict of interest: Dr. Hogman has nothing to disclose. Conflict of interest: Dr. Thornadtsson has nothing to disclose. Conflict of interest: Dr. Broms has nothing to disclose. Conflict of interest: Dr. Janson has nothing to disclose. Conflict of interest: Dr. Lisspers has nothing to disclose. Conflict of interest: Dr. Stallberg has nothing to disclose. Conflict of interest: Dr. Hedenstrom has nothing to disclose. Conflict of interest: Dr. Malinovschi has nothing to disclose.