Extended NO analysis applied to patients with COPD, allergic asthma and allergic rhinitis

Abstract

The recommended method to measure exhaled nitric oxide (NO) cannot reveal the source of NO production. We applied a model based on the classical Fick's first law of diffusion to partition NO in the lungs. The aim was to develop a simple and robust solution algorithm with a data quality control feature, and apply it to patients with known alterations in exhaled NO. Subjects with allergic rhinitis, allergic asthma, chronic obstructive pulmonary disease (COPD) smokers and controls were investigated. NO was measured at three expiratory flow rates. An iteration method was developed to partition NO. The airway tissue content of NO was increased in asthma, 144 +/- 80 ppb (P = 0.04) and decreased in smokers, 56 +/- 36 ppb (P = 0.02). There was no difference between subjects with rhinitis, 98 +/- 40 ppb and controls, 98 +/- 44 ppb. The airway transfer rate was increased in allergic asthma and allergic rhinitis, 12 +/- 4 vs. 12 +/- 5 ml sec(-1), compared to controls, 8 +/- 2 ml sec(-1) (P < 0.001). The alveolar levels were no different from controls, 2 +/- 1 ppb. In COPD the alveolar levels were increased, 4 +/- 2 ppb (P < 0.001). Extended NO analysis reveals from where in the respiratory system NO is generated. Hence, this new test can be added to the tools the physician has for the diagnosis and treatment of patients with respiratory disorders.

Nitric Oxide Airway Diffusing Capacity and Mucosal Concentration in Asthmatic Schoolchildren

“…This is in good agreement with previous findings in adults (14,17). An increase in FawNO in asthmatic subjects seems logical inasmuch as iNOS is induced in the bronchial epithelium in asthma (9).…”

“…The model used in this study has been described in detail elsewhere (17). Briefly, it is based on the relationship between FENO and the NO formation in the two compartments: the alveolar region and the conducting airway tube.…”

“…Then DawNO is solved by finding the intercept of the V ENO axis and the line used for defining the slope, and thereafter a computer-powered iterative algorithmic process is used to solve DawNO. In a final step the accuracy is improved further still by using a second-order iteration to correct for the minimal alinearity in the FANO slope (17). Once FANO and DawNO have been estimated, FawNO can be calculated.…”

“…However, a few investigators have put a lot of effort into measuring exhaled NO at multiple exhalation flow rates, to gain more information on NO formation in the lower respiratory tract (13)(14)(15)(16)(17). Some of these investigators have proposed models for NO diffusion in which alveolar and airway mucosal NO concentrations can be estimated.…”

Exhaled Nitric Oxide is Highly Increased in a Case of Hodgkin's Disease

“…By using an extended NO analysis on the exhaled NO fractions at different flow rates, it was seen that the patient had extremely high F w NO and D w NO, much higher than in airway hyperreactivity or asthma (10). Corticosteroids are known to reduce the exhaled NO, but inhaled corticosteroid therapy only decreased the airway wall concentration and not the diffusion rate of NO (11).…”