Source: Annual Congress 2011 - Role of the biomarkers in airway diseases
Disease area: Airway diseases

Abstract

Background: By measuring eNO at multiple flows and applying mathematical models of eNO exchange dynamics, the signal can be partitioned into its proximal airway [Jno (nl/sec)] and distal airway/alveolar contributions [CA(NO)(ppb)]. This method is time consuming, requires at least 3 exhalations and is affected by a number of limitations such as axial diffusion and turbulent flow. We eveloped a more practical method based on the production of NO (Vno) at two exhalation flow rates.
Methods: In a group of 27 normal subjects (38±2 yr; 20 male), 13 steroid naive asthmatic patients (34±3 yr; 6 male, FEV1 70±4% predicted), 14 patients with chronic obstructive pulmonary disease (COPD) (65±2 yr; 10 male, FEV1 58±3%), and 12 patients with cystic fibrosis (21±4 yr; 8 male, FEV1 60±3%) we compared CA(NO) and Jno with the variation of total NO production at 50 and 200 ml/s [Vno50-200 (nl/s)]. Vno was measured by calculating the average area under the curve (NO concentration/time) of two successive exhalations at each flow rate.
Results: Vno50-200 was strongly correlated with Jnoin normal subjects (r=0.94, p<0.001), asthma (r=0.98, p<0.001), COPD r=0.93, p<0.001), and CF patients (r=0.74, p<0.05). This agreement was confirmed by the Bland and Altman test. Vno50-200 did not correlate significantly with CA(NO) in any of the study groups.
Conclusions: The flow dependent component of exhaled NO, which is affected by its bronchial production, can be estimated by measuring Vno50-200. This method is simple, does not require sophisticated equipment or equations and is in agreement with Jno calculated mathematically.

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P. Paredi, O. Usmani, K. Hurt, N. Pride, P. Barnes (London, United Kingdom). There is no need for complicated equations and mathematical models. Exhaled nitric oxide can be partitioned with two simple exhalations. Eur Respir J 2011; 38: Suppl. 55, 4781

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