Determinación de la concentración de óxido nítrico alveolar en aire espirado: procedimiento y valores de referencia en personas sanas

Measurement of nitric oxide and assessment of airway diseases in children: an update

INTRODUCTION

Nitric oxide (NO) is a gas synthesized by the inducible NO synthase enzyme in airway cells and it is thought to make important functions in the airway inflammation of several respiratory diseases.

EVIDENCE ACQUISITION

This current study is a review of the literature from 1990 to present about NO and its use in clinical practice. The databases used were PubMed, Scopus, and Cochrane Library.

EVIDENCE SYNTHESIS

At the respiratory level there are three different measurements sites of NO: nNO (nasal nitric oxide), FeNO (exhaled fraction of nitric oxide), CaNO (alveolar nitric oxide). Each of them is produced at different levels of the respiratory tract and is involved in various diseases. nNO finds its use, principally, in the allergic rhinitis in fact it can be used as a measure of therapeutic efficacy, but not for the evaluation of the severity; also in primary ciliary dyskinesia (PCD), where high levels exclude the disease, and in chronic rhinosinusitis, but it is not currently used as a diagnostic or prognostic marker. FeNO has a greatest use in bronchial asthma, particularly, it is considered a non-invasive biomarker to identify and to monitor airway inflammation but currently, there is not a consensus on the use of the FeNO in the management of asthma treatment. Finally, CaNO is the least used in clinical practice, because lack of standardization of measurement techniques.

CONCLUSIONS

Nitric oxide is a sensitive indicator of the presence of airway inflammation and ciliary dysfunction, although some studies have shown varying or conflicting results.

Utility of two-compartment models of exhaled nitric oxide in patients with asthma

Two-compartment models provide more precise information about the contribution of the different portions of the airways to exhaled nitric oxide (NO). Airway wall concentration of NO (Caw,NO) and maximum flux of NO in the airways (J'aw,NO) reflect the tissue production rate of NO and they can be modified by corticosteroids. The airway wall diffusing capacity of NO (Daw,NO) depends on diverse physical and anatomical determinants of the airways, such as gas exchange surface area. Daw,NO can be modified by structural and physiological changes that are characteristic of airway remodeling, which take place over the long term. The alveolar concentration of NO (Calv,NO) represents the degree of small airway inflammation. The persistence of high Calv,NO in patients treated with inhaled corticosteroids could reflect the incapacity of these drugs to reach distal locations due to the heterogeneity of the acinar ventilation. In this review, we evaluate the parameters provided by the compartmentalized analysis of exhaled NO that could be useful in characterizing asthma patients.

[Asthma in the Archivos de Bronconeumología: a review of publications in the year 2009]

A total of 16 articles (Table 1), were published in the Archivos de Bronconeumología in the past year (December 2008 to November 2009), 9 of which were Originals, which was 17.6% of the originals published in that period. Fortunately, the tendency of a decreasing interest in asthma by pneumologists does not seem to have materialised as was feared a few years ago, on the contrary it seems that research is increasing. All articles that appeared in the journal during the period mentioned are reviewed.