Asthma diagnosis and treatmentNitric oxide as a clinical guide for asthma management
Section snippets
Starting and stopping inhaled steroid therapy
The decision to commence inhaled corticosteroid (ICS) therapy in patients with chronic symptoms of cough, wheeze, and shortness of breath is often empiric. The assumption is made that these symptoms are a result of uncontrolled airway inflammation, and in turn, that anti-inflammatory treatment is appropriate. However, this approach is flawed. First, the correlation between respiratory symptoms and airway inflammation is very weak,5 and second, not all airway inflammation is steroid-responsive.6
Optimizing inhaled steroid therapy
At least in this country, there has been a trend over recent years for increasingly high doses of ICS therapy to be prescribed in patients with persistent asthma. In addition to the economic cost, the risk of adverse systemic effects also increases significantly with higher doses.11 Clearly, any practical strategy that might improve the cost-benefit ratio for ICS prescribing would be an advance.
The concept that “inflammometry” might be used to guide anti-inflammatory therapy in asthma—as an
Difficult asthma
We have recently introduced FENO measurements into the range of tests provided in our local pulmonary function laboratory. Apart from their diagnostic role in the work-up of patients with nonspecific respiratory symptoms, they are also helpful in ongoing asthma management, particularly if it is severe, difficult, or both.
There are now sufficient data16 to provide a provisional schema for interpreting FENO results in patients with asthma. To summarize, low FENO levels (<25 ppb) in an
Practical problems
A number of important questions regarding the application of FENO measurements in asthma still remain to be resolved. Perhaps the most important of these is the issue of clinically meaningful cut-points. This is an important issue in the design and interpretation of clinical studies. It is also problematic in practice. The interpretation of intermediate values (in the range 25-50 ppb) remains unclear. The suggested cut-points for low and high FENO have been obtained in either healthy
Conclusion
Measurements of FENO provide a perspective on airway pathology that complements conventional assessment of airway function in the diagnosis and ongoing management of asthma. They shed light on whether symptoms are attributable to uncontrolled eosinophilic airway inflammation, and in turn on whether the patient may benefit from more or less inhaled corticosteroid—or none at all. The technique is coming of age, and FENO measurements now have a useful place in day-to-day practice. But we are still
References (18)
- et al.
Sputum eosinophilia and short-term response to prednisolone in chronic obstructive pulmonary disease: a randomised controlled trial
Lancet
(2000) - et al.
Characterization of within-subject responses to fluticasone and montelukast in childhood asthma
J Allergy Clin Immunol
(2005) - et al.
Asthma exacerbations and sputum eosinophil counts: a randomised controlled trial
Lancet
(2002) - et al.
Non-eosinophilic asthma: importance and possible mechanisms
Thorax
(2002) ATS/ERS recommendations for standardized procedures for the online and offline measurement of exhaled lower respiratory nitric oxide and nasal nitric oxide, 2005
Am J Respir Crit Care Med
(2005)- et al.
Relationship between exhaled nitric oxide and mucosal eosinophilic inflammation in children with difficult asthma, after treatment with oral prednisolone
Am J Respir Crit Care Med
(2001) - et al.
Relationship between the inflammatory infiltrate in bronchial biopsy specimens and clinical severity of asthma in patients treated with inhaled steroids
Thorax
(1996) - et al.
Analysis of induced sputum in adults with asthma: identification of subgroup with isolated sputum neutrophilia and poor response to inhaled corticosteroids
Thorax
(2002) - et al.
Exhaled nitric oxide: a predictor of steroid response
Am J Respir Crit Care Med
(2005)
Cited by (77)
Fraction of exhaled nitric oxide in healthy elderly Tunisian subjects
2015, Nitric Oxide - Biology and ChemistryThe use of biomarkers of inflammation in the airway in the management of asthma
2012, Revista de Patologia RespiratoriaAsthma
2012, Emergency Medicine: Clinical Essentials, SECOND EDITIONElevated exhaled nitric oxide is a clinical indicator of future uncontrolled asthma in asthmatic patients on inhaled corticosteroids
2011, Journal of Allergy and Clinical ImmunologyHuman exhaled breath analysis
2011, Annals of Allergy, Asthma and ImmunologyCitation Excerpt :Another lucrative possibility is to titrate the optimal maintenance dose of inhaled steroids.26 Taken together, these applications held the promise to use FeNO to guide asthma management.27 However, a carefully designed study by Szefler and coworkers28 showed that the use of FeNO neither improved asthma control nor allowed reduction in the dose of inhaled glucocorticosteroid.28
Guest editors: William W. Busse, MD, and Stanley J. Szefler, MD
Disclosure of potential conflict of interest: D. Taylor has received money and has spoken on behalf of Aerocrine.