Passive smoking lowers FeNO values in asthmatic children
MedWire News: Exposure to second-hand smoke is associated with reduced fraction of exhaled nitric oxide (FeNO) values in children with asthma, research shows.
“FeNO is considered, by some authors, to be a treatment follow-up parameter in allergic asthmatics,” write Yacine Laoudi (Groupe Hospitalier Trousseau – La Roche Guyon, Paris, France) and team in the journal Allergy.
They explain that in adults, active smoking can influence FeNO values, but “in children, the evidence in favor of an impact of passive smoking on FeNO values is controversial.”
To investigate further, the team studied 70 untreated children with allergic asthma who were older than 5 years-of-age. Exposure to second-hand tobacco smoke in the home was ascertained through parental questionnaires.
All the children underwent FeNO measurements, spirometry, and skin prick tests, and their levels of total and specific serum immunoglobulin (Ig)E, and blood eosinophilia were also assessed.
In total, 22 children were exposed to passive smoking at home on a daily basis. Analysis revealed that children exposed to second-hand smoke had an average FeNO value of 26.3 ppb compared with an average value of 56.3 ppb among the 48 unexposed children.
After accounting for age, asthma severity, blood eosinophilia levels, allergic sensitizations, total IgE, dust mite sensitization and other variables, the researchers found that increased levels of exposure to second hand smoke were significantly associated with reduced FeNO values in the children.
Laoudi and team conclude: “This study shows that passive smoking significantly lowers FeNO values, after adjustment for various confounders and risk factors, and might be a major determinant of FeNO levels in untreated allergic asthmatic children exposed to daily passive smoking.
“It, therefore, appears essential to take this exposure into account when interpreting results of FeNO measurements in this category of children, both in clinical practice and in research approach.”
They add: “Further studies are required to determine appropriate management of the effect of passive smoking on FeNO values and to evaluate this effect on treated asthmatic children.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009
By Mark Cowen