BACKGROUND: Exhaled NO (FE(NO)) is a useful biomarker for the monitoring of 
asthma control and response to therapy. However, there is a lack of data on 
FE(NO) levels and their interpretation in Primary Care asthma population 
depending on their treatment and smoking habit. Besides, the majority of current 
FE(NO) tests have been done by stationary chemiluminescence analysers whose use 
is limited to research laboratories.
METHODS: FE(NO) measurements by the novel hand-held NO monitoring device (NIOX 
MINO) were made in 96 asthma patients (32 males, mean age 53+/-12) at five local 
General Practices during their scheduled 15-20 min visits for lung function 
assessment.
RESULTS: Success rate was 78% and the intra-subject coefficient of variation was 
8.7%. Inhaled corticosteroid treatment had an overall reducing effect on the 
FE(NO) value (30.5 [19.8-49.8]) vs. patients not on the ICS (26.5 [19-94]) 
(p<0.044). FE(NO) levels in the ICS treated current or ex-smokers group of 
patients were still significantly above the normal values (p<0.0001). FE(NO) 
levels were similar in patients receiving ICS whether there were current, 
ex-smokers or non-smokers. The highest FE(NO) levels (94 [15.8-151]) were found 
in asthmatic current smokers and not receiving treatment with ICS. The most 
"normalised" FE(NO) levels (35.3 [13.5-35.3]) were seen in ex-smokers.
CONCLUSIONS: FE(NO) measurements performed with a new hand-held monitoring 
device are reproducible and feasible in General Practice in the majority of 
patients of different ages and asthma severities. A high percentage of patients 
with different severities of asthma and regardless of their treatment with ICS 
and current smoking habit (current and/or ex-smokers) had highly elevated FE(NO) 
values, suggesting that their current therapy was possibly insufficient to 
control the underlying degree of airway inflammation and asthma symptoms.