Association between fraction of exhaled nitrous oxide, bronchodilator response and inhaled corticosteroid type

Effects of the salbutamol bronchodilator response on measurements of fractional exhaled nitric oxide in children with asthma: a prospective, observational study

BACKGROUND

Salbutamol bronchodilator response (BDR) test and fractional exhaled nitric oxide (FeNO) have been recommended for the diagnosis of asthma in children, but FeNO levels is affected by many factors. Nonetheless, data of the effect on the FeNO values throughout the bronchodilator test and the differences in FeNO values between BDR positive (BDR+) and negative (BDR-) children with asthma are still limited. We aimed to evaluate the effect of the BDR test on FeNO and the differences in FeNO levels between BDR+ and BDR- children with asthma.

METHODS

This was a prospective, observational study performed over a 5-month period (December 2018 to April 2019) and involved 57 children with asthma. The FeNO levels at pre-spirometry, post-spirometry, and post-salbutamol BDR testing were estimated. Finally, the children were divided into two groups i.e., BDR+ and BDR-, and differences in the FeNO levels were compared between the two groups.

RESULTS

The spirometry results were normal in 2 patients (3.5%). There were 53 (93%) patients with obstructive lung disease, including 40 (70.2%), 11 (19.3%), and 2 (3.5%) patients with mild, moderate, and severe obstruction, respectively. The remaining two patients had mixed lesions (3.5%), none of which were restrictive. The baseline median FeNO levels were significantly higher in the BDR+ group than in the BDR- group [33.00 (23.78, 46.73) vs. 23.00 (9.80, 37.80), (P=0.048)]. Following spirometry, there was a statistically significant decrease in median FeNO levels from baseline to post-spirometry (P=0.002). However, there was no significant difference between the median FeNO levels at baseline and following the BDR test (P=0.976). The impact of spirometry on FeNO was not statistically different in BDR+ versus BDR- children (Z=-0.186, P=0.853); however, the impact of bronchodilators on FeNO exhibited a statistically significant difference between the two groups (Z=3.160, P=0.002).

CONCLUSIONS

This study revealed dynamic changes in the FeNO levels during the BDR test. The use of a bronchodilator results in a statistically significant difference in FeNO levels between BDR+ and BDR- children with asthma. Moreover, spirometry leads to a marked decrease in the FeNO levels. Our results will allow clinicians to better interpret FeNO, BDR and pulmonary function outcomes and better develop clinical protocols.

Persistence of both reversible airway obstruction and higher blood eosinophils may predict lung function decline in severe asthma

OBJECTIVE

This study analysed whether the persistence of both reversible airway obstruction (RAO) and elevated BE counts was associated to reduced asthma control and accelerated lung function decline in treated severe asthmatics.

METHODS

About 202 severe asthmatics were studied after 12-120 months of step-5 treatment associated to anti-IgE therapy. Following treatments, reversibility tests, after inhaling 400 mcg of Salbutamol, were performed. FEV₁  > 12% or ≤12% changes differentiated RAO+ from RAO- subjects. Blood eosinophil (BE) counts after treatment were considered.

RESULTS

Pre-/post-treatment bronchodilator FEV₁ % and ACT were lower (61% [50-71], 74.4% [62.5-83.7] and 20[18-22]), whereas BE were higher (380 cells/µl [170-590]) in RAO+ compared to RAO- subjects (77% [64-88], p = 0.0001, 81.8% [66.1-94.3], p = 0.0001, 21[18-23], p = 0.045 and 230 cells/µl [80-360], p = 0.003). A negative relationship between SABA-induced FEV₁ % changes and pre-bronchodilator FEV₁ % (β = -0.551%; p = 0.0001) and ACT (β = -0.059; p = 0.038) was found. Conversely, post-treatment BE levels were positively related (β = 145.565 cells/µl; p = 0.003) to FEV₁  > 12% increases. A rising trend of pre-/post-bronchodilator FEV₁ % in time was observed in RAO- subjects with BE < 300 cells/µl. Conversely, we highlighted significant declining tendencies of pre/post-bronchodilator FEV₁ % in RAO+ patients with BE > 300 cells/µl reaching lower values after more than 36 months of step-5 treatment (59.6% [39.9-72.1] vs 74[66.5-89.2] of RAO+ individuals with BE < 300 cells/µl [p = 0.026] and 81.6% [66.1-91.8] of RAO-subjects with BE > 300 cells/µl [p = 0.009]).

CONCLUSION

Persistent SABA-induced FEV₁  > 12%, especially when associated to BE > 300 cells/ml, may be a marker of accelerated lung function decline in severe asthmatics despite maximal step-5 treatment. The highest bronchodilation associated to the lowest BE levels should be the main goal of asthma treatment to prevent such decline.

How should treatment approaches differ depending on the severity of asthma?

INTRODUCTION

Asthma is nowadays regarded as a syndrome of various overlapping phenotypes with defined clinical characteristics, different underlying inflammatory mechanisms, identifiable genetic background, environmental risk factors and possible biomarkers. There are no doubts that due to the diversity of asthma, a 'one size fits all' management of the disease is no longer valid. Areas covered: Nowadays asthma management is based on the control of the disease, and the goals of asthma treatment are defined as good symptom control, decreased future risk of exacerbations, fixed airflow limitation, and side-effects of treatment. Alternative strategies for adjusting asthma treatment such as sputum or exhaled nitric oxide guided protocols have been evaluated and despite some effectiveness, are regarded as impractical in every-day clinical conditions. Further studies in the field of asthma phenotypes/endotypes and biomarkers are warranted with the main goal to define which of those possible subgroups will be useful in clinical practice in regards to the potential allocation of successful treatment. Expert commentary: Despite the availability of guidelines on the diagnosis and management of asthma, it seems that the disease is still not optimally controlled. Addressing unmet needs in every day care, improving education, adherence/compliance and inhalation technique may significantly improve asthma control across all severities of the disease.

Bronchodilator response as a marker of poor asthma control

BACKGROUND

Asthma guidelines emphasise the importance of monitoring disease control in managing asthma.

OBJECTIVE

The aim of this study was to evaluate the relationship between lung function, including bronchodilator response in terms of improving in FEV1 after administration of salbutamol, and asthma control.

METHODS

246 patients with known asthma and in regular chronic treatment according to international guidelines were consecutively enrolled in a 12 month-period. All patients were evaluated by asthma control test (ACT), spirometry and bronchodilator test with salbutamol 400 mcg.

RESULTS

Mean ACT value was 18.8. Patients with significant bronchial reversibility had lower ACT mean values. This finding was confirmed in both patients with airway obstruction and in those with normal spirometry. There was a significant correlation between ACT values and bronchodilator response.

CONCLUSIONS

The persistence of a significant degree of bronchodilator response despite regular treatment according to guidelines was a marker of worse asthma control.

CLINICAL IMPLICATIONS

Bronchodilator response, correlating with worse asthma control even in patients with normal spirometry, should be test at every visit as it may add information on asthma control.