Effect of mannitol dry powder challenge on exhaled nitric oxide in children

Eucapnic voluntary hyperventilation test decreases exhaled nitric oxide level in children

BACKGROUND

Exhaled nitric oxide (FeNO) measurements and eucapnic voluntary hyperventilation (EVH) tests have been used as diagnostic tools for asthma. Data on the impact of hyperventilation on the level of FeNO are limited.

AIM

We aimed to evaluate whether EVH tests affect the level of FeNO in children aged 10-16 years.

METHODS

A total of 234 children aged 10-16 years had a 6-min EVH test performed. In total, FeNO values for 153 of 234 children were measured before the test and within 15 min after the test. According to a baseline FeNO level of 20 ppb, children were divided into two groups: those with low values (FeNO < 20 ppb) and those with high values (FeNO ≥ 20 ppb).

RESULTS

The median age of the children was 13.4 years (interquartile range 12.3-15.3 years); 58% were boys and 42% were girls. Of these children, 51% were sensitized to aeroallergens. In 101 of 153 children (66%), the FeNO values decreased after the EVH test. In children with low and high baseline levels, the median level of FeNO decreased after the EVH test: 10.5 ppb before versus 9.5 ppb after (p < .011), and 31.0 ppb before versus 28.0 ppb after (p < .011), respectively. The decrease in FeNO after EVH test was not associated with induced bronchoconstriction expressed as a change in FEV1 (R_s  = .19).

CONCLUSIONS

The EVH test decreases FeNO levels. Therefore, FeNO should be measured before an EVH test is performed.

Diagnosis of asthma in children: the contribution of a detailed history and test results

INTRODUCTION

There are few data on the usefulness of different tests to diagnose asthma in children.

AIM

We assessed the contribution of a detailed history and a variety of diagnostic tests for diagnosing asthma in children.

METHODS

We studied children aged 6-16 years referred consecutively for evaluation of suspected asthma to two pulmonary outpatient clinics. Symptoms were assessed by parental questionnaire. The clinical evaluation included skin-prick tests, measurement of exhaled nitric oxide fraction (F _eNO), spirometry, bronchodilator reversibility and bronchial provocation tests (BPT) by exercise, methacholine and mannitol. Asthma was diagnosed by the physicians at the end of the visit. We assessed diagnostic accuracy of symptoms and tests by calculating sensitivity, specificity, positive and negative predictive values and area under the curve (AUC).

RESULTS

Of the 111 participants, 80 (72%) were diagnosed with asthma. The combined sensitivity and specificity was highest for reported frequent wheeze (more than three attacks per year) (sensitivity 0.44, specificity 0.90), awakening due to wheeze (0.41, 0.90) and wheeze triggered by pollen (0.46, 0.83) or by pets (0.29, 0.99). Of the diagnostic tests, the AUC was highest for F _eNO measurement (0.80) and BPT by methacholine (0.81) or exercise (0.74), and lowest for forced expiratory volume in 1 s (FEV₁) (0.62) and FEV₁/forced vital capacity ratio (0.66), assessed by spirometry.

CONCLUSION

This study suggests that specific questions about triggers and severity of wheeze, measurement of F _eNO and BPT by methacholine or exercise contribute more to the diagnosis of asthma in school-aged children than spirometry, bronchodilator reversibility and skin-prick tests.

Do clinical investigations predict long-term wheeze? A follow-up of pediatric respiratory outpatients

INTRODUCTION

The contribution of clinical investigations to prediction of long-term outcomes of children investigated for asthma is unclear.

AIM

We performed a broad range of clinical tests and investigated whether they helped to predict long-term wheeze among children referred for evaluation of possible asthma.

METHODS

We studied children aged 6 to 16 years referred to two Swiss pulmonary outpatient clinics with a history of wheeze, dyspnea, or cough in 2007. The initial assessment included spirometry, fractional exhaled nitric oxide, skin prick tests, and bronchial provocation tests by exercise, methacholine, and mannitol. Respiratory symptoms were assessed with questionnaires at baseline and at follow-up 7 years later. Associations between baseline factors and wheeze at follow-up were investigated by logistic regression.

RESULTS

At baseline, 111 children were examined in 2007. After 7 years, 85 (77%) completed the follow-up questionnaire, among whom 61 (72%) had wheeze at baseline, while at follow-up 39 (46%) reported wheeze. Adjusting for age and sex, the following characteristics predicted wheeze at adolescence: wheeze triggered by pets (odds ratio, 4.2; 95% CI, 1.2-14.8), pollen (2.8, 1.1-7.0), and exercise (3.1, 1.2-8.0). Of the clinical tests, only a positive exercise test (3.2, 1.1-9.7) predicted wheeze at adolescence.

CONCLUSION

Reported exercise-induced wheeze and wheeze triggered by pets or pollen were important predictors of wheeze persistence into adolescence. None of the clinical tests predicted wheeze more strongly than reported symptoms. Clinical tests might be important for asthma diagnosis but medical history is more helpful in predicting prognosis in children referred for asthma.

Bronchial hyperresponsiveness to mannitol, airway inflammation and Asthma Control Test in atopic asthmatic children

INTRODUCTION

The aim of this study was to evaluate the relationship between airway hyperresponsiveness (AHR) to mannitol and bronchial inflammation measured as exhaled nitric oxide (FeNO) and to assess whether asthma control correlates with AHR to mannitol and FeNO in atopic asthmatic children.

MATERIAL AND METHODS

Allergy evaluation, the mannitol challenge test, FeNO levels and the Asthma Control Test (ACT) questionnaire were assessed in 40 children with intermittent and mild persistent allergic asthma.

RESULTS

All the subjects showed positive AHR to mannitol. Pearson's correlation test revealed a significant inverse correlation between AHR (mannitol PD15) and FeNO (p = 0.020). There was also a significant positive correlation between ACT and PD15 (p = 0.020) and a significant negative correlation between ACT and FeNO levels (p = 0.003). The study population was divided into two groups according to FeNO levels (group A ≥ 16 ppb vs. group B < 16 ppb). In group A mannitol PD15 was significantly lower (p = 0.040) and ACT score values were significantly lower (p = 0.001) compared to group B. In group A, the ACT showed that 13.3% of subjects had well-controlled asthma, 80% had partially controlled asthma and 6.7% had uncontrolled asthma. In group B, the ACT showed that 72% of subjects had well-controlled asthma and 28% had partially controlled asthma.

CONCLUSIONS

Our findings indicate that the degree of AHR to mannitol correlates with the degree of airway inflammation in asthmatic atopic children; moreover, better control of asthma correlates with a lower degree of AHR to both mannitol and FeNO.