Small airways and bronchial hyper-responsiveness in cough-variant asthma

Background Cough variant asthma (CVA) is one of the special populations of asthma. The study was to compare spirometric parameters of small airways and the degree of bronchial hyper-responsiveness (BHR) between CVA and classic asthma (CA), and examine the relationship between BHR and small airways to determine the accuracy of these markers as indicators of CVA. Methods A total of 825 asthmatic patients were screened for the study and 614 were included. All patients performed spirometry and underwent a bronchial challenge with methacholine. It has been estimated that less than 65% of the small airways must be obstructed before changes can be detected using routine pulmonary function tests. Results CVA patients showed less small airway dysfunction (< 65%) than those of CA patients with MMEF% predicted (70% vs 80.91%, p = 0.002) and FEF50% predicted (62.71% vs 73.5%, p = 0.004). The function of small airways was higher in the CVA group compared with the CA group (p < 0.001). CVA patients had a mild BHR (p = 0.005). Significant positive correlations were observed between PD20 and MMEF% predicted (r = 0.282, p < 0.001), FEF50% predicted (r = 0.2522, p < 0.001), FEF75% predicted (r = 0.2504, p < 0.001) in patients with CVA. The area under curve of MMEF, FEF50 and FEF75 (% predicted) was 0.615, 0.621, 0.606, respectively. 0.17mcg of PD20 was the best diagnostic value for CVA with an AUC of 0.582 (p = 0.001). Conclusions Small airway dysfunction is milder showed in CVA. The value of BHR combined with small airways in CVA prediction, which reflected significant, but not enough to be clinically useful.

Peak expiratory flow rate assessment to screen for asthma in children with allergic rhinitis

Background: Allergic rhinitis is a common disease affecting around 10-25% of the population worldwide. There is a temporal relationship between the onset of allergic rhinitis and asthma and the ‘unified airway hypothesis’ explains this. Many researchers have demonstrated bronchial hyper-responsiveness prior to onset of asthma symptoms further validating this hypothesis. Further many studies favour treating allergic rhinitis may prevent the onset of asthma. So, detecting allergic rhinitis earlier and treating it adequately is of vital importance. The aims and objectives of this study is to identify bronchial hyper responsiveness in children with allergic rhinitis, prior to the onset of asthmatic symptoms, by measuring PEFR and its clinical correlates.Methods: A prospective observational study was conducted in Department of Paediatrics in Sree Balaji Medical College and Hospital. Inclusion and Exclusion Criteria were defined, and the study was conducted on a total of 85 children. After taking informed consent from parents, the children coming under the study population were analyzed for their baseline characteristics and PEFR is measured using a low reading Mini Wright peak flow meter and compared with mean value of south Indian children using the formula, PEFR= {(HEIGHT IN CM-100) X5} +100.Results: The mean PEFR as expressed in percentage of expected PEFR is 77.28% in males and 83.34% in females. The mean percentage of expressed PEFR does not vary significantly between different age groups. Of the 85 children,48(56.5%) have mild intermittent allergic rhinitis,28(32.9%) have mild persistent allergic rhinitis,5(5.9%) have moderate-severe intermittent allergic rhinitis and 4(4.7%) have moderate-severe persistent allergic rhinitis. There were 37(43.5%) blockers (with predominant nose block) and 48(56.5%) runners (with predominant rhinorrhea).Conclusions: PEFR is abnormal in 41.2% of children with allergic rhinitis. PEFR reduces linearly as the severity of allergic rhinitis increases. PEFR decreases as the number of cardinal symptoms increases. PEFR increases significantly after treatment of allergic rhinitis alone.