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What Is New In Small Airways Research

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Author: Ves Dimov, M.D.
Cleveland Clinic Florida
Wheaton, Florida

Vitamin D 50,000 IU per week together with ICS or ICS/LABA improved FEV1 in asthma after 6 months

This randomized trial included 130 patients with asthma aged 10 to 50 years from Iran during a 6-month period. Vitamin D was measured before, and 4 and 6 months after the intervention. Patients were divided in 2 groups randomly. Both groups received asthma controllers (budesonide or budesonide plus formoterol) according to their stage. The intervention group received vitamin D supplementation (100,000-U bolus intramuscularly plus 50,000 U orally weekly).

FEV1 was significantly better in the intervention group after 6 months. The authors concluded that vitamin D supplementation associated with asthma controllers could significantly improve FEV1 in mild to moderate persistent asthma. It takes time to work and the effect took months to emerge.

Source: Arshi S, Fallahpour M, Nabavi M, Bemanian MH, Javad-Mousavi SA. The effects of vitamin D supplementation on airway functions in mild to moderate persistent asthma. Annals of Allergy, Asthma & Immunology 2014; 113(4): 404 – 409. (doi:

Image Source: Vitamin D (Calcitriol), Wikipedia, public domain.

Small airway dysfunction contributes independently to clinical expression of asthma and BHR

Small airways are an important site of inflammation in asthma. However, the relation between small airway dysfunction and clinical expression of asthma has not been extensively studied. Resistance at 20 Hz is considered to reflect the large airways (R20) and resistance at 5 Hz the total airways. Small airway resistance can be calculated with the difference between the resistance at 5 Hz and 20 Hz (R5–R20). Reactance of the respiratory system at 5 Hertz (X5) and total reactance area (AX) are also assumed to reflect small airway function.

This study included 58 patients with asthma. Wheezing was associated with higher values of difference between R5 and R20 (R5–R20) and AX. Lower FEF25–75% and higher R5–R20 were associated with more severe bronchial hyper-responsiveness (BHR) to methacholine, but not FEV1. The increase in dyspnea during the methacholine provocation was strongly and independently correlated with the decrease in FEV1 and reactance of the respiratory system at 5 Hertz.

Deteriorations in small airway dysfunction are strongly related to an increase in dyspnea during bronchial provocation with methacholine. Small airway dysfunction contributes also independently to the clinical expression of asthma, as reflected by the severity of BHR.

Source: van der Wiel E, Postma DS, van der Molen T, Schiphof-Godart L, ten Hacken NHT, and van den Berge M. Effects of small airway dysfunction on the clinical expression of asthma: a focus on asthma symptoms and bronchial hyper-responsiveness. Allergy 2014; published online before print, 3 October. (doi:10.1111/all.12510)

Severe Asthma in Children – 2014 free full text review in JACI: In Practice

Severe asthma in children is characterized by sustained symptoms despite treatment with high doses of inhaled corticosteroids or oral corticosteroids. Severe asthma is divided into 2 categories:

  • difficult-to-treat asthma – poor control due to an incorrect diagnosis or comorbidities, or poor adherence
  • severe therapy-resistant asthma – poor control despite management of the factors above

Severe asthma is a highly heterogeneous disorder associated with a number of clinical and inflammatory phenotypes.

Guideline-based drug therapy of severe childhood asthma is based primarily on extrapolated data from adult studies. Children with severe asthma should be treated with higher-dose inhaled or oral corticosteroids combined with long-acting β-agonists and other add-on therapies, such as antileukotrienes and methylxanthines.

It is important to identify and address the influences that make asthma difficult to control, including reviewing the diagnosis and removing causal or aggravating factors.

Better definition of the phenotypes and better targeting of therapy based upon individual patient phenotypes is likely to improve asthma treatment in the future.

Source: Guilbert TW, Bacharier LB, and Fitzpatrick AM. Severe asthma in children. The Journal of Allergy and Clinical Immunology: In Practice 2014; 2(5): 489-500. (doi: 
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Last updated: Thursday, October 23rd, 2014