The Effect of Viral Infection on Exhaled Nitric Oxide in Children with Acute Asthma Exacerbations.

BACKGROUND: Fraction of exhaled nitric oxide (Feno) level is used as an aid in the diagnosis and management of chronic asthma. Its role in acute asthma remains to be studied. OBJECTIVE: To determine whether Feno levels are elevated in children with asthma exacerbations compared with baseline, and whether there is a difference in Feno levels based on PCR positive (+) (respiratory virus isolated by PCR analysis) versus PCR negative (-) (respiratory virus not isolated by PCR analysis) status. METHODS: Children with a previous Feno level measurement while stable and who presented to an urgent care facility with an asthma exacerbation were enrolled. Feno levels, spirometry, and nasal swabs for viral PCR were obtained at the time of the exacerbation and following a course of prednisone. Data were available on 66 children. Linear mixed models were used to regress the outcomes of interest (FEV1, FEV1/forced vital capacity, forced expiratory flow at 25% to 75% of forced vital capacity, and natural log Feno) on detected virus (yes/no), visit (baseline, exacerbation, follow-up), and the interaction between the detected virus and visit. RESULTS: Compared with baseline, higher Feno values and lower lung function were found at the time of an exacerbation. A respiratory virus was detected in 59% of the exacerbations. The interaction between PCR (+) and PCR (-) groups and visit on log Feno was marginally significant (P = .07). There was no difference in log Feno between the PCR (+) and PCR (-) groups at baseline, while higher log Feno was found in the PCR (-) group at the time of exacerbation and following prednisone (P = .05 and .001, respectively). CONCLUSIONS: Higher Feno concentration in PCR (-) exacerbations suggests an eosinophilic predominance in nonviral compared with viral exacerbations.

Predictors of asthma control and lung function responsiveness to step 3 therapy in children with uncontrolled asthma.

BACKGROUND: Predictors of improvement in asthma control and lung function to step 3 therapy in children with persistent asthma have not been identified despite reported heterogeneity in responsiveness. OBJECTIVE: We sought to evaluate potential predictors of asthma control and lung function responsiveness to step 3 therapy. METHODS: A post hoc analysis from the Best Add-On Giving Effective Response (BADGER) study tested the association between baseline biological, asthma control, pulmonary function, and demographic markers and responsiveness to step-up to a higher dose of inhaled corticosteroid (ICS step-up therapy) or addition of leukotriene receptor antagonist (LTRA step-up therapy) or long-acting ß2-agonist (LABA step-up therapy). RESULTS: In multivariate analyses higher impulse oscillometry reactance area was associated (P = .048) with a differential FEV1 response favoring LABA over ICS step-up therapy, whereas higher urinary leukotriene E4 levels were marginally (P = .053) related to a differential FEV1 response favoring LTRA over LABA step-up therapy. Predictors of differential responses comparing ICS with LTRA step-up therapy were not apparent, probably because of suppression of allergic markers with low-dose ICS treatment. Minimal overlap was seen across FEV1 and asthma control day predictors, suggesting distinct mechanisms related to lung function and asthma control day responses. CONCLUSION: Levels of impulse oscillometry reactance area indicating peripheral airway obstruction and urinary leukotriene E4 levels indicating cysteinyl leukotriene inflammation can differentiate LABA step-up responses from responses to LTRA or ICS step-up therapy. Further studies with physiologic, genetic, and biological markers related to these phenotypes will be needed to predict individual responses to LABA step-up therapy.

Inflammometry in pediatric asthma: a review of fractional exhaled nitric oxide in clinical practice.

The burden of pediatric asthma remains high with one-third of patients being under- or overtreated because of the unique challenges in the assessment and management of childhood asthma. Until recently, there has been no point of care tool for assessing the underlying airway inflammation (i.e., inflammometry) in asthma. Recently, fractional exhaled nitric oxide (FeNO) has emerged as an important biomarker for the assessment and management of asthma. Recent evidence indicates that FeNO identifies T-helper cell type 2 (Th2)­mediated airway inflammation with a high positive and negative predictive value for identifying corticosteroid responsive airway inflammation. This article examines the evidence for FeNO as a predictor of Th2-mediated inhaled corticosteroid (ICS) responsive airway inflammation and reviews recent studies evaluating the role of FeNO, whether helpful or not, in the assessment and management of pediatric asthma. FeNO is a reliable adjunct to traditional tests in the assessment of suspected asthma. Importantly, it is useful for identifying and for excluding ICS-responsive airway inflammation. Although individual study results have varied, collectively, asthma managed using FeNO is associated with lower exacerbation rates compared with clinical algorithms alone. Finally, FeNO may be useful in identifying patients at risk for future impairment or loss of asthma control during reduction/cessation of ICS treatment. FeNO testing has an important role in the assessment of pediatric patients with suspected asthma and in the management of pediatric patients with established asthma. Additional studies will continue to define the exact role of FeNO testing in pediatric asthma.

Alergia inmediata al látex con reacción cruzada a frutas: a propósito de un caso / Inmediate allergy latex with cross reaction a fruits: a purpose of a case

Se expone un caso de alergia al latex en un paciente con reacción cruzada a frutas