Evaluation of exhaled nitric oxide measurements in the emergency department for patients with acute asthma

Fractional exhaled nitric oxide in children with acute exacerbation of asthma

OBJECTIVE

To determine whether fractional exhaled nitric oxide (FENO) has a utility as a diagnostic or predictive maker in acute exacerbations of asthma in children.

DESIGN

Analysis of data collected in a pediatric asthma cohort.

SETTING

Pediatric Chest Clinic of a tertiary care hospital.

METHODS

A cohort of children with asthma was followed up every 3 months in addition to any acute exacerbation visits. Pulmonary function tests (PFT) and FENO were obtained at all visits. We compared the FENO values during acute exacerbations with those at baseline and those during the follow up.

RESULTS

243 asthmatic children were enrolled from August 2009 to December 2011 [mean (SD) follow up - 434 (227) days]. FENO during acute exacerbations was not different from FENO during follow up; however, FENO was significantly higher than personal best FENO during follow up (P < 0.0001). FENO during acute exacerbation did not correlate with the severity of acute exacerbation (P=0.29). The receiver operating characteristics curve for FENO as a marker for acute exacerbation had an area under the curve of 0.59. Cut-off of 20 ppb had a poor sensitivity (44%) and specificity (68.7%) for acute exacerbation.

CONCLUSIONS

FENO levels during acute exacerbation increase from their personal best levels. However, no particular cut off could be identified that could help in either diagnosing acute exacerbation or predicting its severity.

Lung function and biomarkers of airway inflammation during and after hospitalization for acute exacerbations of childhood asthma associated with viral respiratory symptoms

BACKGROUND

There are limited data assessing relationships between biomarkers of inflammation and lung function after hospitalization for asthma exacerbations in children.

OBJECTIVE

To assess the associations in asthmatic children among changes in lung function, fraction of exhaled nitric oxide (FENO), and cysteinyl leukotrienes (CysLTs) in exhaled breath condensate (EBC) after hospitalization for acute asthma.

METHODS

Spirometry and FENO were measured and EBC collected for CysLT measurement from 40 children during and 1, 2, and 4 weeks after hospitalization for an asthma exacerbation and during a single-study visit for 40 healthy children.

RESULTS

Enrollment FENO and EBC CysLT concentrations were higher in the children with asthma than in healthy individuals (mean FENO, 31.6 vs 7 ppb; P < .0001; mean EBC CysLT, 7.9 vs 4.9 ppb; P = .03). Among children with asthma, improvement in lung function reached a plateau within 2 weeks after hospital discharge. The EBC CysLT concentrations were not associated with changes in lung function, use of albuterol, or use of inhaled corticosteroids (ICSs). Among asthmatic children enrollment FENO was not associated with changes in lung function during follow-up. However, among children who had an elevated enrollment FENO (≥25 ppb), patients who did not use ICSs after hospital discharge had lower end-of-study lung function than those who used ICSs. At 2 and 4 weeks after hospital discharge, FENO was higher among patients who reported albuterol use more than twice weekly and among patients who reported no ICS use.

CONCLUSION

FENO measured at hospital discharge among children hospitalized with acute asthma may be useful in identifying patients who will respond to ICS therapy.

An umbrella review: corticosteroid therapy for adults with acute asthma

The objective of this "umbrella" review is to synthesize the evidence and provide clinicians a single report that summarizes the state of knowledge regarding the use of corticosteroids in adults with acute asthma. Systematic reviews in the Cochrane Library and additional clinical trials published in English from 1966 to 2007 in MEDLINE, EMBASE, CINAHL, and Cochrane CENTRAL, and references from bibliographies of pertinent articles were reviewed. Results indicate that the evidence base is frequently limited to small, single-center studies. Findings suggest that therapy with systemic corticosteroids accelerates the resolution of acute asthma and reduces the risk of relapse. There is no evidence that corticosteroid doses greater than standard doses (prednisone 50-100 mg equivalent) are beneficial. Oral and intravenous corticosteroids, as well as intramuscular and oral corticosteroid regimens, seem to be similarly effective. A nontapered 5- to 10-day course of corticosteroid therapy seems to be sufficient for most discharged patients. Combinations of oral and inhaled corticosteroids on emergency department/hospital discharge might minimize the risk of relapse.

Measurement of exhaled nitric oxide in the emergency department in patients with asthma

A great deal of research has been conducted on the utility and usefulness of exhaled nitric oxide (NO) as a biomarker of airway inflammation and its role in the diagnosis of acute asthma exacerbations. This article reviews the pathophysiology of NO in asthma, evidence for the use of exhaled NO in acute asthma exacerbations, and the potential utility of devices available to emergency physicians for measuring exhaled NO.