The Value of Discordant Pulmonary Function Testing and Exhaled Nitric Oxide measurements in the Management of Pediatric Asthma

Article Outline

• Rationale
• Methods
• Results
• Conclusions
• Copyright

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Rationale 

We sought to determine the utility of exhaled nitric oxide (eNO) measurements combined with pulmonary function tests (PFTs) in clinical decision making in pediatric asthma patients. Elevated eNO levels have been described in asthmatics with eosinophilic airway inflammation. However; PFTs have become the standard by which most allergists base their asthma management. Studies correlating PFTs with eNO are inconclusive in the pediatric population.

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Methods 

We obtained eNO measurements on 100 consecutive patients with mild to moderate persistent asthma in a pediatric asthma and allergy clinic at an academic medical center. All subjects had PFTs done at the same visit. Concordance of eNO and PFTs was evaluated.

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Results 

Seventeen patients (17%) had normal PFTs, but elevated eNO (>20 ppb). Twenty-seven patients (27%) had abnormal PFTs, but normal eNO. Decisions to increase, decrease, or maintain asthma therapy were made based on evaluation of PFT and eNO measurements. Using both values, 44% of patients had different management plans, than would have been prescribed if PFTs were used alone.

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Conclusions 

Elevated eNO, with normal PFTs, indicated airway inflammation and the need to intensify or maintain asthma therapy. Low FEV1 and FEF 25-75% and normal eNO suggested triggers other than allergic asthma, such as GERD, bronchomalacia, infection, or airway irritants. Pulmonary function testing, in combination with eNO, is a useful clinical tool in the management of pediatric asthma.