Background: High Flow Congenital Heart Disease (HF-CHD) or those with left to right shunting (e.g. VSD, ASD and PDA) are observed to be prone to wheezing despite management of congestion. Matsuoka et al. concluded that shunt lesions enhance the manifestation of allergic diseases or asthma. Fractional exhaled nitric oxide (FeNO) on the other hand, has been used to screen for allergic type of asthma. Its accuracy is enhanced when used in a population based study. Based on these findings, we hypothesize that the predictive accuracy of FeNO in detecting allergy and asthma will be enhanced when used in children with high flow CHD.
Patients and Methods: All patients with CHD ages 6-18 years old referred to pediatric pulmonology for preoperative risk stratification prior to a contemplated cardiac surgery without any active respiratory infection were included in the study. Presence of asthma, allergic rhinitis and eczema were determined through validated questionnaires. Pulmonary function test was also documented. FeNO determination was done and patients were grouped into high flow or low flow congenital heart disease based on 2D echocardiography. Accuracy of FeNO was determined for each group.
Results: Eighty five patients completed the study. There were more children in the high flow category. Forty-nine (58.3%) had high flow lesions mostly ventricular septal defect. The overall accuracy of FeNO in children with low flow CHD was low at 56.1%. The sensitivity was 25.0%. The specificity was 87.1%, positive predictive value (PPV) of 20.0% and negative predictive value (NPV) of 90.0%. On the other hand, for high flow lesions, the overall accuracy of FeNO was high at 88.6%. The sensitivity, specificity, PPV and NPV are 92.9%, 88.6%, 76.5% and 96.8% respectively.
Conclusion: FeNO is more accurate in detecting asthma, allergic rhinitis and atopy when used in children with high flow CHD than with low flow CHD. FeNO can be utilized to determine eosinophilic airway inflammation among this subset of CHD.