Lower airway nitric oxide is increased in children with sickle cell disease
To determine alveolar and airways nitric oxide (NO) levels in children with sickle cell disease (SCD). Multiple flows fractional exhaled NO (FE(NO)), bronchial NO flux (J'aw(NO)), and alveolar NO concentration (Ca(NO)) were determined prospectively in 16 non-atopic children with SCD in a tertiary ambulatory clinic and compared with those in 10 children with primary ciliary dyskinesia and 22 healthy control subjects. Differences in FE(NO), J'aw(NO), and Ca(NO) were compared with mixed model analysis and Mann-Whitney tests. Children with SCD had reference range FE(NO) at 50 mL/sec, but FE(NO) was elevated across all flows compared with healthy control subjects (mean difference=2.10±0.91 parts per billion, P=.03). Subjects with SCD had increased J'aw(NO) (1177±533 picoliters per second versus 833±343 picolitres per second, P=.03), and Ca(NO) was no different from control subjects. In contrast, children with primary ciliary dyskinesia had decreased FE(NO) (mean difference=3.36±1.24 parts per billion, P<.01) and J'aw(NO) (507±259 picoliters per second versus 833±343 picoliters per second, P<.01). Lower airways NO is increased in children with SCD. Elevation of J'aw(NO) may represent dysregulation of NO metabolism or subclinical airways inflammation.