Serum nitrite and nitrate levels in children with obstructive sleep-disordered breathing

BackgroundDiminished nitric oxide (NO) levels have been reported in adults with obstructive sleep apnea but no data are available for children with obstructive sleep-disordered breathing (SDB).ObjectivesTo assess levels of serum NO metabolites in children with SDB and to explore the effects of NO metabolites, SDB and their interaction on blood pressure.MethodsMorning nitrite, the sum of nitrite and nitrate (NO_x), and the average of evening and morning blood pressure were assessed in children with SDB referred for polysomnography and in controls without SDB.ResultsForty-three children with SDB (age: 5.8 ± 2.1 years) had moderate-to-severe nocturnal hypoxemia (SpO₂ nadir: 85.6 ± 4%), 54 subjects (6.6 ± 2.7 years) had mild hypoxemia (SpO₂ nadir: 91.4 ± 1.3%) and 20 subjects were controls free of SDB (6.7 ± 3.7 years). Subjects with moderate-to-severe hypoxemia had significantly lower ln-transformed NO metabolites (1.4 ± 0.7, nitrites; 2.6 ± 0.5, NO_x) compared to those with mild hypoxemia (1.9 ± 0.8, nitrites; 3 ± 0.6, NO_x) and controls (2.2 ± 0.7, nitrite; 3 ± 0.6, NO_x; p < 0.05). The effects of NO metabolites and SDB or their interaction on blood pressure were not significant (p > 0.05).ConclusionsModerate-to-severe hypoxemia accompanying SDB is associated with reduced concentrations of morning serum NO metabolites, but NO levels do not seem to affect blood pressure.