Reference values for sleep-related respiratory variables in asymptomatic European children and adolescents

Aim: Only a limited number of studies, designed to establish normal values for sleep-related respiratory variables in children, have been reported, and all are non-European. The aim of this study was to expand the knowledge on normative data in children. Methods: Subjects ranging from 6 to 16 years were recruited and underwent full polysomnography. Only subjects without sleep disordered breathing or other sleep problems as assessed by clinical history were included. Results: Sixty subjects were studied (< age > = 11.7 +/- 2.6 years; 28 boys; < relBMI > = 118.8 +/- 30.6%). < Central apnea index > was 0.85 +/- 1.06 (range: 0.0-5.5). < Obstructive apnea index > was 0.06 +/- 0.16 (range: 0.0-0.9); 11 patients had a total of 31 obstructive apneas. Only five obstructive hypopneas were detected with < obstructive apnea hypopnea index > = 0.08 +/- 0.17 (range: 0.0 - 0.9). < Respiratory disturbance index > was 1.98 +/- 1.39 (range: 0.1 - 7.2). < SaO(2)> was 97.0 +/- 0.6% (range: 96.0-98.0); < SaO(2)nadir > was 91.8 +/- 2.7% (range: 82.0-96.0); <% of total sleep time with SaO(2) >= 95%> was 98.7 +/- 2.1% (range: 90.8-100.0); < oxygen desaturation index > was 0.8 +/- 0.9 (range: 0.0-4.9) and < arousal index > was 6.1 +/- 1.8 (range: 2.7-10.9). Snoring was detected in 15 patients (4 overweight subjects), with no difference in patient characteristics and sleep-related respiratory variables between snorers and non-snorers. Subjects in the overweight group (n = 22) had a lower SaO(2)nadir (90.8 +/- 2.7 vs. 92.4 +/- 2.6; P = 0.01) and a higher ODI (1.3 +/- 1.3 vs. 0.4 +/- 0.4; P = 0.0002) than their normal weight peers. Conclusion: Our data are in agreement with other non-European studies, designed to establish normal values in children.