Carbon dioxide levels during polygraphy in children with sleep-disordered breathing

• Published in: Sleep & breathing 2015-03, Vol.19 (1), p.149-157
• Main Authors: Pautrat, Jade, Khirani, Sonia, Boulé, Michèle, Ramirez, Adriana, Beydon, Nicole, Fauroux, Brigitte
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon Dioxide - blood; Dentistry; Diagnosis, Differential; Diagnostic tests; Humans; Hypoventilation - blood; Hypoventilation - diagnosis; Internal Medicine; Lung Diseases - blood; Lung Diseases - diagnosis; Medicine; Medicine & Public Health; Neurology; Neuromuscular Diseases - blood; Neuromuscular Diseases - diagnosis; Original Article; Otorhinolaryngology; Pediatrics; Pneumology/Respiratory System; Polysomnography; Sleep Apnea, Obstructive - blood; Sleep Apnea, Obstructive - diagnosis; Sleep disorders
• ISSN: 1520-9512; 1522-1709
• DOI: 10.1007/s11325-014-0980-2

Purpose The recent scoring rules of the American Academy of Sleep Medicine (AASM) define hypoventilation in children as a carbon dioxide (CO 2 ) level of >50 mmHg for >25 % of total sleep time (partial pressure of CO 2 (PCO 2 ) > 50[>25 %]). As there is no validated level of nocturnal hypoventilation with regard to end-organ damage in children, we evaluated the prevalence of hypoventilation with the AASM definition but also with a lesser degree of elevated CO 2 in children with sleep-disordered breathing (SDB). Methods Transcutaneous CO 2 (PtcCO 2 ) was recorded during overnight polygraphy (PG). Hypoventilation was defined according to four definitions: the AASM score (PCO 2  > 50[>25 %]), the peak value of PtcCO 2  > 50 mmHg (PtcCO 2  > 50[peak]), a percentage of PtcCO 2  > 50 mmHg > 2 % of nighttime recording (PtcCO 2  > 50[>2 %]) or a nocturnal PtcCO 2  > 10 mmHg above waking baseline level (PtcCO 2 [>10 mmHg]). PtcCO 2 indices were correlated to the apnoea–hypopnoea index (AHI) and oxygenation indices. Results PGs from 221 children with suspicion of obstructive sleep apnoea (72 %), neuromuscular diseases (21 %), and lung diseases (7 %) were analysed. The prevalence of hypoventilation according to PCO 2  > 50[>25 %], PtcCO 2  > 50[peak], PtcCO 2  > 50[>2 %] and PtcCO 2 [>10 mmHg] were 16, 27, 31 and 52 %, respectively, and did not differ between the three diagnostic groups. Significant but weak correlations were observed between hypoventilation and AHI and oxygenation indices. Conclusions Nocturnal hypoventilation occurs in a large number of children referred for SDB, independent of the underlying disease, when more stringent criteria than those of the AASM are used. The poor correlation between hypoventilation and AHI or oxygenation indices is in favour of CO 2 being a supplemental index of SDB.