TcCO 2 changes correlate with partial obstruction in children suspected of sleep disordered breathing.

Introduction: Pediatric sleep disordered breathing (SDB) is characterized by long periods of partial upper airway obstruction (UAO) with low apnea-hypopnea indices (AHI). By measuring snoring and stertor, Sonomat studies allow quantification of these periods of partial UAO.
Aim: To determine whether transcutaneous CO ₂ (TcCO ₂ ) levels correlate with increasing levels of partial UAO and to examine patterns of ΔTcCo ₂ in the transitions from (a) wakefulness to sleep and (b) non-rapid eye movement (NREM) to rapid eye movement (REM) sleep.
Methods: This was a retrospective review of sleep studies in seven asymptomatic controls aged 7 to 12 years and 62 symptomatic children with suspected SDB and no comorbidities, aged 2 to 13 years. Both groups underwent overnight polysomnography, including continuous TcCO ₂ , at one of two pediatric hospitals in Sydney. Changes in carbon dioxide levels between wake to NREM (sleep onset) and NREM to REM sleep were evaluated using an all-night TcCO ₂ trace time-linked to a hypnogram. Paired Sonomat recordings were used to quantify periods of UAO in the symptomatic group.
Results: The ΔTcCO ₂ at sleep onset was greater in SDB children than controls and ΔTcCO ₂ with sleep onset correlated with the duration of partial obstruction (r = .60; P < .0001). Children with an increase in TcCO ₂ from NREM to REM had a higher number of snoring and stertor events compared to those in whom TcCO ₂ decreased from NREM to REM (91 vs 30 events/h; P = < .0001).
Conclusions: In children without comorbidities, the measurement of TcCO ₂ during sleep correlates with indicators of partial obstruction.
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