Obstructive sleep apnea syndrome (OSAS) causes hypoxemia and hypercapnia, which may impair cerebral blood flow and cause deficits in behavior. This is a case-control study designed to investigate cerebral blood flow and neurocognitive function in children with OSAS when compared to these findings from normal children. The study hypothesis is that children with OSAS have an impaired cerebral blood flow during wakefulness and sleep compared to normal controls, and that the degree of this impairment correlates with neurocognitive function.
OSAS is characterized by repetitive occlusion of the upper airway during sleep that results in hypoxemia, hypercapnia and arousal from sleep. Children with the obstructive sleep apnea syndrome (OSAS) have impaired behavior and cognition compared to normal controls. Previous studies in adults with OSAS have shown significant alterations of cerebral blood flow during wakefulness and sleep and our preliminary data showed blunted cerebral blood flow response to hypercapnia in children with OSAS during wakefulness. However, it is unknown whether children with OSAS also have impaired cerebral blood flow during sleep. It is also unknown whether the deficits in behavior and cognition in children are associated with cerebral blood flow dysregulation. This study will investigate whether the changes in cerebral blood flow during wakefulness and sleep elicited by hypercapneic challenge, differ in children with OSAS compared to normal controls. Additionally the study will evaluate the changes in cerebral blood flow during wakefulness and sleep elicited by hypercapneic challenge in children with OSAS before and after treatment (adenotonsillectomy, adenoidectomy, or tonsillectomy). Finally, the study will investigate whether the changes in cerebral blood flow elicited by the aforementioned testing correlate with neurocognitive outcomes. Children with OSAS aged 6-12 years will be recruited following a clinical polysomnogram. Normal age- and gender-matched controls will be recruited from the general community. The primary interventions of this study for the two groups (OSAS and controls) are: sleep studies, neurocognitive testing, measurement of cerebral blood flow by near-infrared spectroscopy during hypercapnic challenges conducted during wakefulness and sleep. In addition, OSAS subjects will be re-tested after clinical treatment of OSAS to evaluate for resolution of OSAS, and all subjects will be re-tested at two separate time points after baseline to compare changes due to the treatment of OSAS versus those occurring secondary to normal development.
Study Type
OBSERVATIONAL
Overnight, video-recorded sleep study will be performed in a dedicated pediatric sleep lab. Sleep architecture, apneas and hypopneas, arterial oxygen saturation and end-tidal carbon dioxide tension will be evaluated during the sleep study. Safety measures including arterial oxygen saturation using pulse oximetry, EEG and EKG will be continuously monitored during the study.
Cognitive and behavioral measures including intelligence, attention, working memory, and processing speed will be assessed by a trained psychologist.
Cerebral blood flow (CBF) will be measure using Diffuse optical and correlation spectroscopy (DOS/DCS), a non-significant risk device used to collect data for this study but not being tested as part of the protocol. Light sources and detectors which are embedded in a rubber pad will be attached to the subject's head in order to record right and left hemispheric cerebral blood flow, total hemoglobin concentration and tissue oxygen saturation. Measurements will be continuously recorded during the study and averaged for purposes of statistical analysis. With DOS/DCS in place, ventilatory response to hypercapnia will be determined using the rebreathing technique, a standard clinical test. While CBF is being measured, subjects will wear nose clips and sit comfortably breathing through a mouthpiece while the level of carbon dioxide is adjusted over a 3-4 minute period. Oxygen and carbon dioxide levels will be carefully monitored throughout the testing.
Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, United States
Change in Cerebral Blood Flow (CBF) at Baseline Between Obstructive Sleep Apnea Syndrome (OSAS) and Controls
To determine whether children with OSAS have impaired blood flow regulation elicited by hypercapneic challenge compared to normal controls at baseline.
Time frame: Baseline measurements, up to 24 hours
Comparison of the Change in CBF From Baseline to Study Completion Between OSAS and Control Subjects
Only children who completed 2 or more repeated measurements were included in the analysis. The change in CBF measurements obtained at baseline when compared at 6 and 12 months after baseline for controls and after adenotonsillectomy for OSAS subjects. The slope of the change in CBF over time is reported: Delta CBF/Delta time, units= percentage over year. Minimum values are -100, maximum values +100, positive values mean better outcome.Cerebral blood flow were measured non-invasively while the child was breathing oxygen mixed with carbon dioxide.
Time frame: Up to 12 Months
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Enrollment
47
This is the same as the CBF testing during wakefulness/daytime except that it will be done during a sleep study performed with a continuous positive airway pressure (CPAP) mask not nose clips and a mouthpiece. With DOS/DCS in place, ventilatory response to hypercapnia will be determined using the rebreathing technique. While CBF is being measured, OSAS subjects will receive an individualized positive pressure aimed at treating obstructive sleep apnea and controls will receive a standard pressure. End-tidal carbon dioxide will be measured via a port in the mask. A constant flow of carbon dioxide will be introduced to the circuit, a slowly adjusted until the patient arouses or for a maximum of 3 minutes, whichever occurs first. One trial will be attempted in each sleep stage (slow-wave sleep and rapid-eye-movement) with a minimum of 15 minute of breathing room air between challenges. Oxygen and carbon dioxide levels will be carefully monitored throughout the testing.