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Arousal and ventilatory responses during sleep in children with obstructive sleep apnea
C L Marcus1, J Lutz, J L Carroll
1The Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, Maryland 21287-2533, USA.
Insights
Children with obstructive sleep apnea syndrome (OSAS) show slightly blunted arousal responses to hypercapnia during sleep. However, overall ventilatory and arousal control appear normal, suggesting global respiratory drive deficits are not the primary cause of childhood OSAS.
Area of Science:
- Pediatric Pulmonology
- Sleep Medicine
- Respiratory Physiology
Background:
- Abnormalities in central regulation of upper airway muscles are implicated in childhood obstructive sleep apnea syndrome (OSAS).
- This study investigates whether these abnormalities stem from global ventilatory control dysfunctions during sleep.
Purpose of the Study:
- To compare ventilatory and arousal responses to chemical stimuli during sleep in prepubertal children with OSAS and healthy controls.
- To determine the role of central respiratory control in the pathophysiology of childhood OSAS.
Main Methods:
- Comparison of arousal thresholds to hypercapnia and hypoxia during sleep in children with and without OSAS.
- Assessment of ventilatory responses to chemical stimuli.
- Correlation analysis between apnea index and arousal threshold.
Main Results:
- Children with OSAS had a higher arousal threshold to hypercapnia (PCO2) compared to controls.
- A higher apnea index correlated with a higher arousal threshold.
- Hypercapnia, especially combined with hypoxia, was a potent arousal stimulus and reduced airway obstruction in OSAS patients.
- Ventilatory responses were similar between groups, though the sample size was small.
Conclusions:
- Children with OSAS exhibit slightly blunted arousal responses to hypercapnia.
- Global deficits in respiratory drive are unlikely to be the primary cause of childhood OSAS.
- Subtle abnormalities in ventilatory control may still play a role in the condition.
Abstract:
Abnormal central regulation of upper airway muscles may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). We hypothesized that this was secondary to global abnormalities of ventilatory control during sleep. We therefore compared the response to chemical stimuli during sleep between prepubertal children with OSAS and controls. Patients with OSAS aroused at a higher PCO2 (58 +/- 2 vs. 60 +/- 5 Torr, P < 0.05); those with the highest apnea index had the highest arousal threshold (r = 0.52, P < 0.05). The hypercapnic arousal threshold decreased after treatment. For all subjects, hypoxia was a poor stimulus to arousal, whereas hypercapnia and, particularly, hypoxic hypercapnia were potent stimuli to arousal. Hypercapnia resulted in decreased airway obstruction in OSAS. Ventilatory responses were similar between patients with OSAS and controls; however, the sample size was small. We conclude that children with OSAS have slightly blunted arousal responses to hypercapnia. However, the overall ventilatory and arousal responses are normal in children with OSAS, indicating that a global deficit in respiratory drive is not a major factor in the etiology of childhood OSAS. Nevertheless, subtle abnormalities in ventilatory control may exist.