Developmental changes in upper airway dynamics.

Normal children have a less collapsible upper airway in response to subatmospheric pressure administration (P(NEG)) during sleep than normal adults do, and this upper airway response appears to be modulated by the central ventilatory drive. Children have a greater ventilatory drive than adults. We, therefore, hypothesized that children have increased neuromotor activation of their pharyngeal airway during sleep compared with adults. As infants have few obstructive apneas during sleep, we hypothesized that infants would have an upper airway that was resistant to collapse. We, therefore, compared the upper airway pressure-flow (V) relationship during sleep between normal infants, prepubertal children, and adults. We evaluated the upper airway response to 1). intermittent, acute P(NEG) (infants, children, and adults), and 2). hypercapnia (children and adults). We found that adults had a more collapsible upper airway during sleep than either infants or children. The children exhibited a vigorous response to both P(NEG) and hypercapnia during sleep (P < 0.01), whereas adults had no significant change. Infants had an airway that was resistant to collapse and showed a very rapid response to P(NEG). We conclude that the upper airway is resistant to collapse during sleep in infants and children. Normal children have preservation of upper airway responses to P(NEG) and hypercapnia during sleep, whereas responses are diminished in adults. Infants appear to have a different pattern of upper airway activation than older children. We speculate that the pharyngeal airway responses present in normal children are a compensatory response for a relatively narrow upper airway.

Body position and obstructive sleep apnea in children.

STUDY OBJECTIVES: In adults, sleep apnea is worse when the patient is in the supine position. However, the relationship between sleep position and obstructive apnea in children is unknown. The objective of this study was to evaluate the relationship between obstructive apnea and body position during sleep in children. DESIGN: Retrospective analysis of the relationship between body position and obstructive apnea in obese and non-obese children. SETTING: Tertiary care pediatric sleep center. PATIENTS: Otherwise healthy children, aged 1-10 years, undergoing polysomnography for suspected obstructive sleep apnea syndrome. Obese and non-obese children were evaluated separately. INTERVENTIONS: Retrospective review of the relationship between sleep position and obstructive apnea during polysomnography. MEASUREMENTS AND RESULTS: Eighty polysomnograms from 56 non-obese and 24 obese children were analyzed. Body position was determined by a sensor during polysomnography, and confirmed by review of videotapes. Children had a lower obstructive apnea hypopnea index when supine vs. prone, and shorter apneas when supine then when on their side. There was no difference in apnea duration between the supine and prone positions. Obese and non-obese children showed similar positional changes. CONCLUSIONS: Children with obstructive sleep apnea, in contrast to adults, breathe best when in the supine position.