Relationship between REM density, duty cycle, and obstructive sleep apnea in children.
OBJECTIVE
The pattern and distribution of rapid eye movement (REM) sleep changes during development, yet there have been few studies of REM density in children. Although children with obstructive apnea syndrome (OSAS) obstruct primarily during REM sleep, the relationship between REM density and obstructive apnea has not been established for this population. We hypothesized that (i) REM density and REM cycle duration increases over the course of the night in children, (ii) the duty cycle (inspiratory time divided by respiratory cycle time) increases over the course of the night in children with suspected OSAS, and (iii) the increase in REM density over the course of the night is associated with increased severity of obstructive apnea.


METHODS
REM density and respiratory parameters were measured during polysomnography.


METHODS
Sleep laboratory


METHODS
76 children with suspected OSAS.


METHODS
NA MEASUREMENTS AND RESULTS: REM density and the duration of REM cycles increased over the course of the night until the fifth REM cycle, and then stabilized. The duty cycle increased across the first 6 REM cycles. However, the apnea hypopnea index (AHI) did not increase across REM cycles, and was not affected by the changes in REM density or duty cycle. We speculate that the increase in the duty cycle is a compensatory response to increased upper airway loads during sleep, and that this may lead to ventilatory or upper airway muscle fatigue.
The Sleep Center, The Children's Hospital ofPhiladelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Laurie
L
Karamessinis
Patricia
P
Galster
Brian
B
Schultz
Joanne
J
Elliott
Thornton A
TA
Mason
Lee J
LJ
Brooks
Paul R
PR
Gallagher
Carole L
CL
Marcus
D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007753:Laboratories; D008297:Male; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology*