title: Cardioventilatory coupling and inter-breath variability in children referred for polysomnography.
abstract: Measures of respiratory variability including cardioventilatory coupling (CVC), were examined in 8 Down syndrome (DS), 4 Prader Willi syndrome (PWS) and 42 non-syndromic children (median age 7 years) referred for diagnostic polysomnography. Inspiratory onsets (I) and corresponding ECG R waves were determined, I-I, R-R and R-I intervals derived, and ventilatory frequency (f), standard deviation of f (SDf), coefficient of variation of f (CVf), median I-I and kurtosis and skewness I-I calculated. Proportional Shannon Entropy of the RI(-1) interval (SHα) was measured to quantitate CVC. SHα varied with age (p=0.02), oxygen saturation (p<0.05) and PWS diagnosis (p=0.001) in Stage 4 but not REM sleep. SDf and CVf varied with sleep state (p<0.00001) as did kurtosis I-I (p<0.0001) and skewness I-I (p=0.004). Ventilatory frequency decreased with age in REM sleep (p=0.03) and increased in obese children in REM (p=0.02) and Stage 4 sleep (p=0.004). Sleep state influences respiratory variability in children and CVC may confer a physiological advantage in children with PWS.
authors.affiliation: Department of Paediatrics, University of Otago, Wellington, P.O. Box 7434, Wellington, New Zealand. dawn.elder@otago.ac.nz
authors.forename: D E
authors.initials: DE
authors.lastname: Elder
authors.forename: P D
authors.initials: PD
authors.lastname: Larsen
authors.forename: A J
authors.initials: AJ
authors.lastname: Campbell
authors.forename: D C
authors.initials: DC
authors.lastname: Galletly
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D017286:Polysomnography; D011218:Prader-Willi Syndrome / Q000503:physiopathology*; D012119:Respiration; D056152:Respiratory Rate / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology*