Delayed brachial artery dilation response and increased resting blood flow velocity in young children with mild sleep-disordered breathing

Aim: This study aimed to evaluate whether the vascular dysfunction perceived in adults with sleep-disordered breathing (SDB) was also evident in children with snoring referred for evaluation of clinically suspected SDB. Objectives: This study compared flow-mediated dilatation (FMD), measured at the brachial artery, at rest and during hyperaemic stress between children who snore [n = 23; mean standard deviation (SD) age = 7.51 (1.3) years] and healthy, non-snoring children [n = 11; age = 8.0 (1.3) years]. Methods: Children with suspected obstructive sleep apnoea (OSA) and healthy non-snoring controls underwent overnight polysomnography (PSG). Using standard techniques, non-invasive FMD and brachial arterial blood flow velocity during rest and hyperaemia were subsequently measured by ultrasound imaging Measurements: Resting and hyperaemic velocity time integral (area under the curve of mean systolic velocity x ejection time), maximal dilation response (highest percentage difference from baseline diameter) and the time taken to reach maximal dilation were calculated. Results: Children awaiting adenotonsillectomy compared to healthy non-snoring control children had higher velocity time integrals at rest (14 +/- 3mvs. 20 +/- 8m, p < 0.01) and during hyperaemic stress (56 +/- 6m vs. 63 +/- 13m, p < 0.01) despite having only mild SDB on polysomnographic assessment. Lower nadir oxygen saturation values during non-rapid eye movement sleep were negatively associated with higher resting (r = -0.58, p < 0.001) and hyperaemic (r = -0.36, p < 0.05) velocity time integrals. Maximal FMD dilatation response was not significantly different between snoring and non-snoring groups, but the estimated time to reach maximal dilation was significantly delayed in children who snored (60.7 +/- 28.4 vs. 39.2 +/- 13.2 s, p < 0.05). Conclusions: Children with mild SDB showed increased blood flow velocity at rest and during hyperaemic stress suggesting altered cardiovascular and haemodynamic function. The delay in time to maximal vessel dilatation in children who snored also suggests possible reduced vascular compliance in response to hyperaemic sheer stress. Mild SDB appears to alter the peripheral vascular response in young children. The long-term vascular implications of these changes in the growing child are unknown and warrant further investigation. (C) 2015 Elsevier B.V. All rights reserved.