Nocturnal dipping is preserved in children with sleep disordered breathing regardless of its severity.

OBJECTIVE: Sleep disordered breathing (SDB) in adults has been associated with a loss of nocturnal dipping in blood pressure (BP) and heart rate, however, there have been limited studies in children. We measured BP non-invasively and continuously overnight in 105 children aged 7-12 with a range of severities of SDB and 36 non-snoring controls to examine nocturnal dipping profiles. STUDY DESIGN: Children with SDB were divided into three severity groups according to their obstructive apnea hypopnea index. Nocturnal dipping profiles across sleep stages were described both as a proportion of children exhibiting a ≥10% fall in systolic arterial pressure (SAP) and heart rate (HR) from wake to sleep and according to SAP sleep/SAP wake ratio as extreme dippers (ratio ≤ 0.8), dippers (ratio < 0.8 and ≤0.9), non-dippers (ratio < 0.9 and ≤1.0), and reverse dippers (ratio > 1.0). RESULTS: The mean fall in BP between wake and NREM 1/2, SWS, and REM sleep was not different between the groups and there were no differences between the dipping profiles of children in each group. CONCLUSIONS: SDB did not alter nocturnal dipping patterns of BP and HR compared to controls, a finding which may suggest that these young children have not been exposed to the effects of SDB long enough or that SDB severity was not great enough to affect nocturnal dipping profiles. However, further studies are required to determine if the elevated BP previously reported in this group of children will have long-term effects on the cardiovascular system.

Elevated blood pressure during sleep and wake in children with sleep-disordered breathing.

OBJECTIVE: Sleep-disordered breathing (SDB) in adults has been associated with elevated blood pressure (BP); however, the effects of severity of SDB on BP in children are uncertain. We addressed this issue by measuring BP noninvasively and continuously during sleep in children with a range of severities of SDB and in a group of nonsnoring control children. METHODS: A total of 105 children referred for assessment of SDB and 36 nonsnoring controls were studied. Routine polysomnography (PSG) was performed with continuous BP monitoring. Children were assigned to groups according to obstructive apnea/hypopnea index (OAHI). BP data were categorized as quiet awake (recorded before sleep onset), non-rapid eye movement sleep 1 and 2 combined, slow-wave sleep, and rapid eye movement sleep. RESULTS: BP during awake before sleep onset and during overnight sleep was elevated by 10 to 15 mm Hg in the 3 SDB groups compared with the control group; this finding was independent of SDB severity. BP during stable sleep (with respiratory events and movements excluded) was also elevated in the children with OSA compared with the control group. BP was elevated in rapid eye movement sleep compared with the non-rapid eye movement sleep, and heart rate was higher during wake state than in all sleep states. CONCLUSIONS: We recorded BP continuously overnight and found that SDB, regardless of the severity, was associated with increased BP during sleep and wake compared with nonsnoring control children. These findings highlight the importance of considering the cardiovascular effects of SDB of any severity in children, and the need to review current clinical management that focuses primarily on more severe SDB.

Acute cardiovascular changes with obstructive events in children with sleep disordered breathing.

STUDY OBJECTIVES: Obstructive apneas in adults are associated with acute changes in blood pressure (BP) and heart rate (HR) that may contribute to poor cardiovascular outcome. Children with sleep disordered breathing (SDB) are similarly at risk for cardiovascular complications. We aimed to test the hypothesis that BP and HR are augmented during obstructive events in children equivalent to levels reported in adults. DESIGN: Beat-by-beat mean arterial pressure (MAP) and HR were analyzed over the course of obstructive events (pre, early, late, and post-event) during NREM and REM sleep and compared using 2-way ANOVA with post hoc analyses. SETTING: Pediatric sleep laboratory. PATIENTS OR PARTICIPANTS: 30 children (15M/15F) aged 7-12 y referred for investigation of SDB INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: All children underwent overnight polysomnography with continuous BP recording. MAP and HR increased significantly from late to post event in both sleep states (mean +/- SEM, NREM: MAP, 74 +/- 3 to 93 +/- 3 mm Hg; HR, 76 +/- 2 to 97 +/- 2 bpm. REM: MAP, 76 +/- 3 to 89 +/- 3 mm Hg; HR, 76 +/- 2 to 91 +/- 2 bpm. P < 0.05 for all). NREM sleep state and arousal from sleep were significant independent predictors of the magnitude of cardiovascular change from late to post event (P < 0.05 for all). CONCLUSIONS: Children with SDB experience significant changes in HR and BP during obstructive events with magnitudes that are similar to levels reported in adults. These changes are more pronounced during NREM sleep and with arousal. These acute cardiovascular changes may have important implications for poor cardiovascular outcome in children with OSA as repetitive cardiovascular perturbations may contribute to the development of hypertension.

Central apnoeas have significant effects on blood pressure and heart rate in children.

Brief central apnoeas (CAs) during sleep are common in children and are not usually considered clinically significant unless associated with oxygen desaturation. CAs can occur spontaneously or following a movement or sigh. The aim of this study was to investigate acute cardiovascular changes associated with CAs in children. Beat-by-beat mean arterial pressure (MAP) and heart rate (HR) were analysed across CAs, and spontaneous and movement-induced events were compared using two-way analysis of variance with post hoc analyses. Fifty-three children (28 male/25 female) aged 7-12 years referred for investigation of sleep-disordered breathing (SDB) and 21 age-matched healthy controls (8 male/13 female) were studied. Children underwent routine clinical polysomnography with continuous blood pressure (BP) recordings. Movement-induced, but not spontaneous, CAs were more frequent in children with mild or moderate/severe obstructive sleep apnoea (OSA) compared with healthy controls (P < 0.05 for both). Movement-induced CAs were associated with significantly larger MAP and HR changes across the event compared with spontaneous CAs. The percentage changes in MAP and HR between late-event and post-event were significantly greater for movement-induced compared with spontaneous CAs (MAP 20.6 +/- 2.3 versus 12.2 +/- 1.8%, P < 0.01; HR 28.2 +/- 2.6 versus 14.7 +/- 2.5%, P < 0.001). This study demonstrates that movement-induced CAs are more common in children with OSA, and are associated with significantly greater changes in HR and BP compared with spontaneous CAs. These data suggest that movement-induced CAs should be considered when assessing the cardiovascular impact of SDB.

Surveillance of infections associated with intravenous catheters in dogs and cats in an intensive care unit.

Positive catheter-tip culture rates and risk factors associated with bacterial colonization of intravenous (i.v.) catheters were assessed in dogs and cats. Aerobic and anaerobic bacterial cultures were performed on 151 catheters, and 24.5% were positive. Of the positive cultures, 46.0% grew Enterobacter spp. The type of catheter used, blood sampling through the catheter, the type of i.v. infusate administered, the duration the catheter was in place, the catheter location, complications with the catheter, and the final outcome of the animal were not associated with an increased risk of a positive bacterial culture from the catheter tip.