Ambulatory blood pressure in children with obstructive sleep apnoea: a community based study

Abstract

Background: Childhood obstructive sleep apnoea (OSA) is increasingly being recognised. Its effects on blood pressure (BP) elevation and hypertension are still controversial. Objective: To evaluate the association between OSA and ambulatory BP in children. Methods: Children aged 6-13 years from randomly selected schools were invited to undergo overnight sleep study and ambulatory BP monitoring after completing a validated OSA questionnaire. OSA was diagnosed if the obstructive apnoea-hypopnoea index (AHI) was .1, and normal controls had AHI ,1 and snoring ,3 nights per week. Children with OSA were subdivided into a mild group (AHI 1-5) and moderate to severe group (AHI .5). Results: 306 subjects had valid sleep and daytime BP data. Children with OSA had significantly higher BP than normal healthy children during both sleep and wakefulness. BP levels increased with the severity of OSA, and children with moderate to severe disease (AHI .5) were at significantly higher risk for nocturnal systolic (OR 3.9 (95% CI 1.4 to 10.5)) and diastolic (OR 3.3 (95% CI 1.4 to 8.1)) hypertension. Multiple linear regression revealed a significant association between oxygen desaturation index and AHI with daytime and nocturnal BP, respectively, independent of obesity. Conclusions: OSA was associated with elevated daytime and nocturnal BP, and is an independent predictor of nocturnal hypertension. This has important clinical implications as childhood elevated BP predicts future cardiovascular risks. Future studies should examine the effect of therapy for OSA on changes in BP.In adults, obstructive sleep apnoea (OSA) is an independent risk factor for hypertension and is involved in the initiation and progression of other cardiovascular diseases.1-3 However, corresponding data for the paediatric population are scarce, and the few published studies have provided conflicting results. [4][5][6][7][8][9] Marcus and colleagues 4 suggested that children with OSA had higher daytime and nocturnal diastolic blood pressure (BP) compared with primary snorers, whereas Amin and colleagues 5 found lower diastolic BP among children with OSA. Guilleminault and colleagues 6 demonstrated that a subgroup of children with OSA were hypotensive rather than hypertensive. Kohyama and colleagues 7 found a positive correlation between both nocturnal systolic and diastolic BP with severity of OSA and, similarly, Enright and colleagues 8 found respiratory disturbance index to be significantly associated with systolic and diastolic BP. A recent study, however, failed to confirm such a positive association.9 These inconsistent findings in BP measurements might have been related to the small sample sizes and lack of normal healthy subjects for comparison. A recent meta-analysis concluded that there was inadequate evidence for an increased risk of elevated BP in children with OSA. The authors also found marked heterogeneity among published series and emphasised the need for further studies to clarify this important issue.

Acute and Chronic Effects of Sleep Duration on Blood Pressure

“…Obesity is a well-established risk factor for OSA, 16,17 which has been demonstrated to lead to elevated BP. [18][19][20][21] Obesity itself is also a wellknown risk factor of elevated BP. 22 In the current study, we used more stringent criteria to minimize the confounding effects of obesity and OSA so as to focus on the independent relationship between sleep duration and BP.…”

“…20 All computerized sleep data were further manually edited by experienced polysomnography technologists and clinicians according to standard criteria. 27 All studies were set to record the time in bed as 9.5 hours 6 5 minutes, starting at 21:30 6 30 minutes and ending at 07:00 6 30 minutes the next morning (Fig 1).…”

“…6,7,[9][10][11][12]14,15 OSA has been documented to lead to elevated BP in children and adolescents. [18][19][20][21] Therefore, in assessing the relationship between sleep duration and BP, the OSA status has to be ascertained and controlled for. Most of the previous studies included both obese and nonobese subjects and analyzed the 2 groups together.…”

“…20,37 Another merit of this study was that overnight polysomnography was performed on the same day as 24-hour ABPM, both immediately after completion of the 7-day sleep diary. This study design allowed us to separately delineate the relatively long-term (7 days) and acute effects of sleep duration on BP.…”

Augmented cardiovascular responses to episodes of repetitive compared with isolated respiratory events in preschool children with sleep-disordered breathing

“…SDB has been associated with elevated heart rate (HR) and blood pressure (BP) in children (3)(4)(5)(6)(7). In both adults (8,9) and children (10,11) with SDB, obstructive apneas and hypopneas are associated with a decrease in HR and BP during the event followed by a significant surge in HR and BP at event termination.…”