Effects of sleep-disordered breathing severity on blood pressure in primary school children.

Objectives: Sleep disordered breathing is common in children and ranges in severity from primary snoring (PS) to obstructive sleep apnoea (OSA). OSA has been associated with elevated blood pressure (BP). It is thought that this elevation in BP may be due to the repeated increases in BP at apnoea termination. We have previously shown that children exhibit elevations in BP after apnoea termination equivalent to levels in adults [1,2]. In this study we aimed to examine BP in "stable sleep" (periods without respiratory events), to identify if elevations in BP are persistent. Method(s): Hundred and forty one children (78M/61F) aged 7-13 years were studied. 105 were referred for assessment of SDB and 36 non-snoring controls were recruited from the community. Routine polysomnography (PSG) was performed and BP recorded continuously using a FinometerTM (FMS, BV Arnhem, The Netherlands). None of the children had any significant medical conditions or were on no medication. Children were divided into groups according to obstructive apnoea/hypopnoea index (OAHI). Control children OAHI <= 1 and no history of snoring (n = 36), PS OAHI<= 1 event h-1(n= 61), mild OSA OAHI>1 - <= 5 events/h (n = 23) and moderate/severe OAHI> 5 events h-1(n = 21). BP data were grouped into quiet awake (recorded before sleep onset), NREM 1/2, SWS and REM. BP and HR data were compared with repeated measures linear regression methods with linear contrasts for a priori pairwise comparisons. Result(s): Overall BP was elevated in the 3 SDB groups compared to the control group. During stable sleep, mean, systolic and diastolic blood pressures were all significantly (P < 0.05) higher in both the mild and moderate/severe OSA groups compared to the control group by 7-9 mmHg. Conclusion(s): This study recorded BP continuously overnight and found that OSA was associated with increased BP during "stable sleep" and wake compared to non snoring control children. These findings highlight the importance of considering