In a normotensive cohort, oxygen desaturation index independently predicted nocturnal blood pressure dip (B=-0.351, p<0.01), and CPAP therapy decreased night-time systolic blood pressure (p<0.05).
Observational
Does CPAP therapy improve nocturnal blood pressure dipping in normotensive subjects with obstructive sleep apnoea?
In normotensive subjects with OSA, severity of intermittent hypoxia correlates with blunted nocturnal blood pressure dipping, which may be reversed with CPAP therapy.
Effect estimate: B=-0.351
p-value: p=<0.01
BACKGROUND: Obstructive sleep apnoea (OSA) is strongly associated with systemic hypertension, but there are limited data on the relationship with blood pressure (BP) in normotensive subjects. Here, we examined the relationship of OSA with nocturnal BP in a documented diurnal normotensive cohort, explored potential intermediate pathways and assessed the effects on BP of continuous positive airways pressure (CPAP) therapy. METHODS: , apnoea-hypopnoea index (AHI) 14 (interquartile range 5-26)). Urine and serum were assessed for markers of sympathetic activation, renin-angiotensin-aldosterone system activity, oxidative stress, endothelial function and systemic inflammation. In a subset of patients, 24-hour BP monitoring was repeated after CPAP therapy. RESULTS: Within this normotensive cohort, night-time systolic and diastolic BP and nocturnal BP dip were highest in the fourth OSA severity quartile (p<0.05). Nocturnal BP dip correlated with AHI (r=-0.327, p<0.05) and oxygen desaturation index (ODI) (r=-0.371, p<0.05), but only ODI was an independent predictor of BP dip (B=-0.351, p<0.01) and non-dipping status (B=0.046, p<0.05). Overnight urinary norepinephrine correlated with nocturnal systolic BP (r=0.387, p<0.01) with a trend towards correlation with systolic dipping (p=0.087). In 20 CPAP-treated patients, night-time systolic BP decreased (p<0.05) and mean nocturnal BP dip increased (p≤0.05). CONCLUSION: In this normotensive cohort, OSA severity was associated with higher nocturnal BP, which improved following CPAP therapy, and intermittent hypoxia was the most important OSA-related variable in this relationship.
Crinion et al. (Fri,) conducted a observational in Obstructive sleep apnoea in normotensive subjects. Continuous positive airways pressure (CPAP) therapy was evaluated on Nocturnal blood pressure dip (B=-0.351, p=<0.01). In a normotensive cohort, oxygen desaturation index independently predicted nocturnal blood pressure dip (B=-0.351, p<0.01), and CPAP therapy decreased night-time systolic blood pressure (p<0.05).