PURPOSE: The purpose of this study is to compare the prevalence of nocturnal hypoxemia (NH) in obstructive sleep apnea (OSA) patients with and without systemic hypertension (HT).
METHODS: Analytical, case-control study having examined nocturnal oxymetry data of 76 patients having untreated OSA diagnosed thanks to overnight ventilation polygraphy in a stable clinical condition (New York Heart Association (NYHA) Classification, functional class I or II , and diurnal SaO2 > 90%). All followed OSA patients having HT and fulfilling inclusion criteria (n = 48) were consecutively included. 28 normotensive OSA patients matched to those with HT on age, sex, body mass index (BMI) and apnea-hypopnea index (AHI) were selected. OSA was defined as AHI ≥ 10 events/hour. The patients were categorized as having NH when nocturnal mean SaO2 < 90%, lowest SaO2 < 85%, or percentage of sleep time below 90% oxygen saturation (CT90) > 30%. HT was defined as ongoing pharmacological antihypertensive treatment and/or clinic blood pressure ≥ 140/90 mmHg.
RESULTS: Overnight sleep studies revealed “mean SaO2 < 90%” in 15 OSA patients with HT but only in three control patients (p=0.0422. OR = 3,79). Average mean SaO2 was similar in both groups. Average lowest SaO2 was lower (72,4% versus 80,2%. p = 0,0138), and “lowest SaO2 < 85%” was more common (77,1% versus 50%. p = 0,0153. OR = 3,36) in hypertensive patients compared to normotensive subjects. Percentage of “CT90 > 30%” did not differ significantly between the groups but average CT90 was higher in HT group (23% versus 10,8%. p = 0,0398).
CONCLUSION: The findings of the present study show that NH (defined as mean SaO2 < 90% or lowest SaO2 < 85%) is significantly more common among middle-aged and elderly OSA patients with HT compared not only to age-, sex- and BMI- but also to AHI-matched controls without HT.
CLINICAL IMPLICATIONS: This result suggests that NH and its extent intervene in the increase of diurnal blood pressure among patients with OSA independently of AHI.
DISCLOSURE: Amine Dhouib, No Financial Disclosure Information; No Product/Research Disclosure Information