Relation between Nocturnal Arterial Oxygen Desaturation and Morning Blood Pressure

Abstract

Objective. Arterial oxygen saturation (SpO₂) in volunteers had been previously investigated, and the possibility that a decrease in SpO₂ leads to an increase in blood pressure (BP) in airline passengers experiencing oxygen desaturation at high altitudes was reported. It was also shown that mean nocturnal SpO₂ was lower in subjects with high-normal BP or mild hypertension than in those with normal BP. The present study investigated nocturnal SpO₂, evening BP, and morning BP of volunteers during daily life and examined the relation between nocturnal SpO₂ and change in BP (morning BP minus evening BP) to determine the influence of SpO₂ on BP. Methods. Sixty-two volunteers (31 men and 31 women) aged 40–87 years (mean: 55.9 ± 12 [SD] years) underwent measurement of SpO₂ and heart rate with a ring-shaped pulse oximeter during sleep at home. Evening BP and morning BP were measured by automatic BP recorder. Subjects that were classified as having high SpO₂ (mean nocturnal SpO₂ ≥ 95%; n = 23, 10 men and 13 women; mean age: 53.2 ± 12 years) or low SpO₂ (mean nocturnal SpO₂ < 94%; n = 21, 12 men and 9 women; mean age: 58.7 ± 13 years) were compared. The relation between mean nocturnal SpO₂ and morning BP and the relation between mean nocturnal SpO₂ and change in BP were investigated. Results. There was a significant negative correlation between mean nocturnal SpO₂ and morning systolic BP (SBP; r = −0.50, p < 0.01) and between mean nocturnal SpO₂ and morning diastolic BP (DBP; r = −0.37, p < 0.01). A significant negative correlation between mean nocturnal SpO₂ and change in SBP was observed (r = −0.57, p < 0.01). Morning BP was significantly higher in the low nocturnal SpO₂ group than in the high nocturnal SpO₂ group (p < 0.001). Conclusion. The increase in morning BP from evening BP was significantly greater in subjects with a low nocturnal SpO₂. The decrease in SpO₂ during sleep may affect morning BP rise.

Keywords:

• pulse oximetry
• oxygen saturation
• SpO₂
• hypoxemia
• hypertension
• morning blood pressure
• sleep