Overnight supplemental oxygen can reduce morning blood pressure (BP) by reducing intermittent hypoxia in patients with moderate to severe obstructive sleep apnea (OSA), according to a study published in the American Journal of Respiratory and Critical Care Medicine.

Researchers of this double-blind study evaluated patients diagnosed with moderate to severe OSA for changes in morning BP. Patients were randomly assigned to receive either 2 weeks of overnight supplemental oxygen followed by 2 weeks of normal continuous positive airway pressure (CPAP) usage and then 2 weeks of overnight supplemental air (n=16) or 2 weeks of overnight supplemental air followed by 2 weeks of normal CPAP usage and then 2 weeks of overnight supplemental oxygen (n=9). BP, overnight pulse oximetry, respiratory polygraphy, sleepiness assessments, and urine and serum analysis took place throughout the study time frame.

Supplemental oxygen reduced morning systolic BP by -6.6 mm Hg (95% CI, -11.3 to 1.9; P =.008) and diastolic BP by -4.6 mm Hg (95% CI, -7.8 to -1.5; P =.006). Supplemental oxygen also significantly reduced oxygen desaturation index by -23.8/h (interquartile range, -31.0 to -16.3; P <.001) and decreased time below 90% oxygen saturation by -9.8% (interquartile range, -16.7 to -4.3; P <.001). There were no significant differences in sleepiness or urine and serum analysis, except for an increase of +3.1 mmol/L (95% CI, +1.8 to +4.4; P <.001) in mean venous base excess, between oxygen and air treatments.

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Further research is needed to understand the specific mechanics relating oxygen levels, intermittent hypoxia, and BP in OSA and the clinical benefit patients could have from overnight oxygen treatment.

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The study researchers concluded that overnight supplemental oxygen increased sleeping oxygen levels and decreased BP in patients with OSA.


Turnbull CD, Sen D, Kohler M, Petousi N, Stradling JR. Effect of supplemental oxygen on blood pressure in obstructive sleep apnea (SOX): A randomised, CPAP withdrawal trial [published online July 20, 2018]. Am J Respir Crit Care Med. doi: 10.1164/rccm.201802-0240OC