![]() ![]() “That sympathetic vasoconstriction gives you intra-arterial blood pressures as high as 240/130 mm Hg, which decreased with continuous positive airway pressure (CPAP) therapy. You do not have the hyperventilation and so sympathetic activation becomes excessive. Now hyperventilation has a buffering or protective effect on the sympathetic nervous system, keeping the sympathetic nervous system down, but in obstructive apnea, you’ve got low oxygen and high CO 2, but you are not breathing. Both will cause hyperventilation and sympathetic activation. The high carbon dioxide stimulates central chemoreceptors in the brain stem. “The low oxygen stimulates peripheral chemoreceptors in the internal carotid artery. “Why would sleep apnea be linked to hypertension? When you develop obstructive apnea, you stop breathing and your oxygen levels fall, and your carbon dioxide levels go up,” Somers said during the presentation. Somers also addressed whether OSA was associated with hypertension, and therefore, whether treatment of sleep apnea can improve CV outcomes.Īccording to the presentation, findings from the Wisconsin Sleep Cohort study demonstrated that individuals with worse OSA were more likely to experience incidence of new-onset hypertension. ![]() “Having said that, there is a flip side to this argument, and that is while an absence of a blood pressure fall during sleep is bad, an excessive nighttime blood pressure fall can also be deleterious.”Īccording to a Japanese analysis, individuals whose BP drops too far during sleep experienced multiple silent lacunar infarctions as assessed by a CT scan. “The message here is there is something special about blood pressure during sleep that seems to have a more-than-expected impact on cardiovascular outcomes in people with hypertension,” Somers said during the presentation. According to the presentation, researchers observed that patients, with or without hypertension, who experienced an appropriate drop in BP during sleep had significantly lower left ventricular mass index compared with patients with hypertension and no nocturnal drop in BP. It’s when the system goes awry that we have a problem.”Ī study published in Circulation evaluated BP fluctuations during sleep among patients with and without hypertension. We expect these to happen and these are important to good homeostasis of brain function and also of the cardiovascular system. “On the other hand, during rapid eye movement sleep, a time when dreams are most likely to occur, what you see are very marked increases in sympathetic drive with abrupt fluctuations in blood pressure. ![]() “It is very clear that as you get into deeper non-rapid eye movement sleep, your sympathetic activity goes down, your blood pressure falls and your heart rate slows,” Somers said during the presentation. Somers, MD, PhD, Alice Sheets Marriott Professor and director of the the cardiovascular and sleep facilities at the Mayo Clinic’s Center for Clinical and Translational Science in Rochester, Minnesota, discussed how hypertension, obstructive sleep apnea (OSA), treatment with continuous positive airway pressure (CPAP) and sleep duration could all impact a patient’s risk for CV events. ![]()
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