Blood pressure regulation and sleep apnea: A review

Hypertension and sleep apnea are common diseases and appear associated in epidemiologic studies. Therapy for obstructive sleep apnea (OSA) syndrome reduces blood pressure. Thus, sleep apnea is a treatable factor in the patient with hypertension. Several investigations suggest causal relationships with sleep apnea leading to hypertension; however, multiple factors may play a role. First, patients with OSA may develop excess sympathetic activity leading to chronic vasoconstriction and daytime hypertension. Second, OSA is often associated with hyperinsulinemia and may be another syndrome associated with insulin resistance. Third, hypertension in the patient with OSA is among the low renin forms; unlike most forms of low renin essential hypertension, low renin in sleep apnea is associated with low aldosterone and high atrial natriuretic peptide (ANP) levels. Therefore, an expanded central compartment blood volume may be responsible for the blood pressure elevation. Central neural mechanisms may play a role in the pathogenesis of both sleep apnea and hypertension. Because of this association between sleep apnea and hypertension, questions concerning daytime somnolence and observed apneas should become a routine part of the work-up and therapeutic strategy for management of hypertension.