Hypertension and Sleep Disordered Breathing

Youngsook Yoon, M.D.
Department of Medicine
Division of Pulmonary and Critical Care Medicine

Medical University of Ohio
3120 Glendale Avenue
Toledo, OH 43614-5809


Systemic hypertension has been reported in 50 to 95% of patients with sleep-disordered breathing (SDB) and as many as 40% of the patients with hypertension have been reported to have occult SDB. Determining cause and effect in that relationship has been very difficult to demonstrate. Since the 1970s, after several surgical case reports raised the possibility of an association between systemic hypertension and SDB, many studies were conducted without significant evidence to prove the relationship. Dart et al. conducted a critical review of the literature from 1972 through 2000 to clarify this relationship and several conclusions were drawn.
1. Patients with systemic hypertension have an increased incidence of sleep apnea, although the comorbidities, such as obesity, probably contribute to the hypertension.
2. Increased catecholamines associated with sleep apnea may contribute to daytime systemic hypertension.
3. Obese patients with daytime hypoxemia and hypercapnia will improve with nasal CPAP or tracheostomy.
4. The incidence of ischemic heart disease is threefold higher among patients with SDB than in the general population.
5. Sleep apnea syndrome should be excluded in patients with idiopathic dilated cardiomyopathy and morphologic findings compatible with OSA.
6. In patients with documented coronary artery disease, the increased catecholamine response to the sleep apnea may increase the risk of arrhythmias and ischemic events, including angina, myocardial infarction, and sudden death.
Therefore:
∑ Any causal association between systemic hypertension and SDB is inconsistent and weak
∑ The association is likely to be strongest in the patient with more severe SDB
∑ Cofactors may exist in patients with SDB to account for the presence of systemic hypertension, i.e.,
∑ body mass; alcohol consumption; family history of hypertension
∑ Morbidity of systemic hypertension and SDB are significant when they occur separately and probably more significant when they occur together
Many patients with systemic hypertension, especially those with significant obesity, will have SDB.
SDB is associated with increased ventilatory and sympathetic response to hypoxia. Hypertension post apneic episodes are often associated with increased incidence of cardiac disorder with patients with sleep apnea. Although it is unclear, hypoxia associated with SDB may increase catecholamine release contributing to systemic hypertension.
During periods of hypoxia and apnea termination there is an increased catecholamine release of norepinephrine with increased left ventricular afterload, decreased stroke volume, and increased pulmonary capillary wedge pressure. Myocardial contractility will be impaired resulting in decreased ventricular compliance, diastolic dysfunction and finally, reduced cardiac output. Persistent elevation of systemic blood pressure may eventually result in left ventricular hypertrophy. Therefore, limited echocardiography may have a role in the evaluation of the cardiovascular pathology associated with SDB and systemic hypertension to help assess the left ventricular mass and the potential for increased morbidity and mortality from cardiovascular disease.
How to approach a patient with SDB and systemic hypertension:
1. What is the role of SDB in the development of systemic hypertension?
SDB could potentially cause hypertension. Patients with systemic hypertension complain of insomnia, fatigue, or both. SDB may be an ongoing factor in the anxiety and anxiety can affect sleep patients with systemic hypertension. Also, side effects of the antihypertensive medications and over-treatment can contribute to the fatigue. Central- acting drugs, b- blockers, are more often associated with fatigue and impaired sleep.
2. What hype of patients with hypertension should be evaluated for SDB?
Investigation for SDB should be considered in patients with symptoms (headaches, fatigue) or signs (body habitus) of SDB. Screening for SDB in patients with resistant hypertension, even without clear signs or symptoms of SDB, is a developing practice. Evaluation for SDB might be considered if a patient has unexplained or worse cardiac disease than expected, based on the level of blood pressure. Perhaps due to the significant morbidity of SDB, the possibility of SDB should be considered in any patient with systemic hypertension.
3. How should hypertension be managed in a patient with established SDB?
In patients with established SDB, development of hypertension and cardiovascular disease should be monitored closely. Lifestyle changes should be encouraged, especially weight loss, exercise, sodium restriction, etc. Decision regarding antihypertensive medications of choice should be based on presence or absence of comorbidities.
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