By C. Nathan Okechukwu, M.D., Chairman, Department of Medicine
Per the Centers for Disease Control and Prevention (CDC), one in three Americans 20 years of age and older suffers from high blood pressure (HBP) or hypertension1. Despite the increase in medical knowledge and public awareness over the years, the blood pressure control rate remains suboptimal, especially in people who have serious co-morbid conditions such as chronic kidney disease. Less than 50% of Americans have their hypertension under control; this is much worse in other countries.
Can poor sleep be worsening these conditions? A recent study from the Journal of the American Medical Association found treatment for obstructive sleep apnea (OSA) to improve blood pressure in patients with resistant hypertension.
Understanding HBP and Hypertension
It is well-recognized that HBP is a powerful risk factor for heart attacks, stroke and kidney disease. When you have your blood pressure taken, the results are given to you as a ratio such as 120/80 millimeters of mercury (mm Hg). The systolic pressure (the top number) measures the pressure in the arteries when the heart beats. The diastolic pressure (the bottom number) measures the pressure in the arteries when the heart is relaxing i.e., in between beats. Each increment of 20 mmHg in systolic BP or 10 mmHg increase in diastolic BP doubles the risk of cardiovascular disease.
Management of hypertension involves lifestyle modifications such as weight loss, healthy diet (low in sodium, rich in fruits and vegetables, including low-fat dairy products and reduced content of saturated and total fats) and regular exercise. When these non-pharmacological strategies fail to control the blood pressure, medications are added.
Resistant hypertension is defined as blood pressure that remains above target despite concurrent use of three or more antihypertensive agents of different classes. The American Heart Association (AHA) guidelines also include into this category, patients who are well controlled but who need four or more medications. Data from the National Health and Nutrition Examination Survey (NHANES) puts the prevalence of resistant hypertension in adults in the United States at about 9%.2 Individuals with resistant hypertension have an even higher risk for cardiovascular events when compared to those with non-resistant hypertension.
Understanding Obstructive Sleep Apnea
OSA is a common and serious disorder in which airways collapse and become narrowed or blocked during sleep, resulting in breathing pauses or shallow breaths. This can occur during a few episodes or up to hundreds of times a night. As a result, not enough air reaches the lungs and not enough oxygen gets into the blood. A common symptom of OSA is loud snoring caused as the air tries to squeeze past the blocked air passage.
Continuous Positive Airway Pressure (CPAP) is a technique used to treat OSA. The CPAP machine consists of a motor that pushes air through a tube connected to a mask that fits over the patient’s mouth and/or nose. The pressure generated by the air helps prevent the airway from closing, and thus allows continuous sleep.
Can Better Sleep Improve Blood Pressure?
In a recent study published in the December 11, 2013 issue of the Journal of the American Medical Association,4 researchers from Spain studied 194 patients with resistant hypertension and OSA. They randomly assigned some of them (98 patients) to treatment with CPAP and usual blood pressure medications, and the rest (96 patients) to treatment with medications only. The aim of the study was to evaluate the change in blood pressure after 12 weeks. In this study patients were taking an average of three or more medications to lower their blood pressure. The researchers found that the study subjects treated with CPAP for 12 weeks had a decrease in their 24 hour average blood pressure by 3.1 mm Hg more than those not receiving CPAP. In addition, those treated with CPAP had a 3.2 mm Hg greater decrease in 24-hour average diastolic blood pressure (the bottom number in blood pressure readings) and an improvement in their overall nighttime blood pressure.
Although this study showed a benefit from CPAP in controlling blood pressure it is important to note that this study was for 12 weeks and so it is hard to say at this point whether these improvements in blood pressure can be sustained in the long term.
Additionally, there was no statistically significant difference in the systolic pressure (the top number in blood pressure readings) between the two treatment groups.
Patients with difficult-to-control high blood pressure should consider undergoing a sleep study to rule out obstructive sleep apnea. Talk to your primary care physician and healthcare providers to find out if you could be at risk.
- Persell SD. Prevalence of resistant hypertension in the United States, 2003-2008. Hypertension. 2011; 57:1076–1080.
- Martínez-García, Miguel-Angel et al Effect of CPAP on Blood Pressure in Patients With Obstructive Sleep Apnea and Resistant Hypertension. : The HIPARCO Randomized Clinical Trial. JAMA. 2013;310(22):2407-2415