Obstructive sleep apnea (OSA) is one of the most treatable causes of high blood pressure, yet it is so often ignored and goes untreated with persons preferring to take multiple medications trying to manage their hypertension without addressing many of the major contributing factors.
We all know that discipline is hard. Getting into a routine of exercise and healthy eating takes making decisions for health and wellness on a daily basis. Treating sleep apnea may need to be one of those decisions.
What is obstructive sleep apnea?
By definition, it is having five or more episodes in any given hour where respirations are slowed by more than 30% for 10 seconds or longer. Mild sleep apnea would be considered having 5-15 of these events an hour; moderate sleep apnea is 16-30 events per hour; and severe apnea is having more than 30 events an hour.
These numbers give us a frame of reference called the apnea-hypopnea index, or AHI. Generally, we are familiar with the apneas as causing restless sleeping, snoring, morning and daytime tiredness, and behavioral issues such as decreased attention in both children and adults. But many people do not realize that obstructive sleep apnea also can contribute to and cause high blood pressure.
High blood pressure is considered when the systolic pressure is greater than 140 mgHg and the diastolic pressure greater than 85 mgHg. Typically, treatment of sleep apnea will involve, for milder forms, lowering salt in the diet, weight loss, exercise and medications.
How does sleep apnea increase blood pressure?
When an apnea occurs, think of it like holding your breath. You build up incredible stress on the inside of your blood vessels much like the stress you feel on a whole body level as you continue the act of not breathing while awake.
As the periods of involuntary breath-holding repeat during the night, the pressure buildup puts strain on the innermost lining of the blood vessels, or intima, causing it to become thicker in response to the pressure, much like the pressure of weight lifting causes muscles to become larger.
Unfortunately, a thicker, more muscular intima means that the lumen or blood flow passage becomes smaller. This narrowing of the blood vessel flow is made worse by the effects of the oxygen breakdown products that occur because of lower oxygen and higher carbon dioxide concentration when there is restriction in airflow.
Blood flow then goes from meandering down a wide path to being pushed through a straw, thereby elevating the blood pressure. Therefore, if we can reduce the number of times there is a reduction in airflow both day and night, the “stress” that the inner lining of the blood vessels see is reduced, leading to a thinner endothelium or intima. More room for blood to flow leads to lower blood pressure.
There have been studies, in particular, using canine models that show development of thickening of the intima levels of blood vessels and subsequent development of hypertension when sleep apnea is artificially created in the animal. With reversal of the apnea, over time the intima lining thins and blood flow increases, reversing the hypertension.
Untreated sleep apnea also causes the blood pressure in general to be higher both day and night. Generally during the night the blood pressure naturally lowers by 10-20%, a phenomenon called “blood pressure dipping.” In patients with sleep apnea, especially severe sleep apnea, the blood pressure dipping is much less and may not occur at all. Therefore the body is seeing a much higher blood pressure for longer periods of time, which can cause more damage to organs such as the heart and kidneys.
The American Academy of Cardiology recommends that persons with hypertension needing two or more medications to control be screened for obstructive sleep apnea. So if you are on two or more medications for your blood pressure, have a discussion with your doctor about getting a sleep study. Continue to minimize the salt in your diet, eat a balanced diet, and exercise, but now add treatment of your sleep apnea to this regimen.
Sleep apnea is most often treated with use of positive airway pressure devices, oral appliance therapy, positional therapy and surgery. Your sleep physician will perform a complete head, neck and lung exam and help you determine which option is best for you.
Dr. Inell Rosario is a board-certified ENT and sleep physician practicing at Andros ENT & Sleep Center in Inver Grove Heights, Minnesota. She has many times been recognized as a Top Doctor and Best Doctor in various Minnesota magazines and can be reached at [email protected] or 651-888-7800.