Obstructive Sleep Apnea, Cardiovascular Consequences, and Treatment Options
- By:Bharat Bista
Obstructive Sleep Apnea affects approximately 20 million people in the U.S. alone, and millions more are affected worldwide. Over the last 10 years, significant research has been performed and now there is overwhelming evidence of the connection between Obstructive Sleep Apnea (OSA) and cardiovascular disease. Specifically, people affected by sleep apnea are at increased risk for hypertension (also known as high blood pressure), coronary artery disease (AKA atherosclerosis), heart attacks, strokes, cardiac arrhythmias, heart failure, diabetes, and even death.
This scary list of adverse health outcomes demonstrates the significance of diagnosing sleep apnea in a timely manner, in order to initiate treatment t. This last comment is actually the point --- fortunately, sleep apnea is a treatable condition. And you might be surprised that there are different options for treatment. With the right guidance from qualified experts, successful treatment is readily attainable.
First of all, we must dispel any myths, which prevent many people affected with sleep apnea from seeking the appropriate medical attention. The biggest myth is that only overweight or obese people get OSA. That is simply not true. In fact, many people who are considered to be at their ideal body weight, based on BMI (Body-Mass Index), are in fact diagnosed with OSA or Upper Airway Resistance Syndrome (UARS). UARS is a form of sleep-related breathing disorder in which a person has frequent arousals from sleep due to respiratory airway collapse or obstruction. Often, the events are not as obvious as seen in OSA, and in many cases, a person affected by UARS may not even snore. However, people with UARS may complain of unrefreshing sleep, frequent nocturnal awakenings, or excessive daytime sleepiness or fatigue. UARS, like OSA, is a treatable medical condition.
So how does one get sleep apnea? Well, most people who have sleep apnea are predisposed very early in life. It is actually the size and shape of the jaw and upper airway that determines whether a person will develop OSA. A narrow jaw and upper airway (i.e., oral cavity and throat) results in less space for air to flow during breathing. When a person sleeps, the soft tissues and muscles of the upper airway relax and collapse, leading to increased airflow resistance and airway obstruction. The airway obstruction is what causes OSA.
OSA is simply a repetitive, cyclical pattern in which a person stops breathing or nearly stops breathing for periods of longer than 10 seconds each time. The following is a description of what happens during an episode. As a person sleeps, the upper airway and jaw relax, resulting in collapse of the upper airway (i.e., the back of the throat). The lower jaw often relaxes and drops back a few millimeters when we sleep. Since the tongue base is attached to the lower jaw, the tongue will also drop back a few millimeters further during sleep. This combination of events leads to a very narrow passageway for air to flow through the back of the throat during sleep. Occasionally, the upper airway is so collapsed that little or no air can pass. These episodes are called apneas (complete obstruction with no air movement) or hypopneas (partial obstruction with minimal air movement). When an apnea or hypopnea occurs, it lasts for a period of 10 seconds or more. In some cases, the episodes can last for over a minute! During this time, the blood oxygen saturation starts to drop, because no fresh air or oxygen is being delivered to the lungs. As the blood oxygen saturation drops, the body goes into a fight-or-flight response, resulting in increased heart rate and elevation of blood pressure. In essence, the heart is beating faster in an attempt to bring in more fresh blood and oxygen from the lungs. This sequence of events continues until, ultimately, a person has an arousal from sleep, resulting in a change in body position, a deep breath or gasp, or a brief awakening from sleep for 2-3 seconds (which most people don't recall). This cycle of events may then repeat itself several times per hour or even hundreds of times per night, depending on the severity of the case. These cyclical arousals not only disrupt and fragment one's sleep by resulting in a very shallow and unrefreshing sleep, but they also cause repetitive stress on the cardiovascular system with the elevations in heart rate and blood pressure. This repetitive stress causes the heart to work harder. Night after night, this chronic extra stress on the heart is what many scientists believe leads to the long-term adverse cardiovascular events (such as heart attacks, strokes and cardiac arrhythmias) and the impairment of blood pressure and blood sugar control.
Fortunately, as stated before, sleep apnea is a treatable condition. Further, effective treatment of OSA results in reductions in daytime blood pressure. Effective treatment not only reduces the risk of cardiac arrhythmias such as atrial fibrillation, but it can also reduce the risk of recurrent episodes of arrhythmias. The incidence of stroke and death is also significantly less in people treated for OSA. As compared to those who remain untreated for OSA, people who are treated have lower levels of blood glucose. Studies have highlighted how closely linked OSA and diabetes are. Therefore, people with OSA and diabetes who undergo treatment for OSA have much better control of their diabetes. Finally, treatment of OSA improves sleep quality and duration, associated with deeper and more refreshing sleep. This improvement in sleep carries on into the daytime, resulting in reduced daytime sleepiness and increased energy levels.