Sleep Apnea and Cardiovascular Disease, Research Paper Example

The Causes of Sleep Apnea

As a medical disorder, sleep apnea affects the ability to breath normally during sleep which interrupts the sleep cycle. The term “apnea” refers to breathing pauses that can last up to ten seconds, meaning that the affected person breathes normally for a short period of time while asleep but then lapses into periods of non-breathing. Physiologically, the muscles located at the back of the throat or trachea “fail to keep airways open, despite efforts to breath” normally, known as obstructive sleep apnea. There is also central sleep apnea in which the “brain fails to properly control breathing during sleep.” However, the first type of apnea is much more common and occurs in an estimated 18 million American adults (Sleep Apnea and Sleep, 2013).

As to the basic physiological causes, obstructive sleep apnea (OSA) occurs when the muscles of the trachea prevents air from entering the lungs. This condition is more common in men and those who are overweight or obese, especially if they tend to sleep on their backs which allows the muscles to collapse and block the air passage. There are three phases related to obstructive sleep apnea–1), the airway or trachea becomes blocked by anterior soft tissue when it relaxes and then closes up which causes snoring; 2), the airway collapses, preventing “airflow which either stops totally or is significantly diminished for at least ten seconds and up to two minutes; and 3), the affected person wakes up briefly, gasping for air, then goes back to sleep which causes the cycle to repeat itself (Sleep Apnea, 2014).

With central sleep apnea (CSP), the brain “fails to send normal signals to the chest to breathe properly while asleep. This condition is almost always caused by certain neurological diseases and often some form of heart disease or by medications like morphine. There is also mixed sleep apnea or a combination OSA and CSP (Sleep Apnea, 2014).

Sleep Apnea and the Cardiovascular System

Out of the three types of apnea, obstructive sleep apnea and central sleep apnea have been the focus of many studies on sleep disorders, thus making them well-documented in relation to their negative effects on the human cardiovascular system, composed of the heart, blood vessels, and veins. It should be pointed out that obstructive sleep apnea generally occurs in individuals who already have some kind of a heart condition which can become worse as a result of OSA which can also be found in individuals “with “hypertension and in those with other cardiovascular disorders, including coronary artery disease, stroke, and atrial fibrillation” (Somers, White, Abraham, Costa, et al., 2008). Conversely, central sleep apnea has been identified through research and clinical studies as being the consequence of a pre-existing cardiovascular disorder, meaning that a pre-existing heart aliment can lead to central sleep apnea (Somers, White, Abraham, Costa, et al., 2008).

Somers, White, Abraham, Costa, et al. note that obstructive sleep apnea does hold the potential to cause and/or contribute to progressive heart disease and heart failure, such as having a heart attack or myocardial infarction while asleep and gasping for air. This can occur through four specific ways–1), by “eliciting greater sympathetic outflow to the heart, kidney, and resistance vessels” while wide awake and during sleep; 2), by increasing the resistance against which the left ventricle of the heart must eject a volume of blood during contraction; 3), by inducing hypoxia or causing cells to lose oxygen; and 4), by increasing the risk of myocardial infarction (Somers, White, Abraham, Costa, et al., 2008), due to the lack of sleep and tension upon the vessels and the heart itself.

Complications

The complications that can result from obstructive sleep apnea and central sleep apnea are numerous with some posing the possibility of premature death. A major concern is that many individuals do not know that they suffer from obstructive or central sleep apnea, especially if they live alone or have different sleeping arrangements from their spouses or partners. Several common complications includes feeling tired and worn out upon waking up, feeling sleepy during the daytime, and a general loss of vitality (Sleep Apnea, 2014). Obviously, feeling sleepy during the day makes it rather difficult to focus at work and to concentrate on the task at hand. One of the most common and dangerous complications is daytime drowsiness related to driving a car or operating heavy equipment. Statistically, individuals that suffer from one of the three types of sleep apnea are more often involved in traffic accidents and fatalities, due to falling asleep behind the wheel of a car (Sleep Apnea, 2014).

Medically speaking, a number of serious complications can result from obstructive sleep apnea and central sleep apnea, particularly if it remains undiagnosed by a physician. First, oxygen levels in the blood or the ability of oxygen to combine chemically with hemoglobin and oxygen tension or the force through which oxygen molecules are physically dissolved in the blood are severely interrupted; second, an increase in heart rate occurs in relation to the contractions of the cardiac ventricles; third, an elevation in blood pressure that can result in hypertension which affects the heart and the kidneys; fourth, an impairment of glucose tolerance and insulin resistance which can lead to Type 2 diabetes; and fifth, an increase in strokes, due to tension placed upon blood vessels in the brain for lack of oxygen (Sleep Apnea, 2014).

Prognosis

In relation to the possible or probable outcomes related to suffering from obstructive and/or central sleep apnea, the most important prognosis is heart failure, especially if the individual suffers from OSA. As discussed by Marin, Santiago, and Carrizo, the two main outcomes or consequences of obstructed sleep apnea are 1), daytime sleepiness (also a complication), and 2), cardiovascular sequelae or abnormal conditions concerning the heart which are “responsible for potential increased morbidity and mortality associated” with OSA (2007, p. 593).

For the most part, heart failure or cardiac arrest which can result from obstructive sleep apnea is due to the individual being overweight or obese. Marin, Santiago, and Carrizo note that obesity is closely linked to reductions in “chest wall compliance (i.e., the ability of the muscles in the chest to expand when breathing), decreased lung volumes, and increased upper airway resistance,” especially if the individual has excess weight in the region of the neck which “promotes the collapse of the upper airway during sleep” (2007, p. 595).

The combination of obesity and obstructed sleep apnea creates several other pathophysiological avenues that may lead to an increased risk for developing vascular diseases for those associated with blood vessels. Technically, obesity and OSA significantly reduces insulin sensitivity which enhances “free fatty acid turnover,” creates “hypercoagulable states” or the tendency of the blood to coagulate more rapidly than normal, and promotes systemic inflammation. In the end, all of these conditional outcomes “contribute to the development and progression of atherosclerosis,” an arterial disease often referred to as hardening of the arteries via the buildup of cholesterol and other artery-clogging materials (Marin, Santiago, and Carrizo, 2007, p. 595). Thus, the overall prognosis for OSA and other apneas is premature death, if and when it remains undiagnosed or unrecognized by the individual.

Treatment Options

Fortunately, there are currently a number of treatment options for obstructive and central sleep apnea. There are basically three specific options for those suffering from a form of sleep apnea–continuous positive airway pressure (CPAP), various oral appliances or devices, and surgery. The first option is used as standard treatment for individuals with moderate to severe OSA and involves a “steady stream of pressurized air through a mask” that is worn while sleeping which helps to keep airways open and allows for normal breathing patterns. The second option is used by individuals with mild to moderate OSA and involves a device that keeps the airway open and unobstructed by “repositioning or stabilizing the lower jaw, tongue, soft palate or uvula” (Obstructive Sleep Apnea, 2008).

The third option is only used when options one and two prove to be unsuccessful. Like most types of surgery, this option is “most effective when there is an obvious anatomic deformity that can be corrected to alleviate” breathing difficulties while sleeping. One way is to reduce or remove tissue from the soft palate or the removal of the tonsils and adenoids. In extreme cases, it may be necessary to adjust an individual’s craniofacial bone structure which has been shown to contribute to OSA (Obstructive Sleep Apnea, 2008). However, opting for surgery to correct OSA has been demonstrated through case studies to be only about 50% effective (Sleep Apnea, 2014). In cases where the apnea is mild, an individual may opt to try several other approaches, such as behavioral changes like losing weight and position therapy which involves experimenting with various sleeping positions (Obstructive Sleep Apnea, 2008). Thus, although sleep apnea is a common medical condition and can be effectively treated, it should be mentioned that between eighty and ninety percent of adults with OSA or central sleep apnea are undiagnosed (Obstructive Sleep Apnea, 2008). What this means is that millions of American adults are at risk of heart disease and premature death, all because of being unable to breath properly while sleeping.

References

Marin, J.M., Santiago, J., and Carrizo, M.D. (2007). Mortality in obstructive sleep apnea. Sleep Medicine Clinics 2, 593-601. Retrieved from http://www.rtjournalonline.com/osa.pdf

Obstructive sleep apnea. (2008). American Academy of Sleep Medicine. Retrieved from http://www.aasmnet.org/resources/factsheets/sleepapnea.pdf

Sleep apnea. (2014). Retrieved from http://bodyandhealth.canada.com/channel_condition_info_details.asp?disease_id=201&channel_id=1055&relation_id=17519800

Sleep apnea and sleep. (2013). National Sleep Foundation. Retrieved from http://sleepfoundation.org/sleep-disorders-problems/obstructive-sleep-apnea-and-sleep

Somers, V., White, P.D., Abraham, W.T., Costa, F., et al. (2008). Sleep apnea and cardiovascular disease. Journal of the American College of Cardiology (52) 8, 686-717. Retrieved from http://content.onlinejacc.org/article.aspx?articleid=1139136