Obstructive Sleep Apnea

What is obstructive sleep apnea and what causes it?
In obstructive sleep apnea (OSA), apneas have four components.
  1. First, the airway collapses or becomes obstructed.
  2. Second, an effort is made to take a breath, but it is unsuccessful.
  3. Third, the oxygen level in the blood drops as a result of unsuccessful breathing.
  4. Finally, when the amount of oxygen reaching the brain decreases, the brain signals the body to wake up and take a breath. (This is what the bed partner hears as a silence followed by a gasp for air.)
First, it is necessary to describe a "normal breath." A normal breath of air passes through the nasal passages, behind the soft palate and uvula (part of the soft palate), then past the tongue base, through the throat muscles, and between the vocal cords into the lungs. An obstruction to the flow of air at any of these levels may lead to apnea. The following are some examples:
  • airflow can become diminished if a person has a deviated septum (the middle wall of the nose that separates the two nostrils). A septum can be deviated to one or both sides narrowing the air passages;
  • there are filters in the nose called turbinates that can obstruct airflow when they become swollen;
  • if the palate and uvula (the part of soft palate that hangs down in the back of the throat) are long or floppy, they can fall backwards and close the area through which air flows;
  • the back of the tongue can also fall backwards and obstruct breathing especially when individuals lay flat on their backs; or
  • the side walls of the throat can fall together to narrow or close the airway. To break it down even further:
  • the muscles of breathing work to expand the chest and lower the diaphragm to degenerate a negative pressure between the airways of the lungs and outside;
  • this negative pressure literally sucks air into the lungs;
  • the nasal passages, palate, tongue, and pharyngeal tissues can all contribute to narrowing of the airway;
  • if during an attempt to breathe the airway collapses or is obstructed the tissues of the airway are sucked together by the negative pressure;
  • the harder the chest tries to pull air in the greater the negative pressure and the more the tissues of the airway are sealed together; and
  • finally, when the oxygen in the blood stream decreases the person wakes up or the level of sleep becomes more shallow in order to more consciously take a breath.
People with obstructive sleep apnea have an airway that is more narrow than normal, usually at the base of the tongue and palate. When lying flat, the palate is above the air passage. When the pharyngeal muscles (muscles of the pharynx or throat ) relax the palate can fall backwards and this can obstruct the airway.
  • How common is obstructive sleep apnea?

    Obstructive sleep apnea (OSA) is estimated to affect about 4% of men and 2% of women. In one study of people over 18 years of age, obstructive sleep apnea was estimated to develop in 1.5 % of people per year over the 5 year study. It is probably more common than either of these numbers because the population is becoming more obese, and obesity worsens obstructive sleep apnea. More shocking is the estimate that only 10% of people with obstructive sleep apnea are currently receiving treatment.

    Some groups are more likely to develop obstructive sleep apnea.

    Men are more likely to have obstructive sleep apnea than women before age 50. After age 50, the risk is the same in men and women. Among obese patients, 70% have obstructive sleep apnea. Obstructive sleep apnea worsens in severity and prevalence with increasing obesity. Among patients with heart disease 30%-50% have obstructive sleep apnea, and among patients with strokes, 60% have obstructive sleep apnea.
  • What are obstructive sleep apnea symptoms?

    Obstructive sleep apnea has many well-studied consequences. First, as you would expect, it disrupts sleep. Patients with disrupted sleep cannot concentrate, think, or remember as well during the day. This has been shown to cause more accidents in the work place and while driving. Thus, people with obstructive sleep apnea have a three-fold greater risk of a car accident than the general population.

    Daytime sleepiness, fatigue, frequent naps, headaches, irritability, insomnia, and poor memory and attention are some of the other common symptoms associated with sleep apnea as a result of insufficient sleep.

    It is important to note that the bed partner of individuals with sleep apnea may also suffer from poor night time sleep and can have some of the same symptoms.
  • What are some of the complications of sleep apnea?

    Obstructive sleep apnea (OSA) may be a risk factor for the development of other medical conditions. High blood pressure (hypertension), heart failure, heart rhythm disturbances, atherosclerotic heart disease, pulmonary hypertension, insulin resistance, and even death are some of the known complications of untreated obstructive sleep apnea.
  • High blood pressure

    Sleep apnea causes high blood pressure and heart problems. Cessation of breathing frequently during the night (every 1-4 minutes) can cause increased stress on the heart. As the oxygen saturation in the blood decreases and the apnea continues, the sympathetic nervous system (responsible for the "fight or flight" response of the body) is activated.
  • Heart complications

    The risk for congestive heart failure increases by 2.3 times and the risk of stroke by 1.5 times with obstructive sleep apnea. Obstructive sleep apnea can complicate the treatment of atrial fibrillation. Atrial fibrillation is a condition in which the upper part of the heart (atrium) is beating out of coordination with the lower part (ventricle). The treatment is to cardiovert the heart (resetting the atrium and allowing it to synchronize with the ventricle). After cardioversion, 50% of patients have a recurrence of atrial fibrillation, but patients with obstructive sleep apnea have an 80% recurrence.

    Finally, obstructive sleep apnea can increase the risk of sudden death. Sudden death can kill not only the patient but also their loved ones, for example, if they are driving a car when the death occurs.

    Sleep Apnea is a very serious matter that needs to be addressed. As much as possible, if you find that you might actually have this condition, it is essential to seek help and avail the proper treatments.
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