Obstructive Sleep Apnea

What is obstructive sleep apnea and what causes it?

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 relax, the palate can fall backwards. This can obstruct the airway.

 

The genioglossus muscle is located where the base of the tongue attaches to the jawbone in front. Most people have enough space behind the tongue to take a breath without needing to pull the tongue forward. However, when obstructive sleep apnea patients are awake, this muscle needs to be active to pull the base of the tongue forward to open the airway. During sleep most muscles, including the genioglossus, relax. During one particular stage of sleep, the stage of rapid eye movement (REM), the muscles completely relax. Relaxation of the genioglossus muscle during sleep allows the base of the tongue to fall backwards, and the airway closes.

 

Patients with obstructive sleep apnea often don’t report waking up during the night with each episode of apnea. Frequently, during the apnea, the brain only awakens from a deep sleep (stages 3, 4, or REM) to a shallow level of sleep. The genioglossus muscle then contracts and pulls the tongue forward so that a breath can be taken. The patient may remain asleep, but the deep sleep that is important to be fully rested the following day is disrupted.

 

An apnea event has four components.

1. First, the airway collapses.

2. Second, an effort is made to take a breath, but is unsuccessful.

3. Third, the oxygen level in the blood drops.

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 palate, uvula, and tongue base, through the throat muscles, and between the vocal cords into the lungs.

 

Airflow can become diminished if a person has a deviated septum (the middle wall of the nose). 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 thing that hangs in the back of your throat) are long or floppy, they can fall backwards and close the area for breathing. The back of the tongue can also fall backwards and obstruct breathing especially when laying flat on your back. Finally the side walls of the throat can fall together to narrow or close the airway.

 

Explained further:

• The muscles of breathing work to expand the chest and lower the diaphragm to draw in a breath of air.

• The 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; 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.

• Finally, when the oxygen in the blood stream decreases, the person wakes up or the level of sleep becomes more shallow.

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 cardiac patients, 30–50% have obstructive sleep apnea, and among patients with strokes, 60% have obstructive sleep apnea.

• A recent study estimated that 14% of NFL football players and 34% of NFL linemen 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 (there aren’t many diseases that can kill the patient AND the people in the car next to him or her!).

High blood pressure

Sleep apnea causes high blood pressure and heart problems. Stopping 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 system (“Fight or Flight” response) is activated. This sends nerve signals and adrenaline signals to the blood vessels to constrict and to the heart to work harder. When the vessels constrict, more blood is sent to the brain and muscles. However, this increases the blood pressure, which requires the heart to work harder to pump blood through the smaller vessels. That, combined with the signal for the heart to work harder and the lower available oxygen in the blood, causes increased stress on the heart throughout the night. During sleep is the time when the heart usually has less work to do and can “rest.”

 

Among patients with obstructive sleep apnea that do not have high blood pressure, 45% will develop high blood pressure within 4 years. If you look at patients who have hard-to-control blood pressure, that is, taking more than one medicine for control, 80% have obstructive sleep apnea. When the obstructive sleep apnea is treated, the high blood pressure comes down.

 

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 atrial fibrillation treatment. 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, which resets the atrium and allows 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.

Obstructive sleep apnea has many consequences, some of which can kill patient and their loved ones. Again, it is estimated that only 10% of people with obstructive sleep apnea are being treated. Just treating the obstructive sleep apnea would improve many other areas of their lives.

 

If you think you or a loved one may have symptoms of a sleep disorder, please contact us today. Help is available!