Monday, April 4, 2011

Obstructive Sleep Apnea 101: The Main Facts

I want to start off by saying that I would like you to really look at my title again. It says Obstructive Sleep Apnea. This is very important since there are not only obstructive apneas, but central apneas, mixed apneas, and a slew of other respiratory events at night. The pictures below are reflecting some degree of obstruction. I thought they were well done, so I scanned them in.

You can see in the first one that normal breathing while on the back (when gravity is most likely to pull your tongue and uvula and soft palate into the way) involves breathing some through your mouth and some through your nose. Some people are obligate nose breathers and some are obligate mouth breathers.

This picture below shows breathing obstruction present in OSA (Obstructive Sleep Apnea). Now, obstruction of your mouth by itself is okay; most of us naturally close our mouths and breath through our nose only at night anyway. And obstruction of your nose is okay too, such as when we have a cold. Obstruction of the nose is only a problem with many people when it's hard for them to switch to mouth breathing. But below is complete obstruction the final common pathway, where the nose and throat join up to head down the trachea to supply the brain, heart... body with oxygen and get rid of carbon dioxide.

This is a simpler version of the same thing. Here we see partial obstruction, involving the back of the throat, but air is still getting by through the the nose.

In this drawing, again, as above, we have complete obstruction of the entire airway... the patient is in essence, being choked. 
That really is the accurate way of describing what is happening. In real life, while conscious, people wouldn't choke themselves or allow themselves to be choked as long as they do while they're asleep if they have obstructive sleep apnea. But, since you're asleep, and have to sleep at least a little to live, and eventually, you will literally knock yourself out and be choked, unable to defend yourself against the demands of your own body.

Prevalence of Obstructive Sleep Apnea (OSA) How common is it?
- 42 Million American adults
- 1 in 5 have mild OSA
- 1 in 15 have moderate to severe OSA
- 25% of men the middle-aged work force suffer from OSA
- 9% of middle-aged women suffer from OSA
- About 20 million have asthma in America, and 23 million have diabetes (as of 2007) which makes OSA almost as common as both all asthmatics and diabetics combined in America
- 75% of severe cases remain undiagnosed as of 2008

Are you one of these folks?

Untreated sleep apnea has many common clinical signs & subjective symptoms:

- Lack of energy
- Waking feeling unrefreshed in the morning
- Frequent nocturnal urination
- Excessive daytime sleepiness
- Gastroesophageal reflux (GERD)
- Morning headaches
- Nighttime gasping, choking, coughing
- Snoring
- Decreased concentration
- Accidental naps during the day

Now let's talk about the link between sleep apnea and other medical comorbidities. And, actually, they should be more concerning because of the long term relationship between these other comorbidities and their potential dire consequences.

- Sleep apnea is an independent risk factor for hypertension, separate from obesity, family history, diet...
- 30-80% of patients with hypertension have sleep apnea
- 43% of patients with mild OSA and 49% of patients with severe OSA have hypertension
- Patients with hypertension resistant to medications are likely to have some improvements with treatment of comorbid sleep apnea

- Half of patients with Type 2 Diabetes have sleep apnea
- OSA may actually turn out to be a cause for some people's diabetes
- 30% of patient who present to a sleep clinic have impaired glucose intolerance
- Detecting mild apnea may actually help predict (as a risk) pre-diabetes

- 86% of people with obesity & diabetes together have the additional burden of sleep apnea

- OSA can be an independent contributor to obesity by inducing insulin resistance

Below, I made my own Venn Diagram of overlapping comorbid conditions, expanding on the Hypertension-Diabetes-Obesity diagram above... I included some other well-known links as well. Obviously, as Neurologist, you know I care about stroke a lot, which is a growing concern on linkage.

- 65% of stroke patients have apnea
- Sleep apnea is an independent risk factor for stroke

- Half of people with heart failure have apnea (often the central apnea)
- Untreated sleep apnea causes remodeling of the heart, leading to an increased risk of developing atrial fibrillation and a more difficult time treating it successfully
- Mild/moderate apnea is present in over half of heart attack patients

Depression & Anxiety
-Not only are patients with untreated apnea more likely to have both and more difficult to treat versions of both, they are more likely to have difficult-to-treat chronic pain and more difficult-to-treat psychiatric disorders as well. These in themselves feed into the other comorbidities.

You thought I was finished?

No, there are other things too.

Traffic Accidents:
- 15-fold increase of being involved in a traffic accident
- If we found and treated all sleep apnea patients, it's estimated we'd save 980 lives each year and $11.1 billion dollars in collision costs.

Overall death:
- Severe sleep apnea raises the death risk 46%
- Apnea is associated with a 3-fold increase in death
- Moderate to severe OSA is independently associated with death.

Again, apnea is essentially short periods of choking all during the night. Hold your breath for 10 seconds. It seems like such a simple thing, but if your really think about it, if I choked you of air all day long intermittently for 10 seconds at a time...
A) You would fight me off 
B) You'd be miserable

So why would you let it happen at night?