Dr. Richard Schwab is a professor of medicine at the Hospital of the University of Pennsylvania. His groundbreaking research has used innovative imaging techniques to study the development of sleep apnea (when tissues in the mouth close during sleep, resulting in repeated airway obstructions and associated oxygen drops). In our conversation, he shared his insights on the most important facts in sleep apnea research: the high prevalence of the disorder, how obesity and alcohol can cause sleep apnea, the resulting cardiovascular problems, and the importance and ease of treatments. Here is a lightly edited transcript of our conversation.
What are the primary risk factors and consequences of sleep apnea?
The big-picture message: Sleep apnea is really common. More than 18 million Americans suffer from the disorder. The primary risk factor for sleep apnea is obesity, which increases the size of different structures within your mouth. Given the fact that obesity is rampant in this country and around the world, sleep apnea is extremely common. Sleep apnea can also be seen in thin people, but it is usually related to their jaw being recessed, or having big tonsils. Pretty much everyone who has sleep apnea snores, although not everyone who snores has sleep apnea.
The major consequence of sleep apnea is that patients are often very sleepy. This can increase the risks of car accidents, and you worry in particular about truck drivers. They often get insufficient sleep, and adding sleep apnea on top of that compounds the problem.
The other big consequence of sleep apnea is the association with cardiovascular diseases. Sleep apnea can be associated with high blood pressure, heart attacks, strokes, cardiac arrhythmia, and heart failure. Studies suggest that if you treat sleep apnea, you can reduce the risk of these cardiac conditions, especially for hypertension.
What research is being done on sleep apnea now?
One of the things we are trying to better understand is the correlation between obesity and sleep apnea, so our recent research has studied the relationship between sleep apnea and tongue fat.
Most people don't think there is a lot of fat in the tongue. We eat all the time, we talk all the time, we are always breathing -- we are using our tongue muscle all the time, so why would there be a lot of fat in at the tongue? It turns out that in those with sleep apnea, about 32 percent of the tongue is fat, while in obese people who do not have sleep apnea, the number is about 27 percent, which is a large difference.
We are still trying to understand why there is fat in the tongue, but we know that tongue fat is going to be important in understanding the development of sleep apnea. We are also trying to understand if weight loss reduces tongue fat and if there are other ways to reduce tongue fat.
The anatomy of the pharynx is very important in the development of sleep apnea, and we have spent a lot of time studying the lateral pharyngeal walls, which are the structures lateral to your airway. If a person has big or collapsible lateral walls, that puts the individual at a higher risk of sleep apnea.
The other big message is that alcohol makes sleep apnea worse. Alcohol takes someone who does not snore and makes her or him a snorer; it takes a snorer and causes her or him to develop apnea; and it takes an apneic and makes her or his apnea worse. I think that one of the reasons we have hangovers after a night of drinking is that we develop sleep apnea during that night. Because of this, your sleep is more fragmented, and you wake up sleepier and with a headache.
Sleep apnea is very important if you have surgery. If you are undergoing surgery and have undiagnosed sleep apnea, an anesthesiologist might not handle your upper airway properly. When obese patients undergo surgery, an anesthesiologist should inquire about sleep apnea, perhaps even looking into the mouth. If doctors know that patients going in for surgery have sleep apnea, they can manage their airways better preoperatively by giving them CPAP (continuous positive airway pressure).
In terms of population breakdown, you can see sleep apnea at all ages. But children have a different anatomy. Typically in children, it is related to a large adenoid and/or enlarged tonsils, while in adults it is usually related more to large tongues or lateral walls.
In terms of gender, sleep apnea is more common in men than in women, at about a rate of 2 to 1, though the difference disappears when women become post-menopausal.
What are some of the treatments for sleep apnea?
Sleep apnea is relatively easy to treat. You can use CPAP, and this technology has become more advanced and user-friendly. The masks are lighter and more comfortable, and the machines have become "smart" -- they track how many hours you use it, how many days you use it, if it is working, if the mask leaks, etc. These developments have made using CPAP easy and safe, and use of the machine makes a huge difference. It improves sleep, can help memory, and helps prevent the cardiovascular consequences associated with sleep apnea.
I would estimate that 75 percent of patients do well with CPAP if they are handled properly, but then what about the other 25 percent? For those patients, we consider oral appliances. These pull your jaw forward, thereby increasing the size of your airway. Weight loss can often help patients, and upper-airway surgery is also an option.
The newest treatment is actually a pacemaker -- the treatment is called hypoglossal nerve stimulation. It is like the pacemaker for hearts, but this one goes on the right side of your chest. The leads do not go to your heart but to your chest and the nerve that connects to your tongue, the hypoglossal nerve. The chest leads are designed to detect when you breathe in and breathe out. The pacemaker is only active during sleep. When you breathe in, the hypoglossal nerve will be stimulated and your tongue will be pushed forward towards you lip, opening up your airway.
It's important for people to recognize how many different options there are for treating sleep apnea now. If CPAP is difficult or uncomfortable for you, consider an oral appliance or another alternative. It is just very important to treat sleep apnea in order to prevent cardiovascular consequences and to prevent daytime sleepiness that can lead to car accidents. There are a lot of patients that I see who discard CPAP after a negative experience. These patients are increasing their risks of heart attack, car accidents, and so much more. Thus it is critically important to treat sleep apnea.