At this point, you've had a brief overview of how we assess patients for sleep disorders and what types of sleep disorders exist. Next, we'll talk about one specific sleep disorder, obstructive sleep apnea in more depth. I have selected obstructive sleep apnea for this discussion because it's so common and consequential, and also because to some extent, it serves as a good prototype for the types of sleep disorders that specialists in sleep clinics can see. Obstructive sleep apnea syndrome, the name has several elements. Obviously, obstructive means it's obstructive coming from the throat and not central coming from the brain, and sleep emphasizing that it only occurs during sleep, that obstructive sleep apnea does not occur during wakefulness. People with obstructive sleep apnea do not have any of the same type of breathing problems while they are awake. And finally, when we say apnea, we really mean apnea or hypopneas and sometimes even more subtle types of breathing disturbances, but an apnea occurs when there's complete cessation of breathing for 10 seconds or more, hypopnea when there is a diminution or a significant diminution in breathing for 10 seconds or more, and I'll show you some examples. First, we'll talk a little bit about the anatomy of obstructive sleep apnea, and what you see here is that the air is not able to go farther than what you see it, comes in the nasal cavity, gets to the throat and what you can't see off of the bottom of this slide is that the palate is actually adhering or close to the back of the throat, and so the air is not passing below the palate, and the tongue is also falling back as a person lies often in the supine position, so that the throat essentially completely occludes and the air cannot get past it. So, anatomical narrowing like we just saw is not the only reason to have obstructive sleep apnea. We're still working out all the details of why obstructive sleep apnea occurs, but we believe that it often involves other issues other than just the anatomy. One issue is the compliance or the excessive collapse ability of the throat, and if the walls of the throat don't have their usual lack of compliance, they become more compliant, then there'll be more likely to be throat closure during sleep. So, it has to do with actually consistency, perhaps of those tissues, but then, it also has to do with the neural control of those tissues. By neural control I mean, what are the neurons telling the muscles that line the throat to do, and when we inspire while we are awake, there's actually a tensing of those muscles so that it braces that even if there's a little bit of negative pressure as the air is being drawn into the lungs, the throat is not going to close off. If that neural control, tensing those muscles, and maintaining the airway patency does not work well for any neurological or muscular reason during sleep and someone can be more likely to have obstructive sleep apnea. And there's evidence among patients with obstructive sleep apnea, and most of them don't have another neurological diagnosis. But there's evidence in those people that there is airway narrowing, but also excessive collapse ability of the throat and also abnormal neural control of the muscles. The typical patient with obstructive sleep apnea has excessive daytime sleepiness. It's more common or at least in its most frank forms. Most frank forms of obstructive sleep apnea are more common in men than in women. It certainly increases in frequency as weight becomes excessive, and overweight and obese and morbidly obese individuals have increasing likelihood of obstructive sleep apnea. It typically occurs in someone who snores loudly. That's because when the airway becomes narrowed before closing off, it'll often have an interim state where it's narrow enough to create turbulent airflow during respiration, and that turbulence will set up vibratory patterns in the throat that cause the snoring sound. Obstructive sleep apnea, again in its most frank forms, becomes particularly common in middle age and older individuals. These are some of the most common symptoms, especially the first three there that we look for in obstructive sleep apnea, excessive daytime sleepiness. Sometimes, it will be expressed as fatigue or tiredness or lack of energy. In fact, research that we've done here at the University of Michigan among patients diagnosed with obstructive sleep apnea shows that most of them actually prefer to describe what bothers them as lack of energy. That's about 40 percent, maybe 20 percent approximately prefer to say that they're tired. 20 percent prefer to say they're fatigued, and only 20 percent say sleepiness is the most significant problem that bothers them the most, and that they most like to get rid of. Sleepiness or a symptom as described related to that by the patient, loud usually habitual but not always snoring, disturbing others, can be heard through a closed door, and witnessed apneas meaning that a bed partner sees the person stop breathing, often report that they wake up with a loud snort or snore. Those three symptoms if they're all present suggest a very high likelihood, perhaps not certainty, but near certainty that a person has obstructive sleep apnea. Other symptoms can include insomnia, mouth breathing during the night reflux. So if a person is trying to inhale air past a closed throat, they may create large negative pressures inside the chest, and that pressure can help draw fluid up from the stomach past the gastroesophageal junction and into esophagus creating reflux. Nocturnal hyperhidrosis or excessive sweating is a common symptom in these patients, even here in Michigan sometimes like to keep the window open in January and February when it's slightly cold outside. Cognitive impairment can occur. Decision making, attention abilities, and other spheres can be affected. And nocturia, which means that person gets up typically more than just once a night to urinate, and that's because sleep apnea can cause excess secretion of atrial diuretic hormone from the heart and that creates the excess of urine. Now interestingly, children don't necessarily present the same way that adults do, and while children may be sleepy, you'll have to dig harder in many cases to get at their evidence of their sleepiness. And what families may come in complaining of is that they're inattentive primarily or hyperactive, especially if they're younger or that they're aggressive with their peers. And in fact, some children are diagnosed with attention deficit hyperactivity disorder or ADHD, and sometimes treated for it for a good while before someone realizes that they actually have an underlying sleep disorder, and when their sleep disorder is treated, their behavior can improve markedly. And they perhaps half the time on our research suggests, will no longer qualify for a diagnosis of ADHD. Besides symptoms, there are also signs that we look for on an exam of obstructive sleep apnea. Obesity is certainly a big one, but we also look carefully at creating a facial anatomy. Retrognathia, where the lower jaw is placed farther back compared to the upper arch than you might expect is associated with sleep apnea. We think that a high arched narrow hard palate is associated with narrowing of the throat and therefore, obstructive sleep apnea. Low edge of the soft palate on a visual inspection, a large uvula, large tonsils, or a large tongue may help obstruct the airway. Long face syndrome is a long narrow face where when viewed from the side of a sharp angle of the jaw, and that typically develops in cases where there's been long term chronic nasal instruction during youth. And that long face syndrome can also be a telltale sign that sleep apnea may have developed also. Here are some of the signs that we're looking for in sleep apnea. Obviously, here what you're seeing is obesity. This gentleman has quite a thick neck and a thick neck with a large neck circumference, for example, over 17 inches or thereabouts in men, an inch or two less in women, but large necks circumferences are predictive of increased risk for obstructive sleep apnea. Now, here what you see is an example of a high narrow arched hard palate, probably associated with a narrowing of the airway lower down. Another example of a high arched narrow palate, and here you're looking inside someone's mouth. On the top left you see what it should normally look like. Here, a Mallampati is a Mallampati scoring, it was developed originally by anesthesiologists to judge how hard someone might be to intubate prior to surgery and total anesthesia, but we use it or a variant of it called the Friedmann score, that's measured slightly differently than what's shown here, to just characterize how narrow the airway is likely to be. So as you can see, as you go from level one, two, three to four, when the patient is opening their mouth you're seeing less and then no uvula or not even the edge of the soft palate and sometimes you're not even able to see the soft palate. You're mainly looking at the hard palate and that clearly is increasingly suggesting high risk for obstructive sleep apnea. This is relatively soft sign that some people say that, when you see scalloping of the edge of the tongue, like you're looking at there through the lips, that could represent that the tongue is constantly pushing against a narrow lower arch or a narrow arch of the teeth. So it gets that indentation. And why would it be pushing against the arch, well if it's crowded and there's effort to keep breathing through an narrower airway that might occur. Here, you see a large uvula that is possibly helping to obstruct that airway. And here, you see an example of significantly enlarged tonsils that are pretty much almost touching, what we would call kissing tonsils, a risk factor for obstructive sleep apnea in children. Again, quite enlarged tonsils. They would naturally get smaller as a child gets older, but at this point might contribute to obstructive sleep apnea. Which you see here is prominent overjet. There's a protrusion in the upper incisors, but also a good deal of overjet, and that is anteriorly. When looking laterally, you're seeing evidence that might go along with retrognathia. Again meaning less room for the tongue and possibly risk for obstructive sleep apnea. This is an open bite that can develop again in patients who grow up during their youth especially with chronic nasal obstruction. This patient is probably trying to bite down on their molars, and what you're seeing is that there no contact between the incisors and it's looking in part there an overjet, but also interior open bite. This is a patient who has a deviated nasal septum and asymmetric nares and that may also be a risk factor for obstructive sleep apnea. Remember obstructive sleep apnea, the obstruction isn't happening in the nose, it's happening in the throat. But anything that increases resistance to airflow in the nose or the sinuses, can create more negative pressure down in the throat and make it more likely that someone might also have sleep apnea. Now besides those physical signs, there are also physiological signs that go along with obstructive sleep apnea. One of them is hypertension. And if you wondered how daytime hypertension can arise or might arise from nocturnal sleep apnea, it might be helpful to look at this diagram from a paper that was published more than 20 years ago. What the top line shows is the blood pressure during sleep across several apneas. And you can tell that there's apneas by looking at the third panel down where you see airflow and you see there's air movement, but then a flat line, meaning that the air stopped and then movement and then flat lined. So what you're seeing is, each time there's a flat line that there's apnea. And what you see in the panel that's second from the top is that there are periodic dips in the oxygen saturation because the person is holding their breath periodically. But what you see on the top, is that the blood pressure is actually increasing very dramatically at the termination of each of those apneas. So during the apnea and the other person is probably asleep, but the brain has to wake them up abruptly in order to turn tone to those muscles the upper airway and open the throat and then solve that problem of choking during sleep. So with that abrupt awakening as a surge of sympathetic activity and systemic blood pressure as in this case is going from where it might normally be at 120, 130 level to 160 or 170 as we're seeing in this example, and that's quite a bit of abrupt blood pressure. Blood pressure does go down again, only to encounter another apnea and rise again, and this can happen hundreds of times during the night. Unfortunately over time seems to spill over into more chronic daytime hypertension. The bottom panel on this slide shows the pulse, heart rate like the blood pressure is also increasing intermittently in conjunction with the end of each apnea or hypopnea. So consequences of obstructive sleep apnea syndrome include those acute physiological changes on a chronic timeline. They can have quite a few other consequential effects. So they can cause sleepiness and cognitive impairment, the motor vehicle crashes I told you about initially, the hypertension we just talked about, other types of mishaps during the day when working with dangerous equipment. Depending on how a person works or spends his or her time. And finally, can have very prominent impact on quality of life. So patients with obstructive sleep apnea can have their quality of life affected. Studies suggest as much as patients with severe serious rheumatologic conditions do, or patients who have kidney failure do, or patients with angina. So it's not a trivial matter to have obstructive sleep apnea. So more broadly, this is only a partial list of the types of adverse outcomes that have been linked to obstructive sleep apnea. We know that they have increased risk of stroke even after you adjust for several other types of possible compounds, increased risk for obstructive sleep apnea for MI, for arrhythmias of several types, for heart failure. Patients with obstructive sleep apnea don't appear to live as long as other patients. They often have other elements that allow them a diagnosis of metabolic syndrome. It can affect pregnancy, and we're finding increased evidence that even a milder form of obstructive sleep apnea can be linked with gestational hypertension, for example, preeclampsia. Other conditions include diabetes, depression, dementia, attention deficit, hyperactivity disorder as I had mentioned before in children. Asthma seems to have bi directional links with obstructive sleep apnea. Reflux and GERD as we discussed, and finally erectile dysfunction. So next, we'll transition and talk in a little more depth about what we see in a sleep laboratory when we're recording from a patient with obstructive sleep apnea.
