Correct Grammar and optimize this content Sree Roy: Hello and welcome. I’m Sree Roy with Sleep Review, and I’m thrilled to be here with sleep specialist Indira Gurubhagavatula, MD, MPH. She served as chair of the Count on Sleep Tool Development and Surveillance Workgroup for a national indicator report for obstructive sleep apnea. The Obstructive Sleep Apnea Indicator Report provides an in-depth analysis of the symptoms, risk factors, prevalence, and burden of obstructive sleep apnea, and serves as a resource for both the public and the healthcare communities on the importance of diagnosis and long-term treatment. We are chatting about the hidden risks of obstructive sleep apnea. What is obstructive sleep apnea, also known as OSA for short? Dr. Indira Gurubhagavatula: Thank you for having me, Sree. OSA, or obstructive sleep apnea, is a medical disorder that occurs when a person is asleep. It does not happen when they’re awake. And what happens when they’re asleep is that the upper airway closes intermittently during sleep. The airway muscles relax to the point where there’s actual mechanical obstruction of the throat, and that results in a transient reduction in airflow, which is called a hypopnea, or a complete stoppage in airflow, which is called an apnea. Within a few seconds of partial or complete airway closure, the oxygen level in the bloodstream drops, and the brain responds to this intermittent hypoxia with a surge of adrenaline, which causes the person to arouse briefly from sleep. And then, during the arousal, the airway muscles then reactivate, the airway opens up, the oxygen level gets restored, they take a few deep breaths, and then they can go back to sleep again. But once they do, the muscles relax and collapse, and the whole process starts again. And for some people, this can happen hundreds of times a night. And what sleep studies do is measure how often this is happening, and we characterize the frequency of this airway closure and intermittent hypoxia, and sometimes actual arousal from sleep if EEG waves are being measured, and up to five times per hour is actually considered a normal range for adults, five to 15 is considered in the mild range, 15 to 30 times per hour is moderate, and 30 or more is considered in the severe range. And this is an extremely common problem. We believe 29 million adults in the US, which is roughly 12% of the overall population, have OSA, and yet only about six million are diagnosed. Sree Roy: What do you think is the most troubling risk of not treating obstructive sleep apnea? Dr. Indira Gurubhagavatula: Well, I think that you’ll get a different answer depending on who you ask. But there are so many troubling risks, it’s hard to pick just one. But since you’re asking someone with a special interest in road safety and traffic safety, I would say one of the most troubling risks is fall-asleep crashes. When you think about the risk of not treating sleep apnea, there are a lot of potential adverse consequences in the short term and in the long term. The recurrent drops in oxygen affect the entire body, every tissue, and fragmented sleep can affect every tissue. So the impact is broad if we leave it untreated. And what you get is not only intermittent hypoxia, but also surges in adrenaline. And these are stressful for the heart and for the brain, and the sleep fragmentation and daytime sleepiness can then impair performance. So cardiovascular disease and downstream effects of sleepiness are the two big categories of risks that need to be considered. Daytime sleepiness can have very sudden and serious effects on a person’s function. And obviously, the most dangerous thing is the risk of injury or death if you’re doing safety-sensitive work like driving or operating heavy machinery. Sleepy people, though, can also experience consequences that are very important to them. For example, in the workplace, being late or being absent because they’re tired or they’re sleepy or they feel sick. We also see something called presenteeism, where the person shows up for work but they’re not engaged, or they’re making mistakes, doing things wrong, missing things, serious errors that can affect their livelihood. So that’s a very important outcome, reduced overall quality of life. And then when we look at the other side, the intermittent hypoxia, we see an association with that higher levels of inflammatory cytokines, which can be damaging to blood vessels. And this, along with high sympathetic activity that’s seen in OSA patients over years, can lead to cardiovascular disease. So hypertension, heart attacks, arrhythmia, stroke. And not just the heart and the brain, but other organs are also vulnerable to these effects. So insulin resistance and metabolic syndrome, weight gain, obesity over time, impaired immunity, which can make it harder for our bodies to mount a good immune response to either viruses or vaccine challenges. Certain eye disorders, including glaucoma, which can be vision-threatening. I see patients reporting acid reflux that improves when they get their apnea treated, sexual dysfunction. So the bottom line is that, that we need oxygen and we need sleep, and our entire body needs oxygen and needs sleep, and this is a treatable disorder. So the fact that 80% of people are undiagnosed means that there is a huge burden of preventable illness that can be attributed to sleep apnea, and it is costing us billions annually. In our healthcare system alone, we’re paying for these downstream effects after they’ve already happened, and this can become costly, and instead of preventing them in the first place, we are spending close to $150 billion a year on undiagnosed sleep apnea and its consequences, and the prevalence of obesity is high, and it’s another indicator of how big the problem is because obesity is a major risk factor for sleep apnea. Sree Roy: Let’s dive into some of the aspects that you just touched on, some of the morbidity linked to obstructive sleep apnea. So treatment-resistant hypertension is a frustration for patients and clinicians. How has treatment-resistant hypertension been linked to OSA? Dr. Indira Gurubhagavatula: So let’s just define treatment-resistant hypertension. It means that in spite of using three or more medications, the person’s blood pressure continues to be high. We believe that the recurrent burst of adrenaline contribute to the hypertension that’s seen with OSA. There’s probably overlapping effect as well from obesity, which is a major comorbidity with OSA. Now we have evidence from longitudinal studies as well as randomized trials of people with hypertension who’ve received either CPAP therapy or a placebo. And we know that CPAP is effective in lowering blood pressure. There are several meta-analyses that have been published. So the good thing about this is that treating sleep apnea effectively reduces the levels of adrenaline-type chemicals in the blood and lowers blood pressure. So what that means for people who are sufferers of hypertension is that they may end up needing lower doses of blood pressure medication, or eventually, under the supervision of their healthcare provider, they find that they no longer need blood pressure-lowering medication once they’re on effective therapy. So the amount of money spent on such medications and possible side effects of these medications can then be avoided. So anyone with treatment-resistant hypertension, the estimates of prevalence suggest that 80% of those people have untreated sleep apnea. So if you see somebody who’s on multiple meds for blood pressure lowering, it’s a really good idea to screen those people for sleep apnea and get them treated. Sree Roy: What about impaired brain function? How can the impaired brain function linked to OSA manifest in patients? Dr. Indira Gurubhagavatula: That’s a really important question. We rely on our brains for most of our waking activities, and our brain function can get impaired in a number of ways. So people with sleep apnea, because of the recurrent sleep fragmentation that happens, the constant arousals to reestablish airflow, means that they’re not getting the restful sleep they need. And their brains are now being subjected to not only low oxygen levels off and on throughout their sleep period, but also the constant interruptions in sleep. Without restful sleep, daytime sleepiness becomes a concern. So people may experience actual falling asleep inappropriately in the daytime when they are trying to do things like attending meetings at work or while sitting or trying to be in a conversation or in front of a TV show or at a movie theater, or importantly, while driving, which can be really dangerous and life-threatening for the person and also poses a risk to others on the road. So a number of functions though also get impaired, whether the person feels sleepy or not: our…
