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June 21, 2010

Pause for Concern
By Carolyn Gutierrez
For The Record
Vol. 22 No. 12 P. 24

Sleep apnea may seem innocuous to some, but its long-term effects can be serious.

The chronic condition of sleep apnea is characterized by the cessation of breathing that can last anywhere from 10 seconds to two minutes during sleep. Obstructive sleep apnea, which refers specifically to apneas caused by throat obstruction, comprises 95% of all sleep apneas. Medical descriptions of sleep apnea have existed for more than one century, but only in the past 30 years or so has the general public become more aware of the condition. Research performed during the past 10 years indicates that severe sleep apnea can heighten a patient’s risk of hypertension, stroke, heart attack, and diabetes. However, recent findings suggest that in elder patients, it may actually be protective, preventing or minimizing the risk of cardiovascular events.

Not surprisingly, bedfellows often are the first to notice that something’s awry. “Usually, patients are referred because of observations by the bed partner, such as snoring, periods when they stop breathing, or they’re gasping and choking and having restless sleep. The bed partner could observe those things,” says Brian J. Bohner, MD, medical director of LifeBridge Health Center’s Northwest Hospital Sleep Center in Randallstown, Md. “The patient’s complaints could pertain to things that are happening during sleep or things that can occur when they’re awake.”

During sleep, patients may wake up frequently, awake gasping and choking, or be startled by their snorting sounds. Daytime symptoms include tiredness and general lethargy. “Other symptoms include a headache in the morning that occurs because of the low oxygen level,” Bohner adds. “[Patients] also can describe difficulty concentrating, impacting work performance and the ability to perform tasks; they’re just not getting into a good sleep because they’re having apneas all night long. You also can have many medical conditions—being overweight, having high blood pressure, having diabetes, having history of stroke, history of heart attack—all those medical conditions are directly related to sleep apnea.”

Other, less common symptoms, including nighttime heartburn, exacerbated asthma, panic attacks, and frequent urination, may be indicative of other conditions. “Every time you have one of these pauses in breathing, you end up having a rescue arousal that can create a big burst of blood pressure, which can actually increase urine production. So if you’re waking up 20 times an hour trying to breathe, that will increase urine production to the point where you’ll end up having to go to the restroom at nighttime,” says Raman Malhotra, MD, DABSM, codirector of Saint Louis University’s Sleep Disorders Center. Additional symptoms include insomnia, memory problems, and nodding off while driving.

Testing and Diagnosing
Snoring should not be construed as a de facto sleep apnea diagnosis, according to Malhotra. “Snoring and pauses in breathing can be normal, so we don’t want to automatically assume from our history that, for instance, everyone who snores has sleep apnea, which isn’t the case,” he says.

Practitioners who suspect sleep apnea screen patients to learn whether their history merits undergoing a polysomnogram. “The polysomnogram is a study that we do on a patient at nighttime, or more specifically during their sleep time,” Bohner says. “For instance, if they work at night and sleep during the day, we do the sleep study during the day. During their sleep time, they would be monitored with about 16 different wires. These wires are taped all the way from their scalp to their ankles, and they’re monitoring all kinds of physiological things through the night, including brain wave activity, oxygen level, movement of arms and legs, EKG [electrocardiogram], airflow through the nose and the mouth, and position, so we know if they’re on their back or their side; we also know through an EEG [electroencephalogram] what stages of sleep they’re in. “

The apnea is labeled mild, moderate, or severe based on the number of times per hour a patient stops breathing. The number of breathing pauses is tallied and divided by the number of hours the patient is asleep to determine the Apnea Hypopnea Index (AHI). “If somebody stops breathing 50 times an hour, that usually means that their AHI is 50, well over the 30 that makes it severe, and we know that that particular patient has a very severe problem as opposed to somebody with an index of 10,” Bohner notes.

Risk Factors
According to Malhotra, middle-aged men who are overweight are most likely to suffer with sleep apnea. “Two to three percent of children may get sleep apnea, whereas 10% to 15% of patients over 65 may have it,” he notes. “As we age, our airway becomes more collapsible, and we unfortunately start to gain weight sometimes, so that probably puts us at risk as well as a lot of other factors that I don’t think we fully understand yet.”

Infants born with micrognathia, an abnormally small jaw, have a tendency toward breathing problems if the issue is not corrected. Older children with sleep apnea are often treated by having their tonsils or adenoids removed.

“Children who have sleep apnea are a particularly important group of patients … because if kids don’t have the sleep apnea identified and treated, then they can have big problems with development and growth because growth hormone is secreted during that one very crucial stage of sleep that they don’t get if they have sleep apnea,” Bohner says. “Women are not as prone to have sleep apnea until they hit menopause. And then at menopause, the prevalence of sleep apnea in women goes dramatically up to that of the male population. So there’s definitely a hormonal protective factor until they reach menopause that protects women from having the airway blocked off.”

Although sleep apnea is commonly associated with obesity, researchers have found an equally high incidence of sleep apnea in nonobese populations in Asian cultures. Researchers suggest this may have to do with craniofacial features that have been demonstrated to increase the risk of sleep apnea. It is also thought that sleep apnea may be genetically shared in families.

Cardiovascular Risks
Recent research has underscored the link between sleep apnea and cardiovascular disease. “One of the biggest connections we have is with hypertension. We know that not only can sleep apnea increase your blood pressure while you’re sleeping, but if it’s checked, people with sleep apnea have much higher blood pressure than people without sleep apnea during sleep,” Malhotra says. “It actually translates into the daytime as well, meaning that we know that if you’re not breathing and not getting a good night’s sleep, that will actually increase your blood pressure during the daytime as well.”

There is also some connection with other cardiovascular conditions such as heart attack, stroke, and cardiac arrhythmia, whether it’s atrial fibrillation or other irregular heartbeats. Although researchers don’t know whether sleep apnea is actually a causative factor of diabetes, patients with diabetes and sleep apnea tend to have more problems controlling their blood sugars than those without sleep apnea.

First used in the mid-1980s, the Continuous Positive Airway Pressure (CPAP) machine pumps air through a mask that a patient wears while sleeping. The continuous air pressure prevents the throat from collapsing during sleep. Although it’s difficult for many patients to adapt to wearing the CPAP machine, it is currently the most effective treatment for sleep apnea. In fact, the device has been so successful that comorbidities such as hypertension and diabetes often diminish or resolve once a person’s sleep apnea is treated.

For sleep apnea patients who are overweight, resolution may come with weight loss. Bohner cites the case of a patient who shed 100 pounds and no longer needed to use the CPAP machine. Those who have milder forms of sleep apnea can be fitted with dental appliances that adjust the physiology of the lower jaw during sleep to allow the airway to stretch out and move forward, providing better airflow. Other options have been less successful. “There have been a lot of different devices that have been tried [such as] inserting plastic pillars into your palate—they can be inserted by an ENT [ear, nose, and throat] doctor. That has not worked very well even in mild sleep apnea. Different splints that you put in the throat—as you can imagine when you’re trying to sleep, it’s not very comfortable to have some big plastic thing stuck in your throat,” Bohner says.

Something as simple as changing sleeping positions can help alleviate sleep apnea. “Some people have sleep apnea only on their back, and if they’re able to sleep on their stomach or their side, which is actually not very easy to do, that can sometimes do the trick,” Malhotra says. Surgery, often used as a last resort, has a high failure rate.

New Findings Regarding Elders
After conducting a series of studies over the past 14 years, Technion-Israel Institute of Technology President and noted sleep researcher Peretz Lavie, PhD, has reached an interesting hypothesis about elder sleep apnea patients. Lavie and his wife, Lena Lavie, PhD, a biochemist, theorize that hypoxia (the lack of oxygen that characterizes sleep apnea) may actually protect the heart from adverse cardiovascular events.

“Our first study was done in 1996, in which we studied mortality of sleep apnea patients. And in that study we found out that in patients younger than 50, there was excess mortality—which meant that when you compared our patients with sleep apnea to the general population, you’d find more death than expected based on mortality tables,” Peretz Lavie says. “But the picture changed in older patients.”

The Lavies continued following sleep apnea patients from their database of more than 100,000 patients. “We found again and again that the maximum risk of mortality is for younger patients and, as you grow older, the risk declines and, in fact, once you reach 60, we found there is no more excess risk for mortality,” Lavie says. “This was fascinating because it was counterintuitive, and I didn’t believe it was selection phenomena. People say, of course you don’t see mortality after 60 because all those who were at risk died. So those who are left are the healthy ones. But I had experience with patients who were 90 years old who had the most severe apnea you can imagine; they stopped breathing for 40 seconds every minute throughout sleep. They had had several heart attacks, and they were still alive at the age of 90. So we started to look for a possible mechanism.

“We speculated that the hypoxia is responsible for generating a protein called vascular endothelial growth factor that is responsible for the formation of new blood vessels. … We speculated that perhaps patients with sleep apnea, or at least some of them, develop enough blood vessels around the heart to form a reservoir of blood that protects them in case of a heart attack,” he adds.

The Lavies’ research was recently corroborated by a German study in which researchers at the Heinrich Heine University in Dusseldorf found a proliferation of blood vessels around the hearts of sleep apnea patients compared with patients without the condition. Interestingly, these patients all shared common age, weight, and cardiovascular history. The Lavies discovered that in the German study, elder patients with very severe sleep apnea had exactly the same death ratio as the general population.

Public Perception
Sleep apnea remains a somewhat controversial topic for many in the sleep-study community. Researchers like Peretz Lavie believe the condition can be overdiagnosed, that a certain degree of breathing cessation is a completely normal part of the phenomenon of sleep. Meanwhile, physicians like Bohner believe sleep apnea tends to be underdiagnosed, with only 15% of those with sleep apnea in the United States having been identified.

In the meantime, the public generally has become more informed about sleep apnea and its potential health ramifications. Bohner notes, “The awareness in the community in the last 10 years has gone up dramatically. I think there’s been a lot of media representation of sleep apnea. A lot of the patients that I see now have read about it, they see it on television, they know a friend who has it, whose life has dramatically improved on the therapy. And the awareness is becoming more positive, but we still have a long way to go.”

— Carolyn Gutierrez is a freelance writer based in New York City.