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Tuesday, July 22, 2014
What is Sleep Apnea?
Sleep apnea is a breathing disorder in which abnormal pauses in breathing or shallow breaths occur during sleep. Each pause in breathing is referred to as an apnea and shallow breaths, or partial airway collapses, are called hypopneas. These events (apneas and hypopneas) may last from seconds to nearly a minute. In fact, these pauses can occur at a rate of more than 30 per hour! According to the National Institutes of Health (NIH), sleep apnea affects an estimated 18 million Americans.
Sleep apnea remains underrecognized and underdiagnosed. Because it takes place during sleep, many individuals are unaware that they have a significant medical condition. Even when noticed by a family member, patients often attribute the "snoring" and "choking" described to them as a normal byproduct of sleep. The risk factors for sleep apnea include obesity and having a crowded upper airway, such as from enlarged tonsils, a large tongue, or a crooked nose. In order to determine if one is suffering from sleep apnea, a sleep study is required. Sleep studies, also known as polysomnograms (PSG), is usually conducted in a sleep lab, though testing in the home can be performed in some cases. The sleep specialist uses data collected from the sleep study to look at the person's breathing in sleep, as well as to examine for other sleep disorders and factors that may be associated with these. In some instances, more than one test may be required to fully evaluate for the presence and/or severity of the breathing problems in sleep.
Sleep apnea can be divided into three classifications:
Obstructive Sleep Apnea
Affecting at least 5% of middle aged adults in America, obstructive sleep apnea (OSA) is a common condition typified by loud snoring and excessive sleepiness. OSA is the most common of the sleep breathing disorders and is characterized by the airway partially or completely collapsing during sleep. When the airway collapses, the brain and the body protect themselves by briefly awakening the individual and opening their airway to allow for normal breathing. Most persons with OSA are not aware that this is happening. Unfortunately, as they fall back asleep, the process of airway closure tends to repeat over and over. This results in sleep disruption and, in some, low oxygen levels during sleep. OSA tends to worsen if the person sleeps on their back versus sleeping on his or her side.
Symptoms of OSA include:
Not only does OSA affect how an individual sleeps and how they feel, it has now been associated with a wide range of medical consequences, including significant cardiovascular disease (hypertension, heart failure, strokes) and higher accident rates. As such, identification and treatment of this condition is very important.
There are a number of different treatments available for OSA. Which treatment is best for a given person depends on a number of factors, including the severity of the sleep apnea, the person's body size and shape and airway structure (anatomy), associated medical conditions (co-morbid conditions), and their willingness to accept different treatments.
The primary treatment for OSA is the use of CPAP. CPAP stands for continuous positive airway pressure. By providing a steady stream of pressurized air, CPAP prevents the airway from collapsing. The most common version of CPAP comes in the form of a nasal mask system, which only covers the nose. There are also full face masks that cover both the nose and mouth, and nasal pillows which use silicone tubes that fit into the nostrils. CPAP often proves very effective at keeping the airway open during sleep, and it has been shown in a large number of studies to effectively improve quality of life, daytime alertness, concentration and mood of persons with OSA. In addition, growing data suggests that CPAP may reduce some of the medical consequences associated with sleep apnea. However, there are many people who have difficulty adapting to sleeping with the device. Some patients are unable to use CPAP despite an increasing array of special features that are designed to help with tolerance of the device. In these cases, other treatments may need to be explored.
There are two main categories of alternative OSA treatments: oral appliances and surgery. Oral appliances generally work to advance the lower jaw, hoping to open space in the back of the throat. They tend to work best in mild to moderate OSA and in those who may have a small or more backward sitting (posterior) jaw. Individuals who use oral appliances during sleep often tolerate them; though they can have some annoying side effects, such as jaw achiness, pain when chewing in the morning, headaches, and drooling. Most of the time, these problems resolve with continued use of the device. Caution is warranted if considering using these devices in persons with temporomandibular joint (TMJ) disease, as the appliances put considerable stress on the TMJ and can worsen problems.
Surgery for OSA tends to be most effective in those with clear structural (anatomical) problems that are responsive to surgery (e.g. large tonsils, deviated septum, etc.), those with more mild to moderate sleep apnea, and those who are not obese. There are a variety of surgeries that can be considered, and they are usually tailored based upon the individual and their airway anatomy. A tracheotomy (surgical tube placed in the neck) is usually curative for OSA, but because it is somewhat disfiguring, it is reserved for severe cases that fail all other treatments.
At present, no medication can effectively treat or control OSA. However, a vast array of new and novel therapies for OSA have become available recently, and ongoing research is looking into additional new therapies. None of the new therapies have been proven to be superior to CPAP though some of them may be helpful treatment options in certain cases. These new devices include:
Central Sleep Apnea
Central Sleep Apnea (CSA) differs from OSA, in that it is not caused by a blockage in the airway, but rather it is the result of a failure for the brain (hence, "central") to send to the signal to breath for a period of time. Thus, the airway remains open, but there is no effort made to breath. CSA often occurs in an off-and-on cycle, giving a rhythmic pattern to the breathing problems in sleep. This version of sleep apnea is most often the result of heart or brain problems, though in some cases no clear cause for it is found. The brain is the control center for breathing, but the heart can interact with the brain and affect the process of breathing. Individuals with CSA often have neurological disorders (i.e. Parkinson's Disease, stroke) or heart conditions (usually heart failure), though it can also be seen in those without heart or brain problems who are sleeping at high altitudes or, increasingly, in those on long-acting opiod narcotic medications (i.e. methadone and oxycontin).
Symptoms of CSA typically include:
Just like for OSA, individuals who might have CSA are encouraged to visit a sleep specialist and undergo objective testing; these cases should be studied by an in-lab sleep study and not a home test. The primary treatment of CSA varies with the underlying cause. For many cases, a wide variety of pressure devices (i.e. CPAP, adaptive servo ventilation) can be used successfully. In other cases, other therapies may be appropiate and may include medications that stimulate breathing or oxygen.
Complex Sleep Apnea
Complex sleep apnea is, in some respects, a mix of OSA and central sleep apnea, and is probably the least common of the sleep breathing disorders. This condition is defined based on certain characteristics of a person's sleep during a sleep study. In complex sleep apnea, there is a diagnosis of OSA during monitored sleep. However, when placed on CPAP therapy to eliminate the obstructive events, the person develops a central sleep apnea pattern. In other words, the CPAP is effective at keeping the airway open, but now the brain fails to send the signal to breath. As such, complex sleep apnea can only be diagnosed if one has OSA on a diagnostic sleep study and then central sleep apnea while being monitored on CPAP.
The significance of having complex sleep apnea is not entirely clear. It is not known if this represents a different type of sleep apnea or something we see on a single night sleep study that resolves over time. Some individuals with this condition can be controlled with CPAP and some need a newer device called adaptive servo ventilation (ASV). Oxygen is not considered a treatment for this condition as it is generally not a treatment for OSA.
This article is a NetWellness exclusive.
Last Reviewed: Mar 21, 2014
Dennis Auckley, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University