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Sunday, May 19, 2013
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 an underrecognized and underdiagnosed condition. Because it takes place during sleep, many patients 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 a patient is suffering from sleep apnea, the individual must have a sleep study, which is usually conducted in a sleep lab, though testing in the home can be performed in certain cases. The sleep specialist uses data collected from the sleep study to look at the individual's breathing in sleep, as well as to examine for other sleep disorders and factors that may be associated with these. In some cases, a second test may be required to fully evaluate for the presence and/or severity of the breathing problems in sleep.
The general disorder of sleep apnea is divided into three classifications:
Affecting roughly 5% of middle aged adults in America, obstructive sleep apnea (OSA) is a common condition marked 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 individuals 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 be worse if the person sleeps on their back versus sleeping on his or her side.
Symptoms of OSA include:
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 patient's size and airway structure (anatomy), the other medical conditions (co-morbid conditions) the individual has that may be associated with OSA , and the patient's willingness to accept a given treatment.
The primary treatment for OSA is the use of CPAP. CPAP stands for continuous positive airway pressure. By providing individuals suffering from OSA with 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 the quality of life, daytime alertness, concentration and mood of the individual. 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. Since some patients are unable to use CPAP in spite of their best efforts, other treatments can 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 individuals with more 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, like 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 individuals 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.
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 occus 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 control centers 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 individuals without heart or brain problems who are sleeping at high altitudes or are on long-acting narcotic medications (e.g. Morphine and Oxycontin).
Symptoms of CSA are similar, with some differences, to OSA and include:
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 you have 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, others with Bipap (bi-level pressure support), and some need the newer type of device called adaptive servo ventilation (ASV or VPAP). 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: Feb 17, 2011
Dennis Auckley, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University