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, '''sleep apnoea''' or '''sleep apnœa''' is a
Sleep Disorder characterized by pauses in
Breath ing during
Sleep . These episodes, called
Apnea s (literally, "without breath"), each last long enough so one or more breaths are missed, and occur repeatedly throughout sleep. The standard definition of any apneic event includes a minimum 10 second interval between breaths, with either a neurological arousal (3-second or greater shift in EEG frequency, measured at C3, C4, O1, or O2), or a blood oxygen desaturation of 3-4 percent or greater, or both arousal and desaturation. Sleep apnea is diagnosed with an overnight sleep test called a
Polysomnogram .
Clinically significant levels of sleep apnea are defined as 5 events of any type or greater per hour of sleep time (from the polysomnogram). There are two distinct forms of sleep apnea: Central and Obstructive. Breathing is interrupted by the ''lack of effort'' in central sleep apnea; in obstructive sleep apnea, breathing is interrupted by a physical block to airflow ''despite effort''. In mixed sleep apnea, there is a transition from central to obstructive features during the events themselves.
Regardless of type, the individual with sleep apnea is rarely aware of having difficulty breathing, even upon awakening. Sleep apnea is recognized as a problem by others witnessing the individual during episodes or is suspected because of its effects on the body (
Sequelae ). Symptoms may be present for years, even decades without identification, during which time the sufferer may become conditioned to the daytime sleepiness and fatigue associated with significant levels of sleep disturbance.
Obstructive sleep apnea (OSA) is not only much more frequent than central sleep apnea, it is a common condition in many parts of the world. If studied carefully in a sleep lab by polysomnography, approximately 1 in 5 American adults has at least mild OSA.
Normal sleep/wakefulness in adults has been given
6 Distinct Stages , numbered 1-4 and including REM sleep (stage 5) and wake. The deeper stages (3-4) are required for the physically restorative effects of sleep and in pre-adolescents are the focus of release for human growth hormone. Stages 2 and REM, which combined are 70% of an average person's total sleep time, are more associated with mental recovery and maintenance. During REM sleep in particular, muscle tone of the throat and neck, as well as the vast majority of all skeletal muscles, is almost completely attenuated, allowing the tongue and soft palate/oropharynx to relax, and in the case of sleep apnea, to impede the flow of air to a degree ranging from light
Snoring to complete collapse. In the cases where airflow is reduced to a degree where blood oxygen levels fall, or the physical exertion to breathe is too great, neurological mechanisms trigger a sudden interruption of sleep, called a neurological arousal. These arousals may or may not result in complete awakening, but can have a significant negative effect on the restorative quality of sleep. In significant cases of obstructive sleep apnea, one consequence is sleep deprivation due to the repetitive disruption and recovery of sleep activity. This sleep interruption in stages 3 and 4 (also collectively called slow-wave sleep), can interfere with normal growth patterns, healing, and immune response, especially in children and young adults.
Many people experience elements of obstructive sleep apnea for only a short period of time. This can be the result of an upper respiratory infection that causes nasal congestion, along with swelling of the throat, or tonsillitis that temporarily produces very enlarged tonsils. The
Epstein-Barr Virus , for example, is known to be able to dramatically increase the size of lymphoid tissue during acute infection, and obstructive sleep apnea is fairly common in acute cases of severe
Infectious Mononucleosis . Temporary spells of obstructive sleep apnea syndrome may also occur in individuals who are under the influence of a drug (such as alcohol) that may relax their body tone excessively and interfere with normal arousal from sleep mechanisms.
Results of polysomnography in obstructive sleep apnea show pauses in breathing. As in central apnea, pauses are followed by a relative decrease in blood oxygen and an increase in the blood carbon dioxide. Whereas in central sleep apnea the body's motions of breathing stop, in obstructive sleep apnea the chest not only continues to make the movements of inhalation, the movements typically become even more pronounced. Monitors for airflow at the nose and mouth show the dynamics of airflow, but efforts to breathe are not only present, they are often exaggerated. The chest muscles and diaphragm contract and the entire body may thrash and struggle.
Obstructive sleep apnea is the most common category of sleep-disordered breathing. The prevalence of OSA among the adult population in western Europe and North America has not been confidently established, but in the mid-1990s was estimated to be 3-4% of women and 6-7% of men.
An "event" can be either an apnea, characterised by complete cessation of airflow for at least 10 seconds, or a
Hypopnea in which airflow decreases by 50 percent for 10 seconds or decreases by 30 percent if there is an associated decrease in the oxygen saturation or an arousal from sleep (American Academy of Sleep Medicine Task Force, 1999). To grade the severity of sleep apnea the number of events per hour is reported as the apnea-hypopnea index (AHI). An AHI of less than 5 is considered normal. An AHI of 5-15 is mild; 15-30 is moderate and more than 30 events per hour characterizes severe sleep apnea.
In patients who are at high likelihood of having OSA, a
Randomized Controlled Trial found that home
Oximetry may be adequate and easier to obtain than formal polysomnography
2. High probability patients were indentified by
Epworth Sleepiness Scale (ESS) of 10 or greater and a
Sleep Apnea Clinical Score (SACS) of 15 or greater.
3
Individuals with decreased muscle tone, increased soft tissue around the airway, and structural features that give rise to a narrowed airway are at high risk for obstructive sleep apnea. Men, whose anatomy is typified by increased body mass in the torso and neck, are more typical sleep apnea sufferers, especially through middle age and older. Adult women suffer typically less frequently and to a lesser degree than men do, owing partially to physiology, but possibly to emerging links to levels of progesterone. Prevalence in post-menopausal women approaches that of men in the same age range.
In adults, the most typical individual with obstructive sleep apnea syndrome is obese, with particular heaviness at the face and neck. The hallmark symptom of obstructive sleep apnea syndrome in adults is excessive daytime sleepiness. Typically, an adult or adolescent with severe long-standing obstructive sleep apnea will fall asleep for very brief periods in the course of usual daytime activities if given any opportunity to sit or rest. This behavior may be quite dramatic, sometimes occurring during conversations with others at social gatherings.
Although this so called "hyper-somnolence" (excessive sleepiness) may also occur in children, it is not at all typical of younger children with sleep apnea. Toddlers and young children with severe obstructive sleep apnea instead ordinarily behave as if "over-tired" or "hyper". Adults and children with very severe obstructive sleep apnea also differ in typical body habitus. Adults are generally heavy, with particularly short and heavy necks. Young children, on the other hand, are generally not only thin but may have "s and
Adenoid s and is usually cured with
Tonsillectomy and
Adenoidectomy .
This problem can also be caused by excessive weight. The symptoms are more like the symptoms adults feel; restlessness, exhaustion, and more.
(The signs and symptoms that follow apply to both adults and children suffering with sleep apnea)
Additional signs of obstructive sleep apnea include restless sleep, and loud , trouble concentrating,
Irritability , forgetfulness, mood or behavior changes, decreased sex drive, increased heart rate,
Anxiety ,
Depression , increased frequency of urination, nocturia (getting up during the night to urinate),
Esophageal Reflux and heavy sweating at night.
The most serious consequence of obstructive sleep apnea is to the heart. In severe and prolonged cases, there are increases in pulmonary pressures that are transmitted to the right side of the heart. This can result in a severe form of congestive heart failure (
Cor Pulmonale ).
There are patterns of unusual facial features that occur in recognizable syndromes. Some of these craniofacial syndromes are genetic, others are from unknown causes. In many craniofacial syndromes, the features that are unusual involve the nose, mouth and jaw, or resting muscle tone, and put the individual at risk for obstructive sleep apnea syndrome.
, and large tongue. Obesity and enlarged tonsils and adenoids, conditions that occur commonly in the western population, are much more likely to be obstructive in a person with these features than without them. Obstructive sleep apnea does occur even more frequently in people with Down Syndrome than in the general population. A little over 50% of all people with Down Syndrome suffer from obstructive sleep apnea (de Miguel-Díez, et al 2003), and some physicians advocate routine testing of this group (Shott, et al 2006).
In other craniofacial syndromes, the abnormal feature may actually improve the airway- but its correction may put the person at risk for obstructive sleep apnea ''after'' surgery, when it is modified.
Cleft Palate syndromes are such an example. During the newborn period, all humans are obligate nasal breathers. The palate is both the roof of the mouth and the floor of the nose. Having an open palate may make feeding difficult, but generally does not interfere with breathing, in fact - if the nose is very obstructed an open palate may relieve breathing. There are a number of clefting syndromes in which the open palate is not the only abnormal feature, additionally there is a narrow nasal passage - which may not be obvious. In such individuals, closure of the cleft palate- whether by surgery or by a temporary oral appliance, can cause the onset of obstruction.
Skeletal advancement in an effort to physically increase the pharyngeal airspace is often an option for craniofacial patients with upper airway obstruction and small lower jaws (mandibles). These syndromes include
Treacher Collins Syndrome and
Pierre Robin Sequence .
Mandibular Advancement Surgery is often just one of the modifications needed to improve the airway, others may include reduction of the tongue, tonsillectomy or modified
Uvulopalatoplasty .
Obstructive sleep apnea is a serious complication that seems to be most frequently associated with during sleep are associated with temporary
Airway Obstruction . Following pharyngeal flap surgery, depending on size and position, the flap itself may have an “
Obturator ” or obstructive effect within the
Pharynx during sleep, blocking ports of airflow and hindering effective
Respiration .Pugh, M.B. et al. (2000). Apnea. ''Stedman’s Medical Dictionary (27th ed.)'' Retrieved
June 18 ,
2006 from STAT!Ref Online Medical Library database.Liao, Y., Noordhoff, M.S., Huang, C., Chen, P.K.T., Chen N., Yun, C. et al. (2004). Comparison of obstructive sleep apnea syndrome in children with cleft palate following Furlow palatoplasty or pharyngeal flap for velopharyngeal insufficiency. ''Cleft Palate-Craniofacial Journal'', 41(2), 152-156. There have been documented instances of severe airway obstruction, and reports of post-operative OSA continue to increase as healthcare professionals (i.e. physicians,
Speech Language Pathologists ) become more educated about this possible dangerous condition.Peterson-Falzone, S.J., Hardin-Jones, M.A., & Karnell, M.P. (2001). ''Cleft Palate Speech (3rd ed.)''. St. Louis: Mosby. Subsequently, in clinical practice, concerns of OSA have matched or exceeded interest in speech outcomes following pharyngeal flap surgery.
The surgical treatment for velopalatal insufficiency may cause obstructive sleep apnea syndrome. When
Velopalatal Insufficiency is present, air leaks into the nasopharynx even when the soft palate should close off the nose. A simple test for this condition can be made by placing a tiny mirror at the nose, and asking the subject to say "P". This p sound, a plosive, is normally produced with the nasal airway closed off - all air comes out of the pursed lips, none from the nose. If it is impossible to say the sound without fogging a nasal mirror, there is an air leak - reasonable evidence of poor palatal closure. Speech is often unclear due to inability to pronounce certain sounds. One of the surgical treatments for velopalatal insufficiency involves tailoring the tissue from the back of the throat and using it to purposefully cause partial obstruction of the opening of the nasopharynx. This may actually ''cause'' obstructive sleep apnea syndrome in susceptible individuals, particularly in the days following surgery, when swelling occurs (see below: Special Situation: Anesthesia and Surgery)
There are a variety of treatments for obstructive sleep apnea, depending on an individual’s medical history, the severity of the disorder and, most importantly, the specific cause of the obstruction.
In acute
Infectious Mononucleosis , for example, although the airway may be severely obstructed in the first 2 weeks of the illness, the presence of lymphoid tissue (suddenly enlarged
Tonsils and
Adenoids ) blocking the throat is usually only temporary. A course of anti-inflammatory steroids such as prednisone (or another kind of glucocorticoid drug) is often given to reduce this lymphoid tissue. Although the effects of the steroids are short term, in most affected individuals, the tonsillar and adenoidal enlargement are also short term, and will be reduced on its own by the time a brief course of steroids is completed. In unusual cases where the enlarged lymphoid tissue persists after resolution of the acute stage of the
Epstein-Barr infection, or in which medical treatment with anti-inflammatory steroids does not adequately relieve breathing, tonsillectomy and adenoidectomy may be urgently required.
Most children with obstructive sleep apnea have the problem on the basis of chronically enlarged tonsils and adenoids. In these children, tonsillectomy and adenoidectomy is curative. The operation may be far from trivial, however, in the worst cases, in which growth is reduced and abnormalities of the right heart may have developed. Even in these extreme cases, however, the surgery tends to cure not only the apnea and upper airway obstruction - but to allow subsequent normal growth and development. Once the high end-expiratory pressures are relieved, the cardiovascular complications reverse themselves. The postoperative period in these children requires special precautions (see ''surgery and obstructive sleep apnea syndrome'' below).
The treatment for obstructive sleep apnea in the case of adults with poor oropharyngeal airways secondary to heavy upper body type is varied. Unfortunately, in this most common type of obstructive sleep apnea, unlike some of the cases discussed above, reliable cures are not the rule.
Some treatments involve lifestyle changes, such as avoiding alcohol and medications that relax the central nervous system (for example, sedatives and muscle relaxants), losing weight, and quitting smoking. Some people are helped by special pillows or devices that keep them from sleeping on their backs, or oral appliances to keep the airway open during sleep. If these conservative methods are inadequate, doctors often recommend
Continuous Positive Airway Pressure (CPAP), in which a face mask is attached to a tube and a machine that blows pressurized air into the mask and through the airway to keep it open. There are also surgical procedures that can be used to remove and tighten tissue and widen the airway, but the success rate is not high. Some individuals may need a combination of therapies to successfully treat their sleep apnea.
The most widely used current therapeutic intervention is ''positive airway pressure'' whereby a breathing machine pumps a controlled stream of air through a mask worn over the nose, mouth, or both. The additional pressure splints or holds open the relaxed muscles, just as air in a
Balloon inflates it. There are several variants:
- ( CPAP ), or ''continuous positive airway pressure'', in which a controlled air compressor generates an airstream at a constant pressure. This pressure is prescribed by the patient's physician, based on an overnight test or Titration . Newer CPAP models are available which slightly reduce pressure upon exhalation to increase patient comfort and compliance. CPAP is the most common treatment for obstructive sleep apnea.
- ( VPAP ), or ''variable positive airway pressure'', also known as bilevel or BiPAP, uses an electronic circuit to monitor the patient's breathing, and provides two different pressures, a higher one during Inhalation and a lower pressure during Exhalation . This system is more expensive, and is sometimes used with patients who have other coexisting respiratory problems and/or who find breathing out against an increased pressure to be uncomfortable or disruptive to their sleep.
- ( APAP ), or ''automatic positive airway pressure'', is the newest form of such treatment. An APAP machine incorporates pressure sensors and a computer which continuously monitors the patient's breathing performance. It adjusts pressure continuously, increasing it when the user is attempting to breathe but cannot, and decreasing it when the pressure is higher than necessary. Although FDA approved, these devices are still considered experimental by many, and are not covered by most insurance plans.
A second type of physical intervention, a
Mandibular Advancement Splint (MAS), is sometimes prescribed for mild or moderate sleep apnea sufferers. The device is a mouthguard similar to those used in sports to protect the teeth. For apnea patients, it is designed to hold the lower jaw slightly down and forward relative to the natural, relaxed position. This position holds the tongue farther away from the back of the airway, and may be enough to relieve apnea or improve breathing for some patients.
The FDA accepts only 16 oral appliances for the treatment of sleep apnea. A listing is available at their
website
Oral appliance therapy is less effective than CPAP, but is more 'user friendly'. Side-effects are common, but rarely is the patient aware of them.
There are no effective drug-based treatment for obstructive sleep apnea.
Oral administration of the
Methylxanthine Theophylline (chemically similar to
Caffeine ) can reduce the number of episodes of apnea, but can also produce side effects such as palpitations and insomnia. Theophylline is generally ineffective in adults with OSA, but is sometimes used to treat central sleep apnea (see below), and
Infant s and children with apnea.
When other treatments do not completely treat the OSA, drugs are sometimes prescribed to treat a patient's daytime sleepiness or
Somnolence . These range from
Stimulants such as
Amphetamines to modern anti-
Narcoleptic medicines. The anti-narcoleptic
Modafinil is seeing increased use in this role
As Of 2004 .
In most cases, weight loss will reduce the number and severity of apnea episodes. In the morbidly obese, a major loss of weight (such as what occurs after
Bariatric surgery) can sometimes cure the condition.
Many researchers believe that OSA is at root a
Neurological condition, in which nerves that control the tongue and soft palate fail to sufficiently stimulate those muscles, leading to over-relaxation and airway blockage. A few experiments and trial studies have explored the use of pacemakers and similar devices, programmed to detect breathing effort and deliver gentle electrical stimulation to the muscles of the tongue.
This is not a common mode of treatment for OSA patients as of 2004, but it is an active field of research.
A number of different surgeries are available to improve the size or tone of a patient's airway. For decades,
Tracheostomy was the only effective treatment for sleep apnea. It is used today only in rare, intractable cases that have withstood other attempts at treatment. Modern operations employ one or more of several options, tailored to each patient's needs. Long term success rates are low, resulting in most doctors favoring CPAP.
- Nasal surgery, including Turbinectomy (removal or reduction of a nasal Turbinate ), or straightening of the Nasal Septum , in patients with nasal obstruction or congestion which reduces airway pressure and complicates OSA.
- Tonsilectomy and/or Adenoidectomy in an attempt to increase the size of the airway.
- Removal or reduction of parts of the Soft Palate and some or all of the Uvula , such as Uvulopalatopharyngoplasty (UPPP) or Laser-assisted Uvulopalatoplasty (''LAUP''). Modern variants of this procedure sometimes use radiofrequency waves to heat and remove tissue.
- Reduction of the tongue base, either with laser excision or Radiofrequency Ablation .
- '' Genioglossus Advancement '', in which a small portion of the lower jaw that attaches to the tongue is moved forward, to pull the tongue away from the back of the airway.
- ''Hyoid Suspension'', in which the Hyoid Bone in the neck, another attachment point for tongue muscles, is pulled forward in front of the Larynx .
