Sleep Apnea

Learn About Sleep Apnea

Obstructive sleep apnea, a common sleep disorder, occurs when tissue in the upper airway collapses during sleep, blocking airflow into the lungs.  Except perhaps for snoring, most people with obstructive sleep apnea do not have any idea that the obstructions are occurring during the night.  But symptoms present the following day can be a clue to what is happening during sleep:  Daytime sleepiness, headaches upon awakening, impaired emotional stability or mental functioning, heartburn, hoarseness, and obesity are just a few.  Of these, daytime sleepiness is the most noticeable.  Daytime sleepiness can increase the risk for accident-related injuries.  Studies suggest that people with sleep apnea have two to three times as many car accidents, and are at five to seven times the risk for multiple accidents.  

Obstructive sleep apnea, or OSA, is a disorder in which breathing stops during sleep, due to obstruction of the airway by the tongue or other redundant tissue in the mouth and throat.  Apneas, or gaps in breathing lasting 10 seconds or more, may occur hundreds of times in a night.  Air enters through the nose and mouth, combining in the throat on its way to the lungs.  While the back of the throat is soft and prone to collapse under inspiration (breathing in), dilator muscles ordinarily counter this trend.  However if there is sufficient extra tissue in the throat (such as large tonsils), or if the tongue flops back and blocks the airway, or if the dilator muscles are temporarily relaxed (as occurs during rapid eye movement, or REM, sleep), the airway will be blocked.  The body will make movements in an attempt to inspirate and restore ventilation, but paradoxically these efforts can worsen the apnea, and in the process pull stomach acid up into the esophagus (causing heartburn) or even the tissues of the larynx (causing hoarseness).  Only a brief awakening, called an arousal, will terminate the apnea, sometimes with a snorting or sucking sound.  These arousals are typically so brief that the sleeper is not aware they are occurring, but they fragment the sleep and make it nonrestorative, meaning neither restful nor refreshing.  

Airway collapse might not be complete, resulting in a reduction rather than a cessation of airflow.  These episodes are called hypopneas, and like apneas, they terminate in an arousal.  Obstructive sleep apnea is defined as five or more episodes of apnea or hypopnea per hour of sleep (called the apnea-hypopnea index, or AHI); in addition to daytime sleepiness.  15 or more episodes of apnea or hypopnea per hour of sleep constitute moderate sleep apnea.

Obstructive sleep apnea can develop in anyone, at any age; but it most often occurs in people who are overweight, male, age 40 and older, and smokers.  Certain physical characteristics of the face, skull, and neck can affect the size of the airway.  Of these, the feature best predictive of obstructive sleep apnea is a large neck, meaning 17 inches or greater in men and 16 inches or greater in women.  This is especially true if the large neck is due to being overweight, or obese.  Although primarily a problem dealt with by adults, children can develop OSA as well.  In fact, sleep apnea occurs in about 2% of children and can occur even in very young children.  Obesity and overgrown tonsils, adenoids, or both is sufficient to cause the disorder; but weight control and removal of tonsils and adenoids can be curative.

Although OSA is a serious medical condition, some simple lifestyle changes can help quite a lot. Not sleeping on the back, avoiding alcohol within four hours of bedtime, and losing weight – even a small amount of weight loss can substantially alleviate symptoms – are all measures that can mitigate if not eliminate obstructions.  But for many people, the treatment of sleep apnea requires a device to keep the airway open at night.  Continuous positive airway pressure, or CPAP, is a device that blows air through the back of the throat to keep the airway from collapsing.  The air is heated and humidified for comfort.  Dental devices, or oral appliances, can be fitted to keep the airway open by putting mild traction on the lower jaw through the teeth, (Mandibular advancement device (MAD)) or positioning the tongue forward in the mouth to keep it from falling back onto the airway (Tongue retraining device (TRD)).  Finally, surgery can be used to remove or otherwise manage redundant tissue in the back of the mouth and throat that contributes to airway closure.

Obstructive sleep apnea can lead to a number of complications, ranging from daytime sleepiness to possible increased risk of death. Sleep apnea has a strong association with several diseases, particularly those related to the heart and circulation, including high blood pressure (or hypertension), coronary artery disease, heart attack (or myocardial infarction), stroke, heart failure, and the cardiac rhythm disturbance atrial fibrillation.  An association between severe apnea and psychological problems has been reported; for depression, the risk rises with increasing severity of sleep apnea while sleep-related breathing disorders can also worsen nightmares and post-traumatic stress disorder.  Small children with sleep apnea may "fail to thrive," that is, they do not gain weight or grow at a normal rate, and have low levels of growth hormone. In older children, the condition may manifest as hyperactivity and attentional deficits.

Polysomnography is the technical term for an overnight sleep study that involves recording brain waves and other sleep-related activity in order to diagnose and characterize OSA in a given patient.  Overnight polysomnography has been the gold standard for diagnosing obstructive sleep apnea in both adults and children.  After the diagnosis of sleep apnea is made, the patient must come back to the sleep center for another night in order to have CPAP started (CPAP titration).

Drugs are not very helpful with obstructive sleep apnea per se and in fact, some medications, such as sedatives, can worsen the condition.  However there are medications that are quite effective in managing the daytime sleepiness dimension of the illness, when used in combination with CPAP.  In particular, the FDA has approved the alerting agents modafinil (Provigil) and armodafinil (Nuvigil) for this purpose.  Stimulant medication, while not approved for daytime sleepiness, are used nonetheless as well.  


Bibliography:

Obstructive Sleep Apnea | University of Maryland Medical Center
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