An Overview of Sleep Apnea

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What is Sleep Apnea?

Most people breathe easily during their waking hours and also while asleep. However, some persons are unable to breathe regularly and consistently while sleeping. This problem or the inability to breathe regularly is called sleep apnea when the period of pause between two breaths (respirations) is longer than 10 seconds. This means that if one is unable to breathe for more than 10 seconds when asleep, it is sleep apnea. Thus a patient of this disease might miss one or more breaths frequently during the same night. Associated with this is a tendency toward neurological arousal (which means significant changes on an EEG- electroencephalogram) and also significant hypoxemia or decrease in blood oxygen levels. Both of these latter changes can easily be measured to label a patient as suffering from sleep apnea.

What Are the Causes of Sleep Apnea?

There are basically two types of this condition determined based on the causative factors- a) The most common is obstructive sleep apnea b) central sleep apnea– the incidence of which is far less common c) there may be a combination of both obstructive and central apnea and this is called complex sleep apnea.

The vast majority of cases are obstructive in nature. Here there is an improper passage of the respired air via the airways. The most typical source of obstruction is in the airway at the level of the throat- ie: trachea or windpipe and the larynx or voice box. Conditions like obesity and diabetes may compound the problem. Very often, the airways are obstructed by the supine posture of the patient, causing, gravitational collapse, although partial. The airway at the level of the windpipe is composed of significant amounts of loose and flexible tissue, like the mucosa or inner lining of the trachea (windpipe). Any factor which causes these tissues to collapse onto the air passage can lead to obstructive sleep apnea. It must be mentioned here, that obesity is thus a very important factor for obstruction, due to the large amount of fatty tissue that accumulates around the neck.

Central Sleep Apnea

Central sleep apnea is due to faulty control of respiration by the central nervous system. This condition is also called Cheyne-Stokes respiration in medical parlance. Herein, the patient often does not even make the effort to breathe during the periods of apnea and it is usually the result of the brain to receive proper feedback about the low levels of oxygen in the person’s blood (hypoxemia). Thus the patient often swings wildly between phases of low blood oxygen and high blood carbon dioxide to phases of increased respiration to compensate for this problem. This is thus a much more serious problem than obstructive sleep apnea.

What are the Symptoms of Sleep Apnea?

One of the earliest symptoms of sleep apnea of the obstructive variety, is the presence of snoring during sleep. Snoring suggests presence of obstruction in the trachea at the level of the throat. However not all cases of snoring are caused by sleep apnea.  Other symptoms like drowsiness during the day and the inability to concentrate at work or while driving may be evident.

For more information see: Sleep Apnea

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