Sleep Apnea
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Sleep apnea is a dangerous, potentially life-threatening condition. It is characterized by interruptions of breathing during sleep. These interruptions of sleep can compromise a good quality of life and are related to other serious medical conditions such as excessive daytime sleepiness, depression, high blood pressure, heart attack and stroke. It occurs in all age groups including children, but is most prevalent in older adults.
Sleep apnea is a disorder unique to human beings. Speech is another characteristic that distinguishes humans from lower animals. The articulation of speech requires a compliant, collapsible airway. The throat or pharynx is the compliant part of the airway that facilitates speech in humans, and collapses in sleep apnea. Air passes through the nose, mouth and pharynx on its way to the lungs. The pharynx is the conduit for two life supporting functions - swallowing and breathing. Breathing cannot occur simultaneously with swallowing in adult human beings. Normally the muscles of the pharynx maintain the open airway and close it only during swallowing and regurgitation. The exception is sleep apnea, a condition where the pharynx and tongue malfunction, collapse the airway and interrupt breathing during sleep.
(OSA) is defined as an episode of airflow interruption during sleep, characterized by normal breathing effort but no airflow, lasting longer than 10 seconds (approximately two breaths) and with a minimum of five such episodes per hour. Obstructive sleep apnea occurs only during sleep and not during wakefulness. Obstructive sleep apnea results from a complex interaction between nerves, muscles and certain predisposing structural anatomic factors. There is a normal relaxation in muscle tone during sleep but with any combination of the above factors in susceptible individuals, the airway closes. The brain then senses a reduction in oxygen and an increase in carbon dioxide and sends a signal to resume breathing. The patient experiences an from sleep in response to the brain signal, and the muscles of the tongue and pharynx open the airway and breathing resumes.
Often this occurs with a loud snort or gasp.
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Open Airway |
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Closed Airway = Apnea |
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The arousal from sleep is necessary to restart breathing, but prevents the patient from getting good quality sleep; and repeated episodes over the course of a night result in such symptoms as excessive daytime sleepiness, compromised immune system, poor concentration, memory problems, a slow reaction time and the medical problems mentioned previously.
is a partial airway obstruction during sleep, in which there is breathing effort but reduced airflow. There must be at least a 50% reduction in normal airflow for at least 10 seconds and more than five per hour. Hypopneas also result in arousals and symptoms similar to obstructive sleep apnea. The literature is consistent that obstructive sleep apnea to upper airway resistance syndrome represents a continuum from most severe sequelae to least, but that all are serious in terms of having morbid consequences.
(UARS) is defined as a decrease in inspiratory effort caused by a lack of muscular activity and reduction in airway size resulting in arousals from sleep without episodes of apnea or hypopnea, and usually characterized by snoring.
is a loud sound generated by some people as they breathe during sleep. It has been reported that one third of the population snore. It has been estimated that 60% of all males and 40% of all females over the age of 60 snore. The sound of snoring in some people has been measured at 90 decibels - a loudness that would require ear plugs in the industrial workplace. Virtually all people who have apnea snore to some extent, but not all snorers have apnea.
Benign snoring is nonobstructive and is in most cases the uvula fluttering in response to rapid air flow. The analogy is the sound of a flag flapping in a stiff wind.
Obstructive snoring results from a partial airway closure and/or a narrow airway. According to Bernoulli's Principle, "A decrease in the size of the lumen causes an increase in velocity of air, resulting in a decrease in pressure, sucking in the compliant airway walls and facilitating obstruction". The more obstructions, the more turbulence and greater suction on the walls. Tonsils, adenoids, fat tissue in the throat, swollen nasal membranes, long palate, deviated septum, and a large flaccid tongue narrow the airway, increase the speed and turbulence of inspired air. The vibration created by their impediment to airflow creates the sound of obstructive snoring.
results when the brain fails to signal the chest muscles to breathe. A defect in the metabolic control center does not respond properly to carbon dioxide in the blood and shuts down the breathing effort. A 10 second or greater episode of no ventilatory effort and no consequent air flow defines central apnea. Central apneas cause arousals from sleep. In the temporarily awake state normal respiratory effort resumes.
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