What Is Obstructive Sleep Apnea (OSA)? What Causes Sleep Apnea?

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Main Category: Sleep / Sleep Disorders / Insomnia
Also Included In: Ear, Nose and Throat
Article Date: 09 Feb 2010 - 0:00 PST

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Obstructive sleep apnea, or OSA is a sleep disorder in which the patient stops breathing for 10 seconds or more during sleep. It is caused by relaxation of the throat muscles; the soft tissue in the rear of the throat collapses and closes, resulting in blocked airways. The episodes of pauses in breathing are called apneas, which literally means "without breath". An apnea is a period during which breathing either stops or is significantly reduced.

In the USA the spelling is apnea, while in the UK/Ireland and many other countries the word is spelt apnoea.

The English medical word apnea comes from the Greek word apnoia, meaning "absence of respiration". The Greek word apnos means "without breathing"; the prefix a in Greek means "not". The Greek word pneo or pnein means "to breathe".

In obstructive sleep apnea breathing is interrupted by a physical obstruction to airflow, despite efforts to breathe. The patient will often wake up but is rarely aware of the difficulty they had. The problem is typically noticed by whoever is watching the patient sleep, such as partners, parents, siblings, or other people in a dormitory.

There are several types of sleep apnea (sleep-disordered breathing), of which obstructive sleep apnea is the most common.

Most patients with obstructive sleep apnea snore, but not all. According to Medilexicon's medical dictionary, Obstructive Sleep Apnea (OSA) is:

a disorder, first described in 1965, characterized by recurrent interruptions of breathing during sleep due to temporary obstruction of the airway by lax, excessively bulky, or malformed pharyngeal tissues (soft palate, uvula, and sometimes tonsils), with resultant hypoxemia and chronic lethargy. Sleep in the supine position predisposes apnic episodes.

US health authorities believe that approximately 1 in every 5 American adults has some degree of obstructive sleep apnea (OSA). The National Health Service (NHS), UK reports that OSA is common, and affects 3.5% of men and 1.5% of women. People over the age of 40 are more likely to develop the condition; but individuals of all ages may be affected, even children.

Obese people are particularly at risk of having OSA because the extra fat pushes against the throat muscles.

What are the signs and symptoms of sleep apnea?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor detect. For example, pain may be a symptom while a rash may be a sign.

Patients may be unusually sleepy during the day, sleep is fidgety, there is usually snoring which may be loud, during sleep there also be periods of silence (no breathing) and then gasps.

Less commonly, the patient may suffer from morning headaches, insomnia, poor concentration, moodiness, anxiety, irritability, and depression.

The patient's libido (sex drive) may decrease. Adult males may suffer from erectile dysfunction (difficulty in either getting or maintaining an erection). Blood pressure often goes up (hypertension), there may be weight gain, increased urination and getting up at night to urinate (nocturia).

Some patients complain of heartburn.

A significant number of sufferers wake up during the night with a dry mouth/throat.

What causes obstructive sleep apnea?

Experts say that the main causes of OSA are:

• Old age
• Temporary or permanent brain injury
• Decreased muscle tone - could be caused by drugs, alcohol, a neurological problem, or some other disorder.
• Excess soft tissue around the airway; common with obese patients
• Something physical in the throat or mouth/jaw shape

When a person is asleep the muscles in the body relax and become limp, including the throat muscles. For most of us this is not a problem. However, the muscles of people with OSA become so limp that the airway constricts (narrows); the narrowing may become so severe that the airway closes up completely.

Initially, narrowing of the airway causes snoring.

If the airway becomes completely blocked the individual stops breathing for a few seconds - apnea occurs for a few seconds. If a sleeping person with OSA stops breathing they soon wake up, and quickly go back to sleep unaware that breathing had stopped.

If the airway is only partially blocked, breathing will become slow and shallow (hypopnea).

A bedfellow, or other people in the bedroom/dormitory may notice the patient stops breathing, will then suddenly gasp or grunt, wake up for a second or two, and then go back to sleep.

Most people have the occasional apnea during sleep, when breathing stops, following by a snort. People with OSA, however, have several episodes of no breathing while they sleep. For a diagnosis of OSA to be made, the patient should have at least five such episodes per hour. In very severe cases, a patient may have hundreds of episodes in one sleeping session.

Even though the patient with OSA may not be aware of the problem, if they woke up lots of times during the night their sleep was not a good quality restful one. Consequently, during the day they will feel unusually sleepy. People who snore loudly and feel sleepy during the night have probably got OSA.

OSA in children is usually caused by tonsils or adenoids that obstruct the airway.

The following groups of people have a higher risk of developing OSA:

• Diabetes - especially if the diabetes is not well controlled
• Individuals with hypertension (high blood pressure)
• Obese individuals
• People who regularly suffer from nasal congestion
• People whose inner jaw is set back further than normal
• People with enlarged tonsils or adenoids
• People with fat necks
• Smokers - regular smoking significantly increases the risk of OSA
• Regular alcohol consumption - alcohol is a sedative which can over-relax the throat muscles.
• Family history - people whose parent or sibling has/had OSA have a higher risk of developing it themselves.
• Down syndrome - people with Down syndrome are more likely to suffer from OSA, compared to other individuals.
• Some surgeries - OSA is a possible complication of pharyngeal flap surgery

What are the complications of obstructive sleep apnea?

• Hypertension (high blood pressure)
• Automobile accidents - because the patient is sleepy and drowsy during his/her waking hours.
• Family members suffer - especially if a person shares the same bed or bedroom. Loud snoring, a common feature of OSA, can undermine the quality of sleep of other members of the household.
• Later risk of heart attack (link)
• Erectile dysfunction - problems either getting an erection or maintaining one. (link)

How is obstructive sleep apnea diagnosed?

The doctor, usually a GP (general practitioner, primary care physician) at first will ask the patient about symptoms and daytime drowsiness/sleepiness. This will probably be followed by a physical examination, which will include checking the patient's blood pressure.
Blood test - this may be done to rule out any thyroid problems.

Nocturnal Polysomnography - records brain wave changes, eye movements, leg movements, blood oxygen levels, muscle tone, heart rhythms and respiration during sleep. This test helps rule out other possible conditions. A series of electrodes are placed in various parts of the body. This is carried out in a hospital or specialized sleep clinic.

Oximetry - an oximeter is a small sensor that is placed on the finger and sends out light pulses. The sensor is attached to a computer which can measure blood oxygen levels in real time. This test can be done at home.

Epworth sleepiness scale - this scale measures the patient's level of daytime sleepiness, which may help in the diagnosis of sleep disorders. It was introduced by Dr. Murray Johns, Epworth Hospital, Melbourne, Australia. The patient completes a short questionnaire which asks about probabilities of falling asleep in 8 different situations - the patient rates the probabilities on a scale from 0 to 3. A score of 0 to 9 is considered normal, anything above that indicates a higher risk of a sleep disorder.

The Epworth sleeping scale is repeated after treatment to determine whether the patient has improved.

The National Health Service (NHS), UK has three ratings for OSA (the patient may have to spend a night in hospital or specialized sleep clinic for testing):

• Mild - the patient has 5-14 episodes of apnea or hypopnea per hour
• Moderate - 15 to 30 episodes of apnea or hypopnea per hour
• Severe - over 30 episodes of apnea or hypopnea per hour

What is the treatment for obstructive sleep apnea?

Mild obstructive sleep apnea (OSA) - in the UK doctors will probably recommend some lifestyle changes, which may include:

• Losing weight - obesity is a major cause of OSA. (link)
• Alcohol - cutting out alcohol completely until symptoms improve. If this is not possible, not drinking in the evening may help.
• Changing medications - some medications, especially sedatives may cause OSA.
• Smoking - the patient will be advised to quit
• An exercise program - a study found a link between the severity of obstructive sleep apnea and a sedentary lifestyle (link).
• Sleeping position - some people find that symptoms improve if they sleep on their side or slightly propped up.

Positive airway pressure - a machine delivers air pressure through a mask over the nose while the patient sleeps. With this positive airway pressure (CPAP) many patients' airways are kept open, resulting either in no apnea and snoring, or much less. Initially, some individuals may not like sleeping with a mask on; doctors say that with perseverance most patients get used to it and the benefits are worth it. A study found that CPAP improves symptoms of depression in OSA patients. ( link)

Oral devices - these are mouthpieces designed to keep the throat open. A mandibular advancement device is worn inside the mouth during sleep; it pulls the lower jar (mandible) forward slightly so that the throat is less constricted (narrow) at night.

Stimulants - patients with severe daytime drowsiness may be prescribed a stimulant (short-term), such as modfanil.

Surgery - the National Health Service (NHS), UK says that surgery should be used as a last resort because it is not usually as effective as continuous positive airway pressure.

• A tracheostomy may be used - in this surgical procedure an opening (stoma) is created into the windpipe; a tube is inserted directly into the neck, bypassing the blocked area.
• Uvulopalatopharyngoplasty - tissue is surgically removed from the top of the throat and back of the mouth; the adenoids and tonsils may also be taken out.

Playing the didgeridoo - this is a musical instrument of the Aboriginal peoples of Australia. It is a long, hollow branch or stick and makes a deep drone when blown into. Regular didgeridoo playing reduces snoring and daytime sleepiness, according to a study published by the BMJ. (link)

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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