Central sleep apnea

Subject: Central sleep apnea Thu Jan 20, 2011 10:16 am

Central sleep apnea
Filed under: Sleep
Central sleep apnea is a disorder in which your breathing repeatedly
stops and starts during sleep due to lack of respiratory effort. Unlike
obstructive sleep apnea, in which you can't breathe normally because of
upper airway obstruction, central sleep apnea occurs when your brain
doesn't send proper signals to the muscles that control your breathing.
Central sleep apnea is less common, accounting for less than 5 percent
of sleep apneas.

Central sleep apnea may occur as a result of other conditions, such as
heart failure and stroke. Sleeping at a high altitude also may cause
central sleep apnea.

Treatments for central sleep apnea may involve using a device to keep your upper airway open or using supplemental oxygen.

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Symptoms

Common signs and symptoms of central sleep apnea include:

* Observed episodes of stopped breathing or abnormal breathing patterns during sleep
* Abrupt awakenings accompanied by shortness of breath
* Shortness of breath that's relieved by sitting up
* Difficulty staying asleep (insomnia)
* Excessive daytime sleepiness (hypersomnia)
* Difficulty concentrating
* Snoring

Although snoring indicates some degree of increased obstruction to
airflow, snoring may also be heard in the presence of central sleep
apnea. However, snoring may not be as prominent with central sleep apnea
as it is with obstructive sleep apnea.

When to see a doctor
Consult a medical professional if you experience, or if your partner
observes, any signs or symptoms of central sleep apnea, particularly the
following:

* Shortness of breath that awakens you from sleep
* Intermittent pauses in your breathing during sleep
* Difficulty staying asleep
* Excessive daytime drowsiness, which may cause you to fall asleep while you're working, watching television or even driving

Ask your doctor about any sleep problem that leaves you chronically
fatigued, sleepy and irritable. Excessive daytime drowsiness
(hypersomnia) may be due to other disorders, such as narcolepsy or
obstructive sleep apnea.

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Causes

Central sleep apnea occurs when your brain fails to transmit signals to
your breathing muscles. Central sleep apnea can be caused by a number of
conditions that affect the ability of your brainstem — which links your
brain to your spinal cord and controls many functions such as heart
rate and breathing — to control your breathing. The cause varies with
the type of central sleep apnea you have. Types include:

* Idiopathic central sleep apnea. The cause of this uncommon type of
central sleep apnea isn't known. It results in repeated pauses in
breathing effort and airflow.
* Cheyne-Stokes respiration. This type of central sleep apnea is
most commonly associated with congestive heart failure or stroke, and it
is characterized by a rhythmic, gradual increase and then decrease in
breathing effort and airflow. During the weakest breathing effort, a
total lack of airflow (central apneas) can occur.
* Medical condition induced apnea. In addition to congestive heart
failure and stroke, several medical conditions may give rise to central
apneas. Any damage to the part of the brain that controls breathing (the
brainstem) may impair the normal breathing process.
* High-altitude periodic breathing. Periodic breathing occurs in
most people if they're exposed to a high-enough altitude, such as an
altitude greater than 15,000 feet (4,572 meters). The change in
barometric pressure at this altitude can cause loss of breath as well as
rapid breathing (hyperventilation). The breathing pattern can be
similar to Cheyne-Stokes respiration.
* Drug or substance induced apnea. Taking certain medications such
as opioids — for example, morphine, oxycodone or codeine — may cause
your breathing to become irregular, to increase and decrease in a
regular pattern, or to stop completely.

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Risk factors

Certain factors put you at increased risk of central sleep apnea:

* Being male. Males are more likely to develop central sleep apnea than are females.
* Heart disorders. People with atrial fibrillation or congestive
heart failure are more at risk of central sleep apnea. Central sleep
apnea may be present in between 30 and 40 percent of people with
congestive heart failure.
* Stroke or brain tumor. These conditions can impair the brain's ability to regulate breathing.
* High altitude. Sleeping at an altitude higher than you're
accustomed to may increase your risk of sleep apnea. Altitudes above
15,000 feet (4,572 meters) can temporarily cause the condition in most
people. High altitude sleep apnea is no longer a problem when you return
to a lower altitude.
* Taking opioids. Opioids, such as morphine, oxycodone and codeine, increase the risk of central sleep apnea.

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Complications

Central sleep apnea is a serious medical condition. Complications include:

* Cardiovascular problems. Sudden drops in blood oxygen levels that
occur during sleep apnea increase blood pressure and strain the
cardiovascular system. These changes raise the risk of heart failure and
stroke. If there's underlying heart disease, these repeated multiple
episodes of low blood oxygen (hypoxia or hypoxemia) worsen prognosis and
increase the risk of abnormal heart rhythms.
* Daytime fatigue. In addition, the repeated awakenings associated
with sleep apnea make normal, restorative sleep impossible. People with
sleep apnea often experience severe daytime drowsiness, fatigue and
irritability. You may have difficulty concentrating and find yourself
falling asleep at work, while watching TV or even when driving.

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Preparing for your appointment

You're likely to start by first seeing your family doctor or a general
practitioner. However, you may then be referred to a doctor who
specializes in treating sleep disorders.

Because appointments can be brief, and there's often a lot of ground to
cover, it's a good idea to be well prepared for your appointment. Here's
some information to help you get ready for your appointment, and what
to expect from your doctor.

What you can do

* Bring results of prior sleep studies or other tests with you, or ask that they be given to your sleep specialist.
* Ask someone, such as a spouse or partner, who has seen you
sleeping to come with you to your appointment. He or she will likely be
able to provide your doctor with additional information.
* Write down any symptoms you're experiencing, including any that
may seem unrelated to the reason for which you scheduled the
appointment.
* Write down key personal information, including any major stresses or recent life changes.
* Make a list of all medications, as well as any vitamins or supplements, that you're taking.
* Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions
ahead of time will help you make the most of your time together. List
your questions from most important to least important in case time runs
out. For central sleep apnea, some basic questions to ask your doctor
include:

* What's the most likely cause of my symptoms?
* Are there other possible causes for my symptoms?
* What kinds of tests do I need? Do these tests require any special preparation?
* Is this condition temporary or long-lasting?
* What treatments are available, and which do you recommend?
* How will treating — or not treating — my sleep apnea affect my health now, and in the future?
* I have other health conditions. How can I best manage them together?
* Are there any dietary or activity restrictions that I need to follow before bed?
* Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor,
don't hesitate to ask questions during your appointment at any time that
you don't understand something.

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to
answer them may reserve time to go over any points you want to spend
more time on. Your doctor may ask:

* When did you first begin experiencing symptoms?
* Have your symptoms been continuous or occasional?
* Can you describe your typical sleep schedule?
* How long do you sleep, and do you sleep soundly?
* Does anything unusual occur while you're sleeping?
* Do you know if you snore?
* How do you feel when you wake up?
* Do you fall asleep easily during the day?
* Has anyone ever told you that you stop breathing while you're sleeping?
* How many times do you wake up at night?
* Are you short of breath when you wake up at night?
* Does anything seem to improve your symptoms?
* Is there anything that seems to worsen your symptoms?
* Do you have any other medical conditions?
* What medications, if any, are you currently taking?

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Tests and diagnosis

Your doctor may make an evaluation based on your signs and symptoms or
may refer you to a sleep disorder center. There, a sleep specialist can
help you decide on your need for further evaluation. Such an evaluation
often involves overnight monitoring of your breathing and other body
functions during sleep. Tests to detect central sleep apnea may include:

* Nighttime monitoring (nocturnal polysomnography). During this
test, equipment monitors your heart, lung and brain activity, breathing
patterns, arm and leg movements, and blood oxygen levels while you
sleep. This can help your doctor rule out other conditions — such as
periodic limb movements or narcolepsy — that can cause excessive daytime
sleepiness but require different treatment.
* Blood oxygen monitoring (oximetry). This screening method involves
using a small device that monitors and records your blood oxygen level
while you're asleep. A small sleeve fits painlessly over one of your
fingers to collect the information overnight at home. If you have sleep
apnea, the results of this test will often show drops in your oxygen
level during apneas and subsequent rises with awakenings. If the results
are abnormal, your doctor may have you undergo polysomnography to
confirm the diagnosis. Oximetry doesn't detect all cases of sleep apnea,
so your doctor may still recommend a polysomnogram even if the oximetry
results are normal.
* Portable breathing (cardiorespiratory) testing. Under unusual
circumstances, your doctor may provide you with tests to be used at home
to detect sleep apnea. These tests usually involve oximetry,
measurement of airflow and breathing patterns.
* Arterial blood gas testing. Under some circumstances, it's
necessary to obtain a measure of both oxygen and carbon dioxide in the
blood to help make the correct diagnosis and assess the severity of your
condition. This test involves drawing blood from an artery, usually one
in your wrist.

An evaluation by a heart specialist (cardiologist) or a doctor who
specializes in the nervous system (neurologist) may be necessary to look
for causes of central sleep apnea.

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Treatments and drugs

Treatments for central sleep apnea may include:

* Treatment for associated medical problems. Possible causes of
central sleep apnea include other disorders, and treating those
conditions may help your sleep apnea. For example, appropriate therapy
for heart failure may eliminate central sleep apnea.
* Reduction of opioid medications. If opioid medications are causing
your sleep apnea, your doctor may gradually reduce your dose of those
medications.
* Supplemental oxygen. Using supplemental oxygen while you sleep may
help if you have central sleep apnea. Various forms of oxygen are
available as well as different devices to deliver oxygen to your lungs.
This treatment generally isn't recommended for those with heart failure.
* Medications. Certain medications have been used to stimulate
breathing in people with central sleep apnea. For example, some doctors
prescribe acetazolamide to prevent central sleep apnea in high altitude.
* Continuous positive airway pressure (CPAP). This method, also used
to treat obstructive sleep apnea, involves wearing a mask over your
nose while you sleep. The mask is attached to a small pump that supplies
pressurized air which holds open your upper airway. CPAP may prevent
the airway closure that can trigger central sleep apnea. As with
obstructive sleep apnea, it's important that you use the device only as
directed. If your mask is uncomfortable or the pressure feels too
strong, talk with your doctor so that adjustments can be made.
* Bilevel positive airway pressure (bilevel PAP). Unlike CPAP, which
supplies steady, constant pressure to your upper airway as you breathe
in and out, bilevel PAP builds to a higher pressure when you inhale and
decreases to a lower pressure when you exhale. The goal of this
treatment is to boost the weak breathing pattern of central sleep apnea.
Some bilevel PAP devices can be set to automatically deliver a breath
if the device detects you haven't taken a breath after a certain number
of seconds.
* Adaptive servo-ventilation (ASV). This newer airflow device is
designed to treat central sleep apnea and complex sleep apnea. The
device monitors your normal breathing pattern and stores the information
in a built-in computer. After you fall asleep, the machine uses
pressure to regulate your breathing pattern and prevent pauses in your
breathing.

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