Central Sleep Apnea

Do you always feel sleepy during the day? Though you might be suffering from watching too many late-night talk shows, your sleepiness may also be a sign of a much more serious condition-sleep apnea.

People with sleep apnea stop breathing, something hundreds of times a night. Sleep apnea not only can rob you of a good night’s sleep, but it also can put you at increased risk for heart disease, stroke, and several other serious health conditions.

Three types of sleep apnea exist:

• Obstructive
• Central
• Mixed

Obstructive sleep apnea is the most common type. Central sleep apnea is far less common, affecting less than 5% of patients referred to sleep centers, but it can be just as serious if left untreated. Sometimes central sleep apnea can occur together with obstructive sleep apnea, and their symptoms often overlap.

Causes
Unlike obstructive sleep apnea, which often occurs in people who are obese when soft tissue in the back of the throat collapses during sleep and partially or completely blocks the airway, central sleep apnea has to do with a problem in the brain.

Normally, breathing is controlled by the brain stem, which responds to rising levels of carbon dioxide in the blood by triggering the respiratory muscles to stimulate breathing. This feedback loop is called the respiratory control system.

In people with central sleep apnea, the brain doesn’t respond as quickly as it should to changing blood levels of carbon dioxide, which leads to pauses in breathing. These problems become most apparent at night, when the drive to breathe is minimized, and the body becomes more dependent on the respiratory control system to breathe.

The condition most commonly associated with central sleep apnea is congestive heart failure. Other diseases that can cause central sleep apnea include:

• An illness or damage to the brain stem (encephalitis, polio, or a tumor)
• Conditions that affect the nervous system (stroke)
• Diseases that affect the muscles involved with breathing (Lou Gehrig’s disease, myotonic dystrophy)

Other possible causes of central sleep apnea include:

• Sleeping at a high altitude (the change in altitude can affect breathing patterns)
• The use of opioid pain medications (morphine or codeine)

In some cases, breathing stops repeatedly during the night without any obvious cause. This is referred to as idiopathic central sleep apnea.

Risk Factors
Your risk of central sleep apnea may be higher if you:

• Are male. Men are about twice as likely to develop sleep apnea as women.
• Have a heart disorder. Congestive heart failure is a significant risk factor for central sleep apnea. Atrial fibrillation will also increase the risk of developing central sleep apnea.
• Have a neurological condition, such as a stroke. Such conditions can affect the brain’s ability to regulate breathing.
• Have had trauma to the head.
• Have a degenerative brain disorder such as Alzheimer’s disease.
• Have a neuromuscular disorder. Amyotrophic lateral sclerosis (Lou Gehrig’s disease) and spinal cord injuries, among other conditions, can affect the nerve pathways that control breathing.
• Visit a higher altitude. Sleeping at above 15,000 feet can trigger sleep apnea in many people. Anything above 25,000 feet almost guarantees that you will develop sleep apnea.
• Take narcotic pain medications. Opioid pain medications (such as codeine, morphine, and oxycodone) may cause breathing to slow, become irregular, or even stop.

Symptoms and Signs
The main symptom is stopping to breathe during sleep, often many times each night. Pauses in breathing can last anywhere from 5 to 30 seconds. Snoring may or may not occur along with sleep apnea. Although you may not notice when you stop breathing, all of those breathing disruptions prevent you from reaching the deep, restful period of sleep and can leave you feeling overly tired the next day. Other symptoms can include:

• Repeated, abrupt awakenings during the night
• Insomnia (difficulty falling asleep or staying asleep)
• Periodic breathing (breathing becomes rapid, slows down, stops, than starts again)
• Shortness of breath at night
• Daytime sleepiness
• Morning headaches
• Difficulty concentrating

If an underlying illness such as a neurological disorder is causing your sleep apnea, you might experience such symptoms as:

• Weakness
• Numbness
• Difficulty swallowing
• Lightheadedness

When to Seek Medical Advice
Because its symptoms aren’t always obvious, sleep apnea is often overlooked.
Call the doctor if you experience any of the following:

• Observed pauses in breathing while you sleep
• Shortness of breath at night
• Excessive daytime sleepiness including falling asleep while working, watching TV or driving.
• Snoring that disrupts the sleep of yourself or others
• Difficulty falling asleep or staying asleep

Diagnosis
The doctor may call for a night time sleep study (nocturnal polysomnography), in which you stay overnight in a hospital or sleep laboratory while technicians monitor your heart rate, breathing, blood-oxygen levels, brain activity, and other body functions. Portable monitors, which allow you to check most of these functions at home, may be available.

Depending on the cause of the sleep apnea, you might also need to see a doctor who specializes in disorders of the nervous system (neurologist) or heart (cardiologist).

Complications
If you don’t get treatment for central sleep apnea, your risk may increase for:

• Heart disease
• High blood pressure
• Heart failure
• Stroke
• Diabetes
• Vehicle accidents (due to daytime sleepiness)

Treatment
Treatment begins by addressing the condition that is causing the problem.

The following may improve your central sleep apnea and help you sleep better:

• Continuous positive airway pressure (CPAP) – a mask that gently blows air into the lungs while you sleep. This treatment is particularly helpful in patients with central sleep apnea who also have congestive heart failure.
• Supplemental oxygen through a nose mask while you sleep
• Medications (such as the respiratory stimulants acetazolamide and theophylline)
• Adaptive servo-ventilation (ASV) – a newer device that records your normal breathing pattern and then uses that information to bring your nighttime breathing back to normal.

If you’ve been diagnosed with central sleep apnea, avoid using sedatives, which will worsen the problem.

Prognosis
The prognosis depends on the health condition causing the problem. Receiving treatment for the underlying health condition-particularly heart disease can improve the prognosis. While some underlying conditions can be treated, others, such as brain stem injuries or neurological conditions may be more difficult to treat.

People with sleep apnea are prone to complications during and right after surgery, as they are more likely to have breathing problems. It is important to tell your doctor before surgery if you have sleep apnea.

Sources:
National Heart, Lung, and Blood Institute. Sleep Apnea.
http://www.nhlbi.nih.gov/health/dci/Diseases/SleepApnea/SleepApnea_WhatIs.html
Mayo Clinic. Central Sleep Apnea
http://www.mayoclinic.com/health/central-sleep-apnea/DS00995
Mason RJ, Murray JF, Broaddus VC, Nadel JA. Mason: Murray and Nadel’s Textbook of Respiratory Medicine.
4th ed. Philadelphia, PA: Saunders Elsevier; 2005:chap 74.
Connolly TA, Sharafkhaneh A. Sleep-related breathing disorder and heart disease - central sleep apnea. Sleep Medicine Clinics. 2007;2:107-117.
Eckert DJ, Jordan AS, Merchia P, Malhotra A. Central sleep apnea pathophysiology and treatment. Chest. 2007;131: