Sleep Apnea-Obstructive, Central and Mixed

Sleep Apnea is part of the spectrum of what is called "Sleep Disordered Breathing" or "SDB." The condition Sleep Apnea is commonly broken into three main categories. The three main categories of Sleep Apnea are as follows:

Obstructive Sleep Apnea (OSA)

Central Sleep Apnea (CSA)

Mixed Sleep Apnea (MSA)

The three main categories, or types, of Sleep Apnea will be discussed in more detail below. Sleep Apnea is commonly and effectively treated with CPAP therapy (Continuous Positive Airway Pressure). Keep in mind that this is not a comprehensive treatment on the subject of Sleep Apnea. For more information please reference the citations at the end of the article or speak with your doctor.

Obstructive Sleep Apnea (OSA)
With Obstructive Sleep Apnea, the soft tissue of the upper airway collapses during the night and slows air intake, eventually eliminating air intake altogether. When oxygen intake is reduced or eliminated and blood oxygen levels fall significantly, the brain sends an emergency signal to wake up and resume a normal breathing pattern. This process can happen as many as a few hundred times a night for some people with severe OSA. The use of a CPAP machine either drastically reduces these "apneic" events or eliminates them altogether. This results in the restoration of a normal breathing pattern and the CPAP user is able to achieve deep, REM(3) sleep, allowing the body to do routine maintenance and restore many healthful functions in the body.

Central Sleep Apnea (CSA)
Central Sleep Apnea is similar to OSA in its final effect on the sufferer, however, the mechanism of oxygen reduction is different. The principal mechanism of oxygen reduction in CSA is due to a failure of the brain to send a proper breathing "signal" to the muscles that control the breathing process. This type of Sleep Apnea is more rare than OSA and according to the Mayo Clinic accounts "for less than 5 percent of sleep apneas."(4) Even though CSA is different in function than OSA, the outcome for the sufferer is the same--reduced oxygen intake through out the night, failure to reach deep sleep cycles and general fatigue throughout the day. Fortunately, in most cases, CSA can be treated with the same equipment that is used for those that suffer with OSA. Most CPAP, BiPAP and APAP machines have sophisticated circuitry which allows for the detection of different types of apneas, allowing the machine to adjust to the needs of the user throughout the night.

Mixed Sleep Apnea (or Complex Apnea)
According to the National Institutes of Health, Mixed Sleep Apnea is defined as a combination of both Obstructive Sleep Apnea and Central Sleep Apnea. The technical explanation for Mixed Sleep Apnea according to the NIH is as follows: "intervals of ten seconds or longer during which there was a complete cessation of airflow accompanied by an absence of respiratory effort in the early part of the apneic episode and a resumption of respiratory effort in the latter part." Basically, this means that a CSA-related apneic event occurs, followed by an OSA-related apneic event. Interestingly, according to the study by the NIH, the sequence of events is always from CSA to OSA and never in reverse. In other words, the brain fails to send a signal to breath, resulting in an apneic event, followed by a collapse of the airway that further impedes oxygen flow. This makes sense, as it would not seem vary likely that an airway collapse related to an OSA-type event would cause the brain to misfire a breathing signal, however, a misfire by the brain would include the muscles involved in breathing and may lead to a loss of good muscle tone in the upper airway.

(1)http://www.webmd.com/sleep-disorders/sleep-apnea/sleep-apnea
(2)http://www.sleepapnea.org/info/index.html
(3)http://www.webmd.com/sleep-disorders/guide/sleep-101
(4)http://www.mayoclinic.com/health/central-sleep-apnea/DS00995