Sleep Apnea?

What is it? How do I know? What Can I Do?

The science of relieving sleep apnea has come a long way since 1981 when Australian Dr. Colin Sullivan and his colleagues Berthon-Jones, Issa and Eves introduced the first sleep-apnea machine. This is what is commonly called the C-PAP. This machine applies positive air pressure into the upper airway and pushes a constant flow of air into the lungs. The formal name of the machine is Constant Positive Air Pressure Machine. Prior to this the introduction of the C-PAP, severely affected patients were often given a tracheostomy to open the windpipe. Tubing was inserted so the upper airway could be bypassed.

Sleep apnea can be found in one of two forms. The first is called obstructive sleep apnea and the second is called central sleep apnea. While both of these are primarily defined as the temporary stopping of breathing during sleep, they have differing causes and require different treatments. It is important to understand that while the treatments are quite effective, at this time there is no cure so it is important to maintain treatment in order to control the symptoms of sleep apnea regardless of the originating cause.  

The original sleep apnea machine involved reversing the workings of a vacuum cleaner motor so that it would blow air into a patient's nasal cavity via tubing to keep the passage open. Pushing a constant flow of air into the lungs keeps the upper airway open because of the positive air pressure. The CPAP machine delivers a stream of compressed air via a hose to a nasal pillow, nose mask or full-face mask, keeping the airway open under positive pressure so that unobstructed breathing becomes possible. It is important to understand, however, that it is the air pressure, and not the movement of the air, that prevents the apneas.

The CPAP machine blows air at a prescribed pressure which is called the titrated pressure. In order to determine the appropriate pressure an overnight sleep study is undertaken. This procedure is called polysomnography. It is done in a sleep laboratory and supervised by a trained sleep technician. Normally the procedure takes two sessions.  In certain situations this study is taken at home.

Polysomnography is a comprehensive recording of the bio-physiological changes that occur during sleep. It is usually performed at night, when most people sleep, though some labs can accommodate shift workers and people with circadian rhythm sleep disorders and do the test at other times of day. The PSG monitors many body functions including brain (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG) and heart rhythm (ECG) during sleep. 

The test is used to determine the number of apneas and hypopneas that an individual experiences during sleep. The Greek word "apnea" literally means "without breath. An apnea is defined as the period of time during which breathing stops completely and hypopnea is defined as the period of time when an individual is breathing at a lower than normal volume for a period of at least 10 seconds.  Apneas usually occur during sleep, therefore sleep is usually disrupted. A person may wake up completely, but sometimes the person comes out of a deep level of sleep and into a more shallow level of sleep. The sleep study is conducted for a number of hours and preferably through a complete sleep period.  

In a person without sleep disorders, there are usually 4 stages of sleep that one goes though and they may go through these multiple times during their sleeping period. There are two main categories, one called REM or Rapid Eye Movement and the other Is NREM or Non Rapid Eye Movement. It is only during the REM cycles that one experiences dreams.  Sleep proceeds in cycles of REM and NREM. There is a greater amount of deep sleep early in the night, while the proportion of REM sleep increases later in the night and just before natural awakening. In a person with apneas and hypopneas many individuals never reach the level of REM sleep and do not remain in deep NREM sleep for very long.  

An estimate of the severity of apnea is calculated by dividing the number of apneas by the number of hours of sleep, giving an apnea index (AI). The greater the apnea index, the more severe the apnea.  During the second half of the sleep test if it is found that there are significant apneas, the technician will introduce either a C-PAP or Bi-PAP machine. Depending on the need the technician will increase the titrated pressure until the apneas cease.  

The titrated pressure is the pressure of air at which most of the apneas and hypopneas have been prevented.  It is usually measured in centimeters of water (cm H₂O). The pressure required by most patients with sleep apnea ranges between 6 and 14 cm H₂O. A typical CPAP machine can deliver pressures between 4 and 20 cm H₂O. More specialized units can deliver pressures up to 25 or 30 cm H₂O. It is for this reason that sleep-apnea machines require a physician’s prescription to be sold and all machines must be certified by the Food and Drug Administration.  

While the technician will read the test while it is being performed and has the ability and authority to introduce C-PAP or Bi-PAP, in order for a prescription to be written, a Doctor of Osteopathy, a Medical Doctor, a PhD or PsyD in a health related field must review the test and determine the applicability of the devices. Most insurance will cover the cost of the machine.  

We have included information of the typical accessories that might accompany your CPAP or Bi-PAP machine if that is the device that is determined to be the best treatment for your particular situation. We also have a list of manufacturers of CPAP and Bi-PAP. Read the symptoms of Sleep Apnea that you and those you live with can look for to see if you need to be evaluated for Sleep Apnea.