Sleep Apnea

Description

Diagnosis

Chronic daytime sleepiness and habitual snoring are the primary signs of sleep apnea. The risks are even higher in people who are overweight, hypertensive, or both. Not all people with suspected sleep apnea require diagnostic tests. For example, expensive diagnostic efforts are probably not required for individuals who have no health risk factors and no impairment of quality of life or higher risk for accidents.

If sleep apnea is suspected, physicians should seek diagnostic sleep studies under the following circumstances:

• In patients with serious medical conditions that might be worsened or caused by sleep apnea. Such conditions may include heart disease, hypertension, heart failure, diabetes, chronic headaches, epilepsy, obstructive lung disease, or severe acid reflux (GERD).
• In children who show signs of sleep apnea and who have attention deficit problems or failure to thrive.
• In cases where sleep apnea is severe enough to impair quality of life, increase the risk for accidents, or both.

In some cases of an uncertain diagnosis, high-risk patients may need to consult a sleep specialist or go to a sleep disorders center. At most centers, patients undergo an in-depth analysis, usually supervised by a multi-disciplinary team of consultants who can provide both physical and psychiatric evaluations. Centers should be accredited by the American Academy of Sleep Medicine.

Medical and Sleep History

To help determine the presence of sleep apnea, the physician needs the answers to a number of questions, including the following:

• Is the patient taking any medications?
• How many periods of sleepiness are there each day and when do they occur? (Patients with apnea often do not describe this symptom as feeling "sleepy." They are more apt to describe this feeling as "lack of energy" or "feeling tired all day.")
• How restful is sleep?
• Do headaches occur regularly in the morning?
• Is the patient taking or withdrawing from stimulants, such as coffee or tobacco?
• How much alcohol is consumed per day?
• Does the patient have any problems with mental or emotional functioning?
• Does the patient suffer from heartburn?
• What is the normal sleeping position (back, side, or stomach)?
• If there is a sleeping partner, does he or she complain about the patient's snoring or gasping for breath? (Many times it is useful to interview the bed partner.)

Keeping a Record of Sleep. To help answer these questions, the patient may need to keep a sleep diary. Every day for two weeks, the patient should record all sleep-related information, including responses to questions listed above described on a daily basis. Recording sleep behavior using an extended-play audio or videotape can be very helpful in diagnosing sleep apnea.

Physical Examination

To diagnose sleep apnea, the physician will check for physical indications of sleep apnea, including the following:

• Abnormalities in the soft palate or upper airways, including enlarged tonsils.
• Upper body obesity.
• A wide neck measurement.

In fact, some evidence suggests that physicians may accurate identify nearly all cases of suspected sleep apnea using physical criteria, including taking measurements of body mass (the indication of obesity), neck circumference, and four areas inside the mouth.

Ruling Out Other Disorders

If sleep apnea is not obvious after a physical examination and history, the physician will need to rule out any other problems. These include sleep disorders (e.g., narcolepsy, insomnia, restless legs disorder) or any medical or psychologic conditions (e.g., chronic fatigue syndrome, depression) that may be causing daytime sleepiness.

Polysomnography

Overnight polysomnography involves many measurements and is typically performed in a sleep center.

The patient arrives about two hours before bedtime without having made any changes in daily habits. Polysomnography electronically monitors the patient as he or she passes, or fails to pass, through the various sleep stages. Polysomnography tracks the following:

• Brain waves.
• Body movements.
• Breathing.
• Heart rate. One study suggested that many patients with obstructive sleep apnea display distinctive heart rhythms as detected by electrocardiogram (ECG).
• Eye movements.

Changes in breathing and the levels of oxygen in the blood are also recorded. In patients with suspected sleep apnea, the sleep expert will track instances of apnea and hypopnea that last longer than 10 seconds. In general, if there are more than five episodes per hour, apnea is significant and if there are more than 15, the condition is serious.

Overnight polysomnography has been the gold standard for diagnosing obstructive sleep apnea in both adults and children. It is very labor intensive and expensive, however, and also misses snoring-induced arousals. A full set of tests including a night at a sleep clinic may cost $2,000 to $3,000 and is not always covered by insurance. In addition, some centers have waiting lists that can be months long.

Home Diagnostic Portable Devices

A number of portable devices are available or being developed so that patients will have the convenience of being monitored at home. Experts hope that such monitors eventually will replace the need for overnight sleep clinics or the need for attended monitoring at home. Limited evidence exists, however, on the accuracy of many portable monitors. The presence of a sleep professional at home may be important to ensure accuracy. In any case, patients with serious medical conditions, including heart failure or a history of stroke or respiratory failure, should not use home tests.

The following are descriptions of some home monitoring techniques.

Home Oximetry. Pulse oximetry is a procedure that may be used to determine if oxygen levels in the blood are low (called hypoxia). Normal levels during the night would generally rule out sleep apnea. With this procedure, a device called a pulse oximeter is attached to the patient's finger. The oximeter transmits a two-wave length beam (red and infrared light) through the capillaries in the finger. Part of the light waves is absorbed by hemoglobin--a molecule in the blood that carries oxygen. The ratio of the two light beams provides the measurement of oxygen. The test is not always accurate, however. A combination with polysomnography, especially heart rate measurements, may prove to be useful for diagnosing sleep apnea.

Home oximetry monitors are available to rule out sleep apnea but their accuracy is unclear. A 2003 study indicated that home oximetry alone was not very helpful in discriminating between patients with or without sleep apnea. Home oximetry however, may be helpful in identifying patients with unsuspected and seriously low oxygen levels.

Unattended Monitoring with Auto-CPAP. This method is a recent and simple method for detecting impaired breathing. It uses an auto-CPAP machine, which is programmed to apply pressure through the airways via a tube that attaches to a mask that fits the nose. A monitor is attached that digitizes and records on a computer all the information on any apnea episodes during sleep.

Nasal Pressure Recording. One promising technique uses a very simple prong device that attaches to the nostrils. A monitor records the airflow through the mouth and nose.

Peripheral Arterial Tonometry. An investigative technique called peripheral arterial tonometry measures changes in blood flow in the arteries of the finger tips during sleep. Such measurements are proving to be accurate in detecting sleep apnea in 80% of cases.

Measuring Sleepiness

The Epworth sleepiness scale uses a simple questionnaire to measure excessive sleepiness during eight situations.