Sleep apnea syndrome is a disorder characterized by intermittent respiratory arrests. By definition, these apneas are at least 10 s long and occur with a frequency of more than 10 times per hour. In most cases, the apnea lasts approximately 20-30 s, and in some patients it lasts as long as 2-3 min. Three forms of sleep apnea are distinguished:
- Central apnea (10%)The respiratory center of the brain is damaged. This leads to failures of cerebral control of breathing. The cause can be hereditary or result from neurological damage.
- Obstructive sleep apnea (OSA) (85%)The cause is obstruction of the upper airway during inspiration (inhalation). The interruption of breathing causes an arousal reaction in which the patency of the airway is restored. The patient falls back asleep, but this process is repeated very frequently.
- Mixed sleep apnea (5%)The cause is composed of the previous clinical pictures.
Patients suffering from sleep apnea very often express abnormal fatigue during the day. This fatigue leads to loss of performance and the so-called microsleep, which leads to accidents, especially in road traffic. For this reason, a detailed diagnosis is useful.
The procedure
The main diagnostic steps to identify sleep apnea syndrome are:
- Medical history or history of others by the partner.
- Ambulatory sleep monitoring
- Polysomnography in the sleep laboratory
- If necessary, further examinations by the ENT physician (see – OSA) or cardiological diagnostics (see hypertension).
A detailed medical history is of great importance, since the history or sleep hygiene (sleep habits and also dietary habits) contributes significantly to the detection of risk factors. The following anamnestic information or risk factors should be asked:
- Partner anamnesis – irregular snoring, apnea.
- Morning fatigue, headaches, tendency to sleep during the day.
- Obesity (morbid overweight)
- Alcohol, nicotine
- Sleeping pills, narcotics
- Nocturnal hypertension (high blood pressure)
- Left ventricular hypertrophy (LVH; enlarged left heart) with an unclear cause
- Difficult to adjust hypertension (high blood pressure).
The following diagnostic methods are available for further clarification of suspected sleep apnea syndrome:
- Ambulatory sleep monitoringMonitoring involves various measurements of different parameters, including: respiratory excursion, oxygen saturation (SpO2), nasal airflow, snoring sounds and heart rate.
- PolysomnographyIt is an examination that takes place in the sleep laboratory. The patient sleeps as undisturbed as possible in a room monitored by an infrared camera. In addition to observation, an electroencephalogram (EEG; recording of the electrical activity of the brain), an electromyogram (EMG; recording of electrical muscle activity), an electrooculogram (EOG; recording of the movement of the eyes or changes in the resting potential of the retina), and an electrocardiogram (ECG; recording of the electrical activity of the heart muscle) are performed. In addition, respiratory flow, respiratory excursion, and oxygen saturation (pulse oximetry) are also monitored.
- ENT examinationThese measures are used to inspect the upper airway to identify any obstructions that prevent airflow.
- Cardiac examinationThis examination consists of a long-term ECG and long-term blood pressure measurement (24-hour blood pressure measurement). This is necessary because patients with sleep apnea syndrome often suffer from bradycardia (heartbeat too slow: < 60 beats per minute, especially during the apnea phase), tachycardia (heartbeat too fast: > 120 beats per minute, especially immediately after the apnea phase) and cardiac arrhythmias.
Sleep apnea diagnosis is an important way to diagnose sleep apnea syndrome, which causes both a significant reduction in quality of life and a hazard in everyday life.
