Sleep apnea syndrome (SAS) is a serious sleep disorder in which breathing stops and starts repeatedly during sleep due to airway obstruction. There are two main types of sleep apnea syndrome, which are:

• Obstructive Sleep Apnea Syndrome (OSAS), which is the most common and occurs when the throat muscles relax and obstruct the flow of air to the lungs.
• Central Sleep Apnea Syndrome (CSAS), which occurs when the brain does not send the necessary signals to the muscles that control breathing.

In order to better understand the SAS, we should give the definition of each parameter related to it. The definitions are as follows (1) :

• Apnea: Reduction in airflow or chest wall mobility to less than 25% of normal and lasting at least 10 seconds.
• Hypopnea: Reduction in airflow or chest wall mobility to less than 75% of normal and lasting at least 10 seconds.
• Hypopnea-apnea index (AHI): The sum of the number of apneas and hypopneas during sleep divided by the number of hours of sleep.
• Desaturation: Decrease in haemoglobin oxygen saturation
• Respiratory effort-related arousal (RERA): The sequence of breaths characterized by increasing respiratory effort by the patient, which leads to arousals, but does not meet the criteria for apnea or hypopnea.
• Respiratory Disturbance Index (RDI): The total number of apneas, hypopneas, and RERAs divided by the number of hours of sleep.

The severity of OSA is categorized based on the hypopnea-apnea index (AHI). The categories are as follows:

• Mild severity (AHI: 5-15/hour)
• Moderate severity (AHI: 15-30/hour)
• Severe severity (AHI: >30/hour)

Epidemiology

Studies have shown that the prevalence of sleep disorders in the community is 20%. A portion of this population experiences repeated episodes of breathing disorder and belong to the category of patients suffering from Sleep Apnea Syndrome (SAS). This percentage amounts to 4-5% of the middle-aged population. The association of sleep apnea syndrome with cardiovascular and cerebrovascular comorbidities is very significant (3). Statistical data from 16 countries and a total of 17 studies showed that the number of people worldwide with mild (AHI: 5-15/hour) and moderate (AHI: 15-30/hour) SAHs amounts to 936 million people, while with severe SAHs (AHI: >30/hour) amounts to 425 million people (4).

Symptoms and Risk Factors for the Occurrence of SAS

The main symptoms of OSAS are snoring, drowsiness and feeling tired during the day, as well as a headache upon waking in the morning. On the other hand, the main risk factors for the occurrence of SAS are:

• Obesity (body mass index -BMI- over 30)
• Neck circumference (over 43 cm for men and over 40 cm for women)
• Hypertension
• Diabetes
• Age and gender (5,6,7)

SAS and Associated Diseases

Multicenter studies have shown that OSAS is directly related to a large number of diseases such as heart failure, stroke, myocardial infarction, arterial and pulmonary hypertension, arrhythmias, atrial fibrillation, hyperlipidemia, diabetes mellitus, quality of life and depression (7).

Diagnosis of Sleep Apnea Syndrome

Polysomnography is the diagnostic test of choice for the diagnosis of SAS (7,8,9). There are two types of Polysomnography Sleep Study, the Polysomnography-PSG or full Sleep Study and the Polygraphy-PG or home Sleep Study (Home Sleep Apnea Test). The recording of both types of Sleep Study includes all the necessary parameters for the diagnosis of SAS syndrome, with the difference that the full Sleep Study includes additional neurophysiological parameters. A home sleep study should be recommended for patients with a strong suspicion of having SAS based on the subject’s sleep history. The advantage of a home sleep study is that it is performed in the home of the person being tested, avoiding admission to a hospital or clinic and possible exposure to viral environments. Also, the cost of a home sleep study is much lower than a full sleep study. In case of a negative result of the home sleep study or with a strong suspicion of the existence of SAS, a full sleep study is recommended (10,11,12) .

Sleep Apnea Syndrome Treatment

Managing SAS is multifactorial, while the effectiveness of therapeutic approaches depends largely on patient compliance. CPAP (Continuous Positive Airway Pressure) is considered the treatment of choice, while other treatment options include weight loss and surgery (removal of parts such as tonsils and replacement of the lower jaw bone). Studies have shown that CPAP therapy contributes to a significant reduction in the number of apneas, hypopneas, and desaturation during sleep (13,14).

Conclusion

If you snore, feel tired every day, wake up with a morning headache, suffer from diabetes, depression, hypertension and if you are overweight, then it is very likely that you belong to the category of patients who have Sleep Apnea Syndrome. Get a Sleep Study now to avoid serious future health problems.

-Dr. Plakia Theodora

Bibliography

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14. Hong-Po Chang1,2 | Yu-Feng Chen3,4 | Je-Kang Du1,5 Kaohsiung J Med 2020;36:7–12.wileyonlinelibrary.com/journal/kjm27