Obstructive sleep apnea is a condition where the airway is blocked during sleep, preventing or reducing airflow. This results in decreased oxygen levels in the blood, increased carbon dioxide levels, elevated blood pressure, increased autonomic nervous system activity, and to stop the breathing interruption during sleep, the brain briefly awakens, sometimes for just seconds, which the patient often does not realize. These events occur multiple times throughout the night. In severe cases, it can happen more than a hundred times per hour, leading to poor sleep quality, waking up unrefreshed, feeling fatigued, poor memory, and is a major cause of road accidents and workplace incidents.
Many studies have found that obstructive sleep apnea is a risk factor for hypertension, diabetes, insulin resistance, and metabolic syndrome. Additionally, obstructive sleep apnea is commonly found in patients with coronary artery disease, stroke, and arrhythmias, suggesting that sleep apnea may be a risk factor for these conditions.
The condition involves obstruction of the upper airway causing reduced or intermittent breathing, leading to decreased oxygen levels in the blood and stimulating brain arousal, preventing continuous normal sleep. Obstructive sleep apnea is the most common disorder among sleep-related breathing disorders. Currently, its prevalence is increasing due to the rising incidence of obesity. The severity of sleep apnea can be classified as follows:
- Apnea is a condition where air cannot pass through the airway.
- Hypopnea is a condition where airflow through the airway is reduced.
Sleep study (Polysomnography) methods include
- Standard in-lab polysomnography
- Home Sleep Test using the Apnea Hypopnea Index (AHI) to indicate severity
Obstructive sleep apnea is diagnosed when apnea or hypopnea occurs at least 5 times per hour. This value is calculated by adding the number of apneas and hypopneas, dividing by total sleep time, and multiplying by 60, which represents the number of airway obstruction events per hour.
Severity of sleep apnea
- AHI less than 5 per hour is normal
- AHI greater than or equal to 5 but less than 15 per hour is mild
- AHI greater than or equal to 15 but less than 30 per hour is moderate
- AHI greater than or equal to 30 per hour is severe
Common symptoms include loud snoring, excessive daytime sleepiness, waking up unrefreshed, fatigue, restless sleep, waking up at night due to breathing difficulty or choking, headaches, dry mouth, sore throat upon waking, frequent nighttime urination, poor concentration and memory, loud snoring, or gasping for air.
Who is at risk?
Excess weight is found in 60% of patients with obstructive sleep apnea with an AHI of 15 or more per hour, caused by obesity. In normal-weight individuals, causes include facial and skull structure, enlarged tonsils and adenoids, thick neck, large tongue, menopause, endocrine disorders such as hypothyroidism, certain types of myasthenia, alcohol consumption, sedative use, nasal congestion, and breathing difficulties from swollen nasal passages or abnormal nasal structure, which worsen sleep apnea. Consultation with a specialist is recommended for diagnosis. The doctor will take a history, perform a physical exam, review comorbidities, and consider polysomnography. For standard testing, the patient must stay overnight in the hospital under expert supervision. Equipment will be attached to monitor brain waves (EEG), eye movements (EOG), and chin muscle activity (Chin EMG) to assess sleep stages such as awake, light sleep, deep sleep, or REM sleep.
Breathing tests measure the severity of sleep apnea, the number of events during the test, oxygen levels, heart rate, and limb movements. Additionally, the Home Sleep Test offers convenience by allowing patients to set up the device at home with simple installation. The doctor will determine which patients are suitable for this test, as it is less accurate than in-hospital testing.
Treatment of obstructive sleep apnea
Continuous Positive Airway Pressure (CPAP) is the standard treatment and can reduce symptoms of obstructive sleep apnea when used continuously.
