Definition and Overview
Obstructive sleep apnea (OSA) is a sleep breathing disorder in which the upper airway is repeatedly partially or completely blocked during sleep, resulting in repeated apnea and hypopnea, resulting in decreased oxygen saturation, sleep fragmentation, and excessive daytime sleepiness.
The adult prevalence rate is approximately 24% in men and 9% in women, making it one of the most common sleep disorders. Distinct from central sleep apnea, obstructive sleep apnea is characterized by airway obstruction while respiratory effort is maintained.
Causes and Pathophysiology
anatomical factors
Anatomical factors such as fat accumulation around the upper airway (obesity), enlarged tonsils and adenoids, micrognathia, retrognathia, and increased neck circumference cause upper airway obstruction.
Decreased muscle tone during sleep
During sleep, the tone of the upper airway muscles (especially the genioglossus) decreases, causing the airway to become narrowed or blocked. Muscle tone is lowest during REM sleep, which tends to worsen apnea.
Autonomic and cardiovascular mechanisms
During repetitive apnea, hypoxia and hypercapnia occur, stimulating chemoreceptors and overactivating the sympathetic nerves. This leads to increased heart rate, constriction of blood vessels, and increased blood pressure. A decrease in heart rate variability (HRV) and a non-dipping pattern of nocturnal blood pressure are characteristically observed.
symptoms
nighttime symptoms
- Severe snoring (usually eyewitness reports)
- Respiratory arrest during sleep (eyewitness report)
- Waking up during sleep with a feeling of choking or gasping for air.
- nocturia
- Sleep fragmentation and insomnia
Daytime symptoms
- Excessive daytime sleepiness (sleeping while driving or at work)
- morning headache
- Dry mouth and sore throat (morning)
- Poor concentration, memory impairment
- Irritability and mood changes
diagnosis
Apnea-Hypopnea Index (AHI)
AHI is the combined number of apneas and hypopneas per hour of sleep: - Normal: AHI < 5 - Mild: AHI 5~14 - Moderate: AHI 15~29 - Severe: AHI ≥ 30
Nocturnal polysomnography (PSG)
PSG is a standard test that simultaneously measures electroencephalography (EEG), eye movements (EOG), electromyography (EMG), respiratory effort, airflow, oxygen saturation, electrocardiogram, and lower limb movements. Analyze breathing patterns and awakening responses at each stage of sleep.
Home Sleep Test (HSAT)
When moderate to severe sleep apnea is suspected in adults without comorbidities, a home sleep test is used as the first screening test. It is simpler than PSG, but sleep stage analysis is limited.
Epworth Sleepiness Scale
It is a self-report scale of daytime sleepiness ranging from 0 to 3 in 8 situations, and a score of 10 or more suggests clinically meaningful daytime sleepiness.
treatment
CPAP treatment
Continuous positive airway pressure (CPAP) is the standard first-line treatment for moderate to severe sleep apnea. Provides continuous positive pressure through a nasal or naso-oral mask to prevent upper airway obstruction during sleep.
Clinical studies have reported that blood pressure decreases by about 2.5 mmHg on average and daytime sleepiness is significantly improved after CPAP treatment. The risk of traffic accidents related to atrial fibrillation, elevated blood pressure at night, and daytime sleepiness is also reduced.
Oral Appliance (MAD)
A mandibular advancement device expands the upper airway by moving the mandible forward during sleep. It is an alternative for patients with mild to moderate sleep apnea or who have difficulty adapting to CPAP.
surgical treatment
Surgical methods such as uvulopalatopharyngoplasty (UPPP), maxillomandibular advancement, and tongue base reduction are selectively performed. It is effective when anatomical abnormalities (tonsil hypertrophy, etc.) are clear.
lifestyle habits correction
In obese patients, weight loss (10% loss reduces AHI by approximately 25%) is effective in improving sleep apnea. Avoiding sleeping in the supine position, limiting the use of alcohol and sedatives, and quitting smoking are recommended.
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This information is provided for medical educational purposes and is not a substitute for individual medical care or treatment. If you have any symptoms, be sure to seek professional advice. Inquiries: Osang Neurosurgery 1599-5453 | osns.co.kr