Sleep is an active process of the human body that can restore the spirit and relieve fatigue. Sufficient sleep, a balanced diet and proper exercise are three health standards recognized by the international community. Many people think that snoring is a reflection of a good sleep, but in fact, snoring is the sound caused by the vibration of the uvula due to the narrowing of the upper respiratory tract during sleep. It is not only not a standard for a good and sweet sleep, but can also lead to daytime sleepiness, fatigue, inattention, headaches, etc. Snoring may also be one of the symptoms of obstructive sleep apnea, which seriously affects people’s health. So, what are the symptoms of sleep apnea syndrome? How should it be diagnosed?
1. Concepts Related To Sleep Apnea
Sleep apnea (SA) refers to the intermittent disappearance of oral and nasal breathing airflow during sleep for more than 10 seconds. Sleep apnea is divided into three types: obstructive (OSA), mixed (MSA), and central (CSA). OSA refers to complete obstruction of the upper airway, in which the breathing airflow disappears, but the chest and abdominal breathing movements still exist. When CSA occurs, both the breathing airflow and the chest and abdominal breathing movements disappear. MSA has the characteristics of both, and CSA usually appears first, followed by OSA. The three often occur during the sleep of the same patient, but one of them is dominant. Sleep apnea-hypopnea syndrome (SAHS) refers to a series of pathophysiological changes and daytime discomfort symptoms caused by frequent apnea during sleep, leading to hypoxemia and sleep disorders. Obstructive sleep apnea-hypopnea syndrome (OSAHS) is the most common, followed by central sleep apnea, and mixed sleep apnea syndrome is rare in adults.
2. Diagnosis Of Sleep Apnea
2.1 Diagnostic Criteria For Sleep Apnea
Diagnostic criteria: SAHS can be diagnosed when apnea and/or hypopnea occur more than 30 times or more than 5 times per hour during a 7-hour sleep, that is, the sleep apnea-hypopnea index (AHI) is greater than 5, and is accompanied by corresponding clinical symptoms. After non-invasive ventilation treatment, the corresponding clinical symptoms improve with the reduction of SA, which helps to establish the diagnosis.
2.2 How To Diagnose Sleep Apnea
(1) Medical history collection
By carefully asking about the patient’s medical history, we can basically understand the patient’s sleep and breathing conditions, provide diagnostic clues about SAHS, indicate possible causes and complications, and preliminarily judge its severity.
The most common reasons for patients to visit the doctor are:
- Daytime sleepiness affects work.
- Snoring at night affects others’ sleep.
- Pharyngitis cannot be cured for a long time.
- Spouse finds frequent breathing pauses at night and worries.
- Holding breath at night;
- Other systemic diseases.
Understanding these will help to find diagnostic clues and further carry out the diagnosis.
Although the symptoms of SAHS are complex and varied, the key points of diagnosis include three aspects:
- Snoring during sleep is one of the most typical symptoms of SAHS. The patient’s snoring is loud and irregular, intermittent, and the sound is high and low. It can also be heard in the next room. The sensitivity of this phenomenon in diagnosing SAHS is over 95%.
- Frequent apnea is often discovered by the patient’s spouse, who often sees frequent breathing pauses during sleep, sometimes accompanied by cyanosis and sweating. This finding has a diagnostic specificity of more than 90% for moderate to severe patients. It should be noted that the above information can only be obtained with the help of the patient’s spouse or family members to obtain more accurate information.
- Daytime sleepiness is manifested as falling asleep uncontrollably regardless of time and place, which often indicates that the patient’s condition has reached moderate or severe levels. However, it is often necessary to set specific scenarios for the patient during the consultation, such as asking whether the patient sleeps during meetings or watches TV. The internationally used Epworth Sleepiness Scale is one of the good tools for subjectively evaluating the severity of sleepiness. When the score exceeds 9 points, it indicates that the patient is sleepy.
- Different OSA screening scales can also help us diagnose sleep apnea. For example, the NoSAS rating scale and the STOP-BANG questionnaire can also help us test the severity of sleep apnea.
Epworth Sleepiness Scale(ESS)
| Situation | Answer | |||
|---|---|---|---|---|
|
1.Sitting and Reading |
Never |
Rarely |
Sometimes |
Often |
|
2.Watching TV |
Never |
Rarely |
Sometimes |
Often |
|
3.Sitting inactive in a public place (e.g. a theatre or meeting) |
Never |
Rarely |
Sometimes |
Often |
|
4.As a passenger in a car without break |
Never |
Rarely |
Sometimes |
Often |
|
5.Lying down to rest during the day when circumstances permit |
Never |
Rarely |
Sometimes |
Often |
|
6.Sitting and talking to someone |
Never |
Rarely |
Sometimes |
Often |
|
7.Sitting quietly after lunch without alcohol |
Never |
Rarely |
Sometimes |
Often |
|
8.In a car, while stopped for a few minutes in traffic |
Never |
Rarely |
Sometimes |
Often |
Scoring method: The ESS scoring scale includes “0 = Never (Would never doze)”, “1 = Rarely (Slight chance of dozing)”, “2 = Sometimes (Moderate chance of dozing)”, or “3 = Often (High chance of dozing)”. The total score of this scale is 24 points, with a score range of 0 to 24 points.
If the total score is greater than or equal to 9 in the scale, it can be considered to be at risk of OSAHS.
The clinical significance of this table: On the 24-point scale, a score of >6 indicates sleepiness, >11 indicates excessive sleepiness, and >16 indicates dangerous sleepiness. The higher the ESS score, the higher the sleeping tendency or “daytime sleepiness”.
0-5 points Low-level normal daytime sleepiness
6-10 points High-level normal daytime sleepiness
11-12 points Mild excessive daytime sleepiness
13-15 points Moderate excessive daytime sleepiness
16-24 Severe excessive daytime sleepiness
Operation guide:
① A score of >6 indicates sleepiness;
② A score of >11 indicates excessive sleepiness;
③ A score of >16 indicates dangerous sleepiness;
④ The questionnaire answering time does not exceed 2 to 3 minutes.
(2) Physical examination
In addition to routine physical examinations, the following aspects should be noted for SAHS patients. Obesity is one of the important factors for sleep apnea, and its risk is four times that of gender and twice that of age. Neck circumference is a highly specific indicator of the caliber and function of the upper airway during sleep. Anatomical stenosis of the upper airway accompanied by poor sleep and daytime sleepiness often indicates the presence of SA, and surgical treatment is possible. Measuring blood pressure before bedtime and after waking up, and finding that blood pressure rises in the morning, can help understand the relationship between hypertension and SAHS. If there are signs of hypothyroidism during physical examination, further examination is required.
(3) Auxiliary examinations
Skull X-ray examinations can quantitatively understand the degree of maxillofacial abnormalities, and nasopharyngeal endoscopy can help evaluate the degree of upper airway anatomical abnormalities, which is helpful for considering surgical treatment. People with hypothyroidism can test thyroid hormone levels. People with daytime hypoventilation or respiratory failure can undergo blood routine, blood gas analysis, and lung function tests. A dynamic electrocardiogram examination that finds patients with sleep arrhythmias or large heart rate fluctuations during sleep can also indicate the possibility of SAHS.
(4) Sleep breathing monitoring
To finally confirm or exclude the diagnosis of SAHS, it is necessary to go to a sleep center and use polysomnography (PSG) for sleep breathing monitoring. The monitoring signals include the following three aspects:
1. Sleep status: electroencephalogram, oculoculogram, and genioglossus electromyography.
2. Respiratory status: oral and nasal airflow, chest and abdominal respiratory movements, and dynamic blood oxygen saturation (SaO2) monitoring.
3. Electrocardiogram.
If necessary, dynamic blood pressure, esophageal pressure, snoring, leg movement, and body position changes can be monitored simultaneously. It is applicable to the following situations:
1. Patients suspected of SAHS;
2. Other symptoms and signs prove that they have sleep breathing disorders, such as nocturnal asthma, lung, or neuromuscular diseases that affect sleep.
3. Unexplained daytime hypoxemia or polycythemia;
4. Unexplained nocturnal arrhythmias, nocturnal angina, and early morning hypertension;
5. Monitor the patient’s hypoxia level during sleep at night to provide an objective basis for oxygen therapy;
6. Evaluate the therapeutic effects of various treatments on SAHS;
7. Diagnose other sleep disorders.
3. Identification Of Sleep Apnea
The prevalence of SAHS is not low, but because sleep apnea only occurs during sleep and the patient’s daytime symptoms are complex and diverse and lack specificity, and many doctors have little understanding of this disease, misdiagnosis is very common and attention should be paid to its differentiation.
3.1 Other Sleep Breathing Disorders
In addition to SAHS, sleep disorders caused by breathing disorders also include upper airway resistance syndrome (UARS), sleep hypoventilation syndrome, sleep hypoxemia in patients with chronic obstructive pulmonary disease (COPD), sleep hypoventilation in patients with neuromuscular diseases, nocturnal asthma, etc. These patients may not have typical sleep snoring, and PSG does not have frequent apnea, but their basic pathophysiological changes are hypoxia, hypercapnia and sleep structure disorders, and the test results are the same as SAHS. In addition, the probability of overlapping with SAHS is also quite high. Although noninvasive positive pressure ventilation therapy is effective for these diseases, they differ in the choice of ventilation mode, pressure setting, etc.
3.2 Other Sleep Disorders
The classification of sleep disorders includes 4 categories with a total of 89 diseases, of which SAHS is only one of the more common ones. Other sleep disorders with daytime sleepiness as the main manifestation are not uncommon and must be differentiated from SAHS.
| Internal Factors | External Factors | Biological Rhythm Disturbance | Other |
|---|---|---|---|
|
Narcolepsy |
Poor Sleeping Habits |
Jet Lag |
Depression |
|
Periodic Sleepiness |
Environmental Factors |
Irregular Sleep Patterns |
Alcohol Addiction |
|
Primary Hypersomnia |
Lack Of Sleep |
Delayed Sleep Phase |
Parkinson’s Disease |
|
Post-Traumatic Lethargy |
Sedatives |
||
|
Restless Leg Syndrome |
Drinking |
||
|
Sleep Apnea |
3.3 Other Systemic Diseases
The blood and gas disorders and sleep disorders caused by SAHS can cause damage to multiple systems of the body. In practice, it is also found that many patients go to related professional clinics due to complications of SAHS, and are transferred to sleep centers after repeated diagnosis and treatment. Statistics from the American Sleep Association (ASDA) show that sleep centers are mostly located in respiratory departments, with a small number in neurology and otolaryngology departments. As many as 66% of patients come from family doctors and other internal medicine departments, while only 6% come from respiratory departments, 20% from otolaryngology departments, and 8% from neurology departments.
