Central Sleep Apnea Vs Obstructive Sleep Apnea
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What Is Obstructive Sleep Apnea?
Obstructive Sleep Apnea-hypopnea Syndrome (OSAHS) is a potentially dangerous source of disease. It is defined as an adult having at least 30 apneas during a 7-hour night’s sleep, with the airflow from the mouth and nose stopping for at least 10 seconds each time; oxygen saturation drops by more than 4% during apnea; or the apnea index (AHI, the average number of apneas and hypopneas per hour) is greater than 5 times/h.
Symptoms Of Obstructive Sleep Apnea
The typical symptom of OSA is snoring, especially loud and irregular snoring. Snoring is the sound caused by the vibration of soft tissue when air flows through the upper airway. When the airway is narrowed or blocked, snoring will be more obvious and louder. However, not all people who snore have OSA, and not all OSA patients snore. Some people may have airway obstruction due to other reasons, such as allergies, colds, nasal polyps, etc.; some people may not have obvious snoring sounds because their airway is too relaxed or their muscles are too stiff. In addition to snoring, OSA can also cause a series of symptoms at night and during the day, mainly including:
Snoring during sleep and irregular snoring
Repeated breathing pauses and awakenings during sleep
Conscious breath holding, can wake up
Obvious daytime sleepiness and memory loss
Can be combined with or aggravated by cardiovascular and cerebrovascular diseases such as hypertension, coronary heart disease, cor pulmonale, and stroke
Diabetes
In severe cases, psychological, intellectual, and behavioral abnormalities may occur, and may cause social problems such as road traffic accidents
Risk Factors for Obstructive Sleep Apnea
1. Upper respiratory tract stenosis or obstruction: Whether the airflow can enter the trachea and bronchi smoothly during breathing depends on the upper respiratory tract above the larynx. Stenosis or obstruction in any anatomical part of the upper respiratory tract can lead to obstructive sleep apnea. From an anatomical point of view, there are three parts that are prone to stenosis or obstruction: the nose and nasopharynx; the oropharynx and soft palate, and the root of the tongue. Common clinical diseases include: nasal diseases such as allergic rhinitis, deviated nasal septum, nasal polyps, nasopharyngeal tumors, etc.; hypertrophy of adenoids and tonsils, excessive uvula, paralysis of pharyngeal muscles; hypertrophy of the tongue, stiff or deformed collar bones, congenital or acquired small collar bones, laryngeal cartilage softening, and cervical vertebrae deformity.
2. Obesity: Obese people are more likely to develop OSAHS because their tongue is thick, and there is too much fat deposited on the soft palate, uvula, and pharyngeal wall, which leads to airway obstruction; in addition, obese people have reduced lung volume, which leads to obesity-induced hypoventilation syndrome. Weight exceeds the standard weight by 20% or more, and body mass index (BMI) ≥ 25.
3. Endocrine disorders, such as acromegaly, causing tongue hypertrophy; hypothyroidism, causing myxedema; and endocrine disorders in postmenopausal women.
4. The relaxation of tissues and decreased muscle tone in the elderly causes the pharyngeal wall to relax, collapse, and move inward, causing airway narrowing or obstruction, snoring, and hypoventilation.
5. Long-term heavy drinking and/or taking sedative hypnotic drugs.
6. Long-term heavy smoking.
7. Other related diseases include hypothyroidism, acromegaly, hypopituitarism, vocal cord paralysis, sequelae of poliomyelitis or other neuromuscular diseases (such as Parkinson’s disease), long-term gastroesophageal reflux, etc.
Treatment Options For Obstructive Sleep Apnea
General Treatment:
Change your lifestyle: Every OSAS patient should receive multi-faceted guidance, including weight loss, diet, and weight control, as well as proper exercise. Changing your lifestyle is the basis of OSA treatment and benefits all patients.
(1) Weight loss: Obesity increases the risk of airway collapse and obstruction. Weight loss can effectively improve the symptoms and complications of OSA patients, especially for patients with mild to moderate OSA.
(2) Quitting smoking and drinking: Smoking and drinking can irritate and damage the upper airway, making it more prone to collapse and obstruction, aggravating the distress of OSA patients.
(3) Regular work and rest: Ensuring adequate and high-quality sleep is the key to improving the daytime function and quality of life of OSA patients. Factors that affect sleep quality should be avoided, such as excessive fatigue, staying up late, working at night, taking sedatives or sleeping pills, etc.
(4) Changing sleeping position: For patients with OSA related to body position, that is, patients with more apnea when lying on their back and less apnea when lying on their side or prone, changing sleeping position can alleviate symptoms. Some special equipment or items can be used to help change body position.
Other Treatments:
(1) Treatment to reduce risk factors: For patients with hypertension, cardiovascular and cerebrovascular diseases, symptomatic treatment should be actively given to lower blood pressure, eliminate arrhythmias, and control blood sugar. Correct the underlying disease that causes OSAS or aggravates it, such as using thyroxine to treat hypothyroidism.
(2) Oral appliances: Suitable for patients with simple snoring and mild OSAS (AHI <15 times /h), especially those with mandibular retraction. They can be tried for those who cannot tolerate CPAP, cannot undergo surgery, or have poor surgical results. Contraindications are patients with temporomandibular arthritis or functional disorders. The advantages are non-invasiveness and low price; the disadvantages are that the effects vary due to different performance of the appliances and the tolerance of different patients.
(3) Positive airway pressure therapy includes continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP), with CPAP through the mouth and nose being the most commonly used. If combined with chronic obstructive pulmonary disease (COPD), it is an overlap syndrome, and BiPAP can be used if conditions permit.
(4) If surgical treatment conditions permit, surgical treatment should be performed in a “two-step” manner. The most commonly used surgical method is uvulopalatopharyngoplasty (UPPP) and its modified surgery, such as pillar bio-pin surgery, but this type of surgery is only suitable for patients with oropharyngeal obstruction of the upper airway (including hypertrophy of pharyngeal mucosal tissue, narrow pharyngeal cavity, hypertrophy of uvula, low soft palate, and hypertrophy of tonsils) and AHI < 20 times; it is not suitable for obese patients and those with AHI > 20 times/h. For some non-obese patients with severe OSAS who have obvious oropharyngeal obstruction, UPPP treatment can be considered after CPAP treatment for 1 to 2 months, when their nocturnal apnea and hypoxia have been basically corrected, but close follow-up is required after surgery, and CPAP treatment should be resumed immediately if it fails.
(5) Drug treatment mainly changes the sleep structure and the neural control function of breathing. The efficacy is not yet certain, and there may be adverse reactions of varying degrees, such as progesterone, feidanning, antidepressant drugs, propylenetriazine, and aminophylline.
(6) Treatment of complications: Patients with hypertension should pay attention to controlling their blood pressure; patients with coronary heart disease should be given coronary dilation therapy and other symptomatic treatments.
What Is Central Sleep Apnea?
Central sleep apnea is related to dysfunction of the brain system that controls breathing, not airway obstruction. Central sleep apnea is caused by disorders in the brain center that controls breathing, which causes the respiratory muscles to fail to work properly, no airflow through the upper airway for more than 10 seconds, and no chest or abdominal respiratory movement. In other words, the brain is unable to send breathing commands to the muscles, resulting in the patient’s inability to breathe. Central sleep apnea accounts for a very small part of the total apnea syndrome population. Studies have found that it accounts for about 10% of all apnea populations.
Symptoms Of Central Sleep Apnea
Disordered sleep structure
The chest and abdomen stop breathing during sleep, and heart failure
Symptoms such as stuffiness and wheezing, sudden awakening
Feeling tired and sleepy during the day, sleepiness
Sometimes headaches
Memory loss, slow reaction
Complications such as hypertension and stroke
Types Of Central Sleep Apnea
(1) Cheyne-Stokes respiration (periodic breathing) is a typical central sleep apnea. In Cheyne-Stokes respiration, breathing gradually becomes faster, then gradually slows down, and then starts again after a short pause. This cycle repeats itself over and over again. Each cycle lasts from 30 seconds to 2 minutes. When breathing stops, carbon dioxide is retained, and the concentration increases, stimulating the respiratory center, causing breathing to resume faster and deeper. Carbon dioxide is discharged, and the respiratory center loses the stimulating substance, causing shallow and slow breathing to occur again, and then pause.
(2) Drug-related central respiratory depression: Some analgesics (such as opioid preparations such as morphine, oxycodone, and codeine) may inhibit the function of the brainstem respiratory center.
(3) High Altitude Periodic Respiration Disorder. Exposure to extreme altitudes above 8,000 feet (2,440 meters) may induce a characteristic Cheyne-Stokes respiration pattern.
(4) Iatrogenic central sleep apnea: Clinical observations have found that approximately 5%-15% of patients with obstructive sleep apnea may develop central sleep apnea events after receiving continuous positive airway pressure (CPAP) treatment.
(5) Pathological central respiratory dysfunction. Many clinical studies have confirmed that pathological conditions such as end-stage renal disease, chronic heart failure, brainstem stroke, and neurodegenerative diseases can lead to non-periodic central respiratory disorders.
(6) Primary central sleep apnea. This special type is classified as a diagnosis of exclusion in the field of sleep medicine. Its pathogenesis involves unknown neural regulation abnormalities, and epidemiological data show that the prevalence rate is less than 0.5%.
Risk Factors For Central Sleep Apnea
1. Gender: Men are more likely to develop CSA than women
2. Age: More common in older people, especially those over 65
3. High altitude: People sleep at a higher altitude than they are used to. Symptoms usually go away after returning to a normal altitude.
4. Opioid use: People who use opioids are at greater risk.
5. Certain obese people, congestive heart failure, nasal obstruction, etc.
6. Some people with obstructive sleep apnea may develop central sleep apnea when treated with a positive airway pressure (PAP) device.
7. Heart disease: People with heart disease, such as atrial fibrillation and congestive heart failure, are at greater risk.
8. Neurological disorders: Bilateral posterior spinal cord disorders caused by anterior myelotomy, vascular embolism, or degenerative lesions; patients with stroke or brain tumors.
9. Abnormalities of the brain and spinal cord: such as Ondinc, sCurse syndrome (exhaustion of respiratory autonomic control in response to normal respiratory stimulation), foramen magnum malformation, poliomyelitis, and lateral medullary syndrome.
10. Abnormalities of autonomic nerve function: such as familial autonomic nerve dysfunction, insulin-related diabetes, Shy-Drager syndrome, and encephalitis.
11. Muscle lesions: such as diaphragmatic lesions, myotonic dystrophy, and myopathy;
Treatment Options For Central Sleep Apnea
1. Treatment of primary disease: CSA is not an independent disease. It often occurs in congestive heart failure, nasal obstruction, non-nasal upper airway obstruction, and pharyngeal airway collapse, which can trigger reflex inhibition of breathing. Neurological diseases such as cerebral arteriosclerosis, hemorrhage, infarction, cranial tumors, trauma, encephalitis, and poliomyelitis can undoubtedly cause CSA. Therefore, treatment of the primary disease is beneficial in improving the onset of CSA.
2. Ventilation therapy: In recent years, mechanical ventilation therapy through the mouth and nasal mask has replaced mechanical ventilation therapy through tracheostomy. Due to the continuous improvement of the performance of ventilators, such as nasal continuous positive airway pressure (CPAP), automatic CPAP bi-level positive airway pressure (BiPAP) ventilators, and other types of constant volume and constant pressure support ventilators, they have been widely used to supplement ventilation during sleep at night and improve patients’ tolerance. They have played an important therapeutic role in stabilizing the patient’s respiratory center, improving nocturnal insomnia and daytime sleepiness, improving cardiopulmonary function, improving patients’ quality of life and reducing mortality in patients with central alveolar hypoventilation, or severe hypoxia and hypercapnia during sleep at night due to respiratory muscle failure, and the vicious cycle of high ventilation and low CO caused by them.
3. Oxygen therapy via nasal cannula: Low-flow oxygen supply via nasal cannula can reduce or eliminate CSA, such as Cheyne-Stokes respiration caused by left heart failure and nocturnal periodic breathing caused by high altitude hypoxia. The mechanism is not very clear and may be related to the stabilization of the respiratory center or hypocapnia caused by hypoxia and hyperventilation during CSA attacks.
4. Drug treatment: Theophylline may be effective for CSA caused by brain stem damage; acetazolamide (Diamox) and acetazolamide can cause metabolic acidosis and stimulate breathing, which is effective for some CSA patients. The progesterone medroxy progesterone acetate has a respiratory stimulating effect; naloxone can relieve respiratory depression; clomipramine is a tricyclic antidepressant, but its efficacy is uncertain.
5. Other treatments: Diaphragmatic pacing, which simulates respiratory drive through electrical stimulation, is feasible in principle, but it can easily cause awakening and interfere with sleep. The main problem is how to avoid these adverse effects and maintain its therapeutic effect.
How to differentiate between OSA and CSA?
| OSA | CSA | |
|---|---|---|
|
Cause |
Airway obstruction due to relaxation of airway muscles during sleep |
Disorders in the brain center during sleep cause the respiratory muscles to not work properly |
|
Symptom |
Often obese
Daytime sleepiness
Rarely awakened
Loud snoring
Sexual dysfunction
Intellectual impairment
Morning headaches, frequent urination at night |
Normal body shape
Insomnia, hypersomnia
Awakening during sleep
Mild and intermittent snoring
Mild sexual dysfunction
Depression |
|
Risk Factors |
Upper airway narrowing or obstruction
Obesity
Endocrine disorders
Alcohol and sedatives
Smoking |
Gender
Age
High altitude
Opioid use
Heart disease
Neurological disorders
Cerebral and spinal cord abnormalities
Autonomic dysfunction |
|
Treatment |
Lifestyle changes
Oral appliances
CPAP
Surgery |
Treatment of the underlying disease
CPAP
Medication
Reducing opioids
Nasal cannula oxygen therapy
Other treatments |
Conclusion
During an apnea event, there may be a change from central to obstructive. The clinical manifestations are similar to those of OSA and CSA, but more complex and varied. Central apnea is usually caused by brainstem lesions, and the brain temporarily stops sending breathing signals to the respiratory muscles. Obstructive sleep apnea syndrome is a common sleep disorder mainly caused by upper airway narrowing or obstruction.
Early diagnosis and treatment are very important, and can be managed through lifestyle changes, continuous positive airway pressure therapy, surgery, etc. Avoiding obesity, quitting smoking and limiting alcohol consumption, and maintaining good sleep habits are important measures to prevent and relieve symptoms. The treatment of sleep apnea syndrome requires personalized plans and long-term management. Patients should choose appropriate treatment methods under the guidance of professional physicians, while paying attention to lifestyle adjustments.
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