1.Diagnostic criteria Clinically, there are typical daytime symptoms such as snoring and irregular breathing during nighttime sleep and daytime sleepiness, and polysomnography (PSG) shows AHI (ApneaHypopneaIndex, apnea hypopnea index) ≥ 5 times/hour; or AHI ≥ 10 times/hour, and although there are no obvious symptoms during the day, there has been damage to one or more important organs . Lu De, Department of Respiratory Medicine, Shandong Qianfo Mountain Hospital AHI is the number of apnea plus hypoventilation per hour of sleep. Apnea refers to the complete cessation of oral and nasal respiratory airflow for more than 10 seconds during sleep; hypoventilation refers to the reduction of respiratory airflow intensity (amplitude) by more than 50% compared with the basal level during sleep, accompanied by a decrease of oxygen saturation by more than or equal to 4% compared with the basal level. OSAHS is classified into mild, moderate and severe according to AHI and nocturnal oxygen saturation, with AHI as the main criterion and the lowest nocturnal arterial oxygen saturation (SaO2) as a reference (Table). Since the degree of increased AHI and decreased minimum SaO2 are not parallel in some clinical patients with OSAHS, the current recommendation is to use AHI as a criterion for judging the degree of OSAHS condition, indicating hypoxemia. For example, an AHI of 25 beats per hour and a minimum SaO2 of 0.88 would be reported as “moderate OSAHS with mild hypoxemia”. Even if the PSG index is judged to be mild, if the disease is combined with hypertension, ischemic heart disease, stroke, type 2 diabetes and other related diseases, it should be treated actively. 3. Main treatment methods 3.1 Etiological treatment to correct the underlying diseases that cause or aggravate OSAHS, such as the application of thyroxine for hypothyroidism, etc. 3.2 General treatment Each patient with OSAHS should be instructed in various aspects, including (1) weight loss, diet and weight control, and appropriate exercise; (2) abstaining from alcohol, smoking, and cautious use of sedative-hypnotic drugs and other drugs that can cause or aggravate OSAHS; (3) sleeping in the lateral position; (4) elevating the head of the bed appropriately; (5) avoiding overexertion during the day. 3.3 Non-invasive positive airway pressure ventilation therapy This is the treatment of choice for adult patients with OSAHS. It includes normal and intelligent continuous positive airway pressure (CPAP) ventilation and bi-level positive airway pressure (BiPAP) ventilation. Indications: (1) Patients with moderate or severe OSAHS (AHI > 15 times/hour); (2) Patients with mild OSAHS (AHI 5 to 15 times/hour) but with obvious symptoms ( (2) patients with mild OSAHS (AHI 5-15 breaths/hour) but with significant symptoms (such as daytime sleepiness, cognitive impairment, depression, etc.), combined or concurrent cardiovascular disease and diabetes mellitus; (3) patients with obstructive sleep apnea (OSA) that persists after other treatments (e.g., oral appliances, etc.); (4) patients with OSAHS combined with chronic obstructive pulmonary disease (COPD), i.e., “overlap syndrome” patients; (5) perioperative treatment of OSAHS patients. It should be used with caution in the following cases: (1) pulmonary maculopathy on chest X-ray or CT examination; (2) pneumothorax or mediastinal emphysema; (3) significantly lower blood pressure (blood pressure below 90/60 mmHg) or shock; (4) unstable hemodynamic index in patients with acute myocardial infarction; (5) cerebrospinal fluid leakage, cranial trauma or intracranial pneumothorax; (6) acute otitis media, rhinitis or sinusitis with uncontrolled infection; (7) glaucoma. (7) glaucoma. The efficacy of positive airway pressure treatment is reflected as follows: (1) Snoring and breath-holding subsided during sleep, no intermittent hypoxia, and normal SaO2. (2) Significant improvement or disappearance of daytime sleepiness and significant improvement or disappearance of other concomitant symptoms such as depression. (3) Related complications, such as hypertension, coronary heart disease, arrhythmia, diabetes and stroke, are improved. 3.4 The oral appliance is suitable for patients with simple snoring and mild to moderate OSAHS, especially those with mandibular recession. It can be tried for those who cannot tolerate CPAP, cannot be operated or have poor surgical results, and can also be used as a complementary treatment to CPAP therapy. Contraindications: severe temporomandibular arthritis or dysfunction, severe periodontal disease, and severe tooth loss should not be used. 3.5 Surgery is only suitable for upper airway oropharyngeal obstruction (including pharyngeal mucosal tissue hypertrophy, narrow pharyngeal cavity, uvula hypertrophy, low soft palate, tonsillar hypertrophy) and AHI <20 times/hour; obese people and AHI >20 times/hour are not suitable. For some patients with severe OSAHS who are not obese but have significant oropharyngeal obstruction, surgery can be considered on a trial basis when CPAP has been applied for 1 to 2 months and their nocturnal apnea and hypoxia have been largely corrected. Pre-operative and intra-operative close monitoring, regular post-operative follow-up is required, and if surgery fails, CPAP treatment should be used. 3.6 Drug treatment There is no drug with definite efficacy. 3.7 Post-treatment follow-up The overall follow-up patients should pay attention to the change of condition if they have not received active treatment methods (such as CPAP, oral appliances and surgery), especially their family members should pay attention to the change of snoring at night, the presence of breath-holding and the patient’s daytime drowsiness; intermittent snoring or the aggravation of daytime drowsiness suggest that the patient’s condition may deteriorate or progress, and the PSG should be rechecked in time for consultation. Active treatment should be taken if necessary; patients who have applied the above treatment refer to the following entries for follow-up observation. After the CPAP pressure is adjusted, the patient takes the machine home for long-term home treatment. The patient should be closely followed up in the early stage of home treatment to understand the patient’s compliance and adverse reactions to the application, and to assist him/her in solving various problems arising from the use. Subsequently, regular follow-up visits should be insisted. PSG review should be performed 3 and 6 months after oral orthodontic and surgical treatment to understand the efficacy, and patients who cannot tolerate or have poor results should be switched to treatments with more certain efficacy, such as CPAP, as soon as possible.