Obstructive Sleep Apnea Hypoventilation Syndrome (OSAHS) refers to apnea and hypoventilation caused by repeated collapsing obstruction of the upper airway during sleep, accompanied by snoring, sleep structure disorders, frequent decrease in oxygen saturation, daytime somnolence, and inattention.OSAHS can occur at any age, but has the highest incidence in middle-aged obese men. It not only seriously affects the quality of life and work efficiency of patients, but also is potentially dangerous as it is prone to complications of cardiovascular and cerebrovascular diseases and type 2 diabetes. With the in-depth of related research, OSAHS as the source disease of many diseases has been agreed, so it is getting more and more attention. I. Etiology (a) Upper airway stenosis The key to whether the airflow can enter the tracheobronchial tubes smoothly when blocking expiration is the upper airway above the larynx. Narrowing or blockage of any anatomical part of the upper airway can lead to obstructive sleep apnea. There are 3 areas above the larynx that are prone to narrowing and blockage. 1, Nose and nasopharynx: narrowing or atresia of the anterior nostril or nasopharynx, deviated nasal septum, nasal polyps, hypertrophic rhinitis, tumors of the nasal cavity and nasopharynx, and adenoid hypertrophy. 2.Oropharynx and soft palate: enlarged tonsils, prolonged uvula, pharyngeal muscle paralysis, etc. 3. Root of tongue: hypertrophy of tongue, jaw deformity, etc. (B) Obesity 1, tongue body hypertrophy, and soft palate, uvula and pharyngeal wall has excessive fat deposits, easy to cause airway obstruction. 2, the volume of the lung is significantly reduced, thus producing obese pulmonary hyperventilation syndrome. (C) endocrine disorders such as acromegaly causing tongue hypertrophy, hypothyroidism causing mucous edema, and endocrine dysfunction in women after menopause. (d) Ageing tissue relaxation, muscle tone, resulting in relaxation of the pharyngeal wall, collapse and inward movement caused by snoring or OSAHS. (e) Abnormal regulation of the respiratory center. Clinical manifestations (1) Symptoms 1. Sleep snoring: with the increase of age and body weight, snoring symptoms can gradually increase and be intermittent, with repeated respiratory transient cessation phenomenon, aggravated by side-lying position, and in severe cases, there may be waking up at night. 2.Daytime sleepiness: in severe cases, the phenomenon of falling asleep during driving or even talking. 3.Dull reaction, memory loss, poor concentration. 4.Dry mouth in the morning, often with foreign body sensation. 5.Headache in the morning, elevated blood pressure. 6.Severe cases may have sexual dysfunction, increased nocturia or even enuresis. 7, the long course of the disease may appear irritability, irritability or depression and other personality changes. 8, children will have growth retardation, inattention, decline in academic performance and other manifestations. (B) physical signs 1, general signs: most adult patients are obese or obviously obese, short and thick neck, severe patients have more obvious lethargy part of the patients have maxillofacial development. 2, upper airway signs: pharyngeal cavity, especially the oropharyngeal cavity narrowing, tonsil hypertrophy, soft palate hypertrophy and flaccid, uvula hypertrophy and overgrowth; some patients can also be seen in the nasal septum deviation, nasal polyp, nasal septum deviation, nasal polyps, adenoid hypertrophy, tongue root hypertrophy, tongue root lymphoid hyperplasia, pharyngeal lateral cord hypertrophy and so on. III. Diagnosis (i) Polysomnography (PSG) is currently an important means of assessing sleep-related disorders and is considered to be considered the laboratory gold standard for the diagnosis of OSAHS. (B) Positional diagnosis and related examination 1, fiberoptic nasopharyngolaryngoscopy supplemented by Muller’s examination method: it can observe the cross-sectional area of various parts of the upper airway and the structures causing stenosis. 2.Sustained pressure measurement of the upper airway: it is the most accurate localization diagnosis method at present. 3.X-ray cephalometric measurements: mainly used to evaluate the morphological characteristics of bony airway. 4, Upper airway CT, MRI examination: it can carry out two-dimensional and three-dimensional observation and measurement of the upper airway, and better understand the morphological and structural characteristics of the upper airway. Fourth, the treatment of OSAHS should be based on the different causes and conditions of patients, choose different treatment methods, and put forward personalized comprehensive treatment plan. (I) General treatment Weight loss, cessation of smoking and alcohol, exercise, and side sleep. (II) Internal medicine treatment 1, continuous positive pressure ventilation treatment: it is the most effective method in internal medicine treatment. 2.Oral orthodontic appliance treatment: mainly applicable to patients with narrow airway behind the tongue root. 3.Drug therapy: no clear and effective drugs have been found yet. (C) Surgical treatment is one of the important means of treatment of OSAHS, for OSAHS patients with different stenosis and obstruction sites, can choose a variety of different surgical procedures, including uvulopalatopharyngoplasty (UPPP) is the most widely carried out. 1.Nasal cavity and nasopharyngeal surgery: deviated nasal septum correction, middle nasal passage opening, inferior turbinate fracture displacement, adenoidectomy and so on. 2.Oral and pharyngeal surgery: uvulopalatopharyngoplasty (UPPP), hard palate truncation and soft palate anterior transfer, soft palate radiofrequency ablation, and so on. 3.Laryngeal and pharyngeal surgery: tongue root resection, chin advancement surgery, hyoid suspension surgery, etc. 4.Others: mandibular anterior reshaping, maxillary and mandibular anterior reshaping, and tracheotomy as a second-stage surgery for the treatment of OSAHS is also a better choice for certain patients with severe OSAHS.