Sleep apnea hypoventilation syndrome definition and classification.
(A) Definition: Sleep apnea hypoventilation syndrome is defined as recurrent episodes of apnea more than 30 times or sleep apnea hypoventilation index (AHI) = 5 times/hour during sleep each night with clinical symptoms such as drowsiness. 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% from the basal level during sleep, accompanied by a decrease in blood oxygen saturation by 4% from the basal level or micro-awakening; sleep apnea hypoventilation index refers to the number of apnea plus hypoventilation per hour of sleep time.
(ii) Classification: 1. Central type (CSAS) 2. Obstructive type (OSAS) 3. Mixed type (MSAS)
Epidemiology.
In OSAHS, for example, the prevalence is 2%-4% in people over 40 years old in the United States, more men than women, and higher in the elderly, up to 6.5% in Australia, 4.1% in Hong Kong, 3.62% in Shanghai, and 4.81% in Changchun, China.
Etiology and pathogenesis.
(i) Central sleep apnea syndrome (CSAS)
CSAS alone is less common, generally not exceeding 10% of apnea patients, and only 4% has been reported. The ventilation can be further divided into two categories: hypercapnia and normocapnia. It can coexist with obstructive sleep apnea ventilation syndrome, and most have neurological or motor system pathology. The pathogenesis may be related to the following factors: 1) reduced responsiveness of the respiratory center to different stimuli during sleep; 2) instability of respiratory feedback regulation of the central nervous system to hypoxemia, especially due to changes in CO2 concentration; 3) abnormalities in the expiratory and inspiratory conversion mechanisms, etc.
(B) Obstructive sleep apnea hypoventilation syndrome (OSAHS)
OSAHS accounts for the majority of SAHS, with family clustering and genetic factors, and most of them have pathological basis of narrowing of the upper airway, especially the nasal and pharyngeal areas, such as obesity, allergic rhinitis, nasal polyps, tonsillar hypertrophy, soft palate relaxation, excessive length and thickness of the palatal lobe, tongue hypertrophy, posterior tongue root, mandibular recession, temporomandibular joint dysfunction and small jaw deformity. Some endocrine diseases can also be combined with the disease. The pathogenesis may be related to the increased collapse of the soft tissues and muscles of the upper airway in the sleep state, the reduced responsiveness of the upper airway muscles to the stimulation of low oxygen and carbon dioxide during sleep, and, in addition, the combined effect of neurological, humoral and endocrine factors. Zunyi First People’s Hospital Otolaryngology Head and Neck Surgery Ma Zuxia Treatment: Treatment of OSAHS is divided into two categories: non-surgical treatment and surgical treatment, in addition to lateral recumbency, smoking and alcohol cessation, and weight loss in obese people.
(I) Non-surgical treatment
1. Transnasal continuous positive airway pressure breathing (CPAP)
This method is currently the most effective treatment for moderate to severe OSAHS, and most patients can achieve satisfactory therapeutic results through CPAP treatment.
2. Oral appliance
Wearing an oral appliance during sleep can elevate the soft palate, traction the tongue forward actively or passively, as well as the jaw forward to achieve enlargement of the oropharynx and hypopharynx, which is the main means of treating simple snoring or one of the important auxiliary means of non-surgical treatment for OSAHS, but it is not effective for patients with moderate to severe OSAHS.
(II) Surgical treatment
The aim of surgical treatment is to reduce and eliminate airway obstruction and prevent collapse of the soft tissues of the airway. The choice of surgical method depends on the site of airway obstruction, severity, presence of morbid obesity and general condition. The following surgical methods are commonly used.
1. Tonsil and adenoidectomy
This type of surgery is suitable for adult patients with tonsillar hyperplasia, or pediatric patients due to adenoid hypertrophy. It is generally effective for a short period of time after surgery, and can still recur with youthful development and the development of the tongue and soft palate muscles.
2. Nasal surgery
If nasal airway obstruction is caused by nasal septum curvature, nasal polyp or turbinate hypertrophy, septoplasty and removal of nasal polyp or turbinate are feasible to reduce symptoms.
3. Tongue surgery
If the tongue is enlarged by hypertrophy, megalingualism, receding tongue root or enlarged tongue tonsils, linguoplasty is feasible.
4. Palatoplasty of palate, palate and pharynx
This surgery is to remove the posterior edge of the soft palate and the loose mucosa of the lateral wall of the pharynx, and to tighten the mucosa of the lateral wall of the pharynx and suture it forward, in order to relieve the obstruction of the soft palate and the airway at the level of the oropharynx, but it cannot relieve the obstruction of the airway of the hypopharynx, so the indications must be chosen well.
5. Orthognathic surgery
Orthognathic surgery is mainly used for OSAHS with oropharyngeal and hypopharyngeal airway obstruction caused by jaw deformity.