Pediatric obstructive sleep apnea

　　1. Etiology

　　The causes of OSA include anatomical factors, congenital diseases, and other factors. Most pediatric OSA is caused by adenoid and tonsil hypertrophy, which are the most common causes of pediatric OSA. In infantile OSA, 52% of the obstruction is located in the upper palate, and 48% is behind the tongue.

　　2. Pathogenesis

　　Children with Obstructive Sleep Apnea Syndrome (OSAS) are caused by diseases of the nose, nasopharynx, oropharynx, or abnormal development of the maxilla, combined with the tongue base sagging during sleep, leading to narrowing of the upper airway. Due to the anatomical narrowing of the upper airway and dysfunction of respiratory regulation, the main force for opening the upper airway is the tension of the pharyngeal dilator muscles, including the genioglossus, palatopharyngeus, and palatoglossus muscles. During sleep, especially during the rapid eye movement (REM) phase, the tension of the pharyngeal dilator muscles is significantly reduced, combined with the inherent narrowing of the pharyngeal cavity, making it easy to close and causing OSA. The main pathophysiological change of OSA is the repeated occurrence of apnea during sleep, leading to hypoxemia and hypercapnia, which can cause imbalances in neuroregulatory function, increased secretion of catecholamines, renin-angiotensin, endothelin, and endocrine dysfunction, changes in hemodynamics, abnormalities in microcirculation, and ischemia and hypoxia of tissues and organs, leading to damage to multiple organ functions, especially the heart, lungs, and brain. It can cause hypertension, pulmonary hypertension, nocturnal arrhythmias, heart failure, and other conditions. Brain dysfunction can manifest as fatigue, drowsiness, decreased memory, and even intellectual impairment during the day.

　　Due to long-term hypoxia in children with OSAS, it can affect their growth and development. 30% to 40% show delayed growth and development. Complications may include hypertension, pulmonary edema, pulmonary heart disease, arrhythmia, congestive heart failure, respiratory failure, even sudden infant death syndrome. Developmental delay, neurological dysfunction, pulmonary hypertension, congestive heart failure, pulmonary heart disease, respiratory failure may occur, and there are also reports of increased intracranial pressure; polycythemia is relatively rare. Most can be spontaneously relieved after correcting upper airway obstruction. However, some children with pulmonary heart disease may spontaneously relieve due to the atrophy of the tonsils and adenoids, which are the most common causes of pediatric upper airway obstruction.

　　1. Nighttime Symptoms

　　The most significant symptom at night is snoring, almost all children with OSAS snore, and most of the snoring sounds are loud. However, severe OSAS can be without snoring or only with high-pitched grunts during sleep. Snoring can be exacerbated during upper respiratory tract infections. In children with OSAS, the main problem is insufficient pulmonary ventilation associated with OSAS or sleep-related conditions. Children show two main forms of snoring: continuous snoring and intermittent snoring, with quiet periods separated by loud sighing or humming sounds.

　　Almost all children with OSAS show signs of respiratory effort, and the esophageal pressure range of children with sleep apnea is -4.90 to -6.87 kPa. The effortful breathing during obstructive respiration is manifested as inward indentation of the intercostal, sternum, supra-sternal, and clavicular areas, expansion of the rib margins, and detectable activity of the accessory respiratory muscles. In addition, an abnormal inward retraction of the chest during inspiration can also be seen, but this is normal during REM sleep in newborns, infants, and older children. The episodes of apnea in OSAS are periodic and can be spontaneously terminated. During an episode, the snoring sound suddenly stops, the effort to inhale increases, but there is no airflow entering the respiratory tract through the mouth and nose. With a longer duration, cyanosis and a slower heart rate may occur. The reappearance of snoring indicates the cessation of the episode, the return of breathing, and the occurrence of loud exhalation sounds, awakening, and changes in posture.

　　2. Daytime Symptoms

　　Symptoms of OSAS children upon awakening in the morning include mouth breathing, headache upon waking up, dry mouth, disorientation, confusion, and irritability; school-age children may show symptoms such as inattention in class, daydreaming, fatigue, a decline in academic performance, and 8% to 62% of children may also have excessive daytime sleepiness. Daytime behavioral problems are relatively common in children with OSAS, mainly manifested as poor school performance, hyperactivity, intellectual disability, emotional problems, shy or withdrawn behavior, aggressive behavior, and learning difficulties. Many children with OSAS have delayed growth and development. It has been clearly shown that adult OSAS can damage attention, memory, alertness, and motor skills, but there is little research on the impact of OSAS on children's daytime cognitive abilities. Most children with OSAS have enlarged tonsils and adenoids, and most of them show mouth breathing, some accompanied by difficulty in eating, swallowing, and halitosis, and a certain degree of language disorders.

　　3. Associated symptoms

　　Hypoxemia usually occurs in many children with OSAS, some severe OSAS children's SaO2 can drop below 50%, the SaO2 of children with continuous partial obstruction decreases at the beginning of the obstruction and remains at a relatively low level for a long time, hypercapnia is also a characteristic of pediatric OSAS, half of the hypercapnia (end-tidal CO2>6.0kPa) is related to OSAS or persistent partial obstruction, weight loss is seen in most children with obstructive lung ventilation insufficiency, in addition, children with airway obstruction during sleep are prone to gastroesophageal reflux, sudden awakening, crying, screaming and other symptoms. Another study found that OSAS children may exhibit some behavioral disorders, such as impulsiveness, defiance, or abnormal shyness and social withdrawal.

　　4. Signs

　　Including dyspnea, nasal flaring, intercostal and supraclavicular depression, paradoxical movement of the chest and abdomen during inspiration; night sweating (limited to the neck and back, especially in infants and young children), parents may notice that the child does not want to cover the blanket at night, followed by apnea and then wheezing, the typical sleep posture is prone position, head turned to one side, neck excessively extended with the mouth open, knees flexed to the chest.

　　Wearing an oral appliance or tongue retainer during sleep has the advantages of simplicity, gentleness, and low cost. The selection of indications for treatment is appropriate, and the recent effective rate is about 70%. After wearing it, the lower jaw and (or) tongue can be moved forward, which can expand the upper airway or increase its stability, increase the posterior airway space at the level of the soft palate and uvula, prevent the tongue from sinking, and alleviate OSAS to varying degrees. It is suitable for mild to moderate patients to prevent the occurrence of complications. The disadvantage is that the discomfort of the patient is obvious, and more than 50% of the patients cannot tolerate it.

　　1. Polysomnography

　　It is considered the gold standard for diagnosing sleep-related breathing disorders. Marcus et al. pointed out that the diagnostic criteria for obstructive sleep apnea in children over 1 year old are: the number of obstructive sleep apnea episodes per hour during sleep is ≥1, accompanied by SaO2 of 253mmHg, or abnormal when PETCO2>45mmHg is observed in more than 60% of the sleep time, the full-night polysomnography should be continuously monitored for more than 6-7 hours at night, including electroencephalogram, electrooculogram, submental electromyogram, leg movement chart, and electrocardiogram, and at the same time, blood oxygen saturation, end-tidal carbon dioxide partial pressure, chest and abdominal wall movement, nasal and oral airflow, blood pressure, snoring, esophageal pH value or pressure, etc. should be monitored.

　　2. Automatic continuous positive airway pressure system

　　There are two modes: diagnosis and treatment. During diagnosis, electroencephalogram, electrooculogram, electromyogram, and electrocardiogram are not monitored, only chest and abdominal breathing movements, nasal airflow, and blood oxygen saturation are monitored, and apnea, snoring, and upper airway resistance can be simultaneously monitored and displayed.

　　3. Electrostatically charged bed

　　This method involves setting a static load layer and motion sensor under the standard foam mattress, where the patient sleeps on the bed, only needing a blood oxygen saturation level without any electrodes, and the original motion signal is pre-amplified and frequency filtered, then entering the lower three leads respectively, and the OSA patients are divided into four types of periodic respiration according to the pattern of increased respiratory resistance. This method is currently mainly used for the initial screening of obstructive and central sleep apnea, as well as severe snoring with increased upper airway resistance.

　　4. Other examinations

　　There are nasopharyngeal lateral X-ray, CT, MRI, nasopharyngoscopy, and other examinations, which are helpful to understand the structure of the upper airway, showing the narrow and blocked parts and degrees, multiple sleep latency tests (multiplesleepplatencytest, MSLT) are helpful to judge the degree of daytime sleepiness and differentiate from narcolepsy. 50% of the obese, 52% of hypothyroidism, and 42.6% of acromegaly may be complicated with OSAS. Therefore, when diagnosing sleep apnea syndrome, attention should also be paid to the diagnosis of other systemic diseases.

　　1. Diet principles

　　Choose a reasonable diet, control total calorie intake to reduce weight. The total calorie intake for male patients should be controlled at 1200~1500 kcal/day, and for female patients at 1000~1200 kcal/day. Pay attention to the quantification of food intake, avoid overeating, and do not eat heavily before going to bed. The total fat in the diet should not exceed 30% of the total calories, protein intake should account for 15%~20% of the total calories, and the rest should be carbohydrates, but sweets should be limited. In daily life, choose light food, eat less animal fatty meat and internal organs, and choose fish, beans, and milk lean meat. Choose fresh vegetables with high vitamins and fiber.

　　2. Diet taboos

　　It is advisable to consume iodine-rich foods with hypolipidemic effects, such as kelp and seaweed. Avoid preserved foods and limit sodium intake to daily

　　I. Treatment

　　1. Medical treatment

　　(1) General treatment: includes changing dietary and sleep habits, avoiding overeating at dinner, sleeping in a lateral position, not supine, avoiding sedative drugs, and overweight patients should lose weight. Weight loss can increase the cross-sectional area of the throat, thereby effectively reducing nocturnal apnea and alleviating hypoxemia.

　　(2) Oxygen therapy: Some studies have reported that oxygen therapy can effectively alleviate nocturnal hypoxemia in children with OSAS, reduce the apnea index of obstructive respiratory暂停 and reduce the number of microarousals. However, some studies suggest that it may prolong the apnea time in patients with OSAS.

　　(3) Medication: For OSAS caused by nasal narrowing and obstruction due to allergic rhinitis, treatment includes nasal inhalation of corticosteroids, oral second-generation antihistamines (first-generation antihistamines have central sedative effects and can worsen OSA, so they are not recommended), and nasal vasoconstrictor drugs, which can reduce snoring and improve airway obstruction. Other medications include carbonic anhydrase inhibitors (such as acetazolamide), estrogens (such as medroxyprogesterone), antidepressants (such as protriptyline), theophylline derivatives, etc., but they have not yet achieved definite and unified clinical effects.

　　(4) Nasal Continuous Positive Airway Pressure (n-CPAP): It is currently recognized as the first-line treatment for adult OSAS, which can eliminate snoring at night, improve sleep structure, improve nocturnal apnea and hypoventilation, correct nocturnal hypoxemia, and thus improve symptoms during the day. However, since the main cause of pediatric OSAS is hypertrophy of the tonsil and (or) adenoid, the surgical removal of the hyperplastic tonsil and adenoid is the main treatment method, and n-CPAP is only the first-line treatment for OSAS in children caused by other reasons.

　　2. Surgical treatment

　　Tonsillectomy and adenoidectomy are the first-line treatment for pediatric OSAS caused by tonsil and adenoid hypertrophy. Other surgical treatment methods adopted according to different causes include nasal surgery (such as nasal septum correction, nasal polyp removal, turbinate resection, etc.), uvulopalatopharyngoplasty, laser-assisted pharyngoplasty, plasma低温radiofrequency ablation, mandibular advancement or maxillomandibular osteotomy, etc. Tracheotomy or tracheostomy has now been basically eliminated. Reports by Padman et al. in the United States show that bilevel positive airway pressure (BiPAP) can reduce the apnea index in children with sleep apnea hypopnea syndrome, improve the minimum arterial oxygen saturation, and is an effective treatment method for pediatric obstructive sleep apnea.

　　II. Prognosis

　　Mild cases have no significant impact on children, while severe cases can cause growth and development delay, intellectual impairment, and abnormal psychological and behavioral disorders. Severe cases may have insufficient heart and lung function and intellectual disability.