Cai Xiaolan, Department of Otolaryngology, Qilu Hospital, Shandong University
(Abstract) The concept, definition, epidemiology, etiology, clinical manifestations, diagnosis and treatment of sleep apnea syndrome in children are analyzed and summarized, with emphasis on the special characteristics of pediatric patients. Cai Xiaolan, Department of Otolaryngology, Qilu Hospital, Shandong University
Sleep-related respiratory disorders in children are divided into three types: simple snoring, obstructive apnea and hypoventilation syndrome, and upper airway resistance syndrome, whose symptoms and signs do not always accurately reflect the severity of the disease. Most children who snore are simple snorers and do not have sleep architecture, alveolar hypoventilation or hypoxic changes. In Obstructive Sleep Apnea Syndrome (OSAS), children have loud snoring, typical apnea or partial obstruction with decreased oxygen saturation; however, some children do not have obvious snoring symptoms (l), and parents may observe significant post-breathing interval wheezing. Children with upper airway resistance syndrome have increased upper airway resistance during sleep, resulting in negative intrathoracic pressure fluctuations during inspiration, increased respiratory work, transient awakening and sleep fragmentation, but normal nasal and oral airflow and blood oxygenation, without apnea hypoventilation, mostly occurring in the REM phase of sleep, and intraesophageal pressure measurement and polysomnography can help confirm the diagnosis (2). These three sleep-related breathing disorders may co-exist or alternate in the same child at different times due to upper respiratory tract infections or changes in sleep position (3). Although OSAS has similar pathophysiological changes in children and adults, it is important for clinicians to identify the significant differences in diagnosis and treatment to avoid underestimating the condition in pediatric patients.
[Epidemiological] studies have confirmed that about 20% of children have intermittent snoring, 10%-12% have frequent simple snoring, and the prevalence of OSAS in children is about 1%-3% (1-5), with about 500,000 affected children in the United States (l), and the prevalence may be higher when snoring is aggravated by upper respiratory tract infections.Ali (3) et al. conducted a survey of 782 young children aged 4-5 years A questionnaire survey found that 12.1% of them snored mostly during sleep, and habitual snoring was associated with daytime sleepiness, restless sleep, and hyperactivity. After observation of video recording and oxygen saturation at home throughout the night, O.7% showed sleep apnea. This study supports the view that most snoring children do not have OSAS, but the actual incidence of OSAS should be higher if monitored by a polysomnograph (PSG) with higher sensitivity. In a recent (3) study using questionnaires and selective polysomnographs in children aged 6 months to 6 years, snoring was reported to be 3.2% and occasionally 16.7%, and Wang (4) estimated the low limit of OSAS prevalence to be 2.9%.
[Other possible causes include (7): nasal obstruction, maxillofacial anomalies, macroglossia, mandibular recession, neuromuscular disorders, and laryngeal tenderness. The first peak of the disease occurs at the age of 2-5 years, which is consistent with adenoid hypertrophy; the second peak is around the middle and late adolescence, after which, with the atrophy of lymphoid tissues, sleep disordered breathing is gradually relieved, with the same incidence in men and women before puberty (1). However, it is also believed that the tonsils and adenoids are the largest in size at the age of 3-6 years, and are the age group with the highest incidence (3), with a male to female ratio of 4.5:1 (6, 8).
[Clinical manifestations] vary according to age (5, 6), with children younger than 5 years old having the most pronounced nocturnal symptoms; children older than 5 years old may also exhibit nonspecific behavioral abnormalities during the day. Most children are seen in otolaryngology or respiratory medicine for sleep snoring, breath-holding, open-mouth breathing, and tonsillar hypertrophy; in pediatrics for growth retardation, malnutrition, and pulmonary hypertension; in neurology or psychiatry for night terrors, nocturnal crying, enuresis, and hyperactivity; and in endocrinology for rapid obesity within a short period of time. Therefore, it is important for physicians to have an understanding of the physiopathological changes involved in children’s sleep.
The most easily observed symptoms in children with OSAS are (l-5) sleep disturbance, labored breathing, open-mouth breathing, snoring, abnormal respiratory movements, most children have abnormally loud snoring at the end of persistent obstructive apnea, but some children do not have obvious snoring symptoms; abnormal sleep positions can also be seen (3), such as neck hyperextension, prone, knee-chest position, semi-sitting, high pillow At least 50% of children have excessive sweating during sleep (3); enuresis (1, 3) can be another non-specific clinical symptom of OSAS in children, the exact mechanism of which is unknown and may be the result of multiple factors. Obstructive hypoventilation or apnea episodes, stage-specific hypoxia are more severe during REM sleep, and nasal flapping, inspiratory depression of the sternum, supraclavicular fossa and intercostal space may occur in infants and children. Abnormal sleep behaviors, such as nocturnal sleepwalking and night terrors, often occur in the REM period; some children may wake up suddenly with crying, choking, moaning, sudden change of sleeping position or sitting up.
Children with frequent nocturnal respiratory disturbances are rarely accompanied by significant daytime sleepiness, i.e., daytime sleepiness is not common in children with OSAS, and this is one of the most important differences in clinical presentation between children with OSAS and adults (3). The reasons for this may be the following: 1) rhythmic changes in sleep arousal are age-related, with a higher proportion of children in deep sleep and REM phase; prolonged partial obstruction can be self-aborted, and sleep arousal does not occur at the end stage (9, 10). 2) daytime napping and snoozing are frequent in children, and are normal physiological phenomena in children under 5 years of age (l), making daytime sleepiness difficult to identify in the pediatric population; 3) obstructive apnea is less frequent in children than in adults, and partial obstructive hypoventilation is more frequent (11); it may not be manifested as obvious awakening during sleep. Although PSG monitoring has shown that microarousals are present during sleep in children with OSAS and result in sleep fragmentation, sleep deprivation due to hypoxia or sleep fragmentation accompanying apnea may be the main reason for the increased incidence of abnormal sleep behavior in children. Microarousals have been considered in relation to the distribution of the overall sleep phase, post-sleep awakening time, and overall sleep quality. Children with severe daytime sleepiness and frequent napping should be considered for sleep deprivation or polysomnolence based on clinical history.
Due to the adverse effects of nasal congestion and open-mouth breathing during sleep on both facial growth and dental occlusion, about 15% of children with OSAS develop adenoid facial features (long face syndrome) (1, 3), which are characterized by long and narrow jaws, high arched palatal lid, short jaw length, receding lower jaw, large craniocervical angle, hypoplastic midface, protruding upper incisors, and dental malocclusion. Because most children complete 60% of their craniofacial development by age 4 and 90% by age 11 (5, 12), childhood is an important stage in the formation of respiratory patterns, and once established, they are difficult to change; 5 years after adenoidectomy, children return to nasal breathing from oral breathing, and all of their original maxillofacial features show varying degrees of recovery (12).
In children with OSAS, especially those with adenoid hypertrophy, nasopharyngeal and oropharyngeal secretions are significantly increased, and aspiration into the lungs is common; in addition, in children with acute or chronic upper airway obstruction, gastroesophageal reflux during sleep may occur (l), causing wheezing and coughing, and manifesting as recurrent unresolved upper respiratory tract infections. Recent studies have shown that apnea, lip cyanosis, and wheezing in infants and children are significantly associated with increased negative intrathoracic pressure and gastroesophageal reflux due to obstruction.
Growth retardation is one of the main features of OSAS patients in adult children, including short stature and low weight, which can be reversed after treatment in young children; after adenoidectomy, appetite improves and growth rate increases, with possible mechanisms (1, 3, 5): sleep structure disorders, hypoxia, hypercapnia, metabolic acidosis, etc. affecting the secretion of growth hormone; or making tissues and organs less responsive to growth hormone The increase of respiratory work makes the energy consumption too much, etc. Although obesity is not necessarily related to the development of OSAS in children, morbidly obese children have a relatively high incidence, and children aged 5-12 years with a history of rapid weight gain are at risk for OSAS (l), which may be related to sleep breath-holding, nighttime hypoxia, and sleep fragmentation, leading to daytime sleepiness and reduced activity, while hypoxic metabolism leads to increased eating and forms a vicious circle. Wang et al. (4) concluded that the two extremes of weight, overweight or growth retardation and underweight, are good predictors of disease status in children with OSAS.
Children may exhibit nonspecific behavioral disturbances (1, 3), such as aloofness, dull expression, abnormal shyness, hyperactivity, irritability, aggressive or rebellious behavior; loss of appetite, malnutrition, and reluctance to go to bed at night in about 1/4 of children; open-mouth breathing when awake due to adenoid hypertrophy, morning headache, dry mouth, and depression; cognitive dysfunction (13), decreased intellectual behavior and learning ability, distractibility, and mood swings. A large number of clinical reports have confirmed that the above symptoms improve and return to normal with the cure of OSAS.
The clinical course of OSAS in children is varied, and with the development of the disease, developmental delay (1-5), neurological dysfunction, pulmonary hypertension, congestive heart failure, pulmonary heart disease, respiratory failure, and increased intracranial pressure have also been reported, while erythrocytosis is less common; after correction of upper airway obstruction, most of them can resolve on their own. However, some children with pulmonary heart disease may resolve on their own due to atrophy of the enlarged tonsils and adenoids, which are the most common causes of upper airway obstruction.
[Diagnostic criteria and assessment] The diagnosis of OSAS in children should rely on (14) 1. basic medical history: children with suspected sleep snoring, enhanced respiratory movement, open-mouth breathing and growth retardation should be carefully questioned about sleep time, sleep quality, sleep behavior and position, nature and intensity of snoring, breathing and its accompanying sounds, morning waking time, daytime snoozing pattern and behavioral functions; and a comprehensive record of height, weight The body mass index (BMI) ≥ 30 Kg/m2 was considered obese, 25 < BMI < 30 Kg/m2 was considered overweight, and BMI ≤ 25 Kg/m2 was considered normal. 2. Physical examination: including l = routine ENT examination, preliminary determination of upper airway patency, Exclude craniofacial structural deformities. The palatine tonsil (15) reduces the right and left oropharyngeal cavity by 0%-25% as 1°, 26%-50% as 2°, 51%-75% as 3°, and 76-100% as 4°. 2 = Fiberoptic nasopharyngoscopy for comprehensive assessment of the upper airway, observing the nasal cavity, nasopharynx, posterior cut-off area of soft palate, tongue root, epiglottis, laryngeal cavity and other structures, which is very important for disease diagnosis and obstruction localization. The size of the posterior nasal aperture was recorded in terms of adenoids (15) obstruction, with 0%-25% as 1°, 26%-50% as 2°, 51%-75% as 3°, and 76%-100% as 4°. 3) Lateral cephalometric radiographs were taken to observe adenoid hypertrophy and nasopharyngeal airway, tongue root hypertrophy, and epiglottis airway obstruction. 4) Blood pressure, electrocardiogram, and chest X-ray were performed to rule out cardiopulmonary complications. 3. The gold standard for diagnosis is PSG monitoring, which is mainly used to clarify the diagnosis, understand the severity of the disease and surgical efficacy observation. The ideal environment for monitoring children is (3): the use of specially trained, professional technicians who have studied sleep in children, who can gain the child's trust and share the parents' anxiety; parents should sleep with the child in a different bed in the same room.
When evaluating PSG reports, clinicians need to have a thorough understanding of the physiological and pathological differences between sleep breathing in children and adults. Routine PSG monitoring prior to surgical treatment has found that 37%-55% of children with typical clinical signs and symptoms can be confirmed by PSG (3, 4), mainly because of differences in outcomes due to researchers using their own different diagnostic criteria for PSG (4); other reports suggest that: Approximately 80% of children with severe upper airway obstruction are not confirmed by the diagnostic criteria of adult OSAS or by recording the number of apneas (5, 6).In 1992, Marcus (16) found in a sleep study of 50 normal children that: under normal conditions, the average apnea index (AI was 0.1 +/- 0.5 breaths/hour and the lowest oxygen saturation ( In 1996, Longhlin (17) concluded that obstructive apnea or hypoventilation in childhood is pathologically significant because of the rapid respiratory rhythm in children, and that obstructive hypoventilation in children can be based on a partial pressure of respiratory uninduced carbon dioxide >5OmmHg for more than the whole night The diagnosis of obstructive hypoventilation in children can be determined based on the fact that the partial pressure of respiratory un-CO2 is more than 8%-10% of sleep. The currently accepted diagnostic criteria for OSAS in children are (l, 4, 5): 1) AI greater than 1 time/hour and AHI greater than 5 times/hour. 2) Minimum oxygen saturation (LSa02) less than 92%, or partial pressure of carbon dioxide (PaC02) greater than 50 mmHg during 10% of sleep time or greater than 45 mmHg during 60% of sleep time. An AHI greater than 20 times/hour is considered severe OSAS.
OSAS in children is mainly characterized by (5, l8) obstructive hypoventilation, persistent hypoventilation with a variable number of apneic episodes, characterized by chest wall retraction and/or enhanced thoracoabdominal paradoxical respiratory movements, often accompanied by phasic hypoxemia and hypercapnia; prolonged partial obstruction may be automatically aborted, with no sleep awakening at the end stage, and may last throughout the night. In neonates with the same daytime sleep as at night, daytime studies can also provide the necessary PSG information, but classical PSG monitoring should be at least 4 hours (5); in infants and children over 6 months of age, most of the sleep time is at night, and the most concentrated segment of REM sleep, i.e., apnea, occurs in the second half of the night, so daytime studies are not accurate; multiple nap latency experiments are applied in children over 8 years of age The application of multiple nap latency experiments in children over 8 years of age is more desirable (3).
The high cost, multiple variables, and long waiting time for appointments of PSG monitoring have limited its usefulness and are controversial. However, PSG monitoring is currently considered essential for the diagnosis and differential diagnosis of children at greater surgical risk (1-6), such as those under 2 years of age, with craniofacial anomalies or other syndromes, developmental delays, cardiopulmonary abnormalities, morbid obesity, nocturnal oxygen saturation below 70%, reduced airway tone, history or consideration of upper airway trauma, and the presence of severe central nervous system disease, as well as for the assessment of The severity of OSAS can help determine the indications for surgery. In children with severe OSAS aged less than 3 years, with AHI >20, or with persistent postoperative symptoms such as craniofacial deformities and morbid obesity, it is recommended that PSG be performed 1-3 months (1, 5, 6) after surgery. However, the current rate of postoperative PSG monitoring is low, ranging from approximately 43%-64% to a maximum of 87% (4).
In addition, many physicians use other modalities to assist in the diagnosis, such as: l) overnight four-lead sleep apnea studies, which record heart rate, respiratory work, oral and nasal airflow, and oxygen saturation. 2) overnight pulse oximetry monitoring and observation by an experienced clinician can provide evidence of respiratory obstruction associated with hypoxia. 3) sleep recordings and videotaped data. However, the lack of sleep staging and thoraco-abdominal respiratory kinetic data, and the inability to redefine apnea according to the criteria of OSAS in children, may lead to underestimation of the condition and make it difficult to distinguish the types of sleep-related breathing disorders and apnea. Esophageal manometry remains the only method to confirm the diagnosis in children suspected of having upper airway resistance syndrome (UARS) (2), but it is difficult to be widely used because of the laborious operation and increased pain in children.
[Treatment of OSAS in children includes: 1) surgery 2) positive pressure ventilation therapy 3) conservative treatment 4) oxygenation with therapeutic interventions, etc. The treatment plan should rely on clinical examination and laboratory monitoring data, with special emphasis on individualized treatment plans chosen according to the individual and time.
Enlarged tonsils and adenoids are the most common cause of upper airway obstruction in children, and tonsil and/or adenoidectomy is the most common treatment for pediatric OSAS patients. Tonsillectomy and/or nasal endoscopy-guided adenoids scraping under general anesthesia is characterized by direct vision, clear vision, less damage to surrounding tissues, and no residual bodies, and can avoid adenoids repopulation and compensatory hypertrophy after surgery (19). The mean AHI decreased in 78% of children after surgical treatment, the mean time to sleep decreased in 92% of children with oxygen saturation (Sa02) below 90%, and the mean time to sleep decreased in 43% of children with partial pressure of carbon dioxide above 50% (1). Sato et al. (20) showed a cure rate of 60% and an efficiency rate of 95% at 10 years of follow-up. However, the surgical results were poor in children with small tonsils, narrow epiglottic airway, maxillary hypoplasia, mandibular recession, age less than 12 months, Down syndrome, and with neurological defects. For older patients with small tonsils and adenoids and severe airway obstruction caused by thick and long uvula, after confirmed by fiberoptic nasopharyngoscopy and Muler’s test, uvulopalatopharyngoplasty can be selected at the discretion of the patient.
Respiratory complications are still one of the important risk factors after surgery, especially in patients with congenital malformations, respiratory system disorders and severe OSAS. Intraoperative and early postoperative administration of intravenous steroids (e.g., dexamethasone) can reduce postoperative pain, prevent pharyngeal edema, and increase transoral feeding, which has positive significance for postoperative recovery (1, 21). In patients with severe OSA, CPAP is helpful in the early postoperative period, but it should be used with caution in children with bloody secretions and saliva accumulation in the oral cavity to prevent misaspiration under positive pressure ventilation. After surgery, the child should be hospitalized overnight for observation, and should be discharged only if there is no bleeding, respiratory distress, or other abnormalities. During the first 4 days after surgery, the child may lose weight due to stress and change in eating habits, so pain and infection should be controlled appropriately.
The literature confirms that lingual root surgery has limited remission even in adult patients with sleep disordered breathing; maxillofacial surgery, such as maxillary and mandibular anterior pelvic surgery, is effective in 80-90% of patients with OSAS (l, 3). In prepubertal children with craniofacial deformities, simple tonsil and/or adenoidectomy is difficult to achieve satisfactory results, and early orthodontic treatment or CPAP treatment should be used to promote maxillofacial development, relieve severe hypoxia, and avoid complications such as pulmonary hypertension and neurological damage. Most children’s craniofacial development is 60% by the age of 4 and 90% by the age of 11. Therefore, the timing of surgery should take into account the growth and development of children, and it is best to perform orthognathic surgery after the development of the middle part of the face is completed. For children with significant mandibular recession caused by trauma and other factors, anterior mandibular migration or bone traction molding (22) can be chosen to enlarge the lingual root and euphemopharyngeal airway to fundamentally improve upper airway ventilation as an alternative to tracheotomy or long-term CPAP treatment.
CPAP or BiPAP is mainly used for surgically incurable airway obstruction, including those who cannot undergo tonsil or adenoidectomy or cannot be relieved after surgery, and also for perioperative treatment. Compared with adults, children have a higher tolerance rate, and the success rate of CPAP treatment is about 90% (1), even for infants and children aged 6 months to 2 years, with a good family environment and attentive parental care, good results can be achieved. The success rate of CPAP in children with obvious craniofacial deformities is about 62%(l), and the average treatment pressure of CPAP in prepubertal children is relatively low(l8), and the pressure level of 8cmH20 is effective in 86% of children(l). Because of the rapid growth and development of children after treatment, the use of home CPAP or BiPAP requires careful pressure titration, routine, follow-up, and adjustment of pressure and mask size at least every 6 months to accommodate changes in children’s growth and development, to prevent complications such as mask leakage, gastrointestinal distention, and misaspiration, and to guide and supervise patients in their treatment (l, 3, 5).
Conservative treatment, which includes encouraging obese patients to lose weight and adjust their sleep position, is not effective in most critically ill patients. Oxygenation can reduce the degree of hypoxia but not the number of apneas and hypoventilation. Simple low-flow oxygenation can help maintain normal blood oxygen levels in infants and children with moderate OSAS or severe hypoxia but who cannot undergo surgery and also cannot tolerate CPAP therapy.
For children with severe OSA with hypertrophy of the tongue root confirmed by fiberoptic nasopharyngoscopy, which cannot be relieved or tolerated by conservative observation, surgery or CPAP, tracheotomy is still an important and last choice of treatment, and can also be used for children with cardiopulmonary disorders, aspiration or other congenital disorders causing upper airway obstruction, postoperative edema, etc. However, after tracheotomy, complications in children with OSAS are significantly higher than those in adults. Central apnea may occur in the early postoperative period due to hypoxic respiration; detubation or mucus blockage may lead to insufficient ventilation at the same time. In addition, it should be considered that it may have serious adverse effects on the child’s language formation, growth and psychological development (1-6).
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