Sleep-Disordered Breathing − Year in Review 2024

The spectrum of obstructive sleep-disordered breathing (oSDB) in children ranges from primary snoring to obstructive sleep apnea syndrome (OSAS). Primary snoring is characterized by snoring occurring more than three nights per week with normal overnight polysomnography (PSG) and is present in 6%–17% of all children. OSAS is defined by an increased apnea-hypopnea index (AHI)—the number of apneas and hypopneas per hour—during PSG and is present in 1%–5% of all children. It is widely acknowledged that an AHI of at least 5 per hour warrants consideration of treatment, most commonly adenotonsillectomy. However, when the AHI is less than 5 per hour and there are no clinical signs of complications related to oSDB, watchful waiting may be a valid approach. Official guidelines generally recommend performing an overnight PSG in all children with a history of chronic snoring to measure the AHI, assess the severity of oSDB, and determine the need for treatment. In practice, however, most children do not have access to overnight PSG due to the limited availability of sleep laboratories worldwide. My personal review of last year's literature on oSDB in children focuses on publications dealing with the recognition of children who require treatment for oSDB, including the place of overnight PSG in their management. Two expert recommendations published in 2023 identify a group of children with a history and clinical examination consistent with oSDB who can be treated without the need for overnight recording. A French Consensus1 focused on recommendations for children with “oSDB type 1,” defined as occurring in young, nonobese children with no associated comorbidities, where oSDB is generally due to adenotonsillar hypertrophy. The experts conclude that significant oSDB-1 is suspected when several nighttime respiratory symptoms related to upper airway obstruction are present in the clinical history. They emphasize that “the diagnosis is above all clinical and OSA severity should also be evaluated on the basis of all the clinical signs.” A specialized otolaryngologist examination is considered essential. They further state that questionnaires can be used to collect clinical history, especially by non-experts. Hence, a score less than 0.3 at the Sleep-Related Breathing Disorder Scale of the Pediatric Sleep Questionnaire has good predictive value for mild OSA with potential spontaneous normalization, allowing for watchful waiting. Conversely, a score greater than 2.72 on the Spruyt and Gozal Severity Questionnaire indicates a high likelihood of moderate OSA (sensitivity = 82%, specificity = 81%) and suggests that treatment should be considered. In addition, it is stated that a sleep study is not mandatory before surgery for a child with oSDB-1 if at least two nighttime symptoms (including snoring) and significant tonsil hypertrophy are present. If a sleep study is required, full nocturnal PSG in hospital (the gold standard) or cardiorespiratory polygraphy—performed in hospital or at home depending on the child's needs and availability—should be performed. The British Thoracic Society Guidelines2 recommend that a score of at least 0.33 at the Sleep-Related Breathing Disordered Scale of the Pediatric Sleep Questionnaire can be used to diagnose moderate-to-severe oSDB in children aged at least 2 years with no comorbidities, if consistent with clinical features. They note, however, that the questionnaire has low specificity, so that if the results do not match the clinical picture, additional tests such as pulse oximetry, cardiorespiratory polygraphy, or full overnight PSG are recommended to aid in the decision. Pulse oximetry is suggested as a first-line diagnostic test for children older than 2 years suspected of oSDB: analysis focuses on mean saturation (<95%), the number of desaturations below 90%, the oxygen desaturation index (ODI)—the number of decreases in SatO2 of 3 or 4% per hour, an ODI3 greater than 7 or an ODI4 greater than 4 per hour being considered abnormal—and the presence of clusters of desaturations. In addition, they state that “Clinicians can use video and audio recordings in a similar way to clinical observation to support intervention to treat oSDB.” If pulse oximetry results do not fit the clinical picture, a higher level of investigation, such as a cardiorespiratory sleep study or full overnight PSG may be required, depending on test availability. These tests allow for computing the AHI. Importantly, however, they emphasize that “Clinicians are cautioned about using AHI alone to guide decision-making.” In summary, the new recommendations from the French consensus of experts and the British Thoracic Society guidelines formally state that a sleep study is not mandatory in a child older than 2 years without comorbidities if the history and clinical examination by an expert otolaryngologist are consistent with significant oSDB due to adenotonsillar hypertrophy. These official statements align in fact with current real-life practices, given the global shortage of PSG laboratories and the typically long wait times for sleep studies. It is acknowledged that nocturnal PSG provides crucial information in challenging cases, such as in children with comorbidities, those younger than 2 years, or when the diagnosis of oSDB is uncertain. An increasing number of experts, however, are questioning the value of the AHI, which, according to current official guidelines, is used to guide treatment decisions for children with oSDB. Notably, leading experts on oSDB in adults have argued for several years that the AHI is “neither adequate nor sufficient to diagnose and characterize oSDB severity.”3 An important publication by Solano-Pérez E et al. in 2023 echoes these concerns in children.4 There are several reasons for questioning the relevance of the AHI to diagnose the presence and severity of oSDB in children. First, computing the AHI is challenging: while identifying obstructive apneas on PSG recordings is usually straightforward, distinguishing central from obstructive hypopneas remains difficult, as emphasized again recently.4 This distinction is crucial for accurately calculating the obstructive AHI, especially in children, where obstructive hypopneas are more frequent than obstructive apneas, unlike in adults. Furthermore, the AHI ignores the duration of breathing cessations and the severity of associated desaturations or arousals, which are critical in determining the long-term consequences of pediatric OSA, such as cardiovascular disease.5 As a result, children with similar AHIs may experience different harmful consequences, and conversely, children with primary snoring and normal AHIs may still require treatment. Therefore, there is a pressing need to better phenotype pediatric oSDB to personalize management strategies more effectively. Several biomarkers of oSDB in children who require treatment have been proposed and warrant further investigation. These include pro-inflammatory markers in blood and urine (IL 6, TNFa, CRP), heart rate variability (indicative of sympathetic activation), increased systemic blood pressure and/or blunting of the nocturnal decrease in systemic blood pressure, and the hypoxic burden (measured as the sum of the areas under 90% of the SpO2/time curve during the recording, expressed as % • min). The relevance of this latter biomarker has been validated in several studies involving adults with oSDB. In summary, it is essential to better phenotype children with oSDB, as the AHI alone appears neither adequate nor sufficient for this purpose. New biomarkers and metrics are being developed and need to be validated. While oSDB in adults differs in many ways from oSDB in children, findings from studies in adults can still provide valuable insights and ideas. In conclusion, last year's publications constitute an important step in the care of children with oSDB. The time has come to abandon the sacrosanct AHI as the sole marker on which we base all decisions for managing children with oSDB. We are entering a new era where better phenotyping of oSDB in children will enable personalized medicine. Jean-Paul Praud: Conceptualization; Writing—review and editing. The author declares no conflicts of interest. Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.

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