In the setting of a child suspected of having OSA, a positive nocturnal oximetry trend graph has at least a 97% positive predictive value. Oximetry could: 1) be the definitive diagnostic test for straightforward OSA attributable to adenotonsillar hypertrophy in children older than 12 months of age, or 2) quickly and inexpensively identify children with a history suggesting sleep-disordered breathing who would require PSG to elucidate the type and severity. A negative oximetry result cannot be used to rule out OSA.

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ABSTRACT. Objective. Obstructive sleep apnea (OSA) in children is usually effectively treated by adenotonsillectomy (T&A). However, there may be a waiting list for T&A, and the procedure is associated with an increased risk of postoperative complications in children with OSA. Needed is a simple test that will facilitate logical prioritization of the T&A surgical list and help to predict children who are at highest risk of postoperative complications. The objective of this study was to develop and validate a severity scoring system for overnight oximetry and to evaluate the score as a tool to prioritize the T&A surgical list.Methods. This study comprised 3 phases. In phase 1, a severity score was developed by review of preoperative overnight oximetry in children who had urgent T&A in 1999 -2000. In phase 2, the score was validated retrospectively in 155 children who had polysomnography (PSG) before T&A in 1992-1998. In a phase 3, a 12-month prospective evaluation of a protocol based on the score was conducted.Results. In phase 1, a 4-level severity score was developed on the basis of the number and the depth of desaturation events (normal to severely abnormal, categories 1-4). In phase 2, the McGill oximetry score correlated with severity of OSA by PSG criteria. In phase 3, a clinical management protocol was developed based on the score. Of 230 children tested, 179 (78%) had a normal/ inconclusive oximetry (category 1) and went on to have PSG. Those with a positive oximetry (categories 2-4; 22%) had no additional sleep studies before T&A. Timing of T&A was based on oximetry score, leading to a significant reduction in waiting time for surgery for those with higher oximetry scores. Postoperative respiratory complications were more common with increasing oximetry score.Conclusions. Overnight pulse oximetry can be used to estimate the severity of OSA, to shorten the diagnostic and treatment process for those with more severe disease, and to aid clinicians in prioritization of T&A and planning perioperative care. Pediatrics 2004;113:e19 -e25. URL: http://www.pediatrics.org/cgi/content/full/113/1/ e19; oximetry, obstructive sleep apnea, child, adenotonsillectomy, postoperative complications.

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The data suggest, but do not prove, that preoperative nocturnal oximetry could be a useful preoperative test to identify children who are at increased risk for postoperative respiratory complications.

Prader-Willi syndrome (PWS) is a genetic disorder, with hypotonia being the predominant feature in infancy, and developmental delay, obesity, and behavioral problems becoming more prominent in childhood and adolescence. Children with this disorder frequently suffer from excessive daytime sleepiness and have a primary abnormality of the circadian rhythm of rapid eye movement sleep. They also have primary abnormal ventilatory responses to hypoxia and hypercapnia, and these abnormalities may be exacerbated by obesity. Children with PWS are at risk of a variety of abnormalities of breathing during sleep, including obstructive sleep apnea and sleep-related alveolar hypoventilation. Clinical evaluation should include a careful history of sleep-related symptoms and assessment of the upper airway and lung function. Polysomnography should be considered for those with symptoms suggestive of sleep-disordered breathing. Treatment options depend on the underlying problem, but may include behavioral interventions, weight control, adenotonsillectomy, and nocturnal ventilation.

The ability of the extrathoracic airway (ETA) to remain open when exposed to negative pressure was investigated in rabbits. Postmortem, the ETA collapsed at -6.3 +/- 0.6 cmH2O whereas, during airway occlusion maneuvers in lightly anesthetized animals, it remained patent at pressures as low as -80 cmH2O. This discrepancy suggested that a neuromuscular mechanism maintains ETA patency. Four findings indicated that the genioglossus and geniohyoid muscles, which pull the tongue and hyoid bone anteriorly, help maintain ETA patency: 1) anterior movement of the hyoid bone increased the negative pressure at which the ETA collapsed postmortem, 2) ETA closure during occluded inspirations occurred after 12th nerve section abolished electromyographic activity in these muscles and 3) after deep anesthesia depressed such activity, and 4) closing pressure was linearly related to peak integrated electromyograms of the two muscles. After 12th nerve section, ETA closing pressure became more negative with progressive asphyxia greatly exceeding postmortem closing pressure, which suggests that other muscles also help maintain ETA patency. Blood gas tensions, respiratory system mechanoreceptors, and depth of anesthesia appear to influence genioglossus and geniohyoid activity.

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