Association of adenotonsillectomy with wheezing episodes in childhood: A secondary analysis of the Childhood Adenotonsillectomy Trial.

BACKGROUND: Observational studies suggest that asthma/wheezing improves after adenotonsillectomy (AT). However, there is a paucity of randomized clinical trial (RCT) specifically studying the effects of AT in asthma/wheezing. Therefore, we conducted a post-hoc analysis of the Childhood Adenotonsillectomy Trial (CHAT), the largest RCT of AT in children with obstructive sleep apnea (OSA) to test the hypothesis that AT would result in fewer wheezing episodes. METHODS: In the CHAT study, 464 children with OSA, aged 5-9 years, were randomized to early AT (n = 226) or watchful waiting with supportive care (WWSC) (n = 227). For this post-hoc analysis, children were categorized as having "any wheezing" versus "no wheezing" at baseline and at 7 months of follow-up. A multivariate analysis was conducted to evaluate the association between "any wheezing" at follow-up and treatment group after controlling for several potential confounders. RESULTS: Children in the "any wheezing" group were predominantly black, had more allergic rhinitis, eczema, second-hand smoke exposure, body mass index, apnea-hypopnea index (AHI), and had lower maternal education and family income than those in the "no wheezing group." In the AT arm, the prevalence of wheezing significantly decreased from baseline to follow-up (at 7 months of the intervention) (47% vs. 21.6%, p < 0.001); while in the WWSC arms did not change (45.2% vs. 43.1%, p = 0.67). In the multivariate analysis, second-hand smoke exposure, wheezing at baseline, and belong to WWSC arm (odds ratio: 3.65 [2.16-6.19]) increase the risk of wheezing at follow-up. CONCLUSION: This study demonstrated that AT decreased the risk of wheezing at 7 months of follow-up.

Upper Airway Vibration Perception in School-Aged Children with Obstructive Sleep Apnea.

STUDY OBJECTIVES: Children with the obstructive sleep apnea (OSA) have impaired upper airway two-point discrimination compared to controls. In addition, blunted vibration threshold detection (VT) in the palate has been recognized in adults with OSA, but has not been studied in children. Both findings are indicative of a defect in the afferent limb of the upper airway dilator reflex that could prevent upper airway dilation secondary to airway loading, resulting in airway collapse. We hypothesized that children with OSA have impaired palate VT compared to controls, and that this improves after OSA treatment. METHODS: Case-control study. Children with OSA and healthy non-snoring controls underwent polysomnography and palate VT measurements. Children with OSA were retested after adenotonsillectomy. RESULTS: 29 children with OSA (median [interquartile range] age = 9.5 [7.5-12.6] years, obstructive apnea-hypopnea index [OAHI] = 11.3 [5.7-19.5] events/h, BMI z = 1.8 [1.3-2.1]) and 32 controls (age = 11.2 [9.3-13.5] years, P = 0.1; OAHI = 0.5 [0.1-0.7] events/h, P < 0.001; BMI z = 1 [0.3-1.7], P = 0.004) were tested. OSA palate VT (1.0 [0.8-1.5] vibration units) was similar to that of controls (1 [0.8-1.3], P = 0.37). 20 children with OSA were retested 4.4 (3.2-7.1) months after treatment. OAHI decreased from 13.1 (5.8-19) to 0.6 (0.2-2.5) events per hour (P < 0.001) postoperatively, but palate VT did not change (before = 1 [0.7-1.5], after = 1.2 [0.8-1.4], P = 0.37). CONCLUSIONS: Children with OSA and controls have similar palate VT. Unlike in adults, palate VT does not seem to be affected by childhood OSA.

Evolution of Obstructive Sleep Apnea in Infants with Cleft Palate and Micrognathia.

STUDY OBJECTIVES: Children with craniofacial anomalies are a heterogeneous group at high risk for obstructive sleep apnea (OSA). However, the prevalence and structural predictors of OSA in this population are unknown. We hypothesized that infants with micrognathia would have more significant OSA than those with isolated cleft palate ± cleft lip (ICP), and those with ICP would have more significant OSA than controls. We postulated that OSA severity would correlate with reduced mandibular size, neurodevelopmental scores, and growth. METHODS: Prospective cohort study. 15 infants with ICP, 19 with micrognathia, and 9 controls were recruited for polysomnograms, neurodevelopmental testing, cephalometrics (ICP and micrognathia groups) at baseline and a follow-up at 6 mo. RESULTS: Baseline apnea-hypopnea index (AHI) [median (range)] of the micrognathia group [20.1 events/h (0.8, 54.7)] was greater than ICP [3.2 (0.3, 30.7)] or controls [3.1 (0.5, 23.3)] (p = 0.001). Polysomnographic findings were similar between ICP and controls. Controls had a greater AHI than previously reported in the literature. Cephalometric measures of both midface hypoplasia and micrognathia correlated with OSA severity. Neurodevelopment was similar among groups. OSA improved with growth in participants with ICP and postoperatively in infants with micrognathia. CONCLUSIONS: Micrognathia, but not ICP, was associated with more significant OSA compared to controls. Both midface and mandibular hypoplasia contribute to OSA in these populations. OSA improved after surgical correction in most infants with micrognathia, and improved without intervention before palate repair in infants with ICP.

Airway Resistance in Children with Obstructive Sleep Apnea Syndrome.

STUDY OBJECTIVES: Enlarged tonsils and adenoids, the main cause of obstructive sleep apnea syndrome (OSAS) in children, results in upper airway (UA) loading. This contributes to the imbalance between structural and neuromotor factors ultimately leading to UA collapse during sleep. However, it is unknown whether this UA loading can cause elevated airway resistance (AR) during wakefulness. We hypothesized that children with OSAS have elevated AR compared to controls and that this improves after OSAS treatment. METHODS: Case control study performed at an academic hospital. Children with OSAS and nonsnoring healthy controls underwent baseline polysomnography and spirometry, and AR measurement by body plethysmography while breathing via an orofacial mask. Children with OSAS repeated the previously mentioned tests after adenotonsillectomy. RESULTS: 31 OSAS participants (mean age ± SD = 9.7 ± 3.0 y, obstructive apnea-hypopnea index (OAHI) median [range] = 14.9 [2-58.7] events/h, body mass index [BMI] z = 1.5 ± 1) and 31 controls (age = 10.5 ± 2.5 y, P = 0.24; OAHI = 0.4 [0-1.4], P < 0.001; BMI z = 0.9 ± 1, P = 0.01) were tested. OSAS AR at baseline was 3.9 [1.5-10.3] cmH2O/L/sec and controls 2.8 [1.4 - 6.2] (P = 0.027). Both groups had similar spirometry results. 20 patients with OSAS were tested 6.4 ± 6.6 mo after adenotonsillectomy. OAHI decreased from 15.2 [2.1-58.7] to 0.5 [0 - 5.1] events/h postoperatively (P < 0.001), and AR decreased from 4.3 [1.5 - 10.3] to 2.8 [1.7 - 4.7] cmH2O/L/sec (P = 0.009). CONCLUSIONS: Children with OSAS have elevated AR that decreases after treatment. This is likely because of upper airway loading secondary to adenotonsillar hypertrophy and may contribute to the increased frequency of respiratory diseases in untreated children with OSAS.

Perinatal Risk Factors Associated with the Obstructive Sleep Apnea Syndrome in School-Aged Children Born Preterm.

STUDY OBJECTIVES: The obstructive sleep apnea syndrome (OSAS) is more prevalent in ex-preterm children compared to the general pediatric population. However, it is unknown whether OSAS in ex-preterm children is associated with specific perinatal risk factors. This multicenter cohort study aimed to determine perinatal factors associated with OSAS at school age. METHODS: 197 ex-preterm (500-1,250 g) children aged 5-12 y who participated as neonates in a double-blind, randomized clinical trial of caffeine versus placebo (Caffeine for Apnea of Prematurity) underwent comprehensive ambulatory polysomnography. A negative binomial regression model was used to identify perinatal risk factors associated with OSAS. RESULTS: 19 children had OSAS (9.6%). Chorioamnionitis and multiple gestation were positively associated with OSAS with P values of 0.014 and 0.03, respectively. Maternal white race (P = 0.047) and maternal age (P = 0.002) were negatively associated with OSAS. Other risk factors, such as birth weight, Apgar score at 5 min, antenatal corticosteroids, delivery route, and sex were not significant. CONCLUSIONS: OSAS is very frequent, and is associated with chorioamnionitis and multiple gestation in ex-preterm children. Those born to older white mothers appear to be protected. We speculate that the former may be due to systemic inflammation and the latter to a higher socio-economic status. COMMENTARY: A commentary on this article appears in this issue on page 721.

Cerebral Blood Flow Response to Hypercapnia in Children with Obstructive Sleep Apnea Syndrome.

STUDY OBJECTIVES: Children with obstructive sleep apnea syndrome (OSAS) often experience periods of hypercapnia during sleep, a potent stimulator of cerebral blood flow (CBF). Considering this hypercapnia exposure during sleep, it is possible that children with OSAS have abnormal CBF responses to hypercapnia even during wakefulness. Therefore, we hypothesized that children with OSAS have blunted CBF response to hypercapnia during wakefulness, compared to snorers and controls. METHODS: CBF changes during hypercapnic ventilatory response (HCVR) were tested in children with OSAS, snorers, and healthy controls using diffuse correlation spectroscopy (DCS). Peak CBF changes with respect to pre-hypercapnic baseline were measured for each group. The study was conducted at an academic pediatric sleep center. RESULTS: Twelve children with OSAS (aged 10.1 ± 2.5 [mean ± standard deviation] y, obstructive apnea hypopnea index [AHI] = 9.4 [5.1-15.4] [median, interquartile range] events/hour), eight snorers (11 ± 3 y, 0.5 [0-1.3] events/hour), and 10 controls (11.4 ± 2.6 y, 0.3 [0.2-0.4] events/hour) were studied. The fractional CBF change during hypercapnia, normalized to the change in end-tidal carbon dioxide, was significantly higher in controls (9 ± 1.8 %/mmHg) compared to OSAS (7.1 ± 1.5, P = 0.023) and snorers (6.7 ± 1.9, P = 0.025). CONCLUSIONS: Children with OSAS and snorers have blunted CBF response to hypercapnia during wakefulness compared to controls. Noninvasive DCS blood flow measurements of hypercapnic reactivity offer insights into physiopathology of OSAS in children, which could lead to further understanding about the central nervous system complications of OSAS.

Prevalence of periodic limb movements during sleep in normal children.

STUDY OBJECTIVES: Although the American Academy of Sleep Medicine (AASM) mandates that periodic limb movements during sleep (PLMS) be scored on every polysomnogram, and considers a periodic limb movement index (PLMI) > 5/h abnormal in children, there is a lack of community-derived data regarding the prevalence of PLMS in children, and no data to support this cutoff value. Therefore, the aim of this study was to determine the prevalence of PLMS in a sample of normal children. DESIGN: Retrospective study. PARTICIPANTS: 195 healthy, non-snoring children aged 5-17 years, recruited from the community, who underwent polysomnography for research purposes. METHODS: PLMS were scored using the AASM 2007 criteria. MEASUREMENTS AND RESULTS: The group age (median [IQR]) was 12.9 [10-15] years, and 58% were male. Sleep architecture was normal, and the obstructive apnea hypopnea index was 0.1 [0-0.3]/h. The median PLMI was 0/h, ranging from 0 to 35.5/h. Fifteen (7.7%) subjects had a PLMI > 5/h, and only 3 (1.5%) met the adult pathologic criterion of more than 15/h. Use of the 95th percentile PLMI cutoff of 7.2/h produced little difference in categorization between groups. Children with a PLMI > 5/h had a higher arousal index than those with a lower PLMI (11.6 [8.8-14.6] vs 8.1 [6.1-9.9]/h, respectively, P = 0.003). CONCLUSIONS: This study provides normative data to the field and supports the clinical periodic limb movement index cutoff of > 5/h based on both prevalence and the correlate of increased sleep fragmentation. Periodic limb movements during sleep are infrequent in normal children recruited from the community. CITATION: Marcus CL, Traylor J, Gallagher PR, Brooks LJ, Huang J, Koren D, Katz L, Mason TB, Tapia IE. Prevalence of periodic limb movements during sleep in normal children.