Upper airway collapsibility during REM sleep in children with the obstructive sleep apnea syndrome

Does REM AHI Predict Persistent OSA After Pediatric Adenotonsillectomy?

OBJECTIVE

The utility of REM AHI in managing pediatric obstructive sleep apnea (OSA) is not fully understood. This study aimed to evaluate the relationship of preoperative REM AHI to postoperative persistence of OSA in children who underwent adenotonsillectomy.

METHODS

This retrospective chart review identified children under the age of 18 years that received an adenotonsillectomy for OSA and a preoperative and postoperative polysomnogram. Children with craniofacial or neuromuscular disorders or a tracheostomy were excluded. The primary outcome was the postoperative persistence of OSA, defined as a postoperative obstructive apnea-hypopnea index (oAHI) ≥ 1.5 events/hour. REM-predominant OSA was defined as a ratio of REM/NREM AHI ≥ 2. REM AHI minus NREM AHI and REM AHI minus oAHI helped to identify patients with a larger distribution of REM AHI.

RESULTS

A total of 353 patients were included. Postoperative persistent OSA was seen in 232 (65.7%) children. The preoperative REM AHI, REM AHI minus NREM AHI, and REM AHI minus oAHI of children with persistent OSA did not differ significantly from children with resolution of OSA. Rates of persistence were not different between those with REM-predominant OSA and REM-independent OSA (63.8% vs 70.7%, P = .218).

CONCLUSION

This study suggests that preoperative REM AHI may be a poor predictor of OSA persistence after adenotonsillectomy. Further study is needed to help characterize how pre-operative REM AHI should impact clinicians' decision making, family counseling and recommendations.

Leptin signaling in the dorsomedial hypothalamus couples breathing and metabolism in obesity

Mismatch between CO2 production (Vco2) and respiration underlies the pathogenesis of obesity hypoventilation. Leptin-mediated CNS pathways stimulate both metabolism and breathing, but interactions between these functions remain elusive. We hypothesized that LEPRb+ neurons of the dorsomedial hypothalamus (DMH) regulate metabolism and breathing in obesity. In diet-induced obese LeprbCre mice, chemogenetic activation of LEPRb+ DMH neurons increases minute ventilation (Ve) during sleep, the hypercapnic ventilatory response, Vco2, and Ve/Vco2, indicating that breathing is stimulated out of proportion to metabolism. The effects of chemogenetic activation are abolished by a serotonin blocker. Optogenetic stimulation of the LEPRb+ DMH neurons evokes excitatory postsynaptic currents in downstream serotonergic neurons of the dorsal raphe (DR). Administration of retrograde AAV harboring Cre-dependent caspase to the DR deletes LEPRb+ DMH neurons and abolishes metabolic and respiratory responses to leptin. These findings indicate that LEPRb+ DMH neurons match breathing to metabolism through serotonergic pathways to prevent obesity-induced hypoventilation.

Change in the Constricted Airway in Patients after Clear Aligner Treatment: A Retrospective Study

This retrospective study evaluated changes in the pharyngeal portion of the upper airway in patients with constricted and normal airways treated with clear aligners (Invisalign, Align). Additionally, we assessed the change of tongue position in the oral cavity from a lateral view. Evaluation was performed with specialized software (Invivo 6.0, Anatomage) on pretreatment and post-treatment pairs of cone beam computed tomography imaging (CBCT) data. The level of airway constriction, volume, cross-section minimal area and tongue profile were evaluated. Patients with malocclusion, with pair or initial and finishing CBCT and without significant weight change between the scans, treated with Invisalign clear aligners were distributed into two groups. Group A consisted of fifty-five patients with orthodontic malocclusion and constricted upper airway. Control group B consisted of thirty-one patients with orthodontic malocclusions without any airway constriction. In the group with airway constriction there was a statistically significant increase in volume during therapy (p < 0.001). The surface of the most constricted cross-section of the airway did not change significantly after treatment in any of the groups. The final tongue position was different from the initial position in 62.2% of all clear aligner treatments. The position of the smallest clearance of the airway in the pharynx was similar for both groups localized at the level of 2nd cervical vertebra.

Polysomnographic comparison of sleep in children with obesity and normal weight without suspected sleep-related breathing disorder

Short sleep and obstructive apneas/hypopneas have been shown to be associated with childhood obesity. Still, few studies have compared sleep in children with obesity, without suspected sleep disordered breathing and normal weight peers by objective sleep measures and compared results with subjective parent assessment of sleep. Children with obesity aged 7-13 years (N = 44) and a matched group of normal weight children (N = 42) completed clinical polysomnography (Embla A10 Recording System). Parents scored their children's sleep on the Children's Sleep Habits Questionnaire (CSHQ). Mann-Whitney U tests were used to compare groups. There was a higher obstructive apnea/hypopnea index (AHI) (median obesity = 1.20 vs. median normal  = 0.66; z = -1.33, U = 560.50, p = 0.002) and number of oxygen desaturation events per hour (median obesity = 0.7 vs. median normal  = 0.2; z = -3.45, U = 402.50, p = 0.001) in the children with obesity compared to children with normal weight. The children with obesity had a significantly longer sleep duration (median obesity 8:50 h = vs. median normal = 8:32 h; z = -2.05, U = 687.00, p = 0.041), longer stage N2 sleep (median obesity = 87 min vs. median normal = 52 min; z = -2.87, U = 576.50, p = 0. 004) and shorter REM sleep (median obesity = 94 min vs. median normal = 121 min; z = 5.05, U = 1477.00, p ≤ .001). No differences were observed for time in sleep stage N1 and N3, wake time after sleep onset or the total arousal index . Further, no group differences were found on the CSHQ sleep-disordered breathing sub-scale (p = 0.399). The children with obesity demonstrated significantly more mild to moderate sleep disordered breathing than children with normal weight, although this was not corroborated by parent report.

Analysis of polysomnogram findings in children with concurrent obstructive and central sleep apnea

OBJECTIVE

Increasing evidence suggests overlap in mechanisms of obstructive and central sleep apnea. Our objective was to compare the patient characteristics and polysomnographic findings of children with concurrent obstructive and central sleep apnea (obstructive sleep apnea + central sleep apnea [OSA + CSA]), to those with OSA only.

METHODS

A retrospective case series of polysomnogram (PSG) from 30 June 2013 to 30 June 2018 of patients 18 years and younger was performed. PSG parameters were analyzed per standard protocol. There were two groups, OSA only group and OSA + CSA group. OSA + CSA was subdivided into groups of central apnea index (CAI) ≤5, and CAI >5. Differences in the age, sex, body mass index (BMI) percentile, prevalence of medical conditions, and PSG parameters between OSA only and OSA + CSA were assessed for statistical significance.

RESULTS

The mean age of the OSA only group was 8.2 years, significantly higher than that of the OSA + CSA group, 5.0 years, P < .00001. The proportion of underweight, normal weight, overweight, and obese patients according to BMI percentiles was not statistically significantly different between the two groups, P > .05. Most common comorbidity in the two groups was pulmonary conditions, which included asthma. Of the PSG parameters, arousals due to respiratory events and obstructive apnea hypopnea index of all OSA + CSA groups were significantly higher than those of the OSA only group, P < .05. Rapid eye movement (REM) sleep was significantly higher in total OSA + CSA group and OSA + CSA subgroup with CAI ≤5, P < .05, compared to OSA only.

CONCLUSION

Children with concurrent OSA + CSA are younger, but there appears to be no difference in BMI percentiles between OSA only and OSA + CSA. Compared to OSA only group, children with concurrent OSA + CSA have significantly different sleep architecture-higher REM %-and experience significantly higher respiratory arousals and obstructive events, especially in the subgroup with CAI >5. There appears to be overlap in mechanisms of CSA and OSA in this cohort.

LEVEL OF EVIDENCE

4.

Apnea hypopnea indices categorized by REM/NREM sleep and sleep positions in 100 children with adenotonsillectomy for obstructive sleep apnea disease

OBJECTIVES

In pediatric obstructive sleep apnea (OSA), the relationship between rapid eye movement sleep and upper airway collapse, and between sleep position and airway dimensions are well known. However, the interrelations between these factors and the obstructive apnea hypopnea index (O-AHI) have not been thoroughly investigated.

METHODS

A retrospective study including 100 children who underwent adenotonsillectomy between March 2010 and July 2017. Total O-AHI was divided into four subcategories by sleep stage and position.

RESULTS

Preoperatively 14 of 47 mild cases of OSA (1 ≤ total O-AHI) and 17 of 18 moderate (5 ≤ total O-AHI) had time showing severe apnea (10 ≤ subcategorized O-AHI). Twenty-two of 24 severe cases (10 ≤ total O-AHI) exhibited very severe apnea (30 ≤ subcategorized O-AHI). All 11 very severe cases (30 ≤ total O-AHI) experienced more than 50 apnea events per hour in at least one of the O-AHI subcategories. After surgery, 23 of 70 cases classified as completely resolved (total O-AHI < 1) still had mild apnea in the O-AHI subcategories, and six of 13 cases who continued to experience apnea events had moderate-to-severe apnea. Seventeen cases worsened in the O-AHI subcategories, and total O-AHI deteriorated in two cases of the 17. The amount of REM sleep and use of the supine position increased significantly postoperatively in the quartile groups with the lowest baseline values (p < 0.0001).

CONCLUSIONS

When an unexpected AHI value is encountered, the O-AHI subcategories may be informative regarding the indications for surgery and evaluating the efficacy thereof.

Utilizing inspiratory airflows during standard polysomnography to assess pharyngeal function in children during sleep

OBJECTIVES

Obstructive sleep apnea (OSA) is the result of pharyngeal obstruction that occurs predominantly during REM in children. Pathophysiologic mechanisms responsible for upper airway obstruction, however, are poorly understood. Thus, we sought to characterize upper airway obstruction in apneic compared to snoring children during sleep. We hypothesized that apneic compared to snoring children would exhibit an increased prevalence and severity of upper airway obstruction, that would be greater in REM compared to non-REM, and would improve following adenotonsillectomy.

STUDY DESIGN

Apneic children were assessed with routine polysomnography before and after adenotonsillectomy, and compared to snoring children matched for gender, age, and BMI z-score. In addition to traditional scoring metrics, the following were used to characterize upper airway obstruction: maximal inspiratory airflow (%VI max) and percent of time with inspiratory flow-limited breathing (%IFL).

RESULTS

OSA compared to snoring children had similar degrees of upper airway obstruction in non-REM; however, during REM, children with sleep apnea exhibited a higher %IFL (98 ± 2% vs.73 ± 8%, P < 0.01) and lower %VI max (56 ± 6 vs.93 ± 10%, P < 0.01). In children with OSA, CO2 levels were elevated during both wake and sleep. Following adenotonsillectomy, upper airway obstruction improved during REM manifest by decreased %IFL (98 ± 2 to 63 ± 9%, P = 0.04), increased %VI max (56 ± 6 to 95 ± 5%, P = 0.01) and decreased CO2 levels.

CONCLUSIONS

Differences in the prevalence and severity upper airway obstruction suggest impaired compensatory responses during REM in children with OSA, which improved following adenotonsillectomy.

Adolescents and young adults with Down syndrome presenting to a medical clinic with depression: co-morbid obstructive sleep apnea

Adolescents and young adults with Down syndrome (DS) sometimes experience new-onset mood disorder and decline in adaptive skills. The clinical phenomenon is poorly characterized and its pathogenesis is not understood. The possible contribution of obstructive sleep apnea syndrome (OSAS) to this phenomenon has not been studied. Subjects were ascertained as a convenience sample through our clinic for persons with DS and medical or mental health concerns between 2004 and 2009. When mood symptoms were present an axis I diagnosis was made using DSM-IV-R criteria. Subjects without an axis I diagnosis served as controls. The Reiss scales for children's dual diagnosis and the aberrant behavior checklist (ABC) were completed by caretakers. Twenty-eight cases meeting criteria for major depressive episode (MDE) and nine controls without psychopathology were referred for overnight polysomnography (PSG). Functional decline was reported in 19 (68%) of cases with MDE, but none of the controls. Twenty-four (86%) cases had OSAS compared with only 4 (44%) of controls. Moderate-severe OSAS was present in 15 (54%) of cases compared to only 1 (11%) of controls. Intermittent sleep-associated hypoxia and REM sleep deficits were also more frequent in cases. Across all subjects, prior tonsillectomy was not related to the presence or absence of OSAS. Our findings suggest that OSAS may be a common co-morbidity in adolescents and younger adults with DS and depression. Recognition of this association maybe critical to understanding the pathogenesis and management of mood-related disorders, and functional decline in affected individuals.

Relationship between body fat distribution and upper airway dynamic function during sleep in adolescents

INTRODUCTION

The obstructive sleep apnea syndrome (OSAS) is associated with increased visceral adipose tissue (VAT) in adults; however, few studies have evaluated VAT in relation to upper airway function in adolescents. We hypothesized that increased neck circumference (NC) and VAT would be associated with increased upper airway collapsibility.

METHODS

Adolescents (24 obese patients with OSAS, 22 obese control patients, and 29 lean control patients) underwent abdominal magnetic resonance imaging, and measurement of upper airway pressure-flow relationships in the activated and hypotonic upper airway states.

RESULTS

Patients with OSAS had a greater activated slope of the pressure-flow relationship (SPF) than control groups (P < 0.001), whereas hypotonic SPF was greater in both obese groups compared with lean control patients (P = 0.01). NC and VAT were greater in obese control patients and those with OSAS than in lean control patients (P < 0.001), but did not differ between obese patients with OSAS and obese control patients. In lean control patients and those with OSAS, increased NC was associated with increased activated SPF, whereas in obese control patients it was associated with decreased activated SPF (P = 0.03). In contrast, increased NC was associated with increased hypotonic SPF in all groups (P < 0.001). There was no significant effect of VAT on either activated or hypotonic SPF for any of the three groups.

CONCLUSIONS

Increased neck circumference was associated with increased upper airway collapsibility in adolescents in the hypotonic but not activated state. These data suggest that obese adolescents without OSAS, despite a narrowed upper airway from adipose tissue, are protected from developing OSAS by upper airway neuromotor activation. Neither neck circumference nor visceral adipose tissue is useful in predicting upper airway collapsibility in obese adolescents.

Respiratory timing and variability during sleep in children with sleep-disordered breathing

Sleep-disordered breathing (SDB) in children is assessed by quantification of hypopnea and apnea events. Little is known, however, about respiratory timing and breath-to-breath variability during sleep. The aim of this study was to investigate respiratory parameters across sleep stages in children with SDB before and after treatment compared with healthy children. Overnight polysomnography (PSG) was conducted in 40 children with SDB prior to and 6 mo following adenotonsillectomy. For comparison, a control group of 40 healthy sex- and age-matched children underwent two PSGs at equivalent time points but without intervention. The following variables were measured breath by breath during obstruction-free periods in stage 2 nonrapid eye movement (NREM), stage 4 NREM, and REM sleep: inspiratory time (Ti), expiratory time (Te), total time (Ttotal), inspiratory duty cycle (DC; =Ti/Ttotal), respiratory frequency (fR), and SD of the parameters Ti, Te, fR, and DC. Variability in waveform morphology was also computed using the residue of respiratory patterns. The severity of SDB was relatively mild in the study cohort (obstructive apnea hypopnea index: baseline, 5.1 ± 9.4 vs. 0.1 ± 0.2, P < 0.001; follow-up, 0.3 ± 0.3 vs. 0.8 ± 1.0, P < 0.01). Compared with healthy controls, children with SDB showed significantly longer Ti and Te and a lower fR at the baseline study. These differences were not significant after adenotonsillectomy. Sleep stages were associated with significant differences in all of the respiratory measures in both groups of children. In conclusion, children with relatively mild SDB showed prolonged inspiration and expiration indicative of chronic narrowing of the upper airway. Treatment of SDB normalizes respiratory timing. Documentation of these parameters may aid in both understanding and management of children with SDB.

Upper airway collapsibility and genioglossus activity in adolescents during sleep

STUDY OBJECTIVES

Obese patients develop obstructive sleep apnea syndrome (OSAS), at least in part because of a narrowed upper airway. However, many obese adolescents do not develop OSAS, despite having a presumably narrower airway. The reasons for this phenomenon are unclear. The authors hypothesized that obese controls have a compensatory neuromuscular response to subatmospheric pressure loads during sleep, making them less likely to develop upper airway collapse.

DESIGN

Patients underwent pressure-flow measurements during sleep while wearing intraoral electrodes to measure genioglossal electromyography (EMGgg). Two techniques were applied to decrease nasal pressure (P(N)) to subatmospheric levels, resulting in an activated and relatively hypotonic upper airway.

SETTING

Sleep laboratory.

PARTICIPANTS

There were 35 obese patients with OSAS, 28 obese controls, and 43 lean controls.

RESULTS

In the activated state, the two control groups had a flatter slope of the pressure-flow relationship and a more negative critical closing pressure (less collapsible) than the OSAS group. In the hypotonic state, the lean controls had a flatter slope of the pressure-flow relationship than the OSAS and obese control groups. In the activated state, the slope of EMGgg versus P(N) was greater in the obese control group than in the OSAS or lean control groups (P = 0.002 and P = 0.028, respectively); there were no differences in the hypotonic state.

CONCLUSIONS

Obese controls have vigorous upper airway neuromuscular responses during sleep. Upper airway reflexes normally decline during adolescent development. It is speculated that obese adolescents without OSAS maintain protective upper airway reflexes during adolescent development, whereas those who go on to develop OSAS do not.

Ventilatory responses to hypercapnia during wakefulness and sleep in obese adolescents with and without obstructive sleep apnea syndrome

STUDY OBJECTIVES

Abnormal ventilatory drive may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). Concomitant with the obesity epidemic, more adolescents are developing OSAS. However, few studies have specifically evaluated the obese adolescent group. The authors hypothesized that obese adolescents with OSAS would have a blunted hypercapnic ventilatory response (HCVR) while awake and blunted ventilatory responses to carbon dioxide (CO(2)) during sleep compared with obese and lean adolescents without OSAS.

DESIGN

CVR was measured during wakefulness. During nonrapid eye movement (NREM) and rapid eye movement (REM) sleep, respiratory parameters and genioglossal electromyogram were measured during CO(2) administration in comparison with room air in obese adolescents with OSAS, obese control study participants, and lean control study participants.

SETTING

Sleep laboratory.

PARTICIPANTS

Twenty-eight obese patients with OSAS, 21 obese control study participants, and 37 lean control study participants.

RESULTS

The obese OSAS and obese control groups had a higher HCVR compared with the lean control group during wakefulness. During both sleep states, all 3 groups had a response to CO(2); however, the obese OSAS group had lower percentage changes in minute ventilation, inspiratory flow, inspiratory time, and tidal volume compared with the 2 control groups. There were no significance differences in genioglossal activity between groups.

CONCLUSIONS

HCVR during wakefulness is increased in obese adolescents. Obese adolescents with OSAS have blunted ventilatory responses to CO(2) during sleep and do not have a compensatory prolongation of inspiratory time, despite having normal CO(2) responsivity during wakefulness. Central drive may play a greater role than upper airway neuromotor tone in adapting to hypercapnia.

Update on pediatric sleep-disordered breathing

Pediatric sleep-disordered breathing (SDB) includes an increasingly recognized, highly prevalent, yet still underdiagnosed spectrum of respiratory disorders, the most common and clinically significant of which is obstructive sleep apnea. SDB is linked with significant end-organ dysfunction across various systems, particularly with cardiovascular, neurocognitive, and metabolic consequences. This review summarizes recent advances in understanding of pediatric SDB and discusses the challenges inherent in diagnosing and treating children with SDB.

Upper airway genioglossal activity in children with sickle cell disease

STUDY OBJECTIVES

The prevalence of obstructive sleep apnea syndrome (OSAS) in sickle cell disease (SCD) has been reported to be higher than that in the general pediatric population. However, not all subjects with SCD develop OSAS. We hypothesized that SCD patients with OSAS have a blunted neuromuscular response to subatmospheric pressure loads during sleep, making them more likely to develop upper airway collapse.

DESIGN

Subjects with SCD with and without OSAS underwent pressure-flow measurements during sleep using intraoral surface electrodes to measure genioglossal EMG (EMGgg). Two techniques were applied to decrease the nasal pressure (P(N)) to subatmospheric levels, resulting in an activated and relatively hypotonic upper airway. The area under the curve of the inspiratory EMGgg moving time average was analyzed. EMGgg activity was expressed as a percentage of baseline. Changes in EMGgg in response to decrements in nasal pressure were expressed as the slope of the EMGgg vs. nasal pressure (slope of EMGgg-P(N)).

SETTING

Sleep laboratory.

PARTICIPANTS

4 children with SCD and OSAS and 18 children with SCD but without OSAS.

RESULTS

THE MAJOR FINDINGS OF THIS STUDY WERE: (1) using the activated but not the hypotonic technique, the slope of EMGgg-P(N) was more negative in SCD controls than SCD OSAS; (2) the slope of EMGgg-P(N) was significantly lower using the activated technique compared to the hypotonic technique in SCD controls only; (3) similarly, the critical closing pressure, Pcrit, was more negative using the activated technique than the hypotonic technique in SCD controls but not in SCD OSAS.

CONCLUSION

This preliminary study has shown that children with SCD but without OSAS have more prominent upper airway reflexes than children with SCD and OSAS.

Effects of race on upper airway dynamic function during sleep in children

STUDY OBJECTIVE

Studies in adults and children have shown that African American race is a risk factor for the obstructive sleep apnea syndrome (OSAS). Therefore, we hypothesized that non-obese, non-snoring African American children would have a more collapsible upper airway during sleep than age-, gender-, and size-matched Caucasians.

DESIGN

Upper airway dynamic function was measured during sleep in normal African American and Caucasian children.

SETTING

Sleep laboratory.

PATIENTS OR PARTICIPANTS

56 normal children between the ages of 8-18 years.

INTERVENTIONS

Pressure-flow relationships were measured during NREM sleep. Nasal pressure was decreased to subatmospheric levels, using previously described techniques that resulted in an activated and relatively hypotonic upper airway.

MEASUREMENTS AND RESULTS

The activated and hypotonic critical pressures (Pcrit) were -25 (-25, -3) (median, range) and -19 (-25, -3) for African Americans, and -25 (-25, -4) and -25 (-25.0, -4) cm H(2)O, respectively, for Caucasians. The slopes of the pressure-flow response (SPF) under activated and hypotonic conditions for African Americans were 10 (-9, 46) and 13 (-20, 46), and for Caucasians 9 (-9, 64) and 8 (-5, 54) mL/s/cm H(2)O, respectively. There were no significant differences between groups for Pcrit or SPF under either activated or hypotonic conditions.

CONCLUSION

Upper airway collapsibility was similar in asymptomatic, non-obese African American and Caucasian children. Differences in upper airway characteristics and neuromotor function cannot explain the increased prevalence of OSAS in African American children.

Metabolic effects of obesity causing disease in childhood

PURPOSE OF REVIEW

Childhood obesity is rising to epidemic proportions throughout the world, and much emphasis has been placed on the long-term consequences that can result later, in adulthood. This article reviews the metabolic consequences of obesity that can manifest as disease during the childhood years.

RECENT FINDINGS

Obese children suffer from many disease processes once thought to affect only adults. They can have type 2 diabetes mellitus, and potentially early β cell failure with rapid progression to an insulin requirement. There is a high prevalence of fatty liver disease in obese children, and complications such as steatohepatitis and even cirrhosis can develop during childhood. Visceral fat has been shown to have many different properties than subcutaneous fat, and children with central adiposity can develop the metabolic syndrome with insulin resistance, hypertension, and dyslipidemia. Hyperandrogenism, sleep disturbances, and many types of orthopedic complications can also develop in young children.

SUMMARY

Physicians should not only warn obese children and their families about the long-term consequences of obesity for which they are at risk in adulthood, they should also screen for the many diseases that may already be present.