Nocturnal hypoventilation in Down syndrome children with or without sleep apnea

Intracapsular Versus Total Tonsillectomy in Patients with Trisomy 21

OBJECTIVES

Intracapsular tonsillectomy and adenoidectomy (iTA) has become a popular alternative to extracapsular tonsillectomy and adenoidectomy (TT) for the treatment of pediatric obstructive sleep apnea (OSA) due to improved recovery and fewer complications. The objective of this study was to compare surgical recovery and impact on OSA of iTA versus TT in patients with Trisomy 21 (T21).

METHODS

This is a case series with chart review of all T21 patients who underwent iTA or TT at our institution between July 1, 2015 and August 15, 2022. Data collected included demographics, comorbidities, preoperative sleep studies, intraoperative data, complications and recovery, postoperative sleep studies, and follow-up data.

RESULTS

There were 62 (21.7%) patients who underwent iTA and 224 (78.3%) patients who underwent TT. The iTA group had significantly lower pain scores (p < 0.001), decreased use of narcotics (p < 0.001), shorter length of stay (p = 0.003), and faster return to oral intake (p = 0.01) during their postoperative hospital admission, and fewer 30-day complications (p = 0.009) compared to the TA group. Both groups showed significant improvements in their sleep studies. For 41 (66.1%) of iTA patients who had follow-up, median follow-up was 1.8 years and for 169 (75.4%) TT patients, median follow-up was 2.6 years. At follow-up, 21 of 41 (51.2%) iTA patients and 83 of 169 (49.1%) TT patients exhibited OSA symptoms (p = 0.084) and tonsillar regrowth was not significantly different between the two groups (p = 0.12).

CONCLUSION

Patients with T21 experience less pain and fewer postoperative respiratory complications from iTA than from TT. The short-term impact of iTA versus TT on OSA, as measured by poysomnography, does not differ between the two techniques.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:2430-2437, 2024.

Obstructive sleep apnea in children with Down syndrome: contribution of upper airway and chemosensitivity

BACKGROUND

The high prevalence of obstructive sleep apnea syndrome (OSAS) in children with Down syndrome (DS) has been attributed to a reduced upper airway size, while the role of ventilatory control is unclear. The objectives of our case-control study were to evaluate the upper airway reduction in children with DS and moderate to severe OSAS as compared to typically developing (TD) children with similar OSAS severity and to evaluate the degree of chemical loop gain modifications including its components: controller and plant gains (CG, PG).

METHODS

Thirteen children with DS were matched for age, sex, OSAS severity and ethnicity with 26 TD children. They had undergone acoustic rhinometry and pharyngometry, chemical LG obtained during awake tidal breathing measurement and hypercapnic-hyperoxic ventilatory response testing.

RESULTS

As compared to TD, children with DS depicted reduced oropharyngeal dimensions, significantly lower CG and LG and no different PG. Their hypercapnic ventilatory response slopes were not different.

CONCLUSIONS

We concluded that the decreased CG in DS was related to decreased peripheral chemoreceptor sensitivity, and while central chemosensitivity was normal, the former explained the increased end-tidal PCO2 observed in children with DS as compared to TD. Pharyngeal dimensions are reduced in children with DS and OSAS.

IMPACT

Reduced upper airway size and nocturnal alveolar hypoventilation in children with Down syndrome (DS) have been previously reported. We confirmed that children with DS and moderate-to-severe OSA have reduced oropharyngeal size as compared to typically developing children with similar OSAS severity and demonstrated decreased peripheral chemosensitivity explaining the alveolar hypoventilation observed in children with DS. Central chemosensitivity appears to be intact in children with DS and moderate to severe OSAS Our results support growing evidence that Down syndrome is associated with autonomic nervous system dysfunction.

Breathing and Oxygen Carrying Capacity in Ts65Dn and Down Syndrome

Individuals with Down syndrome (Ds) are at increased risk of respiratory infection, aspiration pneumonia, and apnea. The Ts65Dn mouse is a commonly used model of Ds, but there have been no formal investigations of awake breathing and respiratory muscle function in these mice. We hypothesized that breathing would be impaired in Ts65Dn vs. wild-type (WT), and would be mediated by both neural and muscular inputs. Baseline minute ventilation was not different at 3, 6, or 12 mo of age. However, VT/Ti, a marker of the neural drive to breathe, was lower in Ts65Dn vs. WT and central apneas were more prevalent. The response to breathing hypoxia was not different, but the response to hypercapnia was attenuated, revealing a difference in carbon dioxide sensing, and/or motor output in Ts65Dn. Oxygen desaturations were present in room air, demonstrating that ventilation may not be sufficient to maintain adequate oxygen saturation in Ts65Dn. We observed no differences in arterial PO2 or PCO2, but Ts65Dn had lower hemoglobin and hematocrit. A retrospective medical record review of 52,346 Ds and 52,346 controls confirmed an elevated relative risk of anemia in Ds. We also performed eupneic in-vivo electromyography and in-vitro muscle function and histological fiber typing of the diaphragm, and found no difference between strains. Overall, conscious respiration is impaired in Ts65Dn, is mediated by neural mechanisms, and results in reduced hemoglobin saturation. Oxygen carrying capacity is reduced in Ts65Dn vs. WT, and we demonstrate that individuals with Ds are also at increased risk of anemia.

Feasibility and performance of home sleep apnea testing in youth with Down syndrome

STUDY OBJECTIVES

In-laboratory polysomnography is recommended for the evaluation of obstructive sleep apnea (OSA) in youth with Down syndrome. However, insufficient sleep laboratories are available, particularly for youth with neurocognitive disabilities such as Down syndrome. We hypothesized that level II home sleep apnea testing (HSAT) would be feasible, acceptable, and accurate in detecting polysomnography-defined moderate-severe OSA in youth with Down syndrome.

METHODS

Youth 6 to 25 years old with Down syndrome were recruited to undergo in-home level II HSAT with electroencephalogram and in-lab polysomnography. Parents completed questionnaires assessing feasibility, acceptability, and test preference. HSAT, scored blinded to polysomnography result, were compared to reference polysomnography.

RESULTS

Forty-three youth (23 female) aged [median (range)] 15.5 (6.1, 25.1) years participated in the study. Forty-one participants were able to complete HSAT and 41 completed polysomnography, with 40 who underwent both tests. HSAT was preferred to polysomnography by 73.7% of parents. Total sleep time for HSAT was 437 ± 123 minutes vs 366 ± 90 minutes for polysomnography (P = .003). Obstructive apnea-hypopnea index by polysomnography was 12.7 events/h (0.2, 113.8), and 32 youth (80%) who completed all testing had OSA. Compared to polysomnography, sensitivity of HSAT was: 0.81, specificity was 0.75, accuracy was 0.8 including 2 youth whose HSAT demonstrated OSA when polysomnography did not.

CONCLUSIONS

In youth with Down syndrome, level II HSAT was well-tolerated, preferred compared to in-lab polysomnography, and had good accuracy for detecting moderate-severe OSA. Level II HSAT could provide a means for expanding the evaluation of OSA in youth with Down syndrome.

CITATION

Cielo CM, Kelly A, Xanthopoulos M, et al. Feasibility and performance of home sleep apnea testing in youth with Down syndrome J Clin Sleep Med. 2023;19(9):1605-1613.

The burden of sleep disordered breathing in infants with Down syndrome referred to tertiary sleep center

INTRODUCTION

Children with Down Syndrome (DS) are at high risk of sleep disordered breathing (SDB). We aimed to examine the burden of SDB in infants with DS referred to tertiary sleep center.

METHODS

Infants (≤12 months old) with DS who underwent consecutive polysomnography (PSG) at a single academic sleep center over a 6-year period were included. obstructive sleep apnea (OSA) (obstructive apnea hypopnea index [oAHI]>1/hr), central sleep apnea (central apnea index > 5/h) and the presence of hypoventilation (% time spent with CO2  > 50 mmHg either by end-tidal or transcutaneous> 25% of total sleep time) and hypoxemia (time spent with O2 saturation <88% >5 min) were ascertained.

RESULTS

A total of 40 infants were included (Mean age 6.6 months, male 66%). PSGs consisted of diagnostic (n = 13) and split night (n = 27, 68%) studies. All met criteria for OSA with mean oAHI 34.6/h (32.3). Central sleep apnea was present in 11 (27.5%) of infants. A total of 11 (27.5%) had hypoxemia. Hypoventilation was present in 10 (25%) infants.

CONCLUSION

This study highlights the high prevalence of SDB in infants with DS referred to a sleep center, and supports early PSG assessment in this patient population.

Recent advances in paediatric sleep disordered breathing

This article reviews the latest evidence pertaining to childhood sleep disordered breathing (SDB), which is associated with negative neurobehavioural, cardiovascular and growth outcomes. Polysomnography is the accepted gold standard for diagnosing SDB but is expensive and limited to specialist centres. Simpler tests such as cardiorespiratory polygraphy and pulse oximetry are probably sufficient for diagnosing obstructive sleep apnoea (OSA) in typically developing children, and new data-processing techniques may improve their accuracy. Adenotonsillectomy is the first-line treatment for OSA, with recent evidence showing that intracapsular tonsillectomy results in lower rates of adverse events than traditional techniques. Anti-inflammatory medication and positive airway pressure respiratory support are not always suitable or successful, although weight loss and hypoglossal nerve stimulation may help in select comorbid conditions.

Educational aims

To understand the clinical impact of childhood sleep disordered breathing (SDB).To understand that, while sleep laboratory polysomnography has been the gold standard for diagnosis of SDB, other diagnostic techniques exist with their own benefits and limitations.To recognise that adenotonsillectomy and positive pressure respiratory support are the mainstays of treating childhood SDB, but different approaches may be indicated in certain patient groups.

Predictors of sleep disordered breathing in children with Down syndrome: a systematic review and meta-analysis

Children with Down syndrome are at increased risk of sleep disordered breathing (SDB). SDB is associated with significant morbidity including neurocognitive impairment, cardiometabolic disease and systemic inflammation. The identification of clinical markers that may predict SDB is critical in facilitating early diagnosis and treatment, and ultimately, preventing morbidity. The objective of this systematic review was to identify predictors of SDB in patients with Down syndrome. A search was conducted using MEDLINE, Embase, the Cochrane Central Register of Controlled Trials and the Cumulative Index to Nursing and Allied Health Literature. A meta-analysis was performed according to the Meta-analyses of Observational Studies in Epidemiology checklist. Our review of the literature identified inconsistent associations between a variety of variables and SDB in children with Down syndrome, although the quality of evidence was poor. Meta-analysis of age and sex identified that children with OSA were older than those without OSA, and there was a similar risk of OSA in males and females, although risk favoured males. Currently, the American Academy of Pediatrics guidelines recommend that children with Down syndrome undergo polysomnography by the age of 4 years. Our review supports the recommendation for routine screening of children with Down syndrome. However, results from our meta-analysis suggest a need for longitudinal screening to diagnose children who may develop SDB as they get older.

This review identified several predictors of sleep disordered breathing (SDB) in children with Down syndrome. Meta-analysis identified older age as a predictor. This supports routine longitudinal screening of all children with Down syndrome for SDB.https://bit.ly/3KGnqFK

Sleep disorders in Down syndrome: a systematic review

BACKGROUND

Sleep disorders are commonly observed in children with Down syndrome (DS) and can lead to significant behavioral and cognitive morbidities in these individuals.

OBJECTIVE

To perform a systematic review evaluating sleep disorders in individuals with DS.

METHODS

Search strategies were based on combinations of keywords: "Down syndrome"; "trisomy 21"; "sleep disorders"; "dyssomnias"; "sleep apnea"; "obstructive"; "sleeplessness"; "insomnia"; "parasomnias"; and "excessive daytime sleepiness". PubMed and Science Direct were used. Only original studies and retrospective reviews in English published between January 2011 and March 2021 were included.

RESULTS

52 articles were included, most of them involving children and adolescents under 18 years of age. The main sleep disorder associated with DS was obstructive sleep apnea (OSA). Some studies reported the presence of cognitive dysfunction in patients with DS and sleep-disordered breathing, and few have been found about parasomnia, insomnia, and daytime sleepiness in these patients. Movement disorders and unusual postures during sleep may be related to disordered sleep breathing in DS. The main treatment options for OSA are continuous positive airway pressure therapy (CPAP), surgery, and weight control. Computational modeling associated with MRI has been used to plan surgical interventions in these patients.

CONCLUSIONS

Individuals with DS are at high risk of developing sleep-related breathing disorders. The main sleep disorder associated with DS was OSA. The presence of sleep-disordered breathing contributes to a worsening of cognitive function in patients with DS.

Pulse transit time as a diagnostic test for OSA in children with Down syndrome

STUDY OBJECTIVES

Children with Down syndrome (DS) are at risk of obstructive sleep apnea (OSA), but the access to sleep lab polysomnography (PSG) is limited. Simplified techniques are needed, such as polygraphy coupled with pulse transit time (PTT-PG) that detects respiratory events and the total autonomic arousals index (PTTAI). Our objective was to assess the ability of PTT-PG compared with PSG to diagnose OSA in children with DS.

METHODS

In this prospective multicenter study, patients with DS underwent a full-night PSG coupled with PTT. Sleep questionnaires (Sleep Disturbance Scale for Children and Pediatric Sleep Questionnaire) were filled by parents. PSG and PTT-PG results were compared to test their sensibility and specificity to diagnose OSA.

RESULTS

A total of 53 patients with DS were included; their median age was 9.3 years. An obstructive apnea-hypopnea index (OAHI) by PSG > 1 event/h was found in 36 (68%) patients, OAHI was > 1 and < 5 events/h in 18 patients (34%), ≥ 5 and < 10 events/h in 11 patients (21%), and ≥ 10 events/h in 7 patients (13%). OAHI was larger on PSG than on PTT-PG (P = .0005). For OSA diagnosis, the sensitivity was excellent for OAHI by PTT-PG if the added total PTTAI was > 1 event/h (1.0) and the specificity was high for the Pediatric Sleep Questionnaire (0.88) and OAHI > 1 event/h on PTT-PG (1.0).

CONCLUSIONS

More than two-thirds of children with DS referred for screening by a genetics specialist had OSA diagnosed by PSG. With its excellent sensitivity and specificity, PTT-PG could be a good and simplified alternative to PSG to diagnose OSA in children with DS.

CITATION

Ioan I, Weick D, Sevin F, et al. Pulse transit time as a diagnostic test for OSA in children with Down syndrome. J Clin Sleep Med. 2022;18(1):119-128.

Assessment of Nocturnal Hypoventilation by Different Methods and Definitions in Children with Neuromuscular Disease: Oxycapnography and Blood Gas Analysis

Objective

To investigate whether partial arterial carbon dioxide pressure (PaCO₂) level in arterial blood gas analysis that was used to predict nocturnal hypoventilation (NH) is concordant with nocturnal end-tidal CO₂ (PetCO₂) measurement obtained by a noninvasive method of oxycapnography in children with neuromuscular disease (NMD).

Methods

Twenty-one patients aged 6-18 years with a confirmed diagnosis of NMD were enrolled. Each patient underwent a nocturnal oxycapnography study using an orinasal probe and a pulse oximetry finger probe to record PetCO₂, oxygen saturation (SpO₂), pulse rate, and respiratory rate. Arterial blood gas analysis was performed to record PaCO₂ levels on three occasions at night (23:00 pm, 03:00 am, 07:00 am).

Results

The mean overnight PaCO₂ level of the three blood gas analyses (mean PaCO₂noct) was 41.78±4.69 mmHg. A significant change was observed between mean PaCO₂ 23:00 and PaCO₂ 07:00 levels (p=0.032). There was no significant difference between PaCO₂, PetCO₂, and SpO₂ levels in the NMD group. The interclass correlation coefficient between PaCO₂ 07:00 and PetCO₂ levels was 0.791 (95% CI: 0.533-0.923); the interclass correlation coefficient between overnight mean PaCO₂ and PetCO₂ levels was 0.811 (95% CI:0.533-0.923).

Conclusion

Our study indicates that nocturnal PetCO₂ and PaCO₂ levels were statistically comparable but the use of PaCO₂ alone is not adequate to make an early diagnosis of NH in NMD. There is a need for making more restrictive definitions for NH, and conducting studies with larger study populations to reach an agreement on the best definition of hypoventilation, and updating consensus guidelines.

Children with down syndrome and sleep disordered breathing display impairments in ventilatory control

OBJECTIVES

To investigate the role of ventilatory control instability (i.e. loop gain) in children with Down syndrome and sleep disordered breathing.

METHODS

Children (3-19 years) with Down syndrome and sleep disordered breathing (n = 14) were compared with typically developing children (n = 14) matched for age, sex and sleep disordered breathing severity. All children underwent overnight polysomnography. Spontaneous sighs were identified and a 180s analysis window (60s pre-sigh to 120s post-sigh) containing flow measurements and oxygen saturation were created. Loop gain, a measure of the sensitivity of the negative feedback loop that controls ventilation, was estimated by fitting a mathematical model of ventilatory control to the post-sigh ventilatory pattern. Results; Loop gain was significantly higher in children with Down syndrome compared to matched typically developing children (median loop gain [interquartile range]: 0.36 [0.33, 0.55] vs 0.32 [0.24, 0.38]; P = 0.0395). While children with Down syndrome also had significantly lower average oxygen saturation associated within each analysis window compared to typically developing children (mean ± standard deviation: 96.9 ± 1.3% vs 98.0 ± 1.0%; P = 0.0155), loop gain was not related to polysomnographic measures of hypoxia.

CONCLUSIONS

Higher loop gain in children with Down syndrome and sleep disordered breathing indicates that these children have more unstable ventilatory control, compared to age, sex and sleep disordered breathing severity matched typically developing children. This may be due to an inherent impairment in ventilatory control in children with Down syndrome contributing to their increased risk of sleep disordered breathing which may inform alternative treatment options for this population.

A respiratory/Hirschsprung phenotype in a three-generation family associated with a novel pathogenic PHOX2B splice donor mutation

BACKGROUND

Mutations in the PHOX2B gene cause congenital central hypoventilation syndrome (CCHS), a rare autonomic nervous system dysfunction disorder characterized by a decreased ventilatory response to hypercapnia. Affected subjects develop alveolar hypoventilation requiring ventilatory support particularly during the non-REM phase of sleep. In more severe cases, hypoventilation may extend into wakefulness. CCHS is associated with disorders characterized by the defective migration/differentiation of neural crest derivatives, including aganglionic megacolon or milder gastrointestinal phenotypes, such as constipation. Most cases of CCHS are de novo, caused by heterozygosity for polyalanine repeat expansion mutations (PARMs) in exon 3. About 10% of cases are due to heterozygous non-PARM missense, nonsense or frameshift mutations.

METHODS

We describe a three-generation Maltese-Caucasian family with a variable respiratory/Hirschsprung phenotype, characterized by chronic constipation, three siblings with Hirschsprung disease necessitating surgery, chronic hypoxia, and alveolar hypoventilation requiring non-invasive ventilation.

RESULTS

The sequencing of PHOX2B revealed a novel heterozygous c.241+2delT splice variant in exon 1 that segregates with the CCHS/Hirschsprung phenotype in the family. The mutation generates a non-functional splice site with a deleterious effect on protein structure and is pathogenic according to ACMG P VS1, PM2, and PP1 criteria.

CONCLUSION

This report is significant as no PHOX2B splice-site mutations have been reported. Additionally, it highlights the variability in clinical expression and disease severity of non-PARM mutations.