Cardioventilatory Control in Preterm-born Children and the Risk of Obstructive Sleep Apnea

Worldwide prevalence and associated risk factors of obstructive sleep apnea: a meta-analysis and meta-regression

PURPOSE

This study aimed to identify the prevalence of obstructive sleep apnea (OSA) and associated risk factors globally.

METHODS

Six databases and registrations and three grey databases were explored for observational field research. Independently and impartially paired reviewers selected research, gathered data, and evaluated the methodological quality. Heterogeneity was investigated using subgroup analysis and meta-regression following the moderating variable in a meta-analysis of proportions with a random-effects model. The critical appraisal instrument developed by the Joanna Briggs Institute was used to evaluate the listed studies' methodology. The certainty of the evidence was evaluated using the GRADE tool.

RESULTS

A total of 8236 articles were collected during the database search, resulting in 99 articles included for qualitative synthesis, and 98 articles were included for the meta-analysis. The estimated combined prevalence of OSA was 54% [CI 95% = 46-62%; I2 = 100%]. Mean age, percentage of moderate-severe cases, and the sample's body mass index (BMI) did not affect the heterogeneity that was already present when meta-regressed (p > 0.05). Ninety-one studies were deemed to have a low risk of bias, while eight were deemed to have a moderate risk. For OSA prevalence outcomes, the GRADE criteria were considered very low.

CONCLUSION

Approximately half of the people worldwide have OSA. High BMI, increasing age, and male gender are described as risk factors in the literature, but these covariates do not affect pre-existing heterogeneity.

Disparities in Sleep-Disordered Breathing: Upstream Risk Factors, Mechanisms, and Implications

Sleep-disordered breathing (SDB) refers to a spectrum of disorders ranging from habitual snoring without frank episodes of obstructed breathing or desaturation during sleep to obstructive sleep apnea, where apneas and hypopneas repetitively occur with resultant intermittent hypoxia, arousal, and sleep disruption. Disparities in SDB reflect its overall high prevalence in children and adults from racially and ethnically minoritized or low socioeconomic status backgrounds coupled with high rates of underdiagnosis and suboptimal treatment.

Quantitative and Qualitative Changes in Peripheral Chemoreceptor Activity in Preterm Infants

Rationale: Preterm infants are at risk for ventilatory control instability that may be due to aberrant peripheral chemoreceptor activity. Although term infants have increasing peripheral chemoreceptor contribution to overall ventilatory drive with increasing postnatal age, how peripheral chemoreceptor contribution changes in preterm infants with increasing postmenstrual age is not known. Objectives: To evaluate peripheral chemoreceptor activity between 32 and 52 weeks postmenstrual age in preterm infants, using both quantitative and qualitative measures. Methods: Fifty-five infants born between 24 weeks, 0 days gestation and 28 weeks, 6 days gestation underwent hyperoxic testing at one to four time points between 32 and 52 weeks postmenstrual age. Quantitative [Formula: see text] decreases were calculated, and qualitative responses were categorized as apnea, continued breathing with a clear reduction in [Formula: see text], sigh breaths, and no response. Measurements and Main Results: A total of 280 hyperoxic tests were analyzed (2.2 ± 0.3 tests per infant at each time point). Mean peripheral chemoreceptor contribution to ventilatory drive was 85.2 ± 20.0% at 32 weeks and 64.1 ± 22.0% at 52 weeks. Apneic responses were more frequent at earlier postmenstrual ages. Conclusions: Among preterm infants, the peripheral chemoreceptor contribution to ventilatory drive was greater at earlier postmenstrual ages. Apnea was a frequent response to hyperoxic testing at earlier postmenstrual ages, suggesting high peripheral chemoreceptor activity. A clearer description of how peripheral chemoreceptor activity changes over time in preterm infants may help explain how ventilatory control instability contributes to apnea and sleep-disordered breathing later in childhood. Clinical trial registered with www.clinicaltrials.gov (NCT03464396).

Defining Age-related OSA Features in Robin Sequence Using Polysomnographic-based Analyses of Respiratory Arousal Responses and Gas-exchange Parameters

INTRODUCTION

Robin sequence (RS) is a leading cause of obstructive sleep apnea (OSA) in newborns. Most studies have focused on understanding anatomic factors leading to OSA and changes in apnea-hypopnea index (AHI) on polysomnography (PSG) beyond the neonatal period. This study aims to define age-related OSA features between patients with RS, without RS and healthy controls using PSG-based analyses of respiratory arousal responses and gas-exchange parameters.

DESIGN

Retrospective comparison of PSG features in a total of 48 children encompassing three groups: (a) infants with RS (n = 24, <1-year old), (b) non-RS older children (1-2 years old) with severe OSA (obstructive AHI (OAHI) of ≥10 events; n = 12), and (c) control infants and children (0-2 years old) without sleep apnea (OAHI ≤1.5/h, n = 12). We examined OSA sleep-stage specific and position-specific indexes, and the relationship between OSA severity and respiratory arousal indexes (OAHI/respiratory arousal indexes).

RESULTS

OSA sleep-stage specific indexes (rapid eye movement [REM] vs non-REM[NREM]) as well as position-specific indexes (supine vs nonsupine) were similar in individuals with and without RS. Relative to the non-RS groups, infants with RS have more sustained hypoxemia (time with SpO₂ < 90%) and reduced arousal responses to OSA demonstrated by higher OAHI/respiratory arousal indexes. OAHI/respiratory arousal indexes significantly correlated with the severity of hypoxemia in infants with RS.

CONCLUSION

Infants with RS and OSA show reduced arousal responses to apneic events, which correlates with higher hypoxemia severity. OAHI/respiratory arousal indexes in RS may identify high-risk individuals with upper airway obstruction and reduced arousal protective responses.

Craniofacial features in children with obstructive sleep apnea: a systematic review and meta-analysis

STUDY OBJECTIVES

This review aimed to evaluate the association between craniofacial features in children and adolescents with pediatric obstructive sleep apnea (OSA).

METHODS

Seven databases were searched to fulfill our research objectives. Clinical studies that included participants younger than 18 years with fully diagnosed OSA or without OSA and that evaluated skeletal, soft craniofacial features, or dental arch morphology were considered for this review. The risk of bias and certainty of evidence were assessed. A meta-analysis was performed when low methodological and clinical heterogeneity were detected. This review followed the protocols recommended by the Preferred Reporting Items for a Systematic Review and Meta-analysis (PRISMA-2020) guidelines.

RESULTS

Nine studies were identified at the end of the selection process, from which 5 did not report differences. Four studies reported differences between craniofacial features when OSA was compared to an asymptomatic control group. Mandibular retrognathia, reduced anteroposterior linear dimensions of the bony nasopharynx (decreased pharyngeal diameters at the levels of the adenoids), longer facial profile, and a narrower intercanine width were described among children with OSA. A meta-analysis was performed considering the studies with a similar methodological approach, and no differences were observed in all the considered cephalometric angles (SNA, SNB, ANB, NSBa, U1-L1, U1-SN). All the included studies were considered at low risk of bias even though some limitations were noted.

CONCLUSIONS

Due to the very low to moderate level of certainty, neither an association nor a lack thereof between craniofacial morphology and pediatric OSA can be supported by these data.

CITATION

Fagundes NCF, Gianoni-Capenakas S, Heo G, Flores-Mir C. Craniofacial features in children with obstructive sleep apnea: a systematic review and meta-analysis. J Clin Sleep Med. 2022;18(7):1865-1875.

The Next Frontier of Prematurity: Predicting Respiratory Morbidity During the First Two Years of Life in Extremely Premature Babies

Background

Advances in perinatal and neonatal medicine have led to an increasing number of infants surviving extreme prematurity (≤27 weeks gestational age, GA). The goal of this study was to examine the respiratory outcomes after neonatal intensive care unit (NICU) discharge of this vulnerable population. We hypothesized that the rates of respiratory hospitalizations are disproportionally higher in the subset of infants born ≤27 weeks GA relative to premature infants born 28-32 weeks GA.

Methodology

A retrospective longitudinal study of severe premature children (≤32 weeks GA, n = 183) was conducted. We subdivided our sample into extremely preterm infants (≤27 weeks GA; n = 101) and those born very preterm (28-32 weeks GA; n = 82). Our main outcome was the presence of respiratory hospitalizations within 24 months of NICU discharge.

Results

Extremely premature infants had more than three times higher odds of respiratory hospitalization at 24 months relative to infants born 28-32 weeks GA (adjusted odds ratio = 3.4; 95% confidence interval = 1.8, 6.4; p < 0.01). The increased risk of respiratory hospitalization in extremely premature infants was independent of GA. Regression models identified that the duration of supplemental oxygen and Black/African American ethnicity were significant predictors of respiratory hospitalizations in both prematurity groups independent of gender and birth weight.

Conclusions

The results support that babies born ≤27 weeks GA represent a distinct high-risk group of severely premature infants that needs novel preventive strategies and targeted interventions to improve their respiratory outcomes after NICU discharge.

Ventilatory control instability as a predictor of persistent periodic breathing in preterm infants

BACKGROUND

Periodic breathing (PB) is common in preterm infants. We aimed to characterize the contribution of ventilatory control instability to the presence and persistence of PB longitudinally.

METHODS

Infants born between 28 and 32 weeks of gestation were studied using daytime polysomnography at: 32-36 weeks postmenstrual age (PMA) (N = 32), 36-40 weeks PMA (N = 20), 3 months corrected age (CA) (N = 18) and 6 months CA (N = 19). Loop gain, a measure of sensitivity of the ventilatory control system, was estimated by fitting a mathematical model to ventilatory patterns associated with spontaneous sighs.

RESULTS

The time spent in PB decreased from 32-36 weeks PMA to 6 months CA (P = 0.005). Across all studies, studies with PB (N = 62) were associated with higher loop gain compared to those without PB (N = 23) (estimated marginal mean ± SEM: 0.445 ± 0.01 vs 0.388 ± 0.02; P = 0.020). A threshold of loop gain >0.415 (measured at 32-36 weeks PMA) provided a sensitivity of 86% and a specificity of 75% to detect the presence of PB at 6 months CA.

CONCLUSIONS

The course of PB in preterm infants is related to changes in loop gain. Higher loop gain at 32-36 weeks PMA was associated with a greater risk of persistent PB at 6 months CA.

IMPACT

The developmental trajectory of periodic breathing and its relationship to ventilatory control instability is currently unclear. Unstable ventilatory control is a determinant of periodic breathing in preterm infants up to 6 months corrected age. Infants who display greater ventilatory control instability at 32-36 weeks postmenstrual age may be at increased risk of persistent periodic breathing at 6 months corrected age. Assessment of ventilatory control stability may assist in the early identification of infants at risk of persistent periodic breathing and its potential adverse effects.

Use of facial stereophotogrammetry as a screening tool for pediatric obstructive sleep apnea by dental specialists

STUDY OBJECTIVES

To evaluate facial 3-dimensional (3D) stereophotogrammetry's effectiveness as a screening tool for pediatric obstructive sleep apnea (OSA) when used by dental specialists.

METHODS

One hundred forty-four participants aged 2-17 years, including children fully diagnosed with pediatric OSA through nocturnal polysomnography or at high-risk or low-risk of pediatric OSA, participated in this study. 3D stereophotogrammetry, Craniofacial Index, and Pediatric Sleep Questionnaire were obtained from all participants. Ten dental specialists with interest in pediatric sleep breathing disorders classified OSA severity twice, once based only on 3D stereophotogrammetry and then based on 3D stereophotogrammetry, Craniofacial Index, and Pediatric Sleep Questionnaire. Intrarater and interrater reliability and diagnostic accuracy of pediatric OSA classification were calculated. A cluster analysis was performed to identify potential homogeneous pediatric OSA groups based on their craniofacial features classified through the Craniofacial Index .

RESULTS

Intrarater and interrater agreement suggested a poor reproducibility when only 3D facial stereophotogrammetry was used and when all tools were assessed simultaneously. Sensitivity and specificity varied among clinicians, indicating a low screening ability for both 3D facial stereophotogrammetry, ranging from 0.36-0.90 and 0.10-0.70 and all tools ranging from 0.53-1.0 and 0.01-0.49, respectively. A high arched palate and reversed or increased overjet contributed to explaining how participating dental clinicians classified pediatric OSA.

CONCLUSIONS

3D stereophotogrammetry-based facial analysis does not seem predictive for pediatric OSA screening, alone or combined with the Pediatric Sleep Questionnaire and Craniofacial Index when used by dental specialists interested in sleep-disordered breathing. Some craniofacial traits, more specifically significant sagittal overjet discrepancies and an arched palate, seem to influence participating dental specialists' classification.

CITATION

Fernandes Fagundes NC, Carlyle T, Dalci O, et al. Use of facial stereophotogrammetry as a screening tool for pediatric obstructive sleep apnea by dental specialists. J Clin Sleep Med. 2022;18(1):57-66.

Prematurity, the diagnosis of bronchopulmonary dysplasia, and maturation of ventilatory control

Infants born before 32 weeks gestational age and receiving respiratory support at 36 weeks postmenstrual age (PMA) are diagnosed with bronchopulmonary dysplasia (BPD). This label suggests that their need for supplemental oxygen (O₂ ) is primarily due to acquired dysplasia of airways and airspaces, and that the supplemental O₂ is treating residual parenchymal lung disease. However, emerging evidence suggests that immature ventilatory control may also contribute to the need for supplemental O₂ at 36 weeks PMA. In all newborns, maturation of ventilatory control continues ex utero and is a plastic process. Among premature infants, supplemental O₂ mitigates the hypoxemic effects of delayed maturation of ventilatory control, as well as reduces the duration and frequency of periodic breathing events. Nevertheless, prematurity is associated with altered and occasionally aberrant maturation of ventilatory control. Infants born prematurely, with or without a diagnosis of BPD, are more prone to long-lasting effects of dysfunctional ventilatory control. This review addresses normal and abnormal maturation of ventilatory control and suggests how aberrant maturation complicates assigning the diagnosis of BPD. Greater awareness of the interaction between parenchymal lung disease and delayed maturation of ventilatory control is essential to understanding why a given premature infant requires and is benefitting from supplemental O₂ at 36 weeks PMA.

Predicting Long-Term Respiratory Outcomes in Premature Infants: Is It Time to Move beyond Bronchopulmonary Dysplasia?

Premature birth has been shown to be associated with adverse respiratory health in children and adults; children diagnosed with bronchopulmonary dysplasia (BPD) in infancy are at particularly high risk. Since its first description by Northway et al. about half a century ago, the definition of BPD has gone through several iterations reflecting the changes in the patient population, advancements in knowledge of lung development and injury, and improvements in perinatal care practices. One of the key benchmarks for optimally defining BPD has been the ability to predict long-term respiratory and health outcomes. This definition is needed by multiple stakeholders for hosts of reasons including: providing parents with some expectations for the future, to guide clinicians for developing longer term follow-up practices, to assist policy makers to allocate resources, and to support researchers involved in developing preventive or therapeutic strategies and designing studies with meaningful outcome measures. Long-term respiratory outcomes in preterm infants with BPD have shown variable results reflecting not only limitations of the current definition of BPD, but also potentially the impact of other prenatal, postnatal and childhood factors on the respiratory health. In this manuscript, we present an overview of the long-term respiratory outcomes in infants with BPD and discuss the role of other modifiable or non-modifiable factors affecting respiratory health in preterm infants. We will also discuss the limitations of using BPD as a predictor of respiratory morbidities and some of the recent advances in delineating the causes and severity of respiratory insufficiency in infants diagnosed with BPD.

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.

Anthropometry: A clue for Otorhinolaryngology surgical indications in children

BACKGROUND

There are reports in literature concerning the relation between some maternal and neonatal factors and future risk of disease, including atopy, recurrent infections and obstructive sleep disturbances, three common pathologies eliciting surgery in children.

OBJECTIVE

To evaluate if maternal and neonatal factors can relate to Otorhinolaryngology surgical indications in a cohort of children treated in a tertiary referral center.

MATERIAL AND METHODS

A retrospective analysis of data from children submitted to primary Otorhinolaryngology surgery in the pediatric ambulatory unit of Centro Hospitalar Universitário do Porto between March 2016 and March 2020 was performed. Children with orofacial congenital anomalies were excluded and 1256 children met the eligibility criteria. The associations between maternal and neonatal factors and the development of atopy, recurrent infections and obstructive sleep apnea were analyzed.

RESULTS

Atopic children showed higher birth weight percentile (p < 0,001) and birth weight-for-length index (p < 0,001) compared with non-atopic. Weight-at-surgery was also higher in atopic patients (p = 0,002). Maternal atopy significantly increased the risk of children atopic disease (p < 0,001; Odds Ratio 4,359). Children indicated for surgery for recurrent infections showed lower birth weight-for-length index (p = 0,038) and lower probability of atopic disease (p < 0,001). Recurrent acute otitis media related to both lower birth weight-for-length index (p = 0,002) and birth body mass index (p = 0,023). There was not a significant higher incidence of sleep apnea in preterm infants (p = 0,488). Obstructive sleep apnea patients showed lower weight-at-surgery percentile (p = 0,045).

CONCLUSION

This work suggests an association between birth anthropometric measurements and atopic and infectious diseases later in life, irrespective of gestational age. There was no consistent association between perinatal parameters and obstructive sleep apnea, but the impact of disordered breathing in childhood anthropometry was significative.

Journey towards a personalised medicine approach for OSA: Can a similar approach to adult OSA be applied to paediatric OSA?

The concept of personalised medicine is likely to revolutionise the treatment of adult obstructive sleep apnoea as a result of recent advances in the understanding of disease heterogeneity by identifying clinical phenotypes, pathophysiological endotypes, biomarkers and treatable traits. Children with the condition show a similar level of heterogeneity and paediatric obstructive sleep apnoea would also benefit from a more targeted approach to diagnosis and management. This review aims to summarise the adult literature on the phenotypes and endotypes of obstructive sleep apnoea and assess whether a similar approach may also be suitable to guide the development of new diagnostic and management approaches for paediatric obstructive sleep apnoea.

Comparison of sleep problems between term and preterm born preschool children

OBJECTIVES

Sleep disorders are common problems among all age groups. If sleep problems detected in childhood are not resolved successfully, they become sleep disorders and a chronic state. In this study, we aimed to compare sleep problems between preterm-born and term-born preschool-age children.

METHODS

In the cross-sectional study, children were grouped according to whether they were born preterm or at term. The preterm group included 137 children aged four to six years. The control group comprised 145 age-matched term-born preschool children. The prenatal, natal, demographical, and clinical characteristics of preterm- and term-born preschool-age children were compared. The Children's Sleep Habits Questionnaire (CSHQ) was used to identify sleep problems. The total score and subscores of the CSHQ were compared between the groups.

RESULTS

The percentage of gastroesophageal reflux (GER) symptoms and obstructive sleep apnea (OSA) symptoms were significantly higher in the preterm group. According to the cutoff point of the CSHQ, 97 children in the preterm group (70.8%) and 88 children in the control group (60.7%) had a sleep disorder. The total score of the CSHQ was significantly higher in the preterm group compared with the control group; however, the scores of the subscales were similar between the groups. In the regression analysis, a significant association was found between being born preterm and having sleep disorder (β = 0.308, OR = 1.36, p = 0.04).

CONCLUSIONS

Our study reported a high percentage of sleep problems in preterm-born preschool children. We suggest that prematurity is associated with sleep problems even if the etiology of sleep problems is heterogeneous. Symptoms regarding GER and OAS should be investigated, and precautions, such as prohibiting maternal cigarette smoking, should be taken in preterm infants.

Effects of Ventilation-Perfusion Mismatch on Severity of Obstructive Sleep Apnea: A Modeling Study

Plant gain quantifies the extent and rapidity with which arterial blood gases change following hypopneic or hyperpneic events. High plant gain, acting in concert with a highly collapsible upper airway and low arousal threshold, may contribute significantly towards increasing the severity of obstructive sleep apnea (OSA), even when controller gain is low. Elevated plant gain may be a manifestation of abnormal gas exchange resulting from ventilation-perfusion mismatch in the lungs. Using a mathematical model, we explore in this paper how ventilation-perfusion mismatch can affect plant gain, as well as the severity of OSA.

Role of ventilatory control instability in children with sleep-disordered breathing

BACKGROUND AND OBJECTIVE

The contribution of non-anatomical factors, such as ventilatory control instability (i.e. LG), to the pathogenesis of obstructive SDB in children is unclear. Therefore, we aimed to identify the relationship between LG and severity of SDB, demographic, anthropometric and anatomical characteristics in a clinically representative cohort of children.

METHODS

Children (aged 3-18 years) with various severities of SDB (n = 110) and non-snoring controls (n = 36) were studied. Children were grouped according to their OAHI. Anthropometric and upper airway anatomical characteristics were measured. Spontaneous sighs were identified on polysomnography and LG, 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

There was no difference in LG between controls and any of the SDB severity groups. However, LG was significantly lower in children with larger tonsils (tonsil grade 4) compared with children with smaller tonsils (tonsil grade 1) (median LG (range): 0.25 (0.20-0.42) vs 0.32 (0.25-0.44); P = 0.009) and in children with a modified Mallampati score of class III/IV compared with class I (0.28 (0.24-0.33) vs 0.37 (0.27-0.44); P = 0.009).

CONCLUSION

A direct relationship was not found between the severity of paediatric SDB and LG. However, an altered ventilatory control sensitivity may contribute to SDB in a subgroup of children depending on their degree of anatomical compromise of the airway.

Validation of a new predictive model to improve risk stratification in bronchopulmonary dysplasia

We need a better risk stratification system for the increasing number of survivors of extreme prematurity suffering the most severe forms of bronchopulmonary dysplasia (BPD). However, there is still a paucity of studies providing scientific evidence to guide future updates of BPD severity definitions. Our goal was to validate a new predictive model for BPD severity that incorporates respiratory assessments beyond 36 weeks postmenstrual age (PMA). We hypothesized that this approach improves BPD risk assessment, particularly in extremely premature infants. This is a longitudinal cohort of premature infants (≤32 weeks PMA, n = 188; Washington D.C). We performed receiver operating characteristic analysis to define optimal BPD severity levels using the duration of supplementary O2 as predictor and respiratory hospitalization after discharge as outcome. Internal validation included lung X-ray imaging and phenotypical characterization of BPD severity levels. External validation was conducted in an independent longitudinal cohort of premature infants (≤36 weeks PMA, n = 130; Bogota). We found that incorporating the total number of days requiring O2 (without restricting at 36 weeks PMA) improved the prediction of respiratory outcomes according to BPD severity. In addition, we defined a new severity category (level IV) with prolonged exposure to supplemental O2 (≥120 days) that has the highest risk of respiratory hospitalizations after discharge. We confirmed these findings in our validation cohort using ambulatory determination of O2 requirements. In conclusion, a new predictive model for BPD severity that incorporates respiratory assessments beyond 36 weeks improves risk stratification and should be considered when updating current BPD severity definitions.

Prematurity as a Risk Factor of Sleep-Disordered Breathing in Children Younger Than Two Years: A Retrospective Case-Control Study

STUDY OBJECTIVES

Sleep-disordered breathing (SDB) is a highly prevalent condition affecting 2% to 4% of children. However, the prevalence and characteristics of SDB in children younger than 2 years and the effect of prematurity as a risk factor remains unclear.

METHODS

Children younger than 24 months referred for PSG at two medical centers between the years 2014 to 2018 were included in this retrospective analysis. We excluded children with genetic syndromes. Polysomnography (PSG) was performed and scored according to American Academy of Sleep Medicine guidelines.

RESULTS

Ninety-eight children were included (age 14.1 ± 6.4 [2-23] months), with 31 born prematurely (PRETERM; 24 to 34 weeks gestational age). PRETERM had increased odds of SDB (age and sex adjusted), using a cutoff of AHI ≥ 5 events/h with an odds ratio of 4.3 (95% confidence interval 1.5-12.9). Gestational age was the only significant predictor for SDB in this cohort, every additional week of gestation reducing the odds of SDB by 12.5%. PRETERM SDB was also characterized by more severe nocturnal hypoxemia, increased frequency of central apnea, and altered sleep architecture.

CONCLUSIONS

Current findings underscore the importance of prematurity antecedents as a risk factor for SDB in young symptomatic children younger than 2 years referred for a PSG. Future studies focused on improved estimates of the prevalence of SDB among nonreferral young children appear warranted.

Assessing ventilatory instability using the response to spontaneous sighs during sleep in preterm infants

Study Objectives

Periodic breathing (PB) is common in newborns and is an obvious manifestation of ventilatory control instability. However, many infants without PB may still have important underlying ventilatory control instabilities that go unnoticed using standard clinical monitoring. Methods to detect infants with "subclinical" ventilatory control instability are therefore required. The current study aimed to assess the degree of ventilatory control instability using simple bedside recordings in preterm infants.

Methods

Respiratory inductance plethysmography (RIP) recordings were analyzed from ~20 minutes of quiet sleep in 20 preterm infants at 36 weeks post-menstrual age (median [range]: 36 [34-40]). The percentage time spent in PB was also calculated for each infant (%PB). Spontaneous sighs were identified and breath-by-breath measurements of (uncalibrated) ventilation were derived from RIP traces. Loop gain (LG, a measure of ventilatory control instability) was calculated by fitting a simple ventilatory control model (gain, time-constant, delay) to the post-sigh ventilatory pattern. For comparison, periodic inter-breath variability was also quantified using power spectral analysis (ventilatory oscillation magnitude index [VOMI]).

Results

%PB was strongly associated with LG (r2 = 0.77, p < 0.001) and moderately with the VOMI (r2 = 0.21, p = 0.047). LG (0.52 ± 0.05 vs. 0.30 ± 0.03; p = 0.0025) and the VOMI (-8.2 ± 1.1 dB vs. -11.8 ± 0.9 dB; p = 0.026) were both significantly higher in infants that displayed PB vs. those without.

Conclusions

LG and VOMI determined from the ventilatory responses to spontaneous sighs can provide a practical approach to assessing ventilatory control instability in preterm infants. Such simple techniques may help identify infants at particular risk for ventilatory instabilities with concomitant hypoxemia and its associated consequences.