Respiratory and polysomnographic values in 3- to 5-year-old normal children at higher altitude

Prevalence of pulmonary hypertension in children with obstructive sleep apnea living at high altitude

Introduction

The prevalence of obstructive sleep apnea (OSA) is 1-4 %. Some reports describe its association with pulmonary hypertension (PH), but its prevalence is unknown. No studies at high altitude have determined the relationship between OSA and PH. The aim of this study was to establish the prevalence of PH in children diagnosed with OSA living in a high-altitude city at 2640 m above sea level.

Methods

Children between 2 and 16 years of age referred to the Sleep Laboratory of the Fundación Neumológica Colombiana in Bogotá with a positive polysomnogram for OSA were included, and a two-dimensional transthoracic echocardiogram (TTE) was performed to evaluate PH. Statistical analysis was performed using median, interquartile range, chi-squared test, and Kruskall-Wallis test.

Results

Of the 55 patients (n: 55), 63.6 % were male, with a median age of 6 years, 14 children (25.5 %) were overweight; 12 children (21.8 %) had mild OSA, 12 (21.8 %) had moderate OSA and 31 (56.4 %) severe OSA. In patients with severe OSA, the minimum saturation during events was 78 % with a desaturation index (DI) of 33.8/hour (p < 0.01). T90 and T85 increased proportionally with OSA severity (p < 0.05). Of the 55 patients with OSA, none had PH according to echocardiography; 4 patients (7.2 %) had pulmonary artery systolic pressure (PASP) at the upper limit of normal (ULN), and it was not related to a higher body mass index (BMI).

Conclusions

We found no association between OSA and PH in children with OSA at high altitude.

Sleep apnea in school-age children living at high altitude

INTRODUCTION

Among adults, sleep apnea is more common in highlanders than in lowlanders. We evaluated the sleep apnea prevalence in children living at high altitude compared to age-matched low-altitude controls.

METHODS

Healthy children, 7-14 y of age, living at 2500-3800m in the Tien Shan mountains, Kyrgyzstan, were prospectively studied in a health post at 3250m. Healthy controls of similar age living at 700-800m were studied in a University Hospital at 760m in Bishkek. Assessments included respiratory sleep studies scored according to pediatric standards, clinical examination, medical history, and the pediatric sleep questionnaire (PSQ, range 0 to 1 with increasing symptoms).

RESULTS

In children living at high altitude (n = 37, 17 girls, median [quartiles] age 10.8y [9.6;13.0]), sleep studies revealed: mean nocturnal pulse oximetry 90% (89;91), oxygen desaturation index (ODI, >3% dips in pulse oximetry) 4.3/h (2.5;6.7), apnea/hypopnea index (AHI) total 1.7/h (1.0;3.6), central 1.6/h (1.0;3.3), PSQ 0.27 (0.18;0.45). In low-altitude controls (n=41, 17 girls, age 11.6y [9.5;13.0], between-groups comparison of age P=0.69) sleep studies revealed: pulse oximetry 97% (96;97), ODI 0.7/h (0.2;1.2), AHI total 0.4/h (0.1;1.0), central 0.3/h (0.1;0.7), PSQ 0.18 (0.14;0.31); P<0.05, all corresponding between-group comparisons.

CONCLUSIONS

In school-age children living at high altitude, nocturnal oxygen saturation was lower, and the total and central AHI were higher compared to children living at low altitude. The greater score of sleep symptoms in children residing at high altitude suggests a potential clinical relevance of the nocturnal hypoxemia and subtle sleep-related breathing disturbances.

Sleep problems in low income, urban pediatric populations living at different altitudes in Colombia

OBJECTIVE

To determine the frequency of sleep problems in low-income, urban pediatric populations in cities at different altitudes in Colombia.

METHODS

A descriptive, cross-sectional population-based observational study was conducted in children aged between 2 and 12 years in the low income, urban areas of three cities in Colombia (Santa Marta, Bucaramanga, and Bogotá) located at 15, 959, and 2640 m above sea level, respectively. Sociodemographic data were collected, and the Spanish version of the Pediatric Sleep Questionnaire was used.

RESULTS

1989 children were surveyed, distributed as follows: Santa Marta (32.0%), Bucaramanga (33.4%), and Bogotá (34.6%). The overall prevalence of sleep problems was 39.0%. Children from Santa Marta had the highest frequency of parasomnias (58.0%); those from Bucaramanga had the highest frequency of attention deficit symptoms (4.0%) and apneic pauses witnessed by parents or caregivers (5.7%). Finally, Bogotá, the only high-altitude location, had the highest frequency of sleep disordered breathing (17.2%).

CONCLUSIONS

The study found a high frequency of sleep problems in the pediatric population, especially at higher altitudes when compared to lower altitude settings. Sleep disorders warrant early detection and timely therapeutic intervention.

Periodic limb movements during sleep: a narrative review

Objective

Using narrative review techniques, this paper evaluates the evidence for separable underlying patho-mechanisms of periodic limb movements (PLMs) to separable PLM motor patterns and phenotypes, in order to elucidate potential new treatment modalities.

Background

Periodic limb movement disorder (PLMD) is estimated to occur in 5–8% of the paediatric population and 4–11% of the general adult population. Due to significant sleep fragmentation, PLMD can lead to functional impairment, including hyperactivity and delayed language development in children, and poor concentration and work performance in adults. Longitudinal data demonstrate that those with PLMD are at greater risk of depression and anxiety, and a 4-fold greater risk of developing dementia. PLMD has been extensively studied over the past two decades, and several key insights into the genetic, pathophysiological, and neural correlates have been proposed. Amongst these proposals is the concept of separable PLM phenotypes, proposed on the basis of nocturnal features such as the ratio of limb movements and distribution throughout the night. PLM phenotype and presentation, however, varies significantly depending on the scoring utilized and the nocturnal features examined, across age, and co-morbid clinical conditions. Furthermore, associations between these phenotypes with major neurologic and psychiatric disorders remain controversial.

Methods

In order to elucidate potential divergent biological pathways that may help clarify important new treatment modalities, this paper utilizes narrative review and evaluates the evidence linking PLM motor patterns and phenotypes with hypothesised underlying patho-mechanisms. Distinctive, underlying patho-mechanisms include: a pure motor mechanism originating in the spinal cord, iron deficiency, dopamine system dysfunction, thalamic glutamatergic hyperactivity, and a more cortical-subcortical interplay. In support of the latter hypothesis, PLM rhythmicity appears tightly linked to the microarchitecture of sleep, not dissimilarly to the apnoeic/hypopneic events seen in obstructive sleep apnea (OSA).

Conclusions

This review closes with a proposal for greater investigation into the identification of potential, divergent biological pathways. To do so would require prospective, multimodal imaging clinical studies which may delineate differential responses to treatment in restless legs syndrome (RLS) without PLMS and PLMS without RLS. This could pave the way toward important new treatment modalities.

Normal values for respiratory sleep polygraphy in children aged 4 to 9 years at 2,560 m above sea level

Obstructive sleep apnea syndrome affects 1%-4% of all children worldwide. Currently, diagnosis of obstructive sleep apnea is based on sea-level guidelines, without taking into account the altitude at which the populations live. It has been shown that at 3,200 m of altitude there is an increase in obstructive events in healthy children aged 7 to 16 years; on the other hand, it is known that SpO₂ dispersion between individuals becomes wider as altitude increases, a phenomenon that is more marked during sleep. About 17 million Colombians live in regions between 2,500 m and 2,700 m, as do significant populations in other Latin American countries. This research aimed to characterize respiratory polygraphy sleep parameters in healthy, non-snoring children aged 4-9 years living at 2,560 m. We carried out home respiratory polygraphy in 32 children with a mean age of 6.2 years (range 4-9 years). The average recorded sleep time was 7.8 h, the median apnea-hypopnea index was 9.2/h, the obstructive apnea-hypopnea index had a median of 8.8/h (p5 4.2 to p95 17.9) and central apnea a median of 0.4/h. The median SpO₂ was 93% (p5 90.5 to p95 94) and transcutaneous CO₂ had a median of 39.4 mmHg (p531.7 to p95 42.3). The median oxygen desaturation index ≥ 3% was 11.2 and median oxygen desaturation index ≥ 4% was 3.9. Normal measurements for respiratory polygraphy obtained at sea level do not apply to children at altitude. If such guidelines are used, obstructive sleep apnea will be over-diagnosed, resulting in unnecessary adenotonsillectomies, among other interventions.

Breathing Patterns and Oxygenation Saturation During Sleep in Children Habitually Living at High Altitude in the Andes: A Systematic Review

BACKGROUND

Human respiratory physiology changes significantly in high altitude settings and these changes are particularly marked during sleep. It is estimated that 170 million people live above 2,500 m in environments where normal sleep parameters differ from those established at sea level or low altitude.

METHODS

We conducted a systematic review of publications reporting sleep studies in healthy children living at high altitude. For this purpose, data from PubMed, EMBASE, SciELO and Epistemomikos bases were retrieved up to August 2021.

RESULTS

Six articles met specified inclusion criteria; all reporting data were from South America involving 245 children (404 sleep studies) in children aged 0.6 months to 18 years, at altitudes between 2,560 to 3,775 m. The main results were: (1) Central apnea index decreased as the age increased. (2) The obstructive apnea/hypopnea index showed a bimodal profile with an increase in young infants up to age of 4 months, decreasing to 15 months of age, and then a second peak in children aged 4 to 9 years of age, dropping in older schoolchildren and adolescents. (3) Periodic breathing in the first months of life is more marked with increasing altitude and decreases with age.

CONCLUSIONS

There are few studies of sleep physiology in children living at high altitude. The international parameters defining normal apnea indices currently used at low altitude cannot be applied to high altitude settings. The interpretation of sleep studies in children living at high altitude is complex because there are important developmental changes across childhood and a wide range of altitude locations. More normative data are required to determine thresholds for respiratory pathology at a variety of high altitude settings.

Prediction of normal values for central apnea-hypopnea index at different ages and altitudes above sea level in healthy children

BACKGROUND

There is a critical need for studies aimed to help clinicians to establish the normal/expected central apnea-hypopnea index (CAHI) at altitudes above sea level and ages other than those reported in the current available studies. The aim of the present study was to develop predictive models useful for determining the normal/expected CAHI in children of different ages born and living at various altitudes above sea level.

METHODS

A systematic review of the literature was performed in order to identify all available studies that reported on CAHI values measured in healthy children of different ages and living at various levels above sea level. In order to identify factors independently associated with CAHI values, they were fit to multiple linear and quantile regression models.

RESULTS

A total of 16 studies that reported on CAHI values measured in healthy children living at various levels above sea level were included in the analyses. Out of the 16 studies, 12 (75%) were conducted in low-altitude cities, 1 (6.2%) was conducted in a medium-altitude city, 2 (12.5%) in high-altitude cities, and 1 (6.2%) in both low- and high-altitude cities. Age and altitude above sea level are independent predictors of CAHI values in the linear regression analysis and in the quantile regression at the ninetieth percentile.

CONCLUSIONS

The best-fitting prediction equations were obtained with linear regression and quantile regression at the ninetieth percentile analyses, and either of the two models could be used to predict the normal/expected CAHI values in healthy children.

Home Oxygen Therapy for Children. An Official American Thoracic Society Clinical Practice Guideline

Background: Home oxygen therapy is often required in children with chronic respiratory conditions. This document provides an evidence-based clinical practice guideline on the implementation, monitoring, and discontinuation of home oxygen therapy for the pediatric population.

Methods: A multidisciplinary panel identified pertinent questions regarding home oxygen therapy in children, conducted systematic reviews of the relevant literature, and applied the Grading of Recommendations, Assessment, Development, and Evaluation approach to rate the quality of evidence and strength of clinical recommendations.

Results: After considering the panel’s confidence in the estimated effects, the balance of desirable (benefits) and undesirable (harms and burdens) consequences of treatment, patient values and preferences, cost, and feasibility, recommendations were developed for or against home oxygen therapy specific to pediatric lung and pulmonary vascular diseases.

Conclusions: Although home oxygen therapy is commonly required in the care of children, there is a striking lack of empirical evidence regarding implementation, monitoring, and discontinuation of supplemental oxygen therapy. The panel formulated and provided the rationale for clinical recommendations for home oxygen therapy based on scant empirical evidence, expert opinion, and clinical experience to aid clinicians in the management of these complex pediatric patients and identified important areas for future research.

Allergic Rhinitis and OSA in Children Residing at a High Altitude

BACKGROUND

OSA affects 2% to 4 % of the pediatric population; allergic rhinitis (AR) has been identified as a risk factor in sleep-disordered breathing, but no studies evaluating such an association have been conducted in high-altitude environments. The goal of this study was to assess whether the severity of AR is associated with the severity of OSA in children undergoing polysomnography (PSG) in the high-altitude city of Bogotá, Colombia.

METHODS

A cross-sectional observational study of children with AR was conducted. Severity of AR was evaluated by using the AR health-related quality of life questionnaire for children (ESPRINT-15) and the Allergic Rhinitis and its Impact on Asthma (ARIA) classification. Diagnosis and severity of OSA were established by using PSG. Potential associations between AR severity and OSA severity were assessed by using binary logistic regression and the Spearman correlation coefficient (ρ).

RESULTS

A total of 99 children (mean age, 7.9 years; 45% female) were included; 53% had OSA. An ESPRINT-15 score was associated with severe OSA (OR, 2.0; 95% CI, 1.12-6.04; P = .01). Patients with moderate/severe persistent rhinitis according to ARIA exhibited a 10.1-fold greater risk of severe OSA (OR, 10.15; 95% CI, 1.15-89.0). Furthermore, the apnea-hypopnea index was associated with the ESPRINT-15 score (ρ = 0.215; P = .03) and with the ARIA severity scale (P = .04; ρ = 0.203).

CONCLUSIONS

In symptomatic children with AR residing at a high altitude, increasing AR severity is associated with more severe OSA.

High Incidence of Sleep-Related Breathing Disorders in Children with Down Syndrome Referred to a High-Altitude Sleep Laboratory

Aims: The aim of the study was to assess the incidence of sleep-related breathing disorders (SRBD) in children with Down Syndrome (DS) living at high altitude. Methods: A retrospective descriptive study was conducted on 53 children with DS who underwent polysomnography (PSG) at San Ignacio University Hospital (2640 m/8660 ft above sea level) from 2009 to 2016. Data were extracted from official PSG reports and analyzed using measures of central tendency and dispersion, frequency calculation, ranges, and confidence intervals. Associations were examined using t-test, chi-square test, and analysis of variance test. Results: Obstructive sleep apnea (OSA) was present in 90.5% of children. Central sleep apnea was evident in 11.3%. Periodic breathing was seen in 15.1% of patients. Snoring was able to predict OSA with a sensitivity of 61.7%, a specificity of 100%, and negative predictive value of 25%. Conclusion: Children with DS who live at high altitude have a high incidence of SRBD. Our findings show a higher incidence of SRBD than previously reported in the population with DS. Furthermore, snoring was not sensitive enough to predict OSA. This high risk of SRBD may increase the risk of other comorbid conditions seen in the population with DS. Our results support the need for routine PSG screening independent of symptoms such as snoring status.

Sleeping chILD: Neuroendocrine cell hyperplasia of infancy and polysomnography

OBJECTIVES

Neuroendocrine cell hyperplasia of infancy (NEHI) is a children's interstitial and diffuse lung disease of unknown etiology that presents in infancy with characteristic findings of tachypnea, retractions, crackles, and hypoxemia. At the present, the mainstay of treatment is oxygen supplementation to normalize oxygen saturations and decrease work of breathing. There are characteristic pulmonary function, radiographic, and histologic findings, but polysomnography (PSG) data has not been reported. We sought to report PSG data and implications for management and treatment of NEHI patients.

METHODS

A retrospective chart review was performed under a Colorado Institutional Review Board approved protocol for which consent was waived. Informatics for Integrating Biology and the Bedside was used to query the electronic medical record at Children's Hospital Colorado for patients with both a diagnosis of NEHI and a PSG. PSG was performed for clinical reasons. Routine sleep quality and respiratory parameters were recorded and analyzed.

RESULTS

Of our 77 patients with NEHI, 14 (19%) children underwent PSG during the study period. Eight children met criteria for OSA and three met criteria for CSA. Ten patients had low oxygen saturations during a study, six had low sleep efficiency, and three had periodic limb movement disorder.

CONCLUSIONS

Patients with NEHI may have sleep related breathing disorders that contribute to disrupted sleep, including obstructive and central sleep apnea, hypoxemia, decreased sleep efficiency, and increased periodic limb movement disorder. PSG should be considered as part of NEHI management, as it may lead to recognition of clinically significant sleep-disordered breathing.

The Impact of Altitude on Sleep-Disordered Breathing in Children Dwelling at High Altitude: A Crossover Study

Study Objectives

Sleep-disordered breathing (SDB) is prevalent among children and is associated with adverse health outcomes. Worldwide, approximately 250 million individuals reside at altitudes higher than 2000 meters above sea level (masl). The effect of chronic high-altitude exposure on children with SDB is unknown. This study aims to determine the impact of altitude on sleep study outcomes in children with SDB dwelling at high altitude.

Methods

A single-center crossover study was performed to compare results of high-altitude home polysomnography (H-PSG) with lower altitude laboratory polysomnography (L-PSG) in school-age children dwelling at high altitude with symptoms consistent with SDB. The primary outcome was apnea-hypopnea index (AHI), with secondary outcomes including obstructive AHI; central AHI; and measures of oxygenation, sleep quality, and pulse rate.

Results

Twelve participants were enrolled, with 10 included in the final analysis. Median altitude was 1644 masl on L-PSG and 2531 masl on H-PSG. Median AHI was 2.40 on L-PSG and 10.95 on H-PSG. Both obstructive and central respiratory events accounted for the difference in AHI. Oxygenation and sleep fragmentation were worse and pulse rate higher on H-PSG compared to L-PSG.

Conclusions

These findings reveal a clinically substantial impact of altitude on respiratory, sleep, and cardiovascular outcomes in children with SDB who dwell at high altitude. Within this population, L-PSG underestimates obstructive sleep apnea and central sleep apnea compared to H-PSG. Given the shortage of high-altitude pediatric sleep laboratories, these results suggest a role for home sleep apnea testing for children residing at high altitude.

Polysomnography in Bolivian Children Native to High Altitude Compared to Children Native to Low Altitude

STUDY OBJECTIVES

To compare polysomnographic parameters in high altitude (HA) native Andean children with low altitude (LA) native peers in order to explain the nocturnal oxyhemoglobin saturation (SpO2) instability reported in HA native children and to study the effect on sleep quality.

METHODS

Ninety-eight healthy children aged 7-10 y and 13-16 y were recruited at LA (500 m) or HA (3,650 m) above sea level. Physical examination was undertaken and genetic ancestry determined from salivary DNA to determine proportion of European ancestry, a risk factor for poor HA adaptation. Attended polysomnography was carried out over 1 night for 58 children at their resident location.

RESULTS

Of 98 children recruited, 85 met inclusion criteria, 58 of 85 (68.2%) completed polysomnography, of which 56 were adequate for analysis: 30 at LA (17 male) and 26 at HA (16 male). There were no altitude differences in genetic ancestry, but a high proportion of European admixture (median 50.6% LA; 44.0% HA). SpO2 was less stable at HA with mean 3% and 4% oxygen desaturation indices greater (both P < 0.001) than at LA. This was not explained by periodic breathing. However, more obstructive hypopnea was observed at HA (P < 0.001), along with a trend toward more central apnea (P = 0.053); neither was explained by clinical findings. There was no difference in sleep quality between altitudes.

CONCLUSIONS

HA native Andean children have more respiratory events when scoring relies on SpO2 desaturation due to inherent SpO2 instability. Use of American Academy of Sleep Medicine scoring criteria may yield false-positive results for obstructive sleep-disordered breathing at HA.

Adaptation to Life in the High Andes: Nocturnal Oxyhemoglobin Saturation in Early Development

STUDY OBJECTIVES

Physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory 'burden' of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude.

METHODS

This was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples.

RESULTS

Children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ≥ 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ≤ 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence.

CONCLUSIONS

Physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observations.

Overnight Polysomnographic Characteristics and Oxygen Saturation of Healthy Infants, 1 to 18 Months of Age, Born and Residing At High Altitude (2,640 Meters)

BACKGROUND

Approximately 8% of the world population resides above 1,600 m, with about 10 million people living above 2,500 m in Colombia. However, reference values for polysomnography (PSG) and oxygen saturation (Spo2) of children < 2 years old residing at high altitude are currently unavailable.

METHODS

Healthy infants aged 1 to 18 months born and residing at high altitude (Bogotá: 2,640 m) underwent overnight PSG. Four age groups were defined: group 1, < 45 days; group 2, 3 to 4 months; group 3, 6 to 7 months; and group 4, 10 to 18 months. Of 122 children enrolled, 50 had three consecutive PSG tests and were analyzed as a longitudinal subcohort.

RESULTS

A total of 281 PSG tests were performed in 122 infants (56% girls): group 1, 106 PSG tests; group 2, 89 PSG tests; group 3, 61 PSG tests; and group 4, 25 PSG tests. Active sleep diminished and quiet sleep increased with maturation. Apnea-hypopnea indexes (total, central, and obstructive) were highest in group 1 (21.4, 12.4, and 6.8/h total sleep time, respectively) and diminished with age (P < .001). Mean Spo2 during waking and sleep increased with age (P < .001). Nadir Spo2 values during respiratory events were lower in younger infants. Longitudinal assessments of 50 infants confirmed the temporal trends described for the cross-sectional dataset.

CONCLUSIONS

Healthy infants (≤ 18 months old) born and residing at high altitude show preserved sleep architecture but higher apnea-hypopnea indexes and more prominent desaturation with respiratory events than do those living at low altitude. The current study findings can be used as reference values for infants at high altitude.

Developmental changes in sleep and breathing across infancy and childhood

Sleep and breathing are physiological processes that begin in utero and undergo progressive change. While the major period of change for both sleep and breathing occurs during the months after birth, considered a period of vulnerability, more subtle changes continue to occur throughout childhood. The systems that control sleep and breathing develop separately, but sleep represents an activity state during which breathing and breathing control is significantly altered. Infants and young children may spend up to 12 hours a day sleeping; therefore, the effects of sleep on breathing are fundamental to understanding both processes in childhood. This review summarizes the current literature relevant to understanding the normal development of sleep and breathing across infancy and childhood.