Effect of oxygen saturation targets on the incidence of bronchopulmonary dysplasia and duration of respiratory supports in extremely preterm infants.

BACKGROUND: Recent clinical practice changes in neonatal care resulted in higher, narrower oxygen saturation target ranges for preterm infants. The effect of targeting higher or lower oxygen saturations on respiratory outcomes of preterm infants and duration of hospitalization has not been extensively reviewed in the context of current care, but could have significant implications. METHODS: A multicentre retrospective cohort of 145 preterm infants was conducted; 105 had lower oxygen saturation targets (88 to 92%), 40 had higher targets (90 to 95%). The primary outcome was bronchopulmonary dysplasia (BPD). Secondary outcomes included duration of invasive/noninvasive respiratory support, oxygen therapy, and hospitalization. The primary outcome was compared using Fisher's exact test. Secondary outcomes were evaluated with survival analysis and Wilcoxon rank sum test. RESULTS: The difference in incidence of BPD in the lower (N=56, 53.3%) and higher saturation groups (N=14, 35.0%) was not statistically significant (relative risk [RR]=0.66 [0.41, 1.04], P=0.06). The difference in duration of mechanical ventilation in the lower (median 7.8 days, interquartile range [IQR] 3.7 to 15.9) and higher saturation groups (median 4.5, IQR 1.9 to 12.3) approached statistical significance (P=0.05). There were no statistically significant differences in the durations of other respiratory supports or hospital stay between the two groups. CONCLUSIONS: The results of this study approached statistical significance and suggest that higher, narrower oxygen saturation targets may result in a clinically important reduction in BPD incidence and duration of mechanical ventilation. These results require validation in a larger sample to refine optimal targets.

Obstructive sleep apnea and hypertension in pediatric chronic kidney disease.

BACKGROUND: Children with chronic kidney disease (CKD) are at risk for obstructive sleep apnea (OSA) and hypertension. The objectives of this study were to explore associations between OSA severity using the apnea-hypopnea-index(AHI) and obstructive apnea-hypopnea-index(OAHI) on polysomnography (PSG), OSA symptoms, and measures of hypertension in children with CKD. METHODS: One-night in-laboratory PSGs and 24-h ambulatory blood pressure monitoring (ABPM) were performed on children with CKD stages 2-5 (non-dialysis dependent). Sleep questionnaires, including the modified Epworth Sleepiness Scale (ESS) and the Pediatric Sleep Questionnaire (PSQ), were administered during the sleep study. RESULTS: Nineteen children and adolescents completed a PSG and questionnaires and thirteen completed ABPMs. Mean (standard deviation) age at the time of the sleep study was 14.1 (3.2) years. Eleven (58%) participants had CKD stage two, and eight (42%) had stage 3-4. None of the participants were found to have OSA on PSG. One participant had a positive ESS score (≥ 11) and five participants had positive PSQ scores (≥  eight). Night systolic and diastolic pressures were strongly correlated with the OAHI (r = 0.67 and r = 0.69, respectively, p < 0.05), while the AHI was not correlated with any blood pressure measures. CONCLUSIONS: Our study did not find OSA on PSG in children with predominantly mild to moderate CKD. The OAHI was found to be strongly correlated with nighttime blood pressures. Future prospective studies with a larger sample size are needed to monitor for potential progression of symptoms and findings on PSG in pediatric patients as they evolve across the spectrum of CKD.

Creation of a reference dataset of neck sizes in children: standardizing a potential new tool for prediction of obesity-associated diseases?

BACKGROUND: Neck circumference (NC), is an emerging marker of obesity and associated disease risk, but is challenging to use as a screening tool in children, as age and sex standardized cutoffs have not been determined. A population-based sample of NC in Canadian children was collected, and age- and sex-specific reference curves for NC were developed. METHODS: NC, waist circumference (WC), weight and height were measured on participants aged 6-17 years in cycle 2 of the Canadian Health Measures Survey. Quantile regression of NC versus age in males and females was used to obtain NC percentiles. Linear regression was used to examine association between NC, body mass index (BMI) and WC. NC was compared in healthy weight (BMI < 85th percentile) and overweight/obese (BMI > 85th percentile) subjects. RESULTS: The sample included 936 females and 977 males. For all age and sex groups, NC was larger in overweight/obese children (p < 0.0001). For each additional unit of BMI, average NC in males was 0.49 cm higher and in females, 0.43 cm higher. For each additional cm of WC, average NC in males was 0.18 cm higher and in females, 0.17 cm higher. CONCLUSION: This study presents the first reference data on Canadian children's NC. The reference curves may have future clinical applicability in identifying children at risk of central obesity-associated conditions and thresholds associated with disease risk.

Paediatric sleep resources in Canada: The scope of the problem.

BACKGROUND: Sleep-disordered breathing (SDB) is prevalent in children and is associated with significant comorbidity. OBJECTIVES: To describe paediatric sleep physician and diagnostic testing resources for SDB in Canadian children. METHODS: A 38-item, Internet-based survey was sent to the 32 members of the Canadian Pediatric Sleep Network (CPSN). A shorter telephone survey was administered to all 182 non-CPSN sleep laboratories across Canada. RESULTS: Responses were obtained from 29 of 31 (91%) CPSN members and 121 of 182 (66%) non-CPSN sleep facilities. Sixty-seven of 121 (55%) of the responding non-CPSN facilities reported that they see children <18 years of age. Thirty-six of 121 (30%) and 23 of 121 (19%), respectively, see children ≤12 years of age or ≤8 years of age. Marked disparities across provinces/territories were observed, with no practitioners or polysomnography in the Yukon, Northwest Territories, Nunavut, Saskatchewan, New Brunswick, Prince Edward Island, and Newfoundland and Labrador. Alberta has the smallest ratio of children to practitioners (approximately 167,000 to 1) and Ontario has the smallest ratio of children to polysomnograms performed per year (approximately 487,000 to 1). Reported wait times for polysomnography ranged from <1 month, to 1.5 to 2 years. In paediatric tertiary care centres, the number of polysomnograms performed per year ranged from 55 to 700 (median 480) and in other laboratories the range was 400 to 4000 (median 1100). CONCLUSIONS: The present study demonstrates a significant lack of resources and services for paediatric SDB care across Canada, with pronounced geographical disparities. Even if only affected children were tested with polysomnography, the authors estimate there are 7.5 times more children with SDB than current testing capacity.

HISTORIQUE: Les troubles respiratoires du sommeil (TRS) sont prévalents chez les enfants et s'associent à une comorbidité importante. OBJECTIFS: Décrire les spécialistes du sommeil en pédiatrie et les tests pour diagnostiquer les TRS chez les enfants canadiens. MÉTHODOLOGIE: Les 32 membres du Canadian Pediatric Sleep Network (CPSN) ont répondu à un sondage virtuel de 38 questions. Les 182 laboratoires du sommeil du Canada ne faisant pas partie du CPSN ont répondu à un sondage téléphonique plus court. RÉSULTATS: Vingt-neuf des 31 membres du CPSN (91 %) et 121 des 182 laboratoires du sommeil non membres du CPSN (66 %) ont répondu. Soixante-sept des 121 établissements répondants ne faisant pas partie du CPSN (55 %) ont déclaré voir des enfants de moins de 18 ans. Trente-six (30 %) et 23 (19 %) de ces 121 établissements, respectivement, voient des enfants de 12 ans ou moins et de huit ans ou moins. Les chercheurs ont observé des disparités marquées entre les provinces et les territoires. Ainsi, il n'y a pas de praticiens ou de polysomnogrammes au Yukon, dans les Territoires du Nord-Ouest, au Nunavut, en Saskatchewan, au Nouveau-Brunswick, à l'Île-du-Prince-Édouard et à Terre-Neuve-et-Labrador. L'Alberta présente le plus petit ratio entre les enfants et les praticiens (environ 167 000 pour 1) et l'Ontario, le plus petit ratio entre les enfants et les polysomnographies effectuées par année (environ 487 000 pour 1). Les temps d'attente déclarés pour subir une polysomnographie variaient entre moins d'un mois et 1,5 à deux ans. Dans les centres pédiatriques de soins tertiaires, le nombre de polysomnographies effectuées par année variait entre 55 et 700 (médiane de 480), tandis que dans les autres laboratoires, il oscillait entre 400 et 4 000 (médiane de 1 100). CONCLUSIONS: La présente étude démontre un manque flagrant de ressources et de services pour les soins des TRS en pédiatrie au Canada, ainsi que des écarts géographiques marqués. Même si seuls les enfants touchés ont subi une polysomnographie, les auteurs estiment qu'il y a 7,5 fois plus d'enfants ayant des TRS que la capacité actuelle de les évaluer.

Factors related to positive airway pressure therapy adherence in children with obesity and sleep-disordered breathing.

STUDY OBJECTIVES: Positive airway pressure (PAP) is used to treat children with concurrent obesity and sleep-disordered breathing (SDB), but achieving adherence remains challenging. We aimed to identify factors associated with PAP adherence in a prospective cohort of children with obesity prescribed PAP for newly diagnosed SDB. METHODS: A questionnaire to assess factors related to PAP adherence was administered to participants and their parent ≥12 months after enrollment. Adherence (PAP use ≥4 hours/night on >50% of nights) was measured with PAP machine downloads, diaries, and physician assessments. Questionnaire responses were compared between adherent/nonadherent participants and between children/parents. Age, total and obstructive apnea-hypopnea index (OAHI), lowest oxygen saturation, and highest carbon dioxide were compared between adherent/nonadherent children with univariate differences of medians, with 95% confidence intervals. RESULTS: Fourteen children (median age: 14.3 years; 93% male; all with obstructive sleep apnea) were included. Eleven (79%) were adherent to PAP. SDB symptom improvement was reported in 9 of 14 children (64%); 8 of 14 children (57%) had positive experiences with PAP. Most children assumed an active role in PAP initiation and felt supported by the clinical team. Responses between adherent/nonadherent groups and between children/parents were similar. Oxygen saturation nadir (median difference between nonadherent and adherent groups: 8.9%; 95% confidence interval: 1.7, 16.1), but not age, apnea-hypopnea index, OAHI, or maximum carbon dioxide, was associated with PAP adherence. CONCLUSIONS: Children with obesity-related SDB with lower nocturnal oxygen saturation nadir were more likely to adhere to PAP therapy. Ensuring adequate understanding of PAP therapy and medical team support are key factors in PAP success.

Predictors of postoperative respiratory complications in children undergoing adenotonsillectomy.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is commonly treated with adenotonsillectomy (AT), bringing risk of perioperative respiratory adverse events (PRAEs). We aimed to concurrently identify clinical and polysomnographic predictors of PRAEs in children undergoing AT. METHODS: Retrospective study of children undergoing AT at a tertiary-care pediatric hospital, with prior in-hospital polysomnography, January 2010 to December 2016. PRAEs included those requiring oxygen, jaw thrust, positive airway pressure, or mechanical ventilation. Relationships of PRAEs to preoperative comorbidities or polysomnography results were examined with univariable logistic regression. Variables with P < .1 and age were included in backward stepwise multivariable logistic regression. Predictive performance (area under the curve, AUC) was validated with bootstrap resampling. RESULTS: Analysis included 374 children, median age 6.1 years; 286 (76.5%) had ≥ 1 comorbidity. 344 (92.0%) had sleep-disordered breathing; 232 (62.0%) moderate-severe; 66 (17.6%) had ≥ 1 PRAE. PRAEs were more frequent in children with craniofacial, genetic, cardiac, airway anomaly, or neurological conditions, AHI ≥ 5 events/h and oxygen saturation nadir ≤ 80% on preoperative polysomnography. Prediction modeling identified cardiac comorbidity (odds ratio [OR] 2.09 [1.11, 3.89]), airway anomaly (OR 3.19 [1.33, 7.49]), and younger age (OR < 3 years: 4.10 (1.79, 9.26; 3 to 6 years: 2.21 [1.18, 4.15]) were associated with PRAEs (AUC 0.74; corrected AUC 0.68). CONCLUSIONS: Prediction modeling concurrently evaluating comorbidities and polysomnography metrics identified cardiac disease, airway anomaly, and young age as independent predictors of PRAEs. These findings suggest that medical comorbidity and age are more important factors in predicting PRAEs than PSG metrics in a medically complex population.

Target oxygen saturation and development of pulmonary hypertension and increased pulmonary vascular resistance in preterm infants.

OBJECTIVE: Determine whether higher targeted oxygen levels are associated with reduced incidence of pulmonary hypertension (PH) and elevated pulmonary vascular resistance (PVR) in extremely premature infants. STUDY DESIGN: Retrospective chart review of 252 extremely preterm infants (<29 weeks), who underwent echocardiogram prior to discharge. PH rates were compared during periods (June 2012-May 2015 and June 2015-April 2016) when lower (88-92%) or higher (90-95%) oxygen saturation targets were used. PH was determined on echocardiography. The ratio of pulmonary artery acceleration time to right ventricular ejection time was computed, with values <0.31 indicative of elevated PVR. Survival analysis compared the effects of oxygen saturation group on development/resolution of PH and elevated PVR. RESULTS: The higher saturation group had significantly lower risk of developing PH (hazard ratio (HR) = 0.50, 95%CI 0.26-0.95; P = 0.03) or elevated PVR (HR = 0.55, 95%CI 0.38-0.81; P = 0.002), compared to the lower oxygen saturation group. Median time to PH development was significantly shorter in the lower saturation group than in the higher saturation group (5 days vs 12 days; P = 0.02), as was time to development of elevated PVR (4 days vs 6 days; P < 0.001). Duration of PH (P = 0.12) and elevated PVR (P = 0.86) did not differ significantly between groups. Cumulative incidence of PH (P = 0.04) and elevated PVR (P = 0.01) at 36 weeks post-menstrual age was significantly lower in the high saturation group compared to the lower saturation group. CONCLUSION: Higher targeted oxygen saturation was associated with reduced risk of PH or elevated PVR in extremely preterm infants compared to lower oxygen saturation target.

Treatment and persistence/recurrence of sleep-disordered breathing in children with Down syndrome.

OBJECTIVE: Sleep-disordered breathing (SDB) is common in children with Down syndrome, but the trajectory and long-term outcomes are not well-described. In a retrospective longitudinal cohort of children with Down syndrome, study objectives were to (1) characterize polysomnography (PSG), treatments received, and persistence/recurrence of SDB and (2) explore predictors of SDB persistence/recurrence. METHODS: A retrospective cohort study was conducted of children who underwent PSGs between 2004 and 2014. SDB was defined as obstructive sleep apnea (OSA)-mixed (apnea-hypopnea index [AHI] >5 events/hour), central sleep apnea or hypoventilation. PSGs, interventions, and trajectory of SDB were described. Age, body mass index (BMI) Z-score and AHI at first SDB diagnosis were evaluated as predictors of persistent/recurrent SDB. RESULTS: Of 506 children, 120 had ≥1 PSG; 54 had subsequent PSGs. Children with ≥2 PSGs were more likely to have higher total AHI (P = .02) and obstructive-mixed AHI (P = .01). Thirty-five of fifty-four (65%) were initially diagnosed with OSA-mixed SDB. After first PSG, 67 of 120 had OSA-mixed SDB, of whom 25 (37.3%) underwent adenotonsillectomy (T&A), 13 (19.4%) received positive airway pressure (PAP). Those who underwent T&A after PSG were significantly younger than those who received PAP (median age 6.2 vs 12.5 years; P = .005). OSA-mixed SDB persisted/recurred in 33 of 54 (73.3%) with ≥2 PSGs. Persistence/recurrence was not associated with age, AHI or BMI Z-score at first SDB. CONCLUSION: Children with Down syndrome undergoing T&A for SDB were significantly younger than those treated with PAP. SDB persisted/recurred in three of four and was not predicted by age, SDB severity or BMI Z-score. Longitudinal PSG assessment for persistence/recurrence of SDB is required in this population.

Long-Term Impact of Sleep-Disordered Breathing on Quality of Life in Children With Obesity.

STUDY OBJECTIVES: (1) To determine baseline quality of life (QOL) among children with obesity and newly diagnosed moderate-severe sleep-disordered breathing (SDB) and to compare it to the reported QOL of children with obesity or SDB alone and healthy children. (2) To evaluate QOL change after 1 year. METHODS: A prospective multicenter cohort study was conducted in children (8-16 years) with obesity, prescribed positive airway pressure (PAP) therapy for moderate-severe SDB. Outcomes included parent-proxy and self-report total and subscale scores on the PedsQL questionnaire (baseline and 1-year). RESULTS: Total PedsQL scores were indicative of impaired QOL in 69% of cases based on parent-report and in 62% on self-report. Parents reported significantly lower QOL in our cohort than that reported in other studies for children with obesity or SDB alone or healthy children, on total PedsQL score and on social and psychosocial subscales. PedsQL total scores for participants were significantly higher (mean difference 7.3 ± 15.3, P = .03) than those reported by parents. Parents reported significant improvements in total PedsQL (mean change 7.29 ± 13.73, P = .04) and social functioning (mean change 17.65 ± 24.69, P = .04) scores after 1 year. No significant differences were found by children's self-report or by PAP adherence. CONCLUSIONS: QOL of children with obesity and SDB is lower than in children with obesity or SDB alone or healthy children. One year later, children reported no significant changes in QOL; parents reported significant improvements in total PedsQL and social functioning scores. PAP adherence did not significantly affect QOL change in this population. COMMENTARY: A commentary on this article appears in this issue on page 307.

The scope of sleep problems in Canadian children and adolescents with obesity.

OBJECTIVE: To determine the scope of sleep concerns, clinical features, and polysomnography (PSG) results and to identify factors that predict obstructive sleep apnea (OSA) in a cohort of children with obesity. METHODS: The study was a multicenter retrospective chart review. Data were collected from three pediatric sleep laboratories over a two year period for all children of age 8-16 years with a body mass index [BMI] ≥95th centile who were undergoing PSG. Data sources included clinical charts and PSG results. Clinical and PSG factors were examined as predictors of OSA. RESULTS: A total of 210 children met inclusion criteria, and 205 had sufficient data for analysis. The mean age was 12.5 ± 2.7 years; and 65% were male. Multiple sleep concerns and comorbidities were reported in most children (90% and 91%, respectively). OSA was identified by PSG in 44% of children; and 28% of children demonstrated moderate/severe OSA. Mouth breathing/nasal congestion (odds ratio [OR] = 0.33, 95% confidence interval [CI] = 0.18-0.61), syndrome/multiple anomalies (OR = 2.4, 95% CI = 1.22-4.93), and family history of OSA (OR = 2.7, 95% CI = 1.2-5.8) or sleep problems (OR = 12.4, 95% CI = 1.5, 99.6) were the only factors predictive of OSA. Oxygen desaturation index <6 events/h measured by PSG showed an OR of 4.96 (95% CI = 2.27-10.86) for the absence of OSA. CONCLUSIONS: Children with obesity who undergo PSG are medically complex with multiple sleep concerns including a high burden of daytime symptoms; slightly less than half of children demonstrate polysomnographic features of OSA. Earlier identification of OSA, recognition of non-OSA sleep concerns, and treatment strategies to improve sleep may contribute to overall health outcomes for children with obesity.

Predicting the presence of sleep-disordered breathing in children with Down syndrome.

OBJECTIVE: Sleep-disordered breathing (SDB) is highly prevalent in children with Down syndrome. Given the scarcity of resources and the presence of risk factors for SDB in this population, the objective of this study is to identify the clinical predictors of SDB, which would assist prioritization of children with Down syndrome for SDB evaluation. METHODS: A retrospective cohort study was conducted on children enrolled in the Down syndrome clinic at CHEO who underwent polysomnography in 2004-2014. Total apnea-hypopnea index (AHI) or obstructive AHI (OAHI) > 5 events/hour was considered clinically significant. Associations between SDB and concurrent diagnoses, referral reasons, and sleep symptoms assessed by questionnaire were examined using Pearson's chi-square test or Fisher's exact test as appropriate. Univariate and multivariate logistic regression analyses were used to examine the predictors of SDB. RESULTS: SDB was present in 42.9% of 119 children, with its highest prevalence at age 8 years. Symptoms were not significantly associated with AHI > 5 events/hour or OAHI > 5 events/hour. Gastroesophageal reflux was associated with lower odds of OAHI > 5 events/hour on univariate testing (odds ratio 0.16, 95% CI 0.04-0.72; p = 0.02) and multivariate analysis (odds ratio 0.05, 95% CI 0.0006-0.50; p = 0.002). CONCLUSIONS: SDB is highly prevalent at all ages in children with Down syndrome. Symptoms did not predict SDB in this population, although gastroesophageal reflux may mimic SDB, which indicates that clinicians should continue to perform ongoing surveillance for SDB throughout the lifespan of children with Down syndrome.

Body Fat Distribution Ratios and Obstructive Sleep Apnea Severity in Youth With Obesity.

STUDY OBJECTIVES: Obesity and regional fat distribution, measured by neck fat mass percentage using dual-energy X-ray absorptiometry (DXA), correlate with obstructive sleep apnea (OSA) severity in adults. In obese children, neck-to-waist-circumference ratio predicts OSA. This study examined associations between body fat percentage and distribution and sleep-disordered breathing (SDB) severity in obese youth, measured with DXA. METHODS: Cross-sectional retrospective study conducted at a tertiary children's hospital. Participants were aged 6 to 18 years with obesity (body mass index [BMI] > 99th percentile [BMI z-score 2.35] or > 95th percentile with comorbidity). They underwent polysomnography and DXA to quantify body fat percentage and distribution ratios (neck-to-abdominal fat percentage [NAF % ratio]). SDB was defined as apnea-hypopnea index (AHI) > 5 and OSA as obstructive AHI (OAHI) > 1 event/h. Relationships of BMI z-score and NAF % ratio to log AHI and log OAHI were evaluated. RESULTS: Thirty individuals participated; 18 male; median age 14.1 years. Twenty-four individuals had BMI z-scores > 2.35. Ten had AHI > 5 events/h. NAF % ratio was significantly associated with log AHI in males and with log OAHI in all, whereas total fat mass percent was not. The association between log OAHI and NAF % ratio was significant in males, but not females. NAF % ratio was significantly associated with log OAHI in those with BMI z-score above 2.35. CONCLUSIONS: NAF % ratio was associated with OSA severity in males and youth with BMI > 99th percentile; however, total fat mass percentage was not, suggesting that body fat distribution is associated with OSA risk in youth.

Insulin Resistance and Hypertension in Obese Youth With Sleep-Disordered Breathing Treated With Positive Airway Pressure: A Prospective Multicenter Study.

STUDY OBJECTIVES: There is evidence that cardiometabolic disease associated with obesity and sleep-disordered breathing (SDB) in adults is present in youth. SDB is often treated with positive airway pressure (PAP) in youth with obesity. Our aims were to determine: (1) the prevalence of cardiometabolic disease and (2) whether PAP improves markers of cardiometabolic disease, in youth with obesity and newly diagnosed moderate-severe SDB. METHODS: A prospective multicenter cohort study was conducted in youth (8 to 16 years old) with obesity, prescribed PAP therapy for newly diagnosed moderate-severe SDB. Assessments occurred at baseline and at 6 and 12 months. Outcomes included markers of insulin resistance (change in homeostasis model assessment of insulin resistance (HOMA-IR) at 6 months = primary outcome), hypertension (24-hour ambulatory/blood pressure) and inflammation (high-sensitivity C-reactive protein: hs-CRP). RESULTS: Twenty-seven participants were enrolled. Of those with baseline testing available, 10/25 (40%) had HOMA-IR above the 97th percentile, 10/23 (44%) were hypertensive, 16/23 (70%) had loss of nocturnal blood pressure dip and hs-CRP was elevated in 16/27 (64%). There were no significant changes over time in markers of metabolic dysfunction or blood pressure, nor between PAP-adherent and non-adherent subgroups. CONCLUSIONS: In youth with obesity and SDB, metabolic dysfunction and hypertension were highly prevalent. There were no statistically significant improvements in cardiometabolic markers 1 year after the prescription of PAP therapy, although clinically relevant improvements were seen in insulin resistance and systolic blood pressure load, important predictors of future risk of cardiovascular disease. Larger, longer-term studies are needed to determine whether PAP improves cardiometabolic outcomes in obese youth. COMMENTARY: A commentary on this article appears in this issue on page 1025.

Long-Term Effects of Lung Volume Recruitment on Maximal Inspiratory Capacity and Vital Capacity in Duchenne Muscular Dystrophy.

RATIONALE: Lung volume recruitment therapy slows rate of decline of lung function in neuromuscular disease, possibly due to enhanced airway clearance, reduced atelectasis, or prevention of chest wall contractures. OBJECTIVES: To determine if lung volume recruitment maintains maximal insufflation capacity (MIC), despite decline in VC. METHODS: This was a retrospective cohort study (1991-2008) of individuals with Duchenne muscular dystrophy at pediatric and adult tertiary centers. Lung volume recruitment was prescribed twice daily, according to protocol. Changes over time in MIC, VC percentage predicted, the difference between MIC and VC, maximum inspiratory and expiratory pressures, and assisted and unassisted peak cough flow (PCF) were assessed using linear mixed effects models. MEASUREMENTS AND MAIN RESULTS: Sixteen individuals, 8.6 to 33.0 years old at initiation of lung volume recruitment, with median VC percentage predicted of 13.5 (interquartile range, 8.0-20.3), were followed over a median of 6.1 years (range, 1.7-16.1 yr). MIC-VC differences were stable (change, 0.02 L/yr; P = 0.06). Post-lung volume recruitment, compared with pretreatment, rate of decline in VC decreased from 4.5% predicted/yr to 0.5% predicted/yr (P < 0.001). Maximal inspiratory and expiratory pressures were unchanged (P = 0.08, 0.59 respectively). Assisted-spontaneous PCF difference was maintained (slope, -1.59 L/min/yr, P = 0.35). CONCLUSIONS: With lung volume recruitment therapy, MIC-VC differences were stable over time, indicating that respiratory system compliance remains stable, despite a loss in VC, in individuals with Duchenne muscular dystrophy. Decline in VC was significantly attenuated, and assisted PCF was maintained in a clinically effective range.

Truncal fat distribution correlates with decreased vital capacity in Duchenne muscular dystrophy.

BACKGROUND: Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder associated with progressive muscle weakness and respiratory failure. Oral corticosteroids are the mainstay of treatment, but are associated with obesity with a central distribution. This study is designed to determine the relationship between body mass index, central adiposity, and lung function in subjects with DMD. METHODS: Retrospective fat distribution data was obtained in boys with DMD from studies using dual X-ray absorptiometry (DXA). Fat distribution data was reviewed at two tertiary academic institutions and compared with concurrent height, weight, body mass index (BMI), measures of lung function, and sleep study data when available. Truncal fat mass used as a measure of central adiposity. RESULTS: Forty-four subjects (age 12.0 ± 3.4 years) were included. Mean BMI was 22.1 ± 5.9 kg/m(2) . Sixty-eight percent (30 patients) were on corticosteroid therapy. Truncal fat mass percentage was inversely correlated with forced vital capacity (% predicted FVC) (Pearson coefficient -0.37, P = 0.01). Linear regression showed that truncal fat distribution, but not total fat mass, age or corticosteroid use negatively predicted FVC (r(2) = 0.24, P = 0.048). BMI had a positive effect (P = 0.04). However, fat distribution did not predict the rate of change of lung function in a smaller sample. Fat distribution, BMI, or age did not predict measures of sleep disordered breathing. CONCLUSIONS: Truncal fat distribution is a significant predictor of lower vital capacity in boys with DMD, whereas BMI has a positive effect.

Neck circumference percentile: A screening tool for pediatric obstructive sleep apnea.

RATIONALE: Large neck circumference (NC) is associated with obstructive sleep apnea (OSA) in adults, especially males. Since NC changes with age and sex, a lack of reference ranges makes neck size difficult to assess as a screening tool in children. METHODS: Using a population-based dataset of 1,913 children, we developed reference ranges for NC by age and sex for children aged 6-17 years. In this study, we collected NC data on 245 children aged 6-17 years presenting to the Children's Hospital of Eastern Ontario for polysomnography. The association between NC>the 95th percentile and OSA (total apnea-hypopnea-index>5 events/hr and/or obstructive-apnea-index ≥ 1 event/hr) was explored. Thresholds of BMI percentile and waist circumference were also examined. RESULTS: Individuals with NC>95th percentile for age and sex had increased risk of OSA (relative risk 1.7 [95% CI 1.0-3.0], P=0.04), compared to those with NC ≤ 95th percentile. BMI ≥ 95th percentile gave similar results (relative risk 1.8 [95% CI 1.1-2.9], P=0.02). When examined by sex, the association was significant in males ≥ 12 years (relative risk 3.3 [95% CI 1.0-10.4], P=0.04), but not females (P=0.63). Neither BMI ≥ 95th percentile nor waist circumference>95th percentile was significant. CONCLUSIONS: Children and youth with NC>95th percentile for age and sex have significantly increased risk of OSA. This effect is significant in males ≥ 12 years, whereas BMI is not. NC percentile may be an additional screening tool for OSA in children and youth.

Respiratory management strategies for Duchenne muscular dystrophy: practice variation amongst Canadian sub-specialists.

PURPOSE: Respiratory management of Duchenne muscular dystrophy (DMD) is not well studied and may vary across centers and practitioners. Our objective was to describe and compare the respiratory management practices of Canadian Pediatric Respirologists and Neuromuscular specialists for children with DMD. METHODS: A web-based survey was sent to all 56 practicing Canadian Pediatric Respirologists and to all 24 members of the Canadian Pediatric Neuromuscular Group (CPNG) who follow children with neuromuscular diseases. The survey included 28 questions about timing and indications for respiratory consultation, sleep disordered breathing (SDB) assessments, and treatments. RESULTS: Thirty eight (68%) pediatric respirologists and 17 (71%) CPNG members responded. Respirologists provide initial consultation after a patient's first admission to hospital with respiratory complications (14/38, 37%) and when symptoms of SDB are present (14/38, 37%). Half of the CPNG members request initial Respirology consultation at the time of DMD diagnosis. Both groups request routine pulmonary function tests. Ninety-six percent of respirologists use maximal inspiratory (MIP) and expiratory pressures (MEP) to assess respiratory muscle strength, whereas 82% of CPNG members additionally use peak cough flow. Assessment for SDB is requested by both groups when pulmonary function is abnormal or patients are symptomatic. Respirologists favor polysomnography, whereas CPNG members use overnight pulse oximetry. Nocturnal non-invasive ventilation and lung volume recruitment (LVR) are used in a minority of patients. CONCLUSIONS: Respirologists and CPNG members provide similar respiratory management of DMD patients, but differ in timing of consultation and choice of tests for pulmonary function and SDB. Canadian practices differ from the American Thoracic Society and Centre for Disease Control guidelines.

Inter- and intra-rater reliability of neck circumference measurements in children.

RATIONALE: Increased neck circumference is a risk factor for obstructive sleep apnea in adults. With rising obesity prevalence in children, it may be an important identifier of obstructive sleep apnea in children. The reliability of measuring neck circumference in children has not been systematically evaluated. OBJECTIVE: To determine the inter- and intra-rater reliability of neck circumference measurements in children aged 2-16 years. METHODS: Children aged 2-16 years with limb fractures were recruited. Neck circumference was measured by three investigators each using two separate unmarked paper tapes in the 2-5 year age group (N = 43), and three separate tapes in the 6-10 and 11-16 year age groups (N = 18 and 40). RESULTS: Neck circumference measurements showed excellent inter-rater reliability for children 6-10 and 11-16 years (ICC = 0.952 and 0.989). Substantial variation was observed for the 2-5 year age group (ICC = 0.701). Good intra-rater reliability was demonstrated for the three groups (ICC range: 0.776, 0.950). Repeatability coefficients were 2.5-3.4 cm in the youngest age group and were 1.2-1.4 cm in the 6-16 year age group. CONCLUSION: In children 6-16 years old, neck circumference shows very good inter and good intra-rater reliability. Multiple measurements are not required for precision and reliability.