Lynda Hoey

Inter‐ and intra‐rater reliability of neck circumference measurements in children

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.

Respiratory management strategies for Duchenne muscular dystrophy: practice variation amongst canadian sub-specialists†

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.

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

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.

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.

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.

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 childrens 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 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 childrens 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.