Obstructive sleep apnea risk factors and symptoms in children with a known parental obstructive sleep apnea diagnosis.

OBJECTIVE: To document symptoms and risk factors of obstructive sleep apnea (OSA) in children who have a parent diagnosed with OSA and compare them to an age and sex matched sample where parents are low risk for OSA. METHODS: We recruited 25 children with a parent diagnosed with OSA (P-OSA) and 29 age and gender matched children from the community whose parents scored low risk for OSA (P-NOSA). Comparisons were made using the OSA-18 questionnaire, anthropometric measurements, and mallampati score. Statistical analysis included t-tests for OSA-18 score and BMI measures and non parametric analysis for mallampati score. OSA-18 domain scores were analysed using T-test and Bonferroni correction for multiple comparisons. RESULTS: Fifty-six percent of the P-OSA group had a mallampati score of III/IV compared to 11% in the P-NOSA sample (p = 0.005). There was a significant difference in BMI between the P-OSA sample (mean ± SD 19.5 ± 5.7 kg/m2) and the P-NOSA sample (16.95 ± 2.08 kg/m2, p = 0.002). Forty-four percent of P-OSA children were found to be either overweight or obese (BMI z-score). None of the P-NOSA children fell into this category. No significant difference was found between the P-OSA and P-NOSA samples on the OSA-18 score (P-OSA 36.5 ± 8.1, P-NOSA 29.2 ± 9.1, p = 0.07). Five children in the P-OSA sample scored >60 but no P-NOSA children scored >60. CONCLUSIONS: This study suggests that children with a parent diagnosed with OSA are more likely to have risk factors of pediatric OSA compared to age and sex matched children of parents without OSA but do not have more symptoms.

Impact of type 1 diabetes mellitus, glucose levels, and glycemic control on sleep in children and adolescents: a case-control study.

STUDY OBJECTIVES: To assess differences in habitual sleep patterns and sleep states between children and adolescents with type 1 diabetes mellitus (T1DM) and control subjects, and to explore the relationships between sleep, glucose levels, and glycemic control. METHODS: Participants included 82 children (5-18 years); 41 with T1DM (cases), and 41 healthy control subjects group matched for age and sex. Sleep was measured by 7-day actigraphy and single-night home-based polysomnography (PSG) recordings. Hemoglobin A1c (HbA1c) and 7 days of continuous glucose monitoring (CGM) data were collected in cases. Regression analyses were used to model all within- and between-group comparisons adjusted for age, sex, and BMI z-scores. RESULTS: There were no significant differences in sleep duration, efficiency, or awakenings as measured by actigraphy and PSG between cases and controls, nor sleep states measured by PSG. However, cases had significantly later sleep onset and offset than controls (both p < 0.05), partially moderated by age. Cases with suboptimal glycemic control (HbA1c ≥ 58 mmol/mol [≥7.5%]) had significantly shorter actigraphy-derived total sleep time (TST) (mean difference = -40 minutes; 95% confidence interval = -77, -3), with similar differences in TST measured by PSG. Cases with mean CGM glucose levels ≥10 mmol/L (≥180 mg/dL) on PSG night had significantly more stage N3 (%) sleep and less stage REM (%) sleep (both p < 0.05). CONCLUSIONS: Short- and long-term suboptimal glycemic control in T1DM children appears to be associated with sleep alterations. Pediatric diabetes care teams should be aware of potential interrelationships between sleep and T1DM, including management and glycemic control.

Comparison of 12-hour and 24-hour oximetry recordings in preterm infants.

AIM: To compare the overnight 12-hour oximetry component of 24-hour oximetry recordings with the complete 24-h recording in terms of cardiorespiratory status data in preterm infants. METHODS: Preterm infants from the Wellington neonatal intensive care unit underwent a 24-h pulse oximetry recording immediately prior to discharge home. Each recording was edited to resemble a 12-h overnight recording and compared to the full 24-h recording. Differences in a range of cardiorespiratory variables were assessed as to whether they were statistically significant and, if so, likely to be clinically significant. RESULTS: The nadirs for heart rate and SpO2 (both P < 0.001), the time spent <80% SpO2 (P = 0.017) and highest heart rate (P < 0.001) were significantly different between the two recordings. Only the heart rate nadir differed by more than 5%, suggesting that this may be of clinical significance (median (interquartile range) 54 (28-69) for 24-h recording vs. 78 (54-96) for 12-h recording). CONCLUSION: The 24-h oximetry reports were clinically similar to 12-h recordings for the majority of variables, and therefore, we suggest that 12-h oximetry studies are sufficient for determining cardiorespiratory status in infants.

Clinical Reproducibility of the Epworth Sleepiness Scale for Patients With Suspected Sleep Apnea.

STUDY OBJECTIVES: To determine the reproducibility of the Epworth Sleepiness Scale (ESS) score in a clinical population referred for diagnostic testing with suspected obstructive sleep apnea. METHODS: A retrospective audit of patients referred for a diagnostic sleep study with suspected sleep apnea was undertaken. Data collection was two 3-month time periods from January to March in 2012 and 2014. To evaluate reproducibility, the ESS score at primary care referral was compared to the ESS score at first specialist assessment/sleep assessment. The proportion of scores changing by more than 2, 3, 5, or 7 points was determined. Data were analyzed using Bland-Altman plots and paired t tests. RESULTS: A total of 154 patients (68% male) with a mean ± standard deviation age of 51 ± 13 years, body mass index 36 ± 10 kg/m2, and apnea-hypopnea index 43 ± 40 events/h were included. The average ESS score change was -0.2 with a standard deviation of 3.9 reflecting a wide scatter. A difference between the sequential ESS scores of 5 or more was seen in 21% of subjects. CONCLUSIONS: In a clinical obstructive sleep apnea referral population, the ESS score was variable when administered sequentially. Given this variability the ESS should not be used as the sole tool to prioritize patients for obstructive sleep apnea assessment. COMMENTARY: A commentary on this article appears in this issue on page 711.

Updates on Influenza Vaccination in Children.

Influenza vaccination is recommended for all children 6 months of age and older who do not have contraindications. This article provides an overview of information concerning burden of influenza among children in the United States; US-licensed influenza vaccines; vaccine immunogenicity, effectiveness, and safety; and recent updates relevant to use of these vaccines in pediatric populations. Influenza antiviral medications are discussed. Details concerning vaccine-related topics may be found in the current US Centers for Disease Control and Prevention/Advisory Committee on Immunization Practices recommendations for use of influenza vaccines (https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html). Additional information on influenza antivirals is located at https://www.cdc.gov/flu/professionals/antivirals/index.htm.

Relationship between parent knowledge of child sleep, and child sleep practices and problems: A pilot study in a children's hospital cohort.

AIM: To describe parent reports of sleep practices, and examine associations with parent knowledge of child sleep, and whether children's sleep practices differ between parents who underestimated, overestimated or accurately estimated children's sleep needs. METHODS: Parents of children aged 2-12 years (n = 115) attending hospital inpatient or day wards were approached and asked to report child sleep routines, sleep problems, parent education, household income and parent knowledge of child sleep via questionnaire. RESULTS: Younger age was associated with earlier bedtimes and wake times, shorter sleep latencies, longer sleep durations and greater sleep problems (P < 0.05). Parents from higher income homes reported earlier bedtimes and wake times, shorter sleep latencies and fewer sleep problems (P < 0.05). Parents with higher education reported shorter sleep latencies (P < 0.05). Parents with greater knowledge about child sleep reported earlier weekday and weekend bedtimes (r s ≥ 0.26) and wake times (r s ≥ 0.21) and greater consistency between their child's weekend and weekday sleep routines (P < 0.05). In comparison with parents who correctly estimated their child's sleep needs: parents who underestimated reported later weekday bedtimes (on average, 46 min), and longer sleep latencies (17 min); parents who overestimated reported longer sleep latencies (22 min). These findings remained significant when controlling for child age (P < 0.05). CONCLUSION: Parents with increased sleep knowledge, higher incomes and higher levels of education were more likely to report earlier bedtimes, wake times and more consistent sleep routines for their children.

Parent knowledge of children's sleep: A systematic review.

We completed a systematic review of literature related to parent knowledge of children's sleep, to determine how much parents know about typical child sleep and symptoms related to sleep problems in childhood and how parent knowledge has been assessed. We also examined whether relationships have been reported between parent knowledge of children's sleep, parent education, child sleep problems, sleep duration, and sleep hygiene. An extensive literature search of five electronic databases was conducted, and of 615 articles identified, eight met inclusion criteria for review: four descriptive studies and four educational interventions. These studies varied considerably in the number of items included in scales, the specific content measured, the response scales used, and the populations included, limiting the conclusions that could be drawn across studies. In general, parent knowledge of child sleep was poor. Greater accuracy was reported for items pertaining to healthy sleep practices at sleep onset and daytime symptoms, in comparison with items pertaining to child sleep problems during the night. More knowledgeable parents were more likely to report that their children exhibited healthy sleep practices; associations with sleep duration were mixed. Small interventions demonstrated an increase in parental knowledge in the short-term, but effects were not maintained at follow-up. Future work is needed to clarify relations between parental knowledge and child sleep, and to design and evaluate effective methods of promoting education about child sleep in a range of parent populations. The further development of validated tools to assess parent knowledge of child sleep will be required to underpin this work.

Oximetry for preterm infants at neonatal discharge: What is current practice in New Zealand and Australia?

AIM: The aim of the study was to survey level 2 and 3 neonatal units in Australasia to determine the prevalence of oximetry studies at discharge for preterm infants, how these oximetry studies are performed, and which measures are included in an oximetry report. METHODS: A 10-question online survey was created using Survey Monkey regarding use of predischarge oximetry and e-mailed to 46 neonatal units (all level 2 and three units in NZ and all level 3 units in Australia). RESULTS: The response rate was 59% (27/46) with a NZ response rate of 78% (18/23). There was variation in the groups of infants receiving predischarge oximetry studies, with one fifth of responding neonatal units never performing oximetry at discharge. Of the units using predischarge oximetry screening, infants being discharged home on supplemental oxygen were the only group for which all units perform predischarge oximetry. Masimo (Masimo, Irvine, California, USA) is the most common oximeter brand and profox Associates, Inc. (PROFOX Associates, Inc., Escondido, CA 92025, USA) the most common analysis software used. Measures included in oximetry reports vary between units, with profox Associates, Inc.'s default event definition of 'a drop in saturation by four or more' being the most commonly reported desaturation definition. CONCLUSIONS: These findings indicate a need for guidelines to standardise preterm infant oximetry monitoring at neonatal discharge. Further research is required to determine the utility of predischarge oximetry and to establish which infants should be screened.

Continuous positive airway pressure treatment for obstructive sleep apnoea: Maori, Pacific and New Zealand European experiences.

INTRODUCTION: Continuous positive airway pressure (CPAP) is an effective treatment of obstructive sleep apnoea (OSA), but can be limited by poor adherence. In New Zealand (NZ), ethnicity has been shown to be a predictor of CPAP adherence. This study aimed to explore Maori , Pacific and NZ European patients' experience of CPAP treatment. METHODS: Patients identifying as Maori , Pacific, or NZ European ethnicity referred for CPAP treatment for OSA attended separate, 1.5-hour group discussions facilitated by a health care worker of the same ethnic group, using an interview template. Thematic analysis was applied to the discussion transcripts independently by two investigators, following published guidelines. FINDINGS: Five Maori , five Pacific, and eight NZ Europeans participated (mean age 47, range 30-71 years, mean ± standard deviation CPAP adherence 6.32 ± 1.25 hours/night). Patients in all three groups reported that they had little knowledge of OSA or CPAP prior to treatment initiation. All groups identified barriers to treatment (both at the CPAP initiation phase and long term), reported feelings of being 'overwhelmed' with information during the initial CPAP education session, and discussed the importance of successful role models. Family and friends were generally reported as being supportive of CPAP therapy. CONCLUSION: The three groups all reported similar initial CPAP experiences, highlighting access barriers to publicly funded assessment and treatment pathways, and sleep health knowledge as key issues. Educational resources to improve access, enable self-management, and increase community awareness of OSA would help overcome some of the issues identified in this study.

Current definitions for neonatal apnoea: are they evidence based?

Apnoea is defined as cessation of breathing with implicit pathophysiology. This review considers definitions of neonatal apnoea currently available and explores the evidence to support their use. For preterm and term infants, apnoea definitions appear arbitrary, are not supported by guidelines and vary from study to study. Although most alarms on infant breathing monitors are set to alert after a respiratory pause >20s duration is detected, this time period is the equivalent of 17 missed breaths in a preterm infant. Apnoea is likely to be better defined by associated consequence than by pause duration alone in this age group; however, the degree of change in heart rate or oxygen saturation that defines a respiratory pause as pathological is yet to be defined. Further research is required to determine the characteristics that differentiate respiratory events of clinical consequence from normal respiratory variability in term and preterm infants.

Nasal versus oronasal continuous positive airway pressure masks for obstructive sleep apnea: a pilot investigation of pressure requirement, residual disease, and leak.

PURPOSE: This single-blinded, randomized, controlled pilot study aimed to investigate whether there is a difference between nasal and oronasal masks in therapeutic continuous positive airway pressure (CPAP) requirement, residual disease, or leak when treating obstructive sleep apnea (OSA) and if differences were related to measures of upper airway size. METHODS: Patients with severe OSA currently using CPAP at ≥4 h/night with a nasal mask were examined (including Mallampati scale, incisal relationship, and mandibular protrusion) and then randomized to receive auto-positive airway pressure (PAP) or fixed CPAP at a manually titrated pressure for 1 week each at home, with immediate crossover. Within each week, a nasal mask and two oronasal masks were to be used for two or three nights each in random order. Data were downloaded from the device. RESULTS: Twelve patients completed the trial (mean ± SD AHI 59.8 ± 28.6 events/h; CPAP 11.1 ± 3.2 cmH(2)O; BMI 37.7 ± 5.0 kg/m(2)). During auto-PAP, the median 95th percentile pressure delivered with all masks was within 0.5 cmH(2)O (p > 0.05). During CPAP, median residual AHI was 0.61 (IQR = 1.18) for the nasal mask, 1.70 (IQR = 4.04) for oronasal mask 1, and 2.48 (IQR = 3.74) for oronasal mask 2 (p = 0.03). The 95th percentile leak was lowest with the nasal mask during both CPAP and auto-PAP (both p < 0.01). Differences in pressure or residual disease were not related to measures of upper airway shape or body habitus. CONCLUSIONS: In obese OSA patients changing from a nasal to oronasal mask increased leak and residual AHI but did not affect the therapeutic pressure requirement. The findings of the current study highlight mask leak as the major difficulty in the use of oronasal masks.

Ethnic disparities in CPAP adherence in New Zealand: effects of socioeconomic status, health literacy and self-efficacy.

STUDY OBJECTIVES: We aimed to investigate the influence of ethnicity on adherence with continuous positive airway pressure (CPAP) in a sample of New Zealand patients. DESIGN: Observational study over one month. SETTING: A university-based sleep laboratory. PATIENTS: 126 consecutively consenting CPAP-naïve patients (19.8% Maori, mean±SD apnea-hypopnea index 57.9 ± 38.9 events/h, CPAP 11.1 ± 3.1 cm H2O). INTERVENTIONS: Patients underwent a 4-week supervised home trial of CPAP following pressure titration. MEASUREMENTS AND RESULTS: Self-identified ethnicity (Maori/non-Maori), Epworth Sleepiness Scale, Self-Efficacy Measure for Sleep Apnea, Rapid Estimate of Adult Literacy in Medicine, New Zealand Deprivation Index (calculated from residential address), New Zealand Individual Deprivation Index (validated 8-item questionnaire), educational history, income, and employment assessed at baseline were compared to objective CPAP adherence after one month. Maori demonstrated significantly lower usage than non-Maori (median 5.11, interquartile range 2.24 h/night compared with median 5.71, interquartile range 2.61 h/night, P = 0.05). There were no significant relationships between adherence and subjective sleepiness, health literacy, or self-efficacy. In a multivariate logistic regression model incorporating 5 variables (ethnicity, eligibility for government-subsidized healthcare, individual deprivation scores, income, and education), non-completion of tertiary education, and high individual socioeconomic deprivation remained significant independent predictors of average CPAP adherence not reaching ≥ 4 h (odds ratio 0.25, 95% CI 0.08-0.83, P = 0.02; odds ratio 0.10, 95% CI 0.02-0.86, P = 0.04, respectively). The overall model explained approximately 23% of the variance in adherence. CONCLUSIONS: The disparity in CPAP adherence demonstrated between Maori and non-Maori can be explained in part by lower education levels and socioeconomic status.

Narcolepsy in New Zealand: pathway to diagnosis and effect on quality of life.

AIMS: There has been no attempt to survey New Zealanders with narcolepsy to determine their pathway to diagnosis, symptoms, treatment, or quality of life. We therefore aimed to develop a comprehensive questionnaire, and compare responses on measures of daytime sleepiness and quality of life between individuals with narcolepsy and the general New Zealand population. METHODS: A questionnaire was developed encompassing descriptive information, daytime sleepiness and sleep habits, general health and wellbeing, diagnosis and treatment of narcolepsy, symptoms, and quality of life. Ninety-two individuals were identified through medical specialists and a local support group. RESULTS: Complete responses were obtained from 54 individuals (63% female, mean age 54.7 ± 18.3 years). The mean Epworth Sleepiness Scale score was 16.4 ± 5.4 (/24). Symptoms first appeared at 20.7 ± 9.7 years of age on average, although diagnosis did not take place until 33.4 ± 13.8 years of age. Individuals with narcolepsy reported substantially lower health-related quality of life than the general New Zealand population. Less than half of those diagnosed with narcolepsy had undergone an objective evaluation including a sleep study. CONCLUSIONS: New Zealanders with narcolepsy suffer from an excessive level of daytime sleepiness, and have significantly poorer health-related quality of life than the general population. There are a number of inconsistencies between the diagnostic pathway in New Zealand and best-practice guidelines for diagnosis and treatment.

Effect of position on oxygen saturation and requirement in convalescent preterm infants.

AIMS: To document the effect of position on oxygen saturation and changes in oxygen requirement in convalescent preterm infants. METHODS: Twelve infants born ≥24 and ≤32 weeks gestation, extubated and without congenital anomaly were studied using nap polysomnography in prone and supine, twice weekly until discharge. Mean oxygen saturation (SpO(2)), minimum SpO(2) , mean minimum SpO(2) and time with SpO(2) < 90% were measured in active sleep. RESULTS: Eight male and four female infants [median gestation 28 (24-31) weeks and median birthweight 1059 (715-1840) g] had 39 studies. For 21 of 39 studies, the infant was on respiratory support. Four infants had chronic lung disease (CLD). SpO(2) varied with postmenstrual age (PMA) (p = 0.003) but not with position (p = 0.36), and PMA did not influence the effect of position on SpO(2) (p = 0.19). SpO(2) was lower for those with CLD (p < 0.0001) and those on respiratory support (p < 0.001), but there was no effect of position (p = 0.97 and p = 0.67, respectively). From 36 weeks PMA, a change to supine did not increase oxygen requirement. CONCLUSION: In preterm infants, PMA and residual respiratory disease have greater effects on oxygenation than position. A supine sleep position is not disadvantageous for preterm infants at discharge.

Home set-up polysomnography in the assessment of suspected obstructive sleep apnea.

Home set-up polysomnography (PSG) has advantages over other portable monitoring devices, but remains unendorsed by professional bodies despite excellent utility in the Sleep Heart Health Study (SHHS). The study aims to determine technical reliability and diagnostic accuracy of unattended, home set-up versus attended laboratory-based PSG in patients with suspected obstructive sleep apnea (OSA). Thirty patients with suspected OSA without significant co-morbidity were recruited. After initial lab-PSG (Compumedics S series), patients underwent home set-up PSG (Compumedics Siesta) and lab-based PSG in random order. Studies were compared for study success, signal loss and likelihood ratio for OSA diagnosis [apnea-hypopnea index (AHI) >10]. Thirty subjects (mean age 49±13.8 years, body mass index 31±6.1 kg m(-2) ) completed investigations. SHHS technical acceptability criteria were met by all lab-based PSGs and 90% of home-based PSGs (93% clinically acceptable). Signal loss was higher at home (P=0.008). Sleep efficiency was similar between sites, but more preferred home-based PSG (50%). ancova revealed AHI was significantly different if initial AHI >26 per h (P=0.006), with an average underestimate of 5.1 per h at home. In technically acceptable studies the likelihood ratios to 'rule in' and 'rule out' OSA were 8.1 and 0.1, respectively. Unattended, home set-up PSG is technically reliable and achieves excellent diagnostic utility. Signal loss was higher at home but mitigated by multi-channel redundancy. Success rate was similar to SHHS and superior to laboratory set-up home studies. Home set-up PSG is a valid alternative to laboratory-based PSG for suspected OSA.

Respiratory events in preterm infants prior to discharge: with and without clinically concerning apnoea.

PURPOSE: This study aimed to determine the characteristics of respiratory events in preterm infants with clinically concerning apnoea at or beyond 35 weeks postmenstrual age and to compare these findings with a group of preterm infants ready for discharge, without clinically concerning apnoea. METHODS: Infants born at <32 weeks of gestation and who underwent nap polysomnography at or beyond 35 weeks corrected age prior to discharge were included. Cases were preterm infants with clinically concerning apnoea, and control infants were preterm infants asymptomatic for apnoea. Infants with upper airway obstruction, congenital malformations or apnoea associated with sepsis were excluded. Studies were retrospectively reviewed for length, type and frequency of apnoea. The relationship between sleep state and changes in oxygen saturation was compared between groups. Peri-natal and demographic data were also compared. RESULTS: Data were complete for 16 case and 18 control infants. Gestational age was similar at birth and at time of study, but cases had a lower birth weight (p = 0.04) and higher weight at study (p = 0.04). There were no group differences in the mean duration, type or numbers of apnoea. The duration of the longest apnoea was greater in case infants (17.4 s vs. 12.3 s, p = 0.02). Lowest oxygen saturation (p < 0.05) and average minimum oxygen saturation (p < 0.05) were lower in case infants. CONCLUSIONS: Preterm infants with clinically concerning apnoea have similar amounts and types of apnoea but lower oxygen saturation after apnoea compared with controls. The use of oxygen saturation monitoring is more useful than respiratory monitoring alone in recognising these events.

Respiratory variability in preterm and term infants: Effect of sleep state, position and age.

The influence of sleep state and position on respiratory variability (RV) was studied in 13 preterm infants (PTIs) and 19 term infants (TIs). Temporally matched epochs of nasal pressure and oxygen saturation (Spo2) data were extracted from nap polysomnography. Inspiratory onset times (I) were determined, and variability measures of the I-I interval compared in quiet sleep and active sleep, prone and supine and with age. Sleep state influenced respiratory variability (RV) in PTI and TI but Spo2 only varied with sleep state in PTI (p=0.03). Position had no effect on RV in TI but influenced the standard deviation of ventilatory frequency (SDf) in PTI (p=0.04). Age did not influence RV in PTI but SDf and the coefficient of variation of ventilatory frequency (CVf) decreased in TI from birth to 3 months. These data confirm sleep state as the predominant influence on RV in healthy term and convalescent preterm infants, with horizontal prone positioning having little effect when sleep state is controlled for.

Pulse wave analysis in a pilot randomised controlled trial of auto-adjusting and continuous positive airway pressure for obstructive sleep apnoea.

PURPOSE: Non-invasive measurements of arterial stiffness including the augmentation index (AIx) and central blood pressure (BP) have been used to assess the cardiovascular health of patients with obstructive sleep apnoea (OSA), a well-established independent risk factor of cardiovascular disease. Continuous positive airway pressure (CPAP) can significantly reduce the AIx, but no studies have analysed the effect of auto-adjusting PAP (APAP) or studied morbidly obese patients with severe OSA at higher risk of cardiovascular disease. In this randomised, single-blinded crossover pilot trial, we aimed to compare the efficacy of CPAP with APAP (ResMed S8 Autoset II) in improving peripheral BP, central BP and the AIx, using SphygmoCor technology. METHODS: Twelve severe OSA patients (mean±SD; apnoea-hypopnoea index, 75.8 ± 32.7; BMI, 49.9 ± 5.2 kg/m(2)) were consecutively recruited and received CPAP (mean pressure, 16.4 cm H(2)O) or APAP in random order for four nights at home, separated by a four-night washout. Cardiovascular measurements were taken at baseline, post-washout and following each treatment arm. RESULTS: The polysomnographically recorded residual apnoea-hypopnoea index and compliance to treatment were not significantly different between arms (p > 0.05). There were no significant differences in peripheral or central BP between arms (p > 0.05). The AIx was lower with CPAP than APAP (by 5.8%), with a large effect size not reaching statistical significance (r = 0.61, p = 0.14). CONCLUSION: The large effect size evident when comparing the AIx following CPAP and APAP indicates the need to perform an adequately powered trial in order to determine if APAP improves arterial stiffness to the same extent as CPAP.