Person:

Quan, Stuart

Study Objectives—This study analyzed the association between the Respiratory Disturbance Index (RDI) and two behavior measures, the Conners’ Parent Rating Scale (CPRS-R) and the Child Behavior Checklist (CBCL) in school-aged children to determine whether there is an optimal threshold of Sleep-disordered Breathing (SDB) associated with increased risk of behavior problems. Methods—The Tucson Children’s Assessment of Sleep Apnea Study (TuCASA) is an observational cohort study of 6–11 year old Caucasian and Hispanic children designed to assess the anatomic, physiologic and neurocognitive correlates of SDB. 403 children with both polysomnography (PSG) and behavioral data were included in this analysis. Three definitions of SDB were used: RDI independent of oxygen desaturation (RDI0), RDI with 2% oxygen desaturation (RDI2) and RDI with 3% oxygen desaturation (RDI3). T-scored behavioral data were dichotomized at a cutoff point of 65, a score indicative of moderate to severe clinical impairment. Logistic regression was used to access the risk associated with SDB. Results—The analyses conducted using three different definitions of RDI suggest that the likelihood of having a clinically significant CPRS-R or CBCL subscale score was not necessarily progressive or linear across RDI categories. Cutoff points and prevalences for each definition of RDI proposed to be indicators of clinically significant SDB were RDI0 ≥ 7 (19.38%), RDI2 ≥ 2 (29.38%) and RDI3 ≥ 0.5 (23.96%) events per hour of sleep. Behaviors such as CPRS oppositional, social problems, psychosomatic and CBCL somatic complaints, social problems and aggressive behaviors were found to be significantly associated with SDB. Conclusions—This analysis found an increased risk of behavior problems such as somatic complaints, oppositional or aggressive behaviors and social problems associated with sleep- disordered breathing in school-aged children. RDI cut points for three definitions of SDB are proposed: 7 for RDI0, 2 for RDI2, and 0.5 for RDI3 respectively.

Background We tested the hypothesis that ventilatory drive in hypoxia and hypercapnia is inversely correlated with the number of hypopneas and obstructive apneas per hour of sleep (obstructive apnea hypopnea index, OAHI) in children.

Methods Fifty children, 6 to 12 years of age were studied. Participants had an in-home unattended polysomnogram to compute the OAHI. We subsequently estimated ventilatory drive in normoxia, at two levels of isocapnic hypoxia, and at three levels of hyperoxic hypercapnia in each subject. Experiments were done during wakefulness, and the mouth occlusion pressure measured 0.1 seconds after inspiratory onset (P0.1) was measured in all conditions. The slope of the relation between P0.1 and the partial pressure of end-tidal O2 or CO2 (PETO2 and PETCO2) served as the index of hypoxic or hypercapnic ventilatory drive.

Results Hypoxic ventilatory drive correlated inversely with OAHI (r = -0.31, P = 0.041), but the hypercapnic ventilatory drive did not (r = -0.19, P = 0.27). We also found that the resting PETCO2 was significantly and positively correlated with the OAHI, suggesting that high OAHI values were associated with resting CO2 retention.

Conclusions In awake children the OAHI correlates inversely with the hypoxic ventilatory drive and positively with the resting PETCO2. Whether or not diminished hypoxic drive or resting CO2 retention while awake can explain the severity of sleep-disordered breathing in this population is uncertain, but a reduced hypoxic ventilatory drive and resting CO2 retention are associated with sleep-disordered breathing in 6–12 year old children.

Background Recent studies in children have demonstrated that frequent occurrence of parasomnias is related to increased sleep disruption, mental disorders, physical harm, sleep disordered breathing, and parental duress. Although there have been several cross-sectional and clinical studies of parasomnias in children, there have been no large, population-based studies using full polysomnography to examine the association between parasomnias and sleep disordered breathing. The Tucson Children's Assessment of Sleep Apnea study is a community-based cohort study designed to investigate the prevalence and correlates of objectively measured sleep disordered breathing (SDB) in pre-adolescent children six to 11 years of age. This paper characterizes the relationships between parasomnias and SDB with its associated symptoms in these children.

Methods Parents completed questionnaires pertaining to their child's sleep habits. Children had various physiological measurements completed and then were connected to the Compumedics PS-2 sleep recording system for full, unattended polysomnography in the home. A total of 480 unattended home polysomnograms were completed on a sample that was 50% female, 42.3% Hispanic, and 52.9% between the ages of six and eight years.

Results Children with a Respiratory Disturbance Index of one or greater were more likely to have sleep walking (7.0% versus 2.5%, p < 0.02), sleep talking (18.3% versus 9.0%, p < 0.006), and enuresis (11.3% versus 6.3%, p < 0.08) than children with an Respiratory Disturbance Index of less than one. A higher prevalence of other sleep disturbances as well as learning problems was observed in children with parasomnia. Those with parasomnias associated with arousal were observed to have increased number of stage shifts. Small alterations in sleep architecture were found in those with enuresis.

Conclusions In this population-based cohort study, pre-adolescent school-aged children with SDB experienced more parasomnias than those without SDB. Parasomnias were associated with a higher prevalence of other sleep disturbances and learning problems. Clinical evaluation of children with parasomnias should include consideration of SDB.

Rationale Most patients who develop persistent airflow limitation do so either as a manifestation of chronic obstructive pulmonary disease that is largely related to smoking or as a consequence of persistent asthma. We sought to compare the natural course of lung function associated with persistent airflow limitation in subjects with and without asthma from early to late adult life.

Methods We studied 2552 participants aged 25 or more who had multiple questionnaire and lung function data from the long-term prospective population-based Tucson Epidemiological Study of Airway Obstructive Disease. Persistent airflow limitation was defined as FEV1/FVC ratio consistently < 70% in all completed surveys subsequent to the first survey with airflow limitation. Participants were divided into nine groups based on the combination of their physician-confirmed asthma status (never, onset ≤ 25 years, or onset > 25 years) and the presence of airflow limitation during the study follow-up (never, inconsistent, or persistent).

Results Among subjects with an asthma onset ≤ 25 years, blood eosinophilia increased significantly the odds of developing persistent airflow limitation (adjOR: 3.7, 1.4–9.5), whereas cigarette smoking was the strongest risk factor for persistent airflow limitation among non-asthmatics and among subjects with asthma onset after age 25 years. Among subjects with persistent airflow limitation, the natural course of lung function differed between subjects with asthma onset ≤ 25 years and non-asthmatics, with the former having lower FEV1 levels at age 25 (predicted value for a 175-cm tall male of 3,400 versus 4,090 ml, respectively; p<0.001) and the latter having greater FEV1 loss between age 25 and 75 (1,590 versus 2,140 ml; p=0.003).

Conclusion In subjects who have asthma onset before 25 years of age and persistent airflow limitation in adult life, the bulk of the FEV1 deficit is already established before age 25 years.

Background Researchers and clinicians are seeking to develop efficacious behavioral interventions to treat overweight children; however, few studies have documented the behavioral correlates of overweight children in community samples. The goal of this study was to determine the nature and prevalence of behavior problems for overweight school-aged children versus normal weight peers before and after controlling for the effect of sleep disordered breathing.

Methods Hispanic and Caucasian children were invited to participate in a study of sleep through public elementary school classrooms. Anthropometric evaluation and behavioral ratings were collected for 402 children aged 6–11 years. Overweight was calculated using the Centers for Disease Control age- and gender-specific guidelines. Children were classified as overweight if they were at or above the 95th percentile for their age and gender group. Behavior problems were measured using the Conners' Parent Rating Scales-Revised and the Child Behavior Checklist. Sleep disordered breathing was assessed using in-home overnight polysomnography.

Results Approximately 15% (59/402) of the sample was classified as overweight. Simple odds ratios indicated that overweight children were more likely to have clinically relevant levels of internalizing symptoms (OR 2.23, CI 1.05–4.72), psychosomatic complaints (OR 2.15, CI 1.02–4.54), withdrawal (OR 4.69, CI 2.05–10.73), and social problems (3.18, 1.53–6.60). When odds ratios were adjusted for level of sleep disordered breathing, withdrawal (OR 3.83 CI 1.59–9.22) and social problems (OR 2.49 CI 1.14–5.44) remained significantly higher for overweight subjects.

Conclusion After controlling for the effect of sleep disordered breathing, behaviors such as withdrawal and social problems, are common in overweight children and need to be taken into account in the design of interventions and services as they may act to moderate the efficacy of behavioral treatments.

Sleep disordered breathing (SDB) is increasingly recognized as an important clinical problem in children. However, the clinical, anatomic and physiologic correlates of SDB have not been extensively studied in a general population sample using polysomnography to document the presence of SDB. The Tucson Children's Assessment of Sleep Apnea Study (TuCASA) is a longitudinal cohort study of 503 6-12 year old Caucasian and Hispanic children who underwent polysomnography and neurocognitive testing at the time of recruitment. Subsets of the cohort had additional MRI imaging and pulmonary physiologic testing. Initial cross-sectional analyses indicate that SDB is associated with behavioral abnormalities, hypertension, learning problems and clinical symptoms such as snoring and excessive daytime sleepiness. Future follow-up of the cohort will assess the impact of SDB on subsequent childhood development.

Study Objectives This report describes the associations, specificities, sensitivities, and positive likelihood ratios of clinical symptoms to a finding of sleep-disordered breathing (SDB) on polysomnography in children.

Methods Four hundred eighty unattended home polysomnograms were completed in a community-based cohort of children 6 to 11 years of age (50% boys, 42.3% Hispanic, and 52.9% between the ages of 6 and 8 years). SDB was present if the child had a respiratory disturbance index of ≥ 1 event per hour.

Measurements and Results Boys were twice as likely as girls to have SDB (p<.01); however, witnessed apnea, ethnicity, age, obesity, and air-way size (based on clinical evaluation) were not significantly different between those with SDB and without SDB. The sensitivity of any individual or combined clinical symptoms was poor, with male sex (60%) and snoring (29.5%) having the greatest proportion of SDB children. However, high specificities for snoring (89.5%), excessive daytime sleepiness (86.3%), and learning problems (95.9%) were noted. Combinations of symptoms such as snoring+male sex (95.1%), snoring+excessive daytime sleepiness (97.0%), and snoring+learning problems (98.9%) had specificities approaching 1. Positive likelihood ratios for snoring (2.8), learning (2.8), and symptoms combined with snoring such as snoring+male sex(3.9), snoring+learning problems (4.0), and snoring+excessive daytime sleepiness (2.9) were observed.

Conclusions Snoring, excessive daytime sleepiness, and learning problems are each highly specific, but not sensitive, for SDB in 6- to 11-year old children. However, specificities and positive likelihood ratios for the combination of some of these symptoms is sufficiently high to suggest that some children may not require a polysomnogram for the diagnosis of SDB.

Sleep Medicine has only recently been recognized as a specialty of medicine. Its development is based on an increasing amount of knowledge concerning the physiology of sleep, circadian biology and the pathophysiology of sleep disorders. This review chronicles the major advances in sleep science over the past 70 years and the development of the primary organizations responsible for the emergence of Sleep Medicine as a specialty, sleep disorders as a public health concern and sleep science as an important area of research.

Objectives This study sought to evaluate respiratory disturbances as potential triggers for arrhythmia in those with sleep-disordered breathing (SDB).

Background SDB is associated with increased risk of atrial fibrillation (AF) and non-sustained ventricular tachycardia (NSVT) as well as a predilection for sudden cardiac death during nocturnal sleeping hours. However, prior research has not established whether respiratory disturbances operate as triggers for nocturnal arrhythmias.

Methods Overnight polysomnograms (PSGs) from the Sleep Heart Health Study (n = 2816) were screened for paroxysmal atrial fibrillation (PAF) and NSVT. We used the case-crossover design to determine whether apneas and/or hypopneas are temporally associated with episodes of PAF or NSVT. For each arrhythmia, 3 periods of sinus rhythm were identified as control intervals. PSGs were examined for the presence of respiratory disturbances, oxygen desaturations, and cortical arousals within a 90-second hazard period preceding each arrhythmia or control period.

Results Fifty-seven participants with a wide range of SDB contributed 62 arrhythmias (76% NSVT). The odds of an arrhythmia following a respiratory disturbance were nearly 18-times (OR 17.5; 95% CI 5.3–58.4) the odds of an arrhythmia occurring following normal breathing. The absolute rate of arrhythmia associated with respiratory disturbances was low (1 excess arrhythmia/40000 respiratory disturbances). Neither hypoxia nor EEG-defined arousals alone increased arrhythmia risk.

Conclusions Although the absolute arrhythmia rate is low, the relative risk of PAF and NSVT during sleep is markedly increased shortly after a respiratory disturbance. These results support a direct temporal link between SDB events and the development of these arrhythmias.

Sleep disturbances are a common problem with chronic insomnia occurring in 10% of the general adult population and obstructive sleep apnea present in 4% and 2% of middle-aged men and women respectively. In addition, Americans are sleeping fewer hours per night than they did 20 years ago. There is now increasing evidence that reductions and increases in sleep duration, and various sleep disorders including obstructive sleep apnea and insomnia may be causal factors in the development of cardiovascular disease. Some of the evidence linking disturbances of sleep with cardiovascular disease is described in this review.