Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study

BACKGROUND

Sleep-disordered breathing is associated with major morbidity and mortality. However, its prevalence has mainly been selectively studied in populations at risk for sleep-disordered breathing or cardiovascular diseases. Taking into account improvements in recording techniques and new criteria used to define respiratory events, we aimed to assess the prevalence of sleep-disordered breathing and associated clinical features in a large population-based sample.

METHODS

Between Sept 1, 2009, and June 30, 2013, we did a population-based study (HypnoLaus) in Lausanne, Switzerland. We invited a cohort of 3043 consecutive participants of the CoLaus/PsyCoLaus study to take part. Polysomnography data from 2121 people were included in the final analysis. 1024 (48%) participants were men, with a median age of 57 years (IQR 49-68, range 40-85) and mean body-mass index (BMI) of 25·6 kg/m(2) (SD 4·1). Participants underwent complete polysomnographic recordings at home and had extensive phenotyping for diabetes, hypertension, metabolic syndrome, and depression. The primary outcome was prevalence of sleep-disordered breathing, assessed by the apnoea-hypopnoea index.

FINDINGS

The median apnoea-hypopnoea index was 6·9 events per h (IQR 2·7-14·1) in women and 14·9 per h (7·2-27·1) in men. The prevalence of moderate-to-severe sleep-disordered breathing (≥15 events per h) was 23·4% (95% CI 20·9-26·0) in women and 49·7% (46·6-52·8) in men. After multivariable adjustment, the upper quartile for the apnoea-hypopnoea index (>20·6 events per h) was associated independently with the presence of hypertension (odds ratio 1·60, 95% CI 1·14-2·26; p=0·0292 for trend across severity quartiles), diabetes (2·00, 1·05-3·99; p=0·0467), metabolic syndrome (2·80, 1·86-4·29; p<0·0001), and depression (1·92, 1·01-3·64; p=0·0292).

INTERPRETATION

The high prevalence of sleep-disordered breathing recorded in our population-based sample might be attributable to the increased sensitivity of current recording techniques and scoring criteria. These results suggest that sleep-disordered breathing is highly prevalent, with important public health outcomes, and that the definition of the disorder should be revised.

FUNDING

Faculty of Biology and Medicine of Lausanne, Lausanne University Hospital, Swiss National Science Foundation, Leenaards Foundation, GlaxoSmithKline, Ligue Pulmonaire Vaudoise.

Time course of sleep-related breathing disorders in first-ever stroke or transient ischemic attack

To investigate the prevalence and behavior of sleep-related breathing disorders (SRBDs) associated with a first-ever stroke or transient ischemic attack (TIA), we prospectively studied 161 consecutive patients admitted to our stroke unit. Complete neurological assessment was performed to determine parenchymatous and vascular localization of the neurological lesion. Stroke subtype was categorized as TIA, ischemic (IS), or hemorrhagic (HS). A portable respiratory recording (PRR) study was performed within 48-72 h after admission (acute phase), and subsequently after 3 mo (stable phase). During the acute phase, 116 patients (71.4%) had an apnea-hypopnea index (AHI) > 10 events/h and 45 (28%) had an AHI > 30. No relationships were found between sleep-related respiratory events and the topographical parenchymatous location of the neurological lesion or vascular involvement. Cheyne-Stokes breathing (CSB) was observed in 42 cases (26.1%). There were no significant differences in SRBD according to the stroke subtype except for the central apnea index (CAI). During the stable phase a second PRR was performed in 86 patients: 53 of 86 had an AHI > 10 and 17 of 86 had an AHI > 30. The AHI and CAI were significantly lower than those in the acute phase (16.9 +/- 13.8 versus 22.4 +/- 17.3 and 3.3 +/- 7.6 versus 6.2 +/- 10.2, respectively) (p < 0.05) while the obstructive apnea index (OAI) remained unchanged. CSB was observed in 6 of 86 patients. The prevalence of SRBD in patients with first-ever stroke or TIA is higher than expected from the available epidemiological data in our country. No correlation was found between neurological location and the presence or type of SRBD. Obstructive events seem to be a condition prior to the neurological disease whereas central events and CSB could be its consequence.

Central sleep apnea in left ventricular dysfunction: prevalence and implications for arrhythmic risk

BACKGROUND

The prevalence and characteristics of sleep-disordered breathing in patients with asymptomatic left ventricular (LV) dysfunction are unknown. Therefore, we evaluated the prevalence of sleep-disordered breathing in patients with LV dysfunction without overt heart failure and tested the hypothesis that sleep-disordered breathing is linked to greater hemodynamic and autonomic impairment.

METHODS AND RESULTS

We studied 47 patients with LV ejection fractions <or=40% without any history of heart failure. Central sleep apnea (CSA), as defined by an apnea-hypopnea index >or=15/h, was present in 26 patients (55%), 17 (36%) of whom had severe CSA (apnea-hypopnea index >or=30/h). Obstructive sleep apnea was evident in 5 patients (11%). The prevalence and severity of CSA were higher in patients with ischemic cardiomyopathy than in patients with nonischemic cardiomyopathy (P<0.05). Exercise tolerance and echocardiographic indices of systolic and diastolic function were similar in patients without CSA, with mild CSA, and with severe CSA. Heart rate variability was markedly depressed in patients with CSA (P<0.05). Patients with severe CSA also had a higher incidence of nonsustained ventricular tachycardia (P=0.05).

CONCLUSIONS

CSA is highly prevalent in patients with asymptomatic LV dysfunction. The severity of CSA may not be related to the severity of hemodynamic impairment. Severe CSA is associated with impaired cardiac autonomic control and with increased cardiac arrhythmias.

The French Congenital Central Hypoventilation Syndrome Registry: general data, phenotype, and genotype

OBJECTIVE

To analyze the main clinical features, genetic mutations, and outcomes of patients of the French Congenital Central Hypoventilation Syndrome (CCHS) Registry.

DESIGN

A country-wide cohort established throughout a long-term multicenter effort.

PATIENTS

Seventy French patients with CCHS (29 male patients and 41 female patients).

METHODS

The following items were analyzed: the most important moments of the disease course; the main clinical characteristics; associated pathologic conditions; management; clinical outcome; and genetic mutations.

RESULTS

An average of four new cases of CCHS per year was observed in the last 5 years. Thus, the incidence may be estimated to be 1 per 200,000 live births in France. The median age at diagnosis was 3.5 months (range, 0.5 to 15 months) before 1995 and < 2 weeks in the last 5 years (p = 0.01). CCHS occurred in isolation in 58 of 70 patients. In the remainder, it was associated with Hirschsprung disease (HSCR) [nine patients], Hirschsprung and neural crest tumor (two patients), and growth hormone deficiency (one patient). Among the 50 patients who lived beyond 1 year of age, all but one received nighttime ventilation, with 10 of them (20%) receiving it noninvasively. Three patients (6%) required daytime ventilatory support in addition to nighttime ventilation. The overall mortality rate was 38% (95% confidence interval [CI], 27 to 49%). The median age at death was 3 months (range, 0.4 months to 21 years). The 2-year mortality rate was greater in male patients than in female patients (p = 0.02; relative risk [RR], 2.71; 95% CI, 1.14 to 6.47) but was not affected by HSCR (p = 0.93; RR, 0.95; 95% CI, 0.28 to 3.2). The 43 patients who are currently alive (11 men; sex ratio, 0.4) have a mean age of 9 years (range, 2 months to 27 years). Among the 34 patients tested thus far, heterozygous mutations of the paired-like homeobox gene 2B (PHOX2B) gene were found in 31 patients (91%).

CONCLUSION

Our four major findings are the extreme rarity of CCHS, the improved recognition over time, the lack of effect of HSCR on the mortality rate, and the high frequency of PHOX2B mutations.

Sleep-disordered breathing and cardiovascular risk

Sleep-disordered breathing, broadly characterized by obstructive sleep apnea (OSA) and central sleep apnea (CSA), is an increasingly recognized public health burden. OSA, consisting of apneas or hypopneas associated with respiratory efforts in the face of upper airway narrowing or collapse, is a common disorder that can be effectively treated with continuous positive airway pressure (CPAP). OSA not only results in daytime sleepiness and impaired executive function, but also has been implicated as a possible cause of systemic disease, particularly of the cardiovascular system. CSA, which may coexist with OSA, has gained attention because of the association of Cheyne-Stokes respiration with an ever-increasing prevalence of heart failure in an aging population. This article reviews some of the extensive literature on pathophysiologic mechanisms as they may relate to the development of cardiac and vascular disease and examine the evidence suggesting OSA as a specific cause of certain cardiovascular conditions. Available evidence regarding the implications of CSA in the context of heart failure is discussed.

High Prevalence of Sleep Apnea Syndrome in Patients With Long-Term Pacing

Background— Cardiovascular diseases leading to pacemaker implantations are suspected of being associated with a high rate of undiagnosed sleep apnea syndrome (SAS). We sought to determine the prevalence and consequences of SAS in pacemaker patients according to pacing indications: heart failure, symptomatic diurnal bradycardia, and atrioventricular block.

Methods and Results— Ninety-eight consecutive patients (mean age, 64±8 years) not known to have sleep apnea were included; 29 patients were paced for dilated cardiomyopathy (29%), 33 for high-degree atrioventricular block (34%), and 36 for sinus node disease (37%). All underwent Epworth Sleepiness Scale assessment and polysomnography with the pacemaker programmed to right ventricular DDI pacing mode (lower pacing rate, 50 pulses per minute). SAS was defined as an apnea-hypopnea index ≥10/h. Mean Epworth Sleepiness Scale was in the normal range (7±4), although 13 patients (25%) had an abnormal score >11/h. Fifty-seven patients (59%) had SAS; of these, 21 (21.4%) had a severe SAS (apnea-hypopnea index >30/h). In patients with heart failure, 50% presented with SAS (mean apnea-hypopnea index, 11±7) compared with 68% of patients with atrioventricular block (mean apnea-hypopnea index, 24±29) and 58% with sinus node disease (mean apnea-hypopnea index, 19±23).

Conclusions— In paced patients, there is an excessively high prevalence of undiagnosed SAS (59%). Whether treating SAS would have changed the need for pacing is unknown. Treatment effects should be further evaluated particularly because these patients are less symptomatic than typical SAS patients. In any case, SAS should be systematically searched for in paced patients owing to potential detrimental effects on their cardiovascular evolution.

Central sleep apnea is a predictor of cardiac readmission in hospitalized patients with systolic heart failure

BACKGROUND

Hospitalized heart failure patients have a high readmission rate. We sought to determine the independent risk due to central sleep apnea (CSA) of readmission in patients with systolic heart failure (SHF).

METHODS AND RESULTS

This was a prospective observational cohort study of hospitalized patients with SHF. Patients underwent sleep studies during their hospitalization and were followed for 6 months to determine their rate of cardiac readmissions; 784 consecutive patients were included; 165 patients had CSA and 139 had no sleep-disordered breathing (SDB); the remainder had obstructive sleep apnea (OSA). The rate ratio for 6 months' cardiac readmissions was 1.53 (95% confidence interval 1.1-2.2; P = .03) in CSA patients compared with no SDB. This rate ratio was adjusted for systolic function, type of cardiomyopathy, age, weight, sex, diabetes, coronary disease, length of stay, admission sodium, creatinine, hemoglobin, blood pressure, and discharge medications. Severe OSA was also an independent predictor of readmissions with an adjusted rate ratio of 1.49 (P = .04).

CONCLUSION

In this first evaluation of the impact of SDB on cardiac readmissions in heart failure, CSA was an independent risk factor for 6 months' cardiac readmissions. The effect size of CSA exceeded that of all known predictors of heart failure readmissions.

Mechanisms and clinical consequences of untreated central sleep apnea in heart failure

Central sleep apnea (CSA) is a highly prevalent, though often unrecognized, comorbidity in patients with heart failure (HF). Data from HF population studies suggest that it may present in 30% to 50% of HF patients. CSA is recognized as an important contributor to the progression of HF and to HF-related morbidity and mortality. Over the past 2 decades, an expanding body of research has begun to shed light on the pathophysiologic mechanisms of CSA. Armed with this growing knowledge base, the sleep, respiratory, and cardiovascular research communities have been working to identify ways to treat CSA in HF with the ultimate goal of improving patient quality of life and clinical outcomes. In this paper, we examine the current state of knowledge about the mechanisms of CSA in HF and review emerging therapies for this disorder.

Influence of cardiac resynchronisation therapy on different types of sleep disordered breathing

AIMS

This study investigates the influence of cardiac resynchronisation therapy (CRT) on sleep disordered breathing (SDB) in patients with severe heart failure (HF).

METHODS AND RESULTS

Seventy-seven patients with HF (19 females; 62.6+/-10 years) eligible for CRT were screened for presence, type, and severity of SDB before and after CRT initiation (5.3+/-3 months) using cardiorespiratory polygraphy. NYHA class, frequency of nycturia, cardiopulmonary exercise, 6-minute walking test results, and echocardiography parameters were obtained at baseline and follow-up. Central sleep apnoea (CSA) was documented in 36 (47%), obstructive sleep apnoea (OSA) in 26 (34%), and no SDB in 15 (19%) patients. CRT improved clinical and haemodynamic parameters. SDB parameters improved in CSA patients only (apnoea hypopnoea index: 31.2+/-15.5 to 17.3+/-13.7/h, p<0.001; SaO2min: 81.8+/-6.6 to 84.8+/-3.3%, p=0.02, desaturation: 6.5+/-2.3 to 5.5+/-0.8%, p=0.004). Daytime capillary pCO2 was significantly lower in CSA patients compared to those without SDB with a trend towards increase with CRT (35.5+/-4.2 to 37.9+/-5.7 mm Hg, ns). After classifying short term clinical and haemodynamic CRT effects, improved SDB parameters in CSA occurred in responders only.

CONCLUSIONS

In patients with severe HF eligible for CRT, CSA is common and can be influenced by CRT, this improvement depends on good clinical and haemodynamic response to CRT.

Association Between Atrial Fibrillation and Central Sleep Apnea

BACKGROUND

We previously described an association between atrial fibrillation and central sleep apnea in a group of patients with congestive heart failure. We hypothesized that the prevalence of atrial fibrillation might also be increased in patients with central sleep apnea in the absence of other cardiac disease.

METHODS AND RESULTS

We compared the prevalence of atrial fibrillation in a series of 60 consecutive patients with idiopathic central sleep apnea (apnea-hypopnea index > 10 events per hour, > 50% central events) with that in 60 patients with obstructive sleep apnea (apnea-hypopnea index > 10, > 50% obstructive events) and 60 patients without sleep apnea (apnea-hypopnea index < 10), matched for age, sex, and body mass index. Subjects with a history of congestive heart failure, coronary artery disease, or stroke were excluded from the study. The prevalence of atrial fibrillation among patients with idiopathic central sleep apnea was found to be significantly higher than the prevalence among patients with obstructive sleep apnea or no sleep apnea (27%, 1.7%, and 3.3%, respectively, P < .001). However, hypertension was most common and oxygen desaturation most extreme among patients with obstructive sleep apnea.

CONCLUSIONS

We conclude that there is a markedly increased prevalence of atrial fibrillation among patients with idiopathic central sleep apnea in the absence of congestive heart failure. Moreover, the high prevalence of atrial fibrillation among patients with idiopathic central sleep apnea is not explainable by the presence of hypertension or nocturnal oxygen desaturation, since both of these were more strongly associated with obstructive sleep apnea.

Sleep apnea in the elderly: a specific entity?

Sleep apnea is highly prevalent in subjects after age 60, and affects older men and women similarly. Central apneas are often observed in addition to obstructive and mixed events. Pathogenesis of obstructive and central events during sleep in the elderly can be attributed to an amplification of well-established causes of sleep-disordered breathing (SDB) in younger adults. As in middle-aged adults, sleep-related complaints, cardiovascular diseases, depression and traffic accidents should prompt an evaluation by a sleep specialist. However, secondary enuresis and nocturia, cognitive impairment, ophthalmic conditions and repeated falls may be the main complaint in elderly subjects. Sleep studies in the elderly should systematically include reliable means to detect central apneas and periodic leg movements. Untreated SDB in the elderly appears to have a lesser impact on mortality than in middle-aged adults. However, the typical morbidity associated with the disorder in younger adults is observed in the elderly. Elderly symptomatic SDB patients tolerate CPAP no differently than younger patients and should be effectively treated. In conclusion, whether sleep apnea in the elderly represents a specific entity or the same disease as in younger subjects, with some distinctive features, is still unclear. Further research, in particular focusing on the impact of age on SDB outcomes, is needed.

Cheyne-Stokes respiration in stroke: relationship to hypocapnia and occult cardiac dysfunction

BACKGROUND

Central sleep apnea (CSA) and Cheyne-Stokes respiration have been reported in association with stroke, but their pathophysiologic correlates have not been well described.

OBJECTIVE

To test the hypotheses that (1) CSA in patients with stroke is associated with nocturnal hypocapnia and (2) in those stroke patients with CSA and with left ventricular (LV) systolic dysfunction, periodic breathing (PB) will have a Cheyne-Stokes respiration pattern in which cycle duration is greater than in those without LV systolic dysfunction.

METHODS

We prospectively performed polysomnography and echocardiography in 93 patients with stroke. CSA was defined as central apneas and hypopneas occurring at a rate of 10 or more per hour of sleep. In patients with CSA, we compared PB cycle duration between those with normal and impaired LV systolic function (LV ejection fraction [LVEF] > 40% and < or = 40%, respectively).

RESULTS

CSA was found in 19% of subjects who had lower nocturnal transcutaneous PCO2 (39.3 +/- 0.9 vs. 42.8 +/- 0.8 mmHg, p = 0.015) and a higher prevalence of LVEF of 40% or less (22 vs. 5%, p = 0.043) than stroke patients without CSA. There was no significant difference in stroke location or type between the two groups. In patients with CSA, those with LVEF of 40% or less had a longer PB cycle than those with an LVEF of more than 40% (66.6 +/- 5.6 vs. 46.6 +/- 2.9 seconds, p = 0.006), but had no symptoms of heart failure.

CONCLUSION

In patients with stroke, CSA is associated with hypocapnia and occult LV systolic dysfunction but is not related to the location or type of stroke. The presence of LV systolic dysfunction is associated with a Cheyne-Stokes pattern of hyperpnea.

Effect of prone and supine position on sleep, apneas, and arousal in preterm infants

OBJECTIVE

Prematurely born compared with term born infants are at increased risk of sudden infant death syndrome, particularly if slept prone. The purpose of this work was to test the hypothesis that preterm infants with or without bronchopulmonary dysplasia being prepared for neonatal unit discharge would sleep longer and have less arousals and more central apneas in the prone position.

METHODS

This was a prospective observational study in a tertiary NICU. Twenty-four infants (14 with bronchopulmonary dysplasia) with a median gestational age of 27 weeks were studied at a median postconceptional age of 37 weeks. Video polysomnographic recordings of 2-channel electroencephalogram, 2-channel electro-oculogram, nasal airflow, chest and abdominal wall movements, limb movements, electrocardiogram, and oxygen saturation were made in the supine and prone positions, each position maintained for 3 hours. The duration of sleep, sleep efficiency (total sleep time/total recording time), and number and type of apneas, arousals, and awakenings were recorded.

RESULTS

Overall, in the prone position, infants slept longer, had greater sleep efficiency (89.5% vs 72.5%), and had more central apneas (median: 5.6 vs 2.2), but fewer obstructive apneas (0.5 vs 0.9). The infants had more awakenings (9.7 vs 3.5) and arousals per hour (13.6 vs 9.0) when supine. There were similar findings in the bronchopulmonary dysplasia infants.

CONCLUSIONS

Very prematurely born infants studied before neonatal unit discharge sleep more efficiently with fewer arousals and more central apneas in the prone position, emphasizing the importance of recommending supine sleeping after neonatal unit discharge for prematurely born infants.

Obstructive sleep apnea is more common than central sleep apnea in methadone maintenance patients with subjective sleep complaints

OBJECTIVES

Opioid-dependent patients treated with methadone have subjective sleep complaints and disrupted sleep on polysomnography (PSG). Previous studies of sleep-disordered breathing (SDB) in this population have focused on central sleep apnea (CSA). Our objectives were to: (1) characterize obstructive sleep apnea (OSA) and CSA in patients in methadone maintenance treatment (MMT) for opioid dependence; (2) examine factors associated with SDB in this population; and (3) investigate whether SDB was related to severity of subjective sleep complaints in MMT patients with subjective sleep disturbances.

METHODS

We analyzed OSA and CSA from one night of home PSG in 71 patients who were in MMT for at least 3 months and had a Pittsburgh Sleep Quality Inventory (PSQI) score >5.

RESULTS

OSA (defined as obstructive apnea-hypopnea index (OAHI) > or = 5) was observed in 35.2% of our sample. OSA was associated with higher body mass index, longer duration in MMT, and non-Caucasian race. CSA (defined as central apnea index (CAI) > or = 5) was observed in 14.1% of the sample. CSA was not associated with methadone dose or concomitant drug use. Subjective sleep disturbance measured with the PSQI was not related to OSA or CSA.

CONCLUSIONS

SDB was common in this sample of MMT patients and OSA was more common than CSA. Given the lack of association between presence of SDB and severity of subjective sleep difficulties, factors other than sleep apnea must account for complaints of disturbed sleep in this population.

Sleep-disordered breathing in multiple sclerosis

BACKGROUND

The objectives of this cross-sectional study were to assess the prevalence and severity of sleep apnea in patients with multiple sclerosis (MS) referred for overnight polysomnography (PSG) and to explore the radiographic and clinical features that might signal risk for undiagnosed sleep apnea.

METHODS

Apnea-hypopnea (AHI) and central apnea indices (CAI) from laboratory-based PSG among 48 patients with MS were compared with those of group A, 84 sleep laboratory-referred patients without MS matched for age, gender, and body mass index; and group B, a separate group of 48 randomly selected, referred patients.

RESULTS

Mean AHI was higher among patients with MS than among control groups A or B (2-way analysis of variance and multiple linear regression, p = 0.0011 and 0.0118, respectively). Median and mean CAI were also increased among patients with MS in comparison to control groups (Wilcoxon signed rank and multiple linear regression, p = 0.0064 and 0.0027, respectively). Among MS patients with available data, those with evidence of brainstem involvement, compared with groups A and B, showed particularly robust differences in AHI (p = 0.0060 and 0.0016) and CAI (p = 0.0215 and <0.0001). In contrast, MS patients without brainstem involvement, compared with groups A and B, showed diminished differences in AHI, and CAI did not significantly differ among groups.

CONCLUSIONS

These data suggest a predisposition for obstructive sleep apnea and accompanying central apneas among patients with MS, particularly among those with brainstem involvement.

Prospective evaluation of nocturnal oximetry for detection of sleep-related breathing disturbances in patients with chronic heart failure

BACKGROUND

Because patients with chronic heart failure (CHF) can benefit from specific treatment for coexisting obstructive and central sleep apnea (CSA), there is a need to develop accurate screening tools to identify or exclude these sleep-related breathing disturbances (SRBDs) in patients with CHF.

OBJECTIVES

To evaluate, prospectively, the diagnostic value of nocturnal home oximetry in identifying SRBD in CHF patients and in distinguishing central events from obstructive events.

DESIGN

Blinded comparison of hospital and home oximetry, and polysomnographic nocturnal recordings

SETTING

Cardiac heart failure and sleep clinics in three tertiary referral centers.

PATIENTS

Fifty consecutive patients who were investigated for participation in the Canadian Continuous Positive Airway Pressure Trial for Congestive Heart Failure with Central Sleep Apnea and were recruited from three different centers.

MEASUREMENTS AND RESULTS

Patients underwent two oximetry recordings, one at home and one during a polysomnographic study. The criterion for an SRBD was the presence of > 15 apneas and hypopneas per hour of sleep during polysomnography or an oxygen desaturation index of > 10 events per hour during oximetry. The pattern of desaturation/resaturation during oximetry was also examined to distinguish obstructive events from central events. Using a 2% fall in pulse oximetric saturation as the criterion for oxygen desaturation, home oximetry had a 85% sensitivity and a 93% specificity (p < 0.001) for detecting an SRBD. However, the desaturation/resaturation pattern did not accurately distinguish between obstructive events and central events (eg, 100% sensitivity, 17% specificity for identifying CSA). The interpretation of the oximetry recording was highly consistent between scorers (p < 0.001).

CONCLUSIONS

Overnight home oximetry is a sensitive and specific tool for identifying SRBDs in patients with CHF, but not for distinguishing between obstructive and central events in such patients.

Is there a clear link between overweight/obesity and sleep disordered breathing in children?

The proportion of children who are overweight or obese has risen steadily in recent decades and approaches a quarter of all children in Western countries. This global epidemic of excess weight and adiposity in humans is associated with increased morbidity and mortality, especially related to diabetes and poor cardiovascular health. It would appear that obesity is also generally accepted to be an important risk factor in the development of sleep disordered breathing (SDB), in children as well as adults. The article, "The prevalence, anatomical correlates and treatment of sleep-disordered breathing in obese children and adolescents", by Verhulst et al., also in this issue, reviews evidence supporting the view that obese children are at higher risk of developing SDB. We believe, however, that the available studies do not support a straightforward association of overweight or obesity with increased prevalence of SDB. Rather, the available data is clearly equivocal mainly due to methodological differences between the previous studies. This review nonetheless examines the factors which may modulate the relationship between overweight or obesity and prevalence of SDB, particularly ethnicity and age.

Respiratory events and obstructive sleep apnea in children with achondroplasia: investigation and treatment outcomes

PURPOSE

We report aspects of sleep-disordered breathing in a cohort of achondroplastic children who attended our hospital.

METHODS

A retrospective chart review was conducted for a 15-year period to further evaluate the diagnosis and treatment of sleep-disordered breathing in children with achondroplasia.

RESULTS

A review of the medical records was undertaken for 46 children (63%, mean age 3.9 years) with achondroplasia that had overnight polysomnography. Among them, 25 (54.3%) had obstructive sleep apnea (OSA). For 19 out of 46 patients (follow-up rate, 41.3%) with a mean follow-up of 31.3 months (range, 3 month to 11 years), 13 had undergone adenotonsillectomy, while nine were treated with continuous positive airway pressure.

CONCLUSIONS

Prospective evaluation of our clinic population confirms a high incidence of SDB in achondroplastic children. OSA has been linked to raise intracranial pressure as well as neurocognitive deficits in children and we hypothesize that associations between neurological and respiratory abnormalities in this disorder are a consequence of the early onset of associated respiratory, rather than the neurological complications.

Central Sleep Apnea in Congestive Heart Failure: Prevalence, Mechanisms, Impact, and Therapeutic Options

Heart failure due to left ventricular systolic dysfunction is a prevalent syndrome and associated with morbidity, mortality, and huge economic cost. According to reports from several laboratories, a large number of patients with heart failure have central sleep apnea. Central sleep apnea causes arousals and sleep disruption, alters blood gases, and increases sympathetic activity. The pathophysiological consequences of central sleep apnea could adversely affect left ventricular structure and functions and worsen prognosis of heart failure. Several treatment options, including use of nocturnal supplemental oxygen, positive airway pressure devices, and theophylline have been systematically studied and have been shown to improve central sleep apnea. Long-term studies, however, are necessary to determine the impact of therapy on natural history of left ventricular systolic dysfunction.

Cheyne–Stokes respiration with central sleep apnoea in chronic heart failure: Proposals for a diagnostic and therapeutic strategy

Central sleep apnoea (CSA) is highly prevalent in the evolutionary course of chronic heart failure. Such a ventilatory pattern during sleep is independently associated with poor prognosis in people with congestive heart failure. Chronic hyperventilation and daytime hypocapnia are the main mechanisms underlying the frequent association between CSA and cardiac failure. Simplified diagnostic strategies allowing easier recognition of CSA among people with severe heart failure are obviously needed but remain to be validated. Treatment of CSA is essentially aimed at improving cardiac function. When CSA persists, after appropriate adjustment of medication and resynchronisation therapy when indicated, specific ventilatory support during sleep should be considered. Continuous positive airway pressure (CPAP), oxygen, adaptive Servo-ventilation (ASV) and non-invasive ventilation have been proposed. Large randomised trials demonstrating survival and time free from heart transplantation are lacking.

Sleep-Disordered Breathing in Patients With Idiopathic Cardiomyopathy

BACKGROUND

Sleep-disordered breathing may adversely affect heart function, and thereby contribute to the progression of heart failure. A study was undertaken in patients with idiopathic cardiomyopathy to document the characteristics of sleep-disordered breathing.

METHODS AND RESULTS

Thirty-five patients with a diagnosis of idiopathic cardiomyopathy, comprising 20 patients with dilated cardiomyopathy (DCM) and 15 patients with hypertrophic cardiomyopathy (HCM), underwent overnight polysomnography. Of these 35, 16 (80%) of the DCM patients and 7 (47%) of the HCM patients had sleep-disordered breathing. Central sleep apnea-hypopnea syndrome (CSAHS) was seen in 10 DCM patients, but not in the HCM patients, and obstructive sleep apnea-hypopnea syndrome (OSAHS) was seen in 6 DCM patients and 7 HCM patients. CSAHS was seen in DCM patients with a low left ventricular ejection fraction. HCM patients with OSAHS had a significantly greater body mass index (BMI) than those without OSAHS and CSAHS (27.6 +/- 3.8 vs 22.0 +/- 4.0 kg/m2, p<0.05). DCM patients with OSAHS had a larger BMI than those with CSAHS (29.3 +/- 5.8 vs 24.2 +/- 4.0 kg/m2, p<0.05) and those without OSAHS and CSAHS (29.3 +/- 5.8 vs 21.3 +/- 3.1 kg/m2, p<0.05).

CONCLUSIONS

Sleep-disordered breathing is common in patients with idiopathic cardiomyopathy; half of DCM patients had CSAHS, which was closely associated with obesity.

The longitudinal effects of persistent periodic breathing on cerebral oxygenation in preterm infants

OBJECTIVES

Periodic breathing is common in preterm infants, but is thought to be benign. The aim of our study was to assess the incidence and impact of periodic breathing on heart rate (HR), oxygen saturation (SpO2), and brain tissue oxygenation index (TOI) over the first six months after term-equivalent age.

STUDY DESIGN

Twenty-four preterm infants (27-36 weeks gestational age) were studied with daytime polysomnography in quiet sleep (QS) and active sleep (AS) and in both the prone and supine positions at 2-4 weeks, 2-3 months, and 5-6 months post-term corrected age. HR, SpO2, and TOI (NIRO-200 spectrophotometer) were recorded. Periodic breathing episodes were defined as greater than or equal to three sequential apneas each lasting ≥3 s.

RESULTS

A total 164 individual episodes of periodic breathing were recorded in 19 infants at 2-4 weeks, 62 in 12 infants at 2-3 months, and 35 in 10 infants at 5-6 months. There was no effect of gestational age on periodic breathing frequency or duration. Falls in HR (-21.9 ± 2.7%) and TOI (-13.1 ± 1.5%) were significantly greater at 2-3 months of age compared to 2-4 weeks of age.

CONCLUSIONS

The majority of preterm infants discharged home without clinical respiratory problems had persistent periodic breathing. Although in most infants periodic breathing was not associated with significant falls in SpO2 or TOI, several infants had significant desaturations and reduced cerebral oxygenation especially during AS. The clinical significance of this on neurodevelopmental outcome is unknown and warrants further investigations.

Relationship between sleep problems and health-related quality of life among pediatric liver transplant recipients

Among adult liver transplant recipients (LTRs), sleep disturbances and fatigue are common. Sleep problems following pediatric liver transplantation may contribute to daytime fatigue and lower health-related quality of life (HRQOL). The aim of this cross-sectional study was to determine the impact of sleep problems on the HRQOL of pediatric LTRs using validated measures. Participants included 47 LTRs. Mean age of the LTRs was 10.9 ± 4.6 years, and mean time since transplantation was 6.2 ± 3.9 years. The primary indication for transplantation was biliary atresia (51%). According to parent reports, pediatric transplant recipients had symptoms of sleep-disordered breathing, excessive daytime sleepiness, daytime behavior problems, and restless legs; 40.4% of parents and 43.8% of children reported significantly lower total HRQOL for the recipients. Age, time since transplantation, and health status were not significantly related to the quality of life. Hierarchical regression analyses revealed that the sleep-disordered breathing subscale of the Pediatric Sleep Questionnaire accounted for significant variance in parent-proxy reports on the Pediatric Quality of Life (PedsQL) summary scales measuring children's psychosocial health (R(2) = 0.36, P < 0.001), physical health (R(2) = 0.19, P = 0.004), and total HRQOL (R(2) = 0.35, P < 0.001). Also, the sleep-disordered breathing subscale accounted for significant variance in the child self-reported school functioning scale (R(2) = 0.18, P = 0.03). Clinically significant sleep problems were more common among children with low total HRQOL. In conclusion, sleep problems were common in this cohort of pediatric LTRs and predicted significant variance in HRQOL. Prospective larger scale studies are needed to assess factors that contribute to sleep difficulties and low HRQOL in this population. The detection and treatment of significant sleep problems may benefit the HRQOL of pediatric LTRs.