Sleep disordered breathing: Effects of adenotonsillectomy on behaviour and psychological functioning

Children on the adenotonsillectomy waiting list aged 6 years or more were screened by questionnaire and overnight sleep monitoring to identify 12 with a moderate sleep and breathing disorder (SBD) group. They were matched by age and sex with 11 children who had a similar history of snoring and sleep disturbance but without an obvious sleep and breathing problem when monitored (snorer group) and also with a group of ten children most of whom were refered for an unrelated surgical procedure (control group). All children were studied before and 3–6 months after surgery. Pre-operatively the SBD and snorer groups both had significantly more restless sleep than the control group. The SBD group also had significantly more (>4%) dips in oxygen saturation than the other two groups. After surgery there were no longer any significant differences between the three groups. After adenotonsillectomy the SBD group showed a significant reduction in aggression, inattention and hyperactivity on the parent Conners scale, and an improvement in vigilance on the Continuous Performance Test. The snorer group also improved showing less hyperactive behaviour than pre-operatively and better vigilance. The control groups's behaviour and performance did not change significantly. There were no significant changes in the performance of the Matching Familiar Figures Test in any of the groups.     

Predictors and prevalence of obstructive sleep apnoea and snoring in 1001 middle aged men.

One thousand and one men, aged 35-65 years, were identified from the age-sex register of one group general practice. Over four years 900 men were visited at home and asked questions about symptoms potentially related to sleep apnoea and snoring. Height, weight, neck circumference, resting arterial oxygen saturation (SaO2), and spirometric values were also determined. All night oximetry was then performed at home and the tracing analysed for the number of dips in SaO2 of more than 4%. Subjects with more than five dips of 4% SaO2 or more per hour were invited for sleep laboratory polysomnography. Seventeen per cent of the men admitted to snoring "often." Multiple linear regression techniques identified and ranked neck circumference (r2 = 7.2%), cigarette consumption (r2 = 3.4%), and nasal stuffiness (r2 = 2%) as the only significant independent predictors of snoring. Together these account for at least a sixfold variation in the likelihood of being an "often" snorer. Forty six subjects (5%) had greater than 4% SaO2 dip rates of over five an hour and 31 of these had full sleep studies. Three subjects had clinically obvious and severe symptomatic obstructive sleep apnoea, giving a prevalence of three per 1001 men (0.3%; 95% confidence interval 0.07-0.9%). Eighteen men had obstructive sleep apnoea only when supine and in 10 the cause of the SaO2 dipping on the original home tracing was not elucidated. The greater than 4% SaO2 dip rates correlated with the history of snoring. Multiple linear regression techniques identified and ranked neck circumference (r2 = 7.9%), alcohol consumption (r2 = 3.7%), age (r2 = 1%) and obesity (r2 = 1%) as the only significant independent predictors of the rate of overnight hypoxic dipping. This study shows that snoring in this randomly selected population correlates best with neck size, smoking, and nasal stuffiness. Obstructive sleep apnoea, defined by nocturnal hypoxaemia, correlates best with neck size and alcohol, and less so with age and general obesity.     

Natural history of snoring and related behaviour problems between the ages of 4 and 7 years.

In 1989-90 a survey was carried out of the prevalence of snoring and related symptoms in 782 4 to 5 year old children. Two years later, in 1992, the same group of children was studied to gather information on the natural history of snoring and the related behaviour problems. A total of 507/782 (64.8%) completed questionnaires were received. Comparison of the responses with the 1989-90 survey showed that those who did not reply to the questionnaire were no different from the respondents in terms of the prevalence of snoring, daytime sleepiness, hyperactivity, and restless sleep. The overall prevalence of habitual snoring did not change between the two surveys (12.1% in 1989-90 v 11.4% in 1992), though more than half of the children who snored habitually in the original survey no longer did so. There was little change in the prevalence of hyperactivity (24.2% in 1989-90 v 20.7% in 1992) or restless sleep (both 39%) among the 507 who responded to the present survey. The prevalence of daytime sleepiness, however, did decrease substantially (20.7% in 1989-90 v 10.2% in 1992). There was moderate agreement between the individual questionnaire responses for the 1989-90 and 1992 surveys for snoring (weighted kappa 0.52), but poor agreement for the other symptoms (daytime sleepiness 0.37, hyperactivity 0.35, and restless sleep 0.38). Trend analysis showed that the increasing prevalence of sleepiness, hyperactivity, and restless sleep across the snoring categories was highly significant. Daytime sleepiness, hyperactivity, and restless sleep were all significantly more common in the habitual snorers than in those who never snored. Relative risks (95% confidence interval) were as follows: daytime sleepiness 6.13 (2.5 to 14.9), hyperactivity 2.78 (1.6 to 4.7), and restless sleep 2.3 (1.6 to 3.2). Though habitual snoring and the associated behaviour problems resolved spontaneously over two years in about half of the children with these symptoms, there is still the same overall percentage with these problems due to the emergence of new cases.     

Endocrine effects of nasal continuous positive airway pressure in male patients with obstructive sleep apnoea

OBJECTIVE: Obstructive sleep apnoea (OSA) is a relatively common condition producing disabling somnolence and profound physiological responses to hypoxaemic episodes during sleep, including significant oscillations in blood pressure. This study aimed to provide controlled data on the interaction between OSA and endocrine axes to establish whether overrepresentation of pathology such as hypertension and hypogonadism in OSA subjects might have an endocrine basis. DESIGN, SETTING AND SUBJECTS: Parallel randomized sham placebo controlled 1-month trial of nasal continuous positive airway pressure (nCPAP) in 101 male subjects with OSA presenting to a respiratory sleep clinic. METHODS: Analysis of gonadotrophins, testosterone, sex hormone binding protein (SHBG), prolactin, cortisol, thyroid stimulating hormone (TSH), free thyroxine (free T4), insulin-like growth factor-1 (IGF-1), renin and aldosterone were performed at baseline and after 1 month's active or placebo nCPAP intervention. Quality of life questionnaire scoring was also recorded over the same time period. RESULTS: Testosterone and SHBG showed significant negative correlations with baseline OSA severity. Active treatment of OSA produced SHBG elevation and TSH reduction (P< or =0.03). Both groups showed an increase in aldosterone (P<0.001) and IGF-1 (P< or =0.03), associated with a large improvement in subjective quality of life scoring. CONCLUSIONS: These findings demonstrate significant changes in endocrine axes not previously reported in a placebo-controlled trial. OSA is a recognized reversible cause of testosterone reduction; SHBG suppression correlating to baseline OSA severity supports a diagnosis of secondary hypogonadism. Significant rises in aldosterone and IGF-1 on treatment coincide with increased physical activity and an improved quality of life score.     

The effects of continuous positive airway pressure therapy withdrawal on cardiac repolarization: data from a randomized controlled trial

Aims The preliminary evidence supports an association between obstructive sleep apnoea (OSA), disturbed cardiac repolarization, and consequent cardiac dysrhythmias. The aim of the current trial was to assess the effects of continuous positive airway pressure (CPAP) therapy withdrawal on the measures of cardiac repolarization in patients with OSA. Methods and results Forty-one OSA patients established on CPAP treatment were randomized to either CPAP withdrawal (subtherapeutic CPAP) or continue therapeutic CPAP for 2 weeks. Polysomnography was performed, and indices of cardiac repolarization (QT(c), TpTe(c) intervals) and dispersion of repolarization (TpTe/QT ratio) were derived from 12-lead electrocardiography (ECG) at baseline and 2 weeks. Continuous positive airway pressure withdrawal led to a recurrence of OSA. Compared with therapeutic CPAP, subtherapeutic CPAP for 2 weeks was associated with a significant increase in the length of the QT(c) and TpTe(c) intervals (mean difference between groups 21.4 ms, 95% CI 11.3-1.6 ms, P < 0.001 and 14.4 ms, 95% CI 7.2-21.5 ms, P < 0.001, respectively) and in the TpTe/QT ratio (mean difference between groups 0.02, 95% CI 0.00-0.03, P = 0.020). There was a statistically significant correlation between the change in apnoea/hypopnoea index (AHI) from baseline, and both the change in the QT(c) interval and the TpTe(c) interval (r = 0.60, 95% CI 0.36-0.77, P < 0.001 and r = 0.45, 95% CI 0.17-0.67, P = 0.003, n = 41, respectively). Conclusion Continuous positive airway pressure withdrawal is associated with the prolongation of the QT(c) and TpTe(c) intervals and TpTe/QT ratio, which may provide a possible mechanistic link between OSA, cardiac dysrhythmias, and thus sudden cardiac death.     

Effect of CPAP therapy on endothelial function in obstructive sleep apnoea: A systematic review and meta‐analysis

Obstructive sleep apnoea (OSA) is a prevalent sleep‐related breathing disorder associated with adverse cardiovascular outcome. Endothelial dysfunction is one of the proposed mechanistic links between OSA and the increased cardiovascular risk. Treatment with continuous positive airway pressure (CPAP) may reverse this detrimental pathophysiological consequence of OSA. Most studies on the effect of CPAP on endothelial function in OSA are limited by their low sample size. The objective of this systematic review was to assess the effect CPAP therapy on endothelial function in patients with OSA. We conducted a systematic review and meta‐analysis searching literature databases up to August 2013 for randomized controlled trials (RCTs) on the effect of CPAP on endothelial function in OSA, assessed by flow‐mediated dilatation (FMD) and other validated techniques. The primary outcome for the meta‐analysis (DerSimonian/Laird random‐effects method) was the treatment effect on FMD. Eight RCTs comparing the effects of therapeutic CPAP versus subtherapeutic CPAP (or no intervention) on endothelial function involving 245 OSA patients were included in the systematic review. The studies are consistent in effect direction, showing an improvement of endothelial function by CPAP. Four RCTs involving 150 patients could be used for the meta‐analysis. Compared to the control group, CPAP therapy (range 2–24 weeks) significantly increased absolute % FMD by 3.87% (95% confidence interval: 1.93–5.80, P < 0.001). In patients with OSA, CPAP therapy improves endothelial function significantly and to a clinically important extent.