Sleep disordered breathing – a new component of syndrome x?

Sleep disordered breathing (SDB) is a complication of obesity estimated to occur in about 4–6% of overweight individuals. These respiratory disturbances during sleep incorporate a number of conditions including snoring, upper airway resistance syndrome and obstructive sleep apnoea syndrome (OSAS). It is thought that as well as having deleterious effects on sleep quality these conditions may also promote cardiovascular and hormonal changes leading to an elevated blood pressure and an increased incidence of cardiovascular morbidity. Evidence reviewed here points to an alteration in sympathovagal balance, baroreceptor sensitivity, insulin resistance and leptin, growth hormone and lipid levels. Whether these changes are a consequence of the associated obesity or the SDB itself remains to be proven.     

Anaesthetic management of sleep‐disordered breathing in adults

Anaesthesia and sleep are different states of unconsciousness with considerable physiological common ground. Because of their shared depressant effects on muscle activation and ventilatory drive, patients with anatomically compromised airways will tend to obstruct in either state and those with impaired ventilatory capacity will tend to hypoventilate. Breathing behaviour in one state is predictive of that in the other. An essential difference is that while arousal responses are preserved during sleep, they are depressed during sedation and abolished by anaesthesia. This renders patients with sleep‐related breathing disorders vulnerable to hypoventilation and asphyxia when deeply sedated. Addressing this vulnerability requires a systematic approach to identification of patients and circumstances that magnify this risk, and methods of managing it that seek to reconcile the need for safety with cost‐effective use of resources.     

Sleep‐disordered breathing in spinal cord‐injured patients: A short‐term longitudinal study

Background and objective: Previous studies have demonstrated an increased incidence of sleep apnoea in spinal cord‐injured patients. Many of these studies were performed in long‐term, stable spinal cord injury (SCI). The aims of this study were: (i) to determine the prevalence of sleep‐disordered breathing (SDB) in acute SCI; (ii) to document the change in SDB over time during the rehabilitation period; and (iii) to correlate the degree of SDB with ventilatory parameters. Methods: Sixteen subjects with an acute SCI level T12 and above with complete motor impairment (American Spinal Injury Association impairment scale A or B) were recruited. Assessment, including polysomnography, respiratory function testing, and hypoxic and hypercapnic ventilatory responses, were performed 6–8 weeks post SCI, and repeated 6 months post SCI. Results: Eleven of 16 subjects (73%) had evidence of sleep apnoea, five of whom were moderate to severe. This high incidence persisted during the acute admission, with 9 of 12 subjects (75%) having sleep apnoea on polysomnography 20 weeks following injury. There was no correlation between the severity of SDB and other measures, such as level or completeness of injury, respiratory function tests or measures of ventilatory responses. Conclusions: We have demonstrated a high incidence of sleep apnoea in the acute phase of SCI that persisted during the acute admission. Despite the high incidence of sleep apnoea, patients were relatively asymptomatic. Screening of this population would appear worthwhile given the high prevalence, although the significance of the sleep apnoea and clinical impact is not known.     

Strategies to augment adherence in the management of sleep‐disordered breathing

Continuous positive airway pressure (CPAP) is highly effective in treating sleep‐disordered breathing (SDB). However, unlike surgical interventions, this treatment modality relies heavily on patient acceptance and adherence. The current definition of adherence is largely arbitrary and is mainly used by third‐party payers to determine CPAP reimbursement but CPAP adherence remains sub‐optimal. Strategies to augment adherence, especially early in the course of a CPAP trial, are needed in the management of SDB. An understanding of the basis for observed differences in CPAP and oral appliance (OA) use is necessary in developing these strategies, but to date no single factor has been consistently identified. Consequently, a multidimensional approach using educational, behavioural, technological and potentially pharmacological strategies to target (i) disease characteristics, (ii) patient characteristics including psychosocial factors, (iii) treatment protocols and (iv) technological devices and side effects that may influence adherence, is likely required to augment the complex behaviour of CPAP and OA use. In the near future, we envision a personalized medicine approach to determine the risk of non‐adherence and set individualized adherence goals aimed at treating specific symptoms (e.g. excessive daytime sleepiness) and reducing the risk of patient‐specific SDB consequences (e.g. atherosclerosis). Resources for interventions to improve adherence such as educational programmes and telemedicine encounters could then be more efficiently allocated.     

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.     

Improvement of Facial Appearance and Nocturnal Breathing with Geniotomy (Sliding Genioplasty): Report of Two Cases

This article reports on two cases of nonobese female patients who presented in an orthodontic practice complaining of dental malocclusion and facial dysharmony. Because of the observed clinically and radiographically extreme mandibular retrognathia, they were referred for a sleep study and were found to have mild sleep apnea. Surgery in the form of advancement geniotomy was offered to relieve their retroglossal obstruction, improve their nocturnal sleep, and simultaneously address their facial esthetic concerns. Advancement geniotomy is useful for sleep apneic patients with exclusively retroglossal obstruction secondary to mandibular retrognathia.     

Prevalence of sleep disturbances: Sleep disordered breathing,short sleep duration,and non-restorative sleep

Recently, interest in sleep disturbances, such as sleep disordered breathing (SDB), short sleep duration, and non-restorative sleep (NRS), has been increasing. The potentially large public health implications of sleep disturbances indicate a need to determine their prevalence in a general population. This review describes the characteristics of population-based sleep cohorts from past to present. Unavoidable methodological and baseline characteristic heterogeneity was found between studies. The prevalence of SDB (apnea hypopnea index (AHI), respiratory disturbance index (RDI), or oxygen desaturation index (ODI) ≥5/h) was 24.0–83.8% in men and 9.0–76.6% in women, and that of moderate-to-severe SDB (AHI, RDI, or ODI ≥15/h) was 7.2–67.2% in men and 4.0–50.9% in women. Additionally, the prevalence of SDB in post-menopausal women was 3–6 times higher than in pre-menopausal women. The prevalence of subjective short sleep duration (<6 h) was 7.5–9.6%, while that of objective short sleep duration (<6 h) was 22.1–53.3%. The prevalence of NRS was 19.2–31.0% in men and 26.3–42.1% in women, as determined from studies using a yes-no questionnaire, while a multi-national survey using a telephone-based expert system showed a wide range of prevalence between countries, from 2.4% to 16.1%. An association between SDB, short sleep duration, and NRS has recently been suggested. To gain a better understanding of the burden of sleep disturbances, a consensus on the definition of several sleep disturbances is needed, as methodological heterogeneity exists, including SDB scoring rules, subjective versus objective data collection for short sleep duration, and the definition of NRS itself.     

Sleep disordered breathing in the elderly

Sleep-disordered breathing, especially obstructive sleep apnea (OSA), has a high prevalence among the elderly, where it may present with atypical symptoms. Untreated OSA can reduce quality of life and have adverse health consequences. Effective treatment is available, so all physicians treating the elderly should be aware of the clinical presentation, diagnostic methods, and treatment options for OSA.     

Sleep-disordered breathing in patients with symptomatic heart failure: a contemporary study of prevalence in and characteristics of 700 patients

AIM: Evaluation of the prevalence and nature of sleep-disordered breathing (SDB) in patients with symptomatic chronic heart failure (CHF) receiving therapy according to current guidelines. METHODS AND RESULTS: We prospectively screened 700 patients with CHF (NYHA class> or =II, LV-EF< or =40%) for SDB using cardiorespiratory polygraphy (Embletta). Furthermore, echocardiography, cardiopulmonary exercise and 6-min walk testing were performed. Medication included ACE-inhibitors and/or AT1-receptor blockers in at least 94%, diuretics in 87%, beta-blockers in 85%, digitalis in 61% and spironolactone in 62% of patients. SDB was present in 76% of patients (40% central (CSA), 36% obstructive sleep apnoea (OSA)). CSA patients were more symptomatic (NYHA class 2.9+/-0.5 vs. no SDB 2.57+/-0.5 or OSA 2.57+/-0.5; p<0.05) and had a lower LV-EF (27.4+/-6.6% vs. 29.3+/-2.6%, p<0.05) than OSA patients. Oxygen uptake (VO(2)) was lowest in CSA patients: predicted peak VO(2) 57+/-16% vs. 64+/-18% in OSA and 63+/-17% in no SDB, p<0.05. 6-min walking distances were 331+/-111 m in CSA, 373+/-108 m in OSA and 377+/-118 m in no SDB (p<0.05). CONCLUSIONS: This study confirms the high prevalence of SDB, particularly CSA in CHF patients. CSA seems to be a marker of heart failure severity.     

Sleep‐disordered breathing in children with thoracic insufficiency syndrome

Thoracic insufficiency syndrome (TIS) is a collection of chest and spine malformations that results in progressively restrictive pulmonary mechanics and an inability of the thorax to adequately support lung growth. Many children with TIS are too young to perform standard pulmonary function tests, yet need functional assessments of their restrictive thoracic disease. We report on the sleep architecture and frequency of sleep‐related breathing abnormalities in 11 children with TIS who underwent overnight polysomnography from retrospective chart review. Ten of 11 (92%) had sleep disordered breathing as defined by currently accepted criteria of apnea–hypopnea index (AHI) >2 events/hr. The median AHI was 4.3 events/hr, with obstructive hypopneas (median 3.7 events/hr) accounting for 75% of abnormalities. Respiratory events occurred most frequently during REM sleep (median REM‐AHI 17.3 events/hr), and were associated with oxyhemoglobin desaturation, and rarely carbon dioxide retention. Sleep disordered breathing with hypoxemia appears to be a common but under recognized problem among children with TIS. Polysomnogram may have a role as a non‐invasive screening tool used in conjunction with other functional respiratory assessments in children with TIS, and warrants further study in a prospective manner. Pediatr Pulmonol. 2010; 45:469–474. © 2010 Wiley‐Liss, Inc.