[Show abstract][Hide abstract] ABSTRACT: Conditions that increase load on respiratory muscles and/or reduce their capacity to cope with this load predispose to type 2 (hypercapnic) respiratory failure. In its milder forms, this imbalance between load and capacity may primarily manifest as sleep hypoventilation which, if untreated, can increase the likelihood of wakeful respiratory failure. Such problems are commonly seen in progressive respiratory neuromuscular disorders, morbid obesity and chronic obstructive pulmonary disease, either separately or together. Identifying patients at risk can be important in determining whether and when to intervene with treatments such as non-invasive ventilatory assistance. Measurements of wakeful respiratory function are fundamental to this risk assessment. These issues are reviewed in this paper.
[Show abstract][Hide abstract] ABSTRACT: This study was designed to determine the effect of ground-based walking training on health-related quality of life and exercise capacity in people with chronic obstructive pulmonary disease (COPD). People with COPD were randomised to either a walking group that received supervised, ground-based walking training two to three times a week for 8-10 weeks, or a control group that received usual medical care and did not participate in exercise training. 130 out of 143 participants (mean±sd age 69±8 years, forced expiratory volume in 1 s 43±15% predicted) completed the study. Compared to the control group, the walking group demonstrated greater improvements in the St George's Respiratory Questionnaire total score (mean difference -6 points (95% CI -10- -2), p<0.003), Chronic Respiratory Disease Questionnaire total score (mean difference 7 points (95% CI 2-11), p<0.01) and endurance shuttle walk test time (mean difference 208 s (95% CI 104-313), p<0.001). This study shows that ground-based walking training is an effective training modality that improves quality of life and endurance exercise capacity in people with COPD.
[Show abstract][Hide abstract] ABSTRACT: Catheters that traverse the pharynx are often in place during clinical or research evaluations of upper airway function. The purpose of this study was to determine whether the presence of such catheters affects measures of upper airway collapsibility itself. To do so, pharyngeal critical closing pressure (Pcrit) and resistance upstream of the site of collapse Rus) were assessed in 24 propofol-anaesthetized subjects (14 men) with and without a multi-sensor oesophageal catheter (external diameter 2.7 mm) in place. Anaesthetic depth and posture were maintained constant throughout each study. Six subjects had polysomnography(PSG)-defined obstructive sleep apnea (OSA) and 18 either did not have or were at low risk of OSA. Airway patency was maintained with positive airway pressure. At intervals, pressure was reduced by varying amounts to induce varying degrees of inspiratory flow limitation. The slope of the pressure flow relationship for flow-limited breaths defined Rus. Pcrit was similar with the catheter in and out (−1.5 ± 5.4 cmH2O and −2.1 ± 5.6 cmH2O, respectively, P = 0.14, n = 24). This remained the case both for those with PSG-defined OSA (3.9 ± 2.2 cmH2O and 2.6 ± 1.4 cmH2O, n = 6) and those at low risk/without OSA (−3.3 ± 4.9 cmH2O and -3.7 ± 5.6 cmH2O, respectively, n = 18). Rus was similar with the catheter in and out (20.0 ± 12.3 cmH2O mL−1 s−1 and 16.8 ± 10.1 cmH2O mL−1 s−1, P = 0.22, n = 24). In conclusion, the presence of a small catheter traversing the pharynx had no significant effect on upper airway collapsibility in these anaesthestized subjects, providing reassurance that such measures can be made reliably in their presence.
Journal of Sleep Research 08/2014; · 3.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Relatively little is known about frequency and extent of respiratory problems in sporadic inclusion body myositis (IBM). To address this issue a study of peripheral muscle and respiratory function and related symptoms was performed in a cohort with biopsy-proven IBM. Dyspnoea, daytime sleepiness, dysphagia, spirometry, respiratory muscle strength, arterial blood gas tensions and ventilation during sleep were assessed. Sixteen patients were studied (10 males; age 68.1±9.9 years; disease duration 11.9±5.0 years; body mass index 28.5±4.0 kg/m2). Four reported excessive daytime sleepiness; 8 had at least mild dysphagia; forced vital capacity was <80% predicted normal in 7; sniff nasal inspiratory pressure was reduced in 3; daytime hypoxemia was present in 9 and hypercapnia in one. Sleep study was performed in 15 and revealed sleep disordered breathing (apnoea-hypopnoea index 23.4±12.8 (range 7-50.3) events/hr) in all. There were no consistent relationships between respiratory function impairment, occurrence of sleep disordered breathing, and severity of peripheral muscle weakness. Thus, asymptomatic impairment of respiratory function was common and sleep disordered breathing observed in all patients tested, irrespective of daytime respiratory function. This suggests respiratory function testing, including sleep study, should be performed routinely in IBM, irrespective of peripheral muscle function or other disease severity parameters.
[Show abstract][Hide abstract] ABSTRACT: Obstructive sleep apnea (OSA) is a common disorder that is associated with impaired attention, memory and executive function. However, the mechanisms underlying such dysfunction are unclear. To determine the influence of sleep fragmentation and hypoxia, this study examined the effect of sleep fragmentation and hypoxia on cognition in OSA, while controlling for potentially confounding variables including sleepiness, age and premorbid intelligence.
[Show abstract][Hide abstract] ABSTRACT: There have been no studies of the effect of continuous positive airway pressure (CPAP) therapy on erectile dysfunction (ED) and serum testosterone in men with type 2 diabetes and obstructive sleep apnoea (OSA), a patient group at increased risk of ED and hypogonadism. The aim of the present study was to determine whether CPAP improves sexual and gonadal function in males with type 2 diabetes and a pre-CPAP apnoea-hypopnoea index >15/hour.
Sub-study of a trial assessing the effect of three months of CPAP on cardiovascular risk in type 2 diabetes.
Of 35 males starting CPAP, 27 (mean±SD age 65.4±9.6 years, median [interquartile range] diabetes duration 12.1 [5.2-15.3] years) completed the trial.
Serum total and free testosterone, responses to the Androgen Deficiency in the Aging Male (ADAM) and Sexual Health Inventory for Men (SHIM) questionnaires.
There were no significant changes in mean total or free testosterone (baseline concentrations 12.7±4.5 nmol/L and 0.26±0.07 pmol/L, respectively), or SHIM score (baseline 13 [5-17]), after three months of CPAP (P>0.20). The ADAM score (baseline 6.2±2.1) fell after one month (to 5.0±2.6) and was maintained at this level at three months (P=0.015). The Epworth Sleepiness Scale score decreased and self-reported physical activity increased over three months (P≤0.017) without a change in body mass index (P=1.00).
These findings imply that CPAP therapy improves somnolence and promotes exercise in men with type 2 diabetes, but that there is no direct benefit for gonadal or sexual function. This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Poor sleep imparts a significant personal and societal burden. Therefore, it is important to have accurate estimates of its causes, prevalence and costs to inform health policy. A recent evaluation of the sleep habits of Australians demonstrates that frequent (daily or near daily) sleep difficulties (initiating and maintaining sleep, and experiencing inadequate sleep), daytime fatigue, sleepiness and irritability are highly prevalent (20%-35%). These difficulties are generally more prevalent among females, with the exception of snoring and related difficulties. While about half of these problems are likely to be attributable to specific sleep disorders, the balance appears attributable to poor sleep habits or choices to limit sleep opportunity. Study of the economic impact of sleep disorders demonstrates financial costs to Australia of $5.1 billion per year. This comprises $270 million for health care costs for the conditions themselves, $540 million for care of associated medical conditions attributable to sleep disorders, and about $4.3 billion largely attributable to associated productivity losses and non-medical costs resulting from sleep loss-related accidents. Loss of life quality added a substantial further non-financial cost. While large, these costs were for sleep disorders alone. Additional costs relating to inadequate sleep from poor sleep habits in people without sleep disorders were not considered. Based on the high prevalence of such problems and the known impacts of sleep loss in all its forms on health, productivity and safety, it is likely that these poor sleep habits would add substantially to the costs from sleep disorders alone.
The Medical journal of Australia 10/2013; 199(8):7-10. · 2.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The global trend of increased life expectancy and increased prevalence of chronic and degenerative diseases will impact on health systems. To identify effective intervention and prevention strategies, greater understanding of the risk factors for and cumulative effects of chronic disease processes and their effects on function and quality of life is needed.The Busselton Healthy Ageing Study aims to enhance understanding of ageing by relating the clustering and interactions of common chronic conditions in adults to function. Longitudinal (3--5 yearly) follow-up is planned.Methods/design: Phase I (recruitment) is a cross-sectional community-based prospective cohort study involving up to 4,000 'Baby Boomers' (born from 1946 to 1964) living in the Busselton Shire, Western Australia. The study protocol involves a detailed, self-administered health and risk factor questionnaire and a range of physical assessments including body composition and bone density measurements, cardiovascular profiling (blood pressure, ECG and brachial pulse wave velocity), retinal photography, tonometry, auto-refraction, spirometry and bronchodilator responsiveness, skin allergy prick tests, sleep apnoea screening, tympanometry and audiometry, grip strength, mobility, balance and leg extensor strength. Cognitive function and reserve, semantic memory, and pre-morbid intelligence are assessed. Participants provide a fasting blood sample for assessment of lipids, blood glucose, C-reactive protein and renal and liver function, and RNA, DNA and serum are stored. Clinically relevant results are provided to all participants. The prevalence of risk factors, symptoms and diagnosed illness will be calculated and the burden of illness will be estimated based on the observed relationships and clustering of symptoms and illness within individuals. Risk factors for combinations of illness will be compared with those for single illnesses and the relation of combinations of illness and symptoms to cognitive and physical function will be estimated.
This study will enable a thorough characterization of multiple disease processes and their risk factors within a community-based sample of individuals to determine their singular, interactive and cumulative effects on ageing. The project will provide novel cross-sectional data and establish a cohort that will be used for longitudinal analyses of the genetic, lifestyle and environmental factors that determine whether an individual ages well or with impairment.
BMC Public Health 10/2013; 13(1):936. · 2.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Reduced upper airway muscle activity during sleep is a key contributor to obstructive sleep apnoea pathogenesis. Hypoglossal nerve stimulation activates upper airway dilator muscles, including the genioglossus, and has the potential to reduce obstructive sleep apnoea severity. The objective of this study was to examine the safety, feasibility and efficacy of a novel hypoglossal nerve stimulation system (HGNS(®) ; Apnex Medical, St Paul, MN, USA) in treating obstructive sleep apnoea at 12 months following implantation. Thirty-one subjects (35% female, age 52.4 ± 9.4 years) with moderate to severe obstructive sleep apnoea and unable to tolerate positive airway pressure underwent surgical implantation and activation of the hypoglossal nerve stimulation system in a prospective single-arm interventional trial. Primary outcomes were changes in obstructive sleep apnoea severity (apnoea-hypopnoea index, from in-laboratory polysomnogram) and sleep-related quality of life [Functional Outcomes of Sleep Questionnaire (FOSQ)]. Hypoglossal nerve stimulation was used on 86 ± 16% of nights for 5.4 ± 1.4 h per night. There was a significant improvement (P < 0.001) from baseline to 12 months in apnoea-hypopnoea index (45.4 ± 17.5 to 25.3 ± 20.6 events h(-1) ) and Functional Outcomes of Sleep Questionnaire score (14.2 ± 2.0 to 17.0 ± 2.4), as well as other polysomnogram and symptom measures. Outcomes were stable compared with 6 months following implantation. Three serious device-related adverse events occurred: an infection requiring device removal; and two stimulation lead cuff dislodgements requiring replacement. There were no significant adverse events with onset later than 6 months following implantation. Hypoglossal nerve stimulation demonstrated favourable safety, feasibility and efficacy.
Journal of Sleep Research 09/2013; · 3.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The most collapsible part of the upper airway in the majority of individuals is the velopharynx which is the segment positioned behind the soft palate. As such it is an important morphological region for consideration in elucidating the pathogenesis of obstructive sleep apnea (OSA). This study compared steady flow properties during inspiration in the pharynges of nine male subjects with OSA and nine body-mass index (BMI)- and age-matched control male subjects without OSA. The k-ωSST turbulence model was used to simulate the flow field in subject-specific pharyngeal geometric models reconstructed from anatomical optical coherence tomography (aOCT) data. While analysis of the geometry of reconstructed pharynges revealed narrowing at velopharyngeal level in subjects with OSA, it was not possible to clearly distinguish them from subjects without OSA on the basis of pharyngeal size and shape alone. By contrast, flow simulations demonstrated that pressure fields within the narrowed airway segments were sensitive to small differences in geometry and could lead to significantly different intraluminal pressure characteristics between subjects. The ratio between velopharyngeal and total pharyngeal pressure drops emerged as a relevant flow-based criterion by which subjects with OSA could be differentiated from those without.
Journal of biomechanics 08/2013; · 2.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: INTRODUCTION: We present the proceedings of the second annual meeting of the Society of Anesthesia and Sleep Medicine. The theme of the meeting was "Anesthesia and Sleep Medicine: What Every Health Professional Needs to Know." DISCUSSION: While upper airway obstruction during sleep and anesthesia received concentrated attention, with particular regard to perioperative assessment and managment of obstuctive sleep apnea, a diversity of issues were raised including: the genetic basis for variations in ventilatory control; shared charactertics of sleep and anesthesia; hazards posed by narcotic use in patients with obstructive sleep apnea (OSA); the respiratory complication that follow surgery in such patients; who amongst them is suitable for ambulatory surgery; and the special circumstances that apply to anesthesia for children with OSA. How principles based on these considerations have been applied to protocol development at two major centers was presented towards the end of the meeting. The proceedings highlight issues discussed by each of the invited speakers but do not include the research abstracts discussed during the poster session.
[Show abstract][Hide abstract] ABSTRACT: Rationale: Increasing lung volume increases upper airway patency and decreases airway resistance and collapsibility. The role of diaphragm contraction in producing these changes remains unclear. Objectives: To determine the effect of selective diaphragm contraction, induced by phrenic nerve stimulation, on upper airway collapsibility and the extent to which any observed change was attributable to lung volume-related changes in pressure gradients or to diaphragm descent-related mediastinal traction. Measurements and Main Results: Continuous bilateral transcutaneous cervical phrenic nerve stimulation (30Hz) was applied to 9 supine, anesthetised human subjects during transient decreases in airway pressure to levels sufficient to produce flow limitation when unstimulated. Stimulation was applied at two intensities (low and high) and its effects on lung volume and airflow quantified relative to unstimulated conditions. Lung volume increased by 386±269 ml (mean±SD) and 761±556 ml during low- and high-stimulation respectively (p<0.05 for the difference between these values), which was associated with peak inspiratory flow increases of 69±57 and 137±108 ml/sec, respectively (p<0.05 for the difference). Stimulation-induced change in lung volume correlated with change in peak flow (r=0.65, p<0.01). Diaphragm descent related outward displacement of the abdominal wall produced no change in airflow unless accompanied by lung volume change. Conclusions: Phrenic nerve stimulation-induced diaphragm contraction increases lung volume and reduces airway collapsibility in a dose-dependent manner. The effect appears primarily mediated by changes in lung volume rather than mediastinal traction from diaphragm descent. The study provides a rationale for use of continuous phrenic stimulation to treat obstructive sleep apnea.
Journal of Applied Physiology 05/2013; · 3.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PURPOSE: Obstructive sleep apnoea (OSA) is a common disorder, for which continuous positive airway pressure (CPAP) therapy is a standard treatment. Despite its well-established efficacy, many patients choose not to initiate CPAP treatment. The present study investigated the degree to which biological measures (e.g. Apnoea-Hypopnoea Index [AHI]), symptom experiences (e.g. fatigue) and illness representations (e.g. perceived consequences) predict the decision of individuals newly diagnosed with OSA to undergo a trial of CPAP therapy. METHODS: Four hundred forty-nine individuals (316 males) newly diagnosed with OSA. Epworth sleepiness scale (ESS), Fatigue Severity Scale, Depression Anxiety Stress Scale and Illness Perception Questionnaire-Revised (IPQ-R) were administered at time of sleep study. These, patient demographics and sleep study variables were used to determine factors predicting patient decision to proceed with a trial of CPAP. RESULTS: The participants were most likely to attribute their OSA to unchangeable and psychological factors. For those with moderate OSA (AHI, 15 to 30) IPQ-R illness consequence was predictive of decision to initiate CPAP (p = 0.002). For severe OSA (AHI >30) age, ESS and IPQ illness causal beliefs were predictive of decision to initiate CPAP (p < 0.001). CONCLUSIONS: Illness beliefs are important determinants of the choice of recently diagnosed OSA patients whether or not to undertake a trial of CPAP therapy. Concerns about illness consequences were important in those with moderate OSA. In severe OSA, sleepiness symptoms are more prominent and a more significant determinant of CPAP uptake along with age and causal beliefs.
[Show abstract][Hide abstract] ABSTRACT: Purpose Obstructive sleep apnoea (OSA) is a common disorder, for which continuous positive airway pressure (CPAP) therapy is a standard treatment. Despite its well-established efficacy, many patients choose not to initiate CPAP treatment. The present study investigated the degree to which biological measures (e.g. Apnoea–Hypopnoea Index [AHI]), symptom experiences (e.g. fatigue) and illness representations (e.g. perceived consequences) predict the decision of individuals newly diagnosed with OSA to undergo a trial of CPAP therapy.
Methods Four hundred forty-nine individuals (316 males) newly diagnosed with OSA. Epworth sleepiness scale (ESS), fatigue severity scale, depression anxiety stress scale and Illness Perception Questionnaire-Revised (IPQ-R) were administered at time of sleep study. These, patient demographics and sleep study variables were used to determine factors predicting patient decision to proceed with a trial of CPAP.
Results The participants were most likely to attribute their OSA to unchangeable and psychological factors. For those with moderate OSA (AHI, 15 to 30) IPQ-R illness consequence was predictive of decision to initiate CPAP (p = 0.002). For severe OSA (AHI >30) age, ESS and IPQ illness causal beliefs were predictive of decision to initiate CPAP (p < 0.001).
Conclusions Illness beliefs are important determinants of the choice of recently diagnosed OSA patients whether or not to undertake a trial of CPAP therapy. Concerns about illness consequences were important in those with moderate OSA. In severe OSA, sleepiness symptoms are more prominent and a more significant determinant of CPAP uptake along with age and causal beliefs.
Sleep And Breathing 03/2013; In press. · 2.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Continuous positive airway pressure (CPAP), the mainstay treatment for obstructive sleep apnea (OSA), involves administration of air under pressure to the upper airway. A well-known but poorly understood side effect of positive airway pressure therapies is aerophagia, air entering the esophagus and stomach rather than the lungs. Gastric distension, a consequence of aerophagia, can increase gastroesophageal reflux (GER) by increasing transient lower esophageal sphincter relaxations, the most common cause of reflux. This study aimed to determine: (i) the prevalence of aerophagia symptoms in a group of OSA patients on CPAP therapy, and (ii) whether aerophagia symptoms are related to an increase in prevalence of GER symptoms.
Consecutive OSA patients undergoing polysomnography for the purpose of optimizing their CPAP therapy completed a validated questionnaire regarding GER symptoms and aerophagia symptoms. Complete datasets were collected for 259 individuals (203 males).
The group with aerophagia symptoms (n = 130) had a greater prevalence of frequent (≥ once a week) GER symptoms (29% vs. 10%, p < 0.05) and nighttime GER symptoms (9 vs. 2%, p < 0.05) than those without aerophagia (n = 129). The group with nighttime GER symptoms (n = 27) had a greater prevalence of aerophagia symptoms (63% vs. 23%, p < 0.05) than those without nighttime GER symptoms (n = 232).
In patients with OSA being treated with CPAP, the prevalence of GER and nighttime GER symptoms is greater in those with symptoms of aerophagia than those without. CPAP-induced aerophagia might precipitate GER, particularly nighttime GER, by exacerbating transient lower esophageal relaxations through gastric distension.
A commentary on this article appears in this issue on page 19. CITATION: Shepherd K; Hillman D; Eastwood P. Symptoms of aerophagia are common in patients on continuous positive airway pressure therapy and are related to the presence of nighttime gastroesophageal reflux. J Clin Sleep Med 2013;9(1):13-17.
Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine 01/2013; 9(1):13-7. · 2.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: (1) To describe the incidence rate of motor vehicle crashes (MVCs) in patients with obstructive sleep apnea (OSA); and (2) to investigate MVC risk factors in OSA patients.
A retrospective case-series observational study was conducted using data from the West Australian Sleep Health Study at a tertiary hospital-based sleep clinic. Participants were patients (N = 2,673) referred for assessment of suspected sleep disordered breathing. Questionnaire data were collected including age, sex, years of driving, near-misses and MVCs, sleepiness, and consumption of alcohol and caffeinated drinks. Overnight laboratory-based polysomnography was performed using standard methodology.(1) Poisson univariate and negative binomial multivariable regression models were used to investigate associations between risk factors and MVC and near-miss risk in patients with untreated OSA.
In patients with untreated OSA, the crash rate was 0.06 MVC/person-year compared with the general community crash rate of 0.02 MVC/person-year. The rate ratio comparing very sleepy men with normal men was 4.68 (95% CI 3.07, 7.14) for near-misses and 1.27 (95% CI 1.00, 1.61) for crashes, after adjusting for confounders. In women there was a significant association with sleepiness score (p = 0.02) but no dose effect across quartiles.
Untreated OSA is associated with an increased risk of near-misses in men and women and an increased risk of MVCs in very sleepy men. There is a strong association between excessive daytime sleepiness and increased report of near-misses. Our data support the observation that it is those patients with increased sleepiness regardless of OSA severity who are most at risk.
Ward KL; Hillman DR; James A; Bremner AP; Simpson L; Cooper MN; Palmer LJ; Fedson AC; Mukherjee S. Excessive daytime sleepiness increases the risk of motor vehicle crash in obstructive sleep apnea. J Clin Sleep Med 2013;9(10):1013-1021.
Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine 01/2013; 9(10):1013-1021. · 2.93 Impact Factor