Positive pressure therapy: a perspective on evidence-based outcomes and methods of application

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Konsensus-Statement der Österreichischen Gesellschaft für Schlafmedizin (ÖGSM/ASRA) zum Management der residualen exzessiven Tagesschläfrigkeit (rETS) bei obstruktiver Schlafapnoe

Hintergrund

Sechs bis zehn Prozent aller Patienten mit einer obstruktiven Schlafapnoe leiden trotz adäquater nächtlicher Überdrucktherapie oder einer effektiven Alternativtherapie an einer residualen exzessiven Tagesschläfrigkeit (rETS). Die Differentialdiagnose der rETS stellt im klinischen Alltag eine interdisziplinäre Herausforderung dar.

Fragestellung

Entwicklung eines übersichtlichen Leitfadens für die Erkennung, die differentialdiagnostischen Abwägungen und die Möglichkeiten der weiterführenden Behandlung der rETS in der klinischen Praxis.

Material und Methode

MeSH-Analyse basierte Recherche und interdisziplinäre Abstimmung von Fachvertreter:innen der Inneren Medizin und Pneumologie, Neurologie sowie Psychiatrie und Psychotherapie.

Ergebnisse

SPAIN-Checkliste zur systematischen differentialdiagnostischen Exploration der rETS mit den Parametern: S chlafverhalten, P sychische Ursachen, A namnese der Medikation, I nternistische Ursachen und N eurologische Ursachen.

Schlussfolgerungen

Die rETS sollte als behandlungswürdiges Symptom erkannt werden. Sie verlangt nach einer interdisziplinären Abklärung und der individuellen Abstimmung der Behandlung auf die Bedürfnisse der Betroffenen.

An Updated Review on the Relationship of Depressive Symptoms in Obstructive Sleep Apnea and Continuous Positive Airway Pressure

Obstructive sleep apnea (OSA) is a common sleep disorder occurring across all age groups, gender, and is multifactorial. The episodic decrease in airflow during sleep results in hypoxia and hypercapnia over time, resulting in morning headache, systemic and pulmonary hypertension, and polycythemia. Fragmentation of sleep at night-time cause daytime somnolence, fatigue, memory problems, and mood symptoms such as depression and anxiety. These secondary mood symptoms could be easily missed by healthcare providers as the primary disorder resulting in unnecessary anti-depressants' prescription. This study investigates the effect of continuous airway pressure (CPAP) on depressive symptoms of OSA. We used PubMed, PubMed Central (PMC), and MEDLINE for data collection. We used OSA, depression, anxiety, mood symptoms, psychological symptoms, and CPAP as the keywords, both alone and in combination. The search ended on November 5, 2020, and it was limited to the year 2010 until the day of the search. However, a few of the papers published earlier than 2010 were also included to have better insight into some aspects of the topic. We included articles measuring the impact of CPAP on mood symptoms using any one of the validated scales, such as the Beck Depression Inventory (BDI), the State-Trait Anxiety Inventory (STAI), Hospital Anxiety and Depression Scale (HADS), or Hamilton Depression Scale (HAM-D). Our initial searches yielded 131 articles. Twenty-one of the 131 papers satisfied the review's criteria. Four studies out of 21 revealed no improvement in OSA-related mood symptoms with CPAP therapy, whereas the others reported beneficial effects on mood, daytime sleepiness, cognition, and patient quality of life.

Can we enhance compliance to treatment by performing a continuous positive airway pressure trial in obstructive sleep apnea?

BACKGROUND

Although continuous positive airway pressure (CPAP) therapy is the most effective treatment for obstructive sleep apnea (OSA), it is not always easy to gain adherence to therapy. We aimed to evaluate how short-term CPAP application during the daytime before the titration night affects polysomnographic data and CPAP adherence in OSA.

METHODS

Patients with moderate to severe OSA for whom CPAP titration was recommended were prospectively randomized to daytime CPAP application (group 1) or usual care (group 2).  For group 1, CPAP was applied for 30-60 min in daytime conditions to acclimate patients to the device. An appointment was then made to perform CPAP titration with PSG. In group 2 (usual care), the first CPAP application was performed on the titration night. PSG recordings and titration night recordings of both groups were compared. All subjects were evaluated 1 month after the initiation of CPAP treatment.

RESULTS

Among 246 cases, first night data were similar in both groups. During the titration night, total sleep time, sleep efficiency, and time in stage N3 were significantly higher in patients who underwent the daytime CPAP trial. Adherence to CPAP treatment at first-month follow-up was significantly higher in the group 1 (5.7 ± 1.0 h/night) compared to the group 2 (3.9 ± 1.1 h/night, p < 0.001).

CONCLUSION

A short-term daytime CPAP trial in patients before the titration night may provide longer and more efficient sleep on the titration night and better CPAP adherence at one month.

More than a Genetic Code: Epigenetics of Lung Fibrosis

At the end of the last century, genetic studies reported that genetic information is not transmitted solely by DNA, but is also transmitted by other mechanisms, named as epigenetics. The well-described epigenetic mechanisms include DNA methylation, biochemical modifications of histones, and microRNAs. The role of altered epigenetics in the biology of various fibrotic diseases is well-established, and recent advances demonstrate its importance in the pathogenesis of pulmonary fibrosis-predominantly referring to idiopathic pulmonary fibrosis, the most lethal of the interstitial lung diseases. The deficiency in effective medications suggests an urgent need to better understand the underlying pathobiology. This review summarizes the current knowledge concerning epigenetic changes in pulmonary fibrosis and associations of these changes with several cellular pathways of known significance in its pathogenesis. It also designates the most promising substances for further research that may bring us closer to new therapeutic options.

Effectiveness of an intensive weight-loss program for severe OSA in patients undergoing CPAP treatment: a randomized controlled trial

STUDY OBJECTIVES

To determine whether an intensive weight-loss program (IWLP) is effective for reducing weight, the severity of obstructive sleep apnea (OSA), and metabolic variables in patients with obesity and severe OSA undergoing continuous positive airway pressure treatment.

METHODS

Forty-two patients were randomized to the control (CG, n = 20) or the intervention group (IG, n = 22), who followed a 12-month IWLP. The primary outcome was a reduction in the apnea-hypopnea index (AHI) as measured at 3 and 12 months by full polysomnography. Metabolic variables, blood pressure, body fat composition by bioimpedance, carotid intima media thickness, and visceral fat by computed tomography were also assessed.

RESULTS

Mean age was 49 (6.7) years, body mass index 35 (2.7) kg/m², and AHI 69 (20) events/h. Weight reduction was higher for the IG than the CG at 3 and 12 months, -10.5 versus -2.3 kg (P < .001), and -8.2 versus -0.1 kg (P < .001), respectively, as was loss of visceral fat at 12 months. AHI decreased more in the IG at 3 months (-23.72 versus -9 events/h) but the difference was not significant at 12 months, though 28% of patients from the IG had an AHI < 30 events/h compared to none in the CG (P = .046). At 12 months, the IG showed a reduction in C-reactive protein (P = .013), glycated hemoglobin (P = .031) and an increase in high density lipoprotein cholesterol (P = .027).

CONCLUSIONS

An IWLP in patients with obesity and severe OSA is effective for reducing weight and OSA severity. It also results in an improvement in lipid profiles, glycemic control, and inflammatory markers.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: Effectiveness of an Intensive Weight Loss Program for Obstructive Sleep Apnea Syndrome (OSAS) Treatment; Identifier: NCT02832414; URL: https://clinicaltrials.gov/ct2/show/record/NCT02832414.

Reduction in sympathetic tone in patients with obstructive sleep apnoea: is fixed CPAP more effective than APAP? A randomised, parallel trial protocol

INTRODUCTION

Obstructive sleep apnoea (OSA) is a prevalent disease associated with cardiovascular events. Hypertension is one of the major intermediary mechanisms leading to long-term cardiovascular adverse events. Intermittent hypoxia and hypercapnia associated with nocturnal respiratory events stimulate chemoreflexes, resulting in sympathetic overactivity and blood pressure (BP) elevation. Continuous positive airway pressure (CPAP) is the primary treatment for OSA and induces a small but significant reduction in BP. The use of auto-adjusting positive airway pressure (APAP) has increased in the last years and studies showed different ranges of BP reduction when comparing both modalities. However, the pathophysiological mechanisms implicated are not fully elucidated. Variations in pressure through the night inherent to APAP may induce persistent respiratory efforts and sleep fragmentation that might impair sympathovagal balance during sleep and result in smaller decreases in BP. Therefore, this double-blind randomised controlled trial aims to compare muscle sympathetic nerve activity (MSNA) assessed by microneurography (reference method for measuring sympathetic activity) after 1 month of APAP versus fixed CPAP in treatment-naive OSA patients. This present manuscript describes the design of our study, no results are presented herein. and is registered under the below reference number.

METHODS AND ANALYSIS

Adult subjects with newly diagnosed OSA (Apnoea-Hypopnoea Index >20/hour) will be randomised for treatment with APAP or fixed CPAP. Measurements of sympathetic activity by MSNA, heart rate variability and catecholamines will be obtained at baseline and after 30 days. The primary composite outcome will be the change in sympathetic tone measured by MSNA in bursts/min and bursts/100 heartbeats. Sample size calculation was performed with bilateral assumption. We will use the Student's t-test to compare changes in sympathetic tone between groups.

ETHICS AND DISSEMINATION

The protocol was approved by The French Regional Ethics Committee. The study started in March 2018 with primary completion expected to March 2019. Dissemination plans of the results include presentations at conferences and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03428516; Pre-results.

Internal nasal dilator in patients with obstructive sleep apnea

The nasal valve area has the minimal cross-sectional area of the upper airways. Obstructive sleep apnea (OSA) is a common disorder. It has been reported that nasal obstruction may be associated with OSA. The aim of this study was to investigate whether the use an internal nasal dilator may be able to affect respiratory pattern in a group of patients with OSA. The use of internal nasal dilator was able to significantly reduce two relevant respiratory outcomes, such as the apnea-hypopnea index and the oxygen desaturation index, notably there was also a positive trend for the reduction of total sleep time with HbO₂ <90%). Nas-air® was also able to significantly improve restorative sleep performance. In conclusion, the present study demonstrates that Nas-air® is a new internal nasal dilator potentially capable to significantly improve respiratory outcomes and sleep quality. (www.actabiomedica.it)

Effects of continuous positive airway pressure on elderly patients with obstructive sleep apnea: a meta-analysis

OBJECTIVE

the aim of the study was to evaluate the efficacy of continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea in the elderly.

METHOD

a comprehensive search for qualified clinical trials was performed on April, 2016. Basic demographic information of enrolled subjects, study design, survival rate, cardiovascular events, quality of life scores, and neurocognitive data were extracted for analysis.

RESULTS

A total of seven clinical trials were included in this meta-analysis, in which untreated elderly patients exhibited worse survival rate than those with CPAP (OR=2.22, 95% CI=1.64 to 3.01, P< 0.00001). Treated elderly patients exhibited less cardiovascular risk than those without CPAP (RR=0.49, 95% CI=0.36 to 0.66, P<0.00001) and a statistically significant improvement on all the domains of Quebec Sleepiness Questionnaire, supported by pooled weighted mean difference. Furthermore, CPAP treatment partially improved the cognitive functions.

CONCLUSION

CPAP treatment achieves improvements in decreasing mortality and controlling cardiovascular events and exhibits few effects on neurocognitive function. Further large-scale, well-designed interventional investigation is needed.

Combined Surgical Approach for Obstructive Sleep Apnea Patient

Obstructive sleep apnea (OSA) is a disease that is associated with high morbidity and mortality and can significantly impact the quality of life in a patient. OSA is strongly associated with obesity, and literature showed that weight loss will lead to improvement in OSA. The gold standard treatment for OSA is continuous positive airway pressure (CPAP). However, other methods of treatment are available. One of these methods is multilevel sleep surgery (MLS). Literature showed that bariatric surgery can also improve OSA. A common question is which surgical procedure of these two should be performed first. We present a 5-year follow-up of a patient who underwent simultaneously bariatric surgery and MLS. His apnea-hypopnea index (AHI) decreased from 53 episodes per hour to 5.2 per hour within the first 18 months, which was measured via a level 3 polysomnography. Five years after the surgery, a repeat level 3 polysomnography showed an AHI of 6.8 episodes per hour, and the patient is asymptomatic. The patient maintained his weight and did not use CPAP after the combined surgery during the five-year period.

The effect of positive and negative message framing on short term continuous positive airway pressure compliance in patients with obstructive sleep apnea

Background

Continuous positive airway pressure (CPAP), the best available treatment for obstructive sleep apnea (OSA), requires long-term compliance to be effective. Behavioral interventions may be used to improve adherence to CPAP. We aimed to investigate whether positive or negative message framing impacts on CPAP compliance in patients with OSA, when compared to standard care.

Methods

Consenting patients with confirmed OSA were randomly allocated to receive along with their CPAP either positively or negatively framed messages (Pos; Neg), or standard care (Con). Standardized motivational messages were read out to patients during an initial teaching session and through weekly telephone calls. Patients' compliance data were reviewed 2 and 6 weeks following CPAP initiation.

Results

We randomized 112 patients to groups that were matched for age, BMI, and OSA severity. The positively framed group (Pos) showed greater CPAP usage after 2 weeks (total use 53.7±31.4 hours) as compared to the negatively framed and the control group (35.6±27.4 and 40.8±33.5 hours, P<0.05); however, no differences were seen at 6 weeks. There were more dropouts in the control group than in either framed groups (Pos n=5; Neg n=8; Con n=11; P<0.05).

Conclusions

Positively framed messages can improve CPAP adherence in patients with OSA in the short-term; however, strategies for implementing its long-term use need to be developed.

Effect of Continuous Positive Airway Pressure on Blood Pressure Variability in Patients With Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common risk factor for cardiovascular disease. Continuous positive airway pressure (CPAP) improves OSA symptoms and blood pressure (BP) control. The effect of CPAP on BP variability (BPV) in patients with and without hypertension treated with autotitrating CPAP (APAP) for 2 weeks was studied. A total of 78 participants (76.9% men, 49% hypertensive, mean body mass index 36.2 [6.9] kg/m2 , age 49.0 [12.9] years) underwent 2 weeks of APAP therapy. Office BP, BPV (standard deviation of three BP measurements), and pulse rate were measured before and after treatment. Systolic BPV (5.3±4.9 vs 4.2±3.4 mm Hg, P=.047) and pulse rate (78.0±14.5 vs 75.5±15.8 beats per minute, P=.032) decreased after treatment, particularly in hypertensive participants. Mask leak was independently associated with reduced changes in systolic BPV (r=-0.237, P=.048). Short-term APAP treatment reduced BPV and pulse rate, particularly in hypertensive patients with OSA.

Cost-effectiveness of Continuous Positive Airway Pressure Treatment in Moderate-Severe Obstructive Sleep Apnea Syndrome

INTRODUCTION

The socioeconomic impact of obstructive sleep apnea-hypopnea syndrome (OSAHS) is considerable. The aim of this study was to evaluate the cost-effectiveness of treating OSAHS with continuous positive airway pressure (CPAP) and the impact of CPAP compliance.

METHODS

This was a retrospective, case-crossover study of 373 patients with OSAHS receiving CPAP. We compared changes in costs, Epworth score and health-related quality of life (EQ-5D questionnaires) between the year before treatment and the year after treatment. The incremental cost-effectiveness ratio (ICER) for the first year of treatment was estimated, and projections were made for the second year, using different effectiveness and cost scenarios.

RESULTS

The visual analog scale score for the EQ-5D questionnaire increased by 5 points and the Epworth score fell by 10 points during the year of CPAP treatment. Mean gain in quality-adjusted life years (QALY) was 0.05 per patient per year (P<.001): 0.07 among compliers and -0.04 among non-compliers. ICER was €51,147/QALY during the first year of CPAP treatment and €1,544/QALY during the second year.

CONCLUSION

CPAP treatment in patients with moderate-severe OSAHS improves the quality of life of compliant patients, and is cost-effective as of the second year.

A Randomized Controlled Trial of Continuous Positive Airway Pressure on Glucose Tolerance in Obese Patients with Obstructive Sleep Apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with an increased prevalence of metabolic syndrome (MetS), even in patients with morbid obesity. Our goal was to address whether continuous positive airway pressure (CPAP) treatment improved glucose metabolism in this population.

METHODS

A prospective randomized controlled trial was performed in severe OSA patients with morbid obesity without diabetes in two university referral hospitals. Patients received conservative (CT) versus CPAP treatment for 12 weeks. MetS components, homeostasis model assessment of insulin resistance (HOMA-IR) and oral glucose tolerance were assessed at baseline and after treatment.

RESULTS

A total of 80 patients completed the study (42 CPAP and 38 CT patients). After 12 w of CPAP treatment, weight loss was similar in both groups and physical activity, prevalence of MetS, and HOMA-IR did not change in either group. In the CPAP group impaired glucose tolerance (IGT) reversed in nine patients and IGT developed in none, whereas IGT reversed in five patients and IGT developed in five patients in the CT group (P = 0.039 in the Fisher test). Changes in 2-h plasma glucose after glucose load were greater in the CPAP group than in the CT group (CPAP: -0.5 ± 1.5 versus CT: 0.33 ± 1.9, P = 0.007).

CONCLUSIONS

The improvement of glucose tolerance in morbidly obese patients with severe obstructive sleep apnea, without changes in homeostasis model assessment of insulin resistance, supports an improvement in peripheral insulin resistance after continuous positive airway pressure treatment.

CLINICAL TRIALS REGISTRATION

NCT 01029561.

The influence of multilevel upper airway surgery on CPAP tolerance in non-responders to obstructive sleep apnea surgery

The aim of this study was to evaluate the influence of multilevel upper airway surgery on subsequent continuous positive airway pressure (CPAP) use and tolerance in patients with moderate to severe obstructive sleep apnea (OSA). The study cohort enrolled 67 consecutive patients, who underwent septoplasty plus modified uvulopharyngopalatoplasty (mUPPP) with or without modified tongue base suspension (mTBS) due to CPAP intolerance, and who had residual OSA requiring CPAP therapy [non-responders to surgery, apnea-hypopnea index (AHI) >15 events/h] that had been confirmed by control polysomnography at the sixth month postoperatively. A questionnaire including questions on postoperative CPAP use, problems faced during CPAP use after the surgery, change in OSA symptoms, and satisfaction with the surgery was designed, and filled through interviews. Seventeen (25.4 %) patients had septoplasty plus mUPPP and 50 (74.6 %) had septoplasty plus mUPPP combined with mTBS. Postoperatively, mean AHI (45.00 ± 19.76 vs. 36.60 ± 18.34), Epworth sleepiness scale (ESS) score (18.00 ± 4.45 vs. 13.00 ± 4.72), oxygen desaturation index (ODI) (48.98 ± 16.73 vs. 37.81 ± 17.03), and optimal CPAP level (11.80 ± 1.40 vs. 8.96 ± 1.20) were decreased (p < 0.001 for all parameters). Fifty-nine percent of patients reported that they fairly satisfied with the surgery and 49.2 % reported that their symptoms were completely resolved. While none of the cases could tolerate CPAP before surgery, almost half (47.8 %) of the cases used CPAP without problems postoperatively. Postoperative CPAP users had significantly higher postoperative AHI (p = 0.001), supine AHI (p = 0.009), ESS (p = 0.019), and ODI (p = 0.014), and significantly lower postoperative minimum O2 saturation (p = 0.001) compared with non-users. Multilevel upper airway surgery with less invasive techniques may improve CPAP tolerance in well-selected patients.

A comparison of CPAP and CPAPFLEX in the treatment of obstructive sleep apnea in World Trade Center responders: study protocol for a randomized controlled trial

Background

Following the World Trade Center disaster, a large number of individuals involved in rescue and recovery activity were exposed to significant amounts of dust, and reported symptoms of chronic nasal and sinus inflammation. An unusually high prevalence of obstructive sleep apnea (OSA) has also been observed in this World Trade Center Responder population. This project aims to examine the relationship between nasal pathology and OSA. Our hypothesis is that increased nasal resistance due to nasal inflammation predisposes to OSA in this population. Continuous Positive Airway Pressure (CPAP) is the standard therapy for OSA but despite its efficacy has poor adherence. Subjects with high nasal resistance may have greater difficulty in tolerating this therapy than those who do not have high nasal resistance. Reduction of excess expiratory positive pressure by the modality known as Cflex™ during Continuous Positive Airway Pressure therapy (CPAP_Flex) has been suggested to improve comfort without compromising efficacy. We will compare CPAP to CPAP_Flex in subjects with OSA.

Study Design

Subjects with new onset habitual snoring will be screened for OSA using home sleep studies and rhinomanometry will be used to determine nasal resistance. In 400 subjects with OSA we will perform a randomized double blind cross-over study comparing CPAP to CPAP_flex, and relate nasal resistance to adherence to CPAP therapy.

Discussion

This is the first multicenter trial designed to test the hypothesis that adherence to CPAP therapy relates to nasal resistance and CPAP_Flex will improve adherence to CPAP in those subjects with high nasal resistance.

We anticipate the following results from this trial: 1. Increased nasal resistance is associated with decreased adherence to CPAP therapy. 2. Use of CPAP_Flex improves adherence with CPAP therapy in subjects with high nasal resistance, but not in those with low nasal resistance. 3. The benefit of CPAP_Flex on adherence is greatest when offered at CPAP therapy initiation rather than as a “rescue” therapy in subjects with high nasal resistance.

Trial Registration

ClinicalTrials.gov Identifier: NCT01753999, Date: 12 December 2012

Clinical effectiveness and cost-effectiveness results from the randomised controlled Trial of Oral Mandibular Advancement Devices for Obstructive sleep apnoea-hypopnoea (TOMADO) and long-term economic analysis of oral devices and continuous positive airway pressure

BACKGROUND

Obstructive sleep apnoea-hypopnoea (OSAH) causes excessive daytime sleepiness (EDS), impairs quality of life (QoL) and increases cardiovascular disease and road traffic accident risks. Continuous positive airway pressure (CPAP) treatment is clinically effective but undermined by intolerance, and its cost-effectiveness is borderline in milder cases. Mandibular advancement devices (MADs) are another option, but evidence is lacking regarding their clinical effectiveness and cost-effectiveness in milder disease.

OBJECTIVES

(1) Conduct a randomised controlled trial (RCT) examining the clinical effectiveness and cost-effectiveness of MADs against no treatment in mild to moderate OSAH. (2) Update systematic reviews and an existing health economic decision model with data from the Trial of Oral Mandibular Advancement Devices for Obstructive sleep apnoea-hypopnoea (TOMADO) and newly published results to better inform long-term clinical effectiveness and cost-effectiveness of MADs and CPAP in mild to moderate OSAH.

TOMADO

A crossover RCT comparing clinical effectiveness and cost-effectiveness of three MADs: self-moulded [SleepPro 1™ (SP1); Meditas Ltd, Winchester, UK]; semibespoke [SleepPro 2™ (SP2); Meditas Ltd, Winchester, UK]; and fully bespoke [bespoke MAD (bMAD); NHS Oral-Maxillofacial Laboratory, Addenbrooke's Hospital, Cambridge, UK] against no treatment, in 90 adults with mild to moderate OSAH. All devices improved primary outcome [apnoea-hypopnoea index (AHI)] compared with no treatment: relative risk 0.74 [95% confidence interval (CI) 0.62 to 0.89] for SP1; relative risk 0.67 (95% CI 0.59 to 0.76) for SP2; and relative risk 0.64 (95% CI 0.55 to 0.76) for bMAD (p < 0.001). Differences between MADs were not significant. Sleepiness [as measured by the Epworth Sleepiness Scale (ESS)] was scored 1.51 [95% CI 0.73 to 2.29 (SP1)] to 2.37 [95% CI 1.53 to 3.22 (bMAD)] lower than no treatment (p < 0.001), with SP2 and bMAD significantly better than SP1. All MADs improved disease-specific QoL. Compliance was lower for SP1, which was unpopular at trial exit. At 4 weeks, all devices were cost-effective at £20,000/quality-adjusted life-year (QALY), with SP2 the best value below £39,800/QALY.

META-ANALYSIS

A MEDLINE, EMBASE and Science Citation Index search updating two existing systematic reviews (one from November 2006 and the other from June 2008) to August 2013 identified 77 RCTs in adult OSAH patients comparing MAD with conservative management (CM), MADs with CPAP or CPAP with CM. MADs and CPAP significantly improved AHI [MAD -9.3/hour (p < 0.001); CPAP -25.4/hour (p < 0.001)]. Effect difference between CPAP and MADs was 7.0/hour (p < 0.001), favouring CPAP. No trials compared CPAP with MADs in mild OSAH. MAD and CPAP reduced the ESS score similarly [MAD 1.6 (p < 0.001); CPAP 1.6 (p < 0.001)].

LONG-TERM COST-EFFECTIVENESS

An existing model assessed lifetime cost-utility of MAD and CPAP in mild to moderate OSAH, using the revised meta-analysis to update input values. The TOMADO provided utility estimates, mapping ESS score to European Quality of Life-5 Dimensions three-level version for device cost-utility. Using SP2 as the standard device, MADs produced higher mean costs and mean QALYs than CM [incremental cost-effectiveness ratio (ICER) £6687/QALY]. From a willingness to pay (WTP) of £15,367/QALY, CPAP is cost-effective, although the likelihood of MADs (p = 0.48) and CPAP (p = 0.49) being cost-effective is very similar. Both were better than CM, but there was much uncertainty in the choice between CPAP and MAD (at a WTP £20,000/QALY, the probability of being the most cost-effective was 47% for MAD and 52% for CPAP). When SP2 lifespan increased to 18 months, the ICER for CPAP compared with MAD became £44,066. The ICER for SP1 compared with CM was £1552, and for bMAD compared with CM the ICER was £13,836. The ICER for CPAP compared with SP1 was £89,182, but CPAP produced lower mean costs and higher mean QALYs than bMAD. Differential compliance rates for CPAP reduces cost-effectiveness so MADs become less costly and more clinically effective with CPAP compliance 90% of SP2.

CONCLUSIONS

Mandibular advancement devices are clinically effective and cost-effective in mild to moderate OSAH. A semi-bespoke MAD is the appropriate first choice in most patients in the short term. Future work should explore whether or not adjustable MADs give additional clinical and cost benefits. Further data on longer-term cardiovascular risk and its risk factors would reduce uncertainty in the health economic model and improve precision of effectiveness estimates.

TRIAL REGISTRATION

This trial is registered as ISRCTN02309506.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 67. See the NIHR Journals Library website for further project information.

Beyond the genome: epigenetic mechanisms in lung remodeling

The lung develops from a very simple outpouching of the foregut into a highly complex, finely structured organ with multiple specialized cell types that are required for its normal physiological function. During both the development of the lung and its remodeling in the context of disease or response to injury, gene expression must be activated and silenced in a coordinated manner to achieve the tremendous phenotypic heterogeneity of cell types required for homeostasis and pathogenesis. Epigenetic mechanisms, consisting of DNA base modifications such as methylation, alteration of histones resulting in chromatin modification, and the action of noncoding RNA, control the regulation of information "beyond the genome" required for both lung modeling and remodeling. Epigenetic regulation is subject to modification by environmental stimuli, such as oxidative stress, infection, and aging, and is thus critically important in chronic remodeling disorders such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), bronchopulmonary dysplasia (BPD), and pulmonary hypertension (PH). Technological advances have made it possible to evaluate genome-wide epigenetic changes (epigenomics) in diseases of lung remodeling, clarifying existing pathophysiological paradigms and uncovering novel mechanisms of disease. Many of these represent new therapeutic targets. Advances in epigenomic technology will accelerate our understanding of lung development and remodeling, and lead to novel treatments for chronic lung diseases.

Cardiovascular mortality in obstructive sleep apnoea treated with continuous positive airway pressure or oral appliance: an observational study

BACKGROUND AND OBJECTIVE

The objective of this study was to evaluate the long-term cardiovascular mortality in patients with severe obstructive sleep apnoea (OSA) treated with either continuous positive airway pressure (CPAP) or mandibular advancing device (MAD).

METHODS

A non-concurrent cohort study of 570 subjects with severe OSA (apnoea/hypopnoea index (AHI) ≥ 30/h) and a control group of 269 subjects (AHI < 5/h) were followed up for a median of 79 months (interquartile range 76-88 months). All patients received CPAP initially. MAD was offered for those who were non-adherent to CPAP. The endpoint was cardiovascular death.

RESULTS

Two hundred and eight control subjects, 177 patients treated with CPAP, 72 with MAD and 212 who declined treatment were analysed. Forty-two patients had a fatal cardiovascular event during the course of the study. The non-apnoeic group had the lowest cardiovascular death rate (0.28 per 100 person-years (95% confidence interval (CI): 0.08-0.71)) followed by the CPAP-treated (0.56 per 100 person-years (95% CI: 0.20-1.23)) and the MAD-treated OSA group (0.61 per 100 person-years (95% CI: 0.13-1.78)), with the highest cardiovascular mortality rate observed in the untreated OSA group (2.1 per 100 person-years (95% CI: 1.37-2.92)). Although residual AHI for MAD-treated patients was significantly higher than CPAP-treated patients (16.3 ± 5.1/h vs. 4.5 ± 2.3/h; P < 0.001), there was no difference in cardiovascular death rate between the two groups (hazard ratio 1.08 (95% CI: 0.55-1.74); P = 0.71).

CONCLUSIONS

Both CPAP and MAD may be equally effective therapy in reducing the risk of fatal cardiovascular events in patients with severe OSA.

Depression, physical activity, energy consumption, and quality of life in OSA patients before and after CPAP treatment

BACKGROUND

A variety of studies have demonstrated improvement in quality of life and depressive symptoms in obstructive sleep apnea (OSA) patients after continuous positive airway pressure (CPAP) treatment. However, very little is known about the effect of OSA treatment on physical activity and energy consumption.

OBJECTIVES

The aim of this study was to evaluate the changes in depression, physical activity, energy expenditure, and quality of life (QoL) in OSA patients before and after CPAP therapy.

METHODS

Forty-one patients with OSA as revealed by polysomnography, were included to the study. They responded to the generic World Health Organization Quality of Life (WHOQoL) questionnaire, to the specific-disease Quebec Sleep Questionnaire, and to Center for Epidemiologic Studies Depression Scale (CES-D) in order to evaluate QoL and the incidence of depression. In addition, all patients wore an accelerometer which measured physical activity and energy expenditure during a week. At least 6 months after initiation of CPAP treatment (mean time, 9 months) we re-examined 24 patients who met the compliance with the treatment criteria.

RESULTS

Patients after CPAP therapy had significantly higher scores in all domains of the Quebec Sleep Questionnaire and in the domains of physical health/level of independence and psychological health/spirituality of the WHOQoL. Depression scores were also better in CES-D after treatment. However, despite the improvement in QoL and psychological status, CPAP therapy had no impact on physical activity and energy expenditure.

CONCLUSIONS

CPAP therapy improves QoL and lessens depressive symptoms in our group of well-treated OSA patients. However, physical activity and energy expenditure did not present statistically significant improvement in the same group of OSA patients.

Reliability of telemedicine in the diagnosis and treatment of sleep apnea syndrome

BACKGROUND

Advances in information technology and telecommunications have provided the option of making it easier to diagnose and treat obstructive sleep apnea syndrome (OSAS) using telemedicine techniques. This study assessed the feasibility and reliability of respiratory polygraphy and prescription of treatment by pressure adjustment with auto-continuous positive airway pressure (CPAP) systems, both being transmitted telematically to the Sleep Unit, with teleconsultation as a support method.

SUBJECTS AND METHODS

Forty patients were studied from a population 80 km from the Sleep Unit using respiratory polygraphy transmitted in real time. They were divided into two groups: one was seen by conventional consultation, and the other was seen using teleconsultation. We also estimated satisfaction with this system and its costs.

RESULTS

The mean patient age was 53 ± 10.3 years, with a body mass index of 31 ± 6.2 kg/m(2) and an Epworth score of 12 ± 5.3. In total, 35 patients were diagnosed with OSAS, with an Apnea-Hypopnea Index of ≥10, and CPAP treatment was started in 16 of them. The agreement in the Apnea-Hypopnea Index, total apneas and hypopneas, mean oxygen saturation, and time with an oxygen saturation <90% was greater than 90% between the studies transmitted in real time and those stored in the polygraph. The level of compliance with CPAP treatment was 85% for the patients who were seen in a conventional clinic and 75% in those seen by teleconsultation.

CONCLUSIONS

The use of telematic techniques is useful to establish a diagnostic and therapeutic strategy for OSAS with the creation of a Wide Core Sleep Laboratory as a process controller.

Emerging therapies for obstructive sleep apnea

Obstructive sleep apnea (OSA) is a prevalent disorder often associated with daytime sleepiness, cognitive dysfunction, and adverse cardiovascular consequences. Available therapies are limited by either lack of long-term adherence or low response rates. Two emerging therapies hold promise in providing alternatives to patients with OSA. The first stems from the importance of the upper-airway dilator muscles in maintaining pharyngeal stability. Electrical stimulation of the genioglossus muscle improves both upper-airway diameter and ameliorates pharyngeal obstruction. The results of phase I and II clinical trials hold promise, but the reported improvements in the apnea-hypopnea index vary between subjects and concerns about long-term safety await long-term studies. The second technology relies on creating an increased expiratory nasal resistance via a bidirectional valve designed to be worn just inside the nostrils. Initial findings of clinical trials suggest reduction in severity of sleep apnea and subjective daytime sleepiness. Considerable heterogeneity in response to the nasal device was noted despite the high adherence rates. It remains unclear which patients will likely benefit a priori from these devices.

The supraglottic effect of a reduction in expiratory mask pressure during continuous positive airway pressure

STUDY OBJECTIVES

Patients with obstructive sleep apnea may have difficulty exhaling against positive pressure, hence limiting their acceptance of continuous positive airway pressure (CPAP). C-Flex is designed to improve comfort by reducing pressure in the mask during expiration proportionally to expiratory airflow (3 settings correspond to increasing pressure changes). When patients use CPAP, nasal resistance determines how much higher supraglottic pressure is than mask pressure. We hypothesized that increased nasal resistance results in increased expiratory supraglottic pressure swings that could be mitigated by the effects of C-Flex on mask pressure.

DESIGN

Cohort study.

SETTING

Sleep center.

PARTICIPANTS

Seventeen patients with obstructive sleep apnea/hypopnea syndrome and a mechanical model of the upper airway.

INTERVENTIONS

In patients on fixed CPAP, CPAP with different C-Flex levels was applied multiple times during the night. In the model, 2 different respiratory patterns and resistances were tested.

MEASUREMENTS AND RESULTS

Airflow, expiratory mask, and supraglottic pressures were measured on CPAP and on C-Flex. Swings in pressure during expiration were determined. On CPAP, higher nasal resistance produced greater expiratory pressure swings in the supraglottis in the patients and in the model, as expected. C-Flex 3 produced expiratory drops in mask pressure (range -0.03 to -2.49 cm H(2)O) but mitigated the expiratory pressure rise in the supraglottis only during a sinusoidal respiratory pattern in the model.

CONCLUSIONS

Expiratory changes in mask pressure induced by C-Flex did not uniformly transmit to the supraglottis in either patients with obstructive sleep apnea on CPAP or in a mechanical model of the upper airway with fixed resistance. Data suggest that the observed lack of expiratory drop in supraglottic pressure swings is related to dynamics of the C-Flex algorithm.

Effects of continuous positive airway pressure on apnea-hypopnea index in obstructive sleep apnea based on long-term compliance

PURPOSE

Although continuous positive airway pressure (CPAP) is the gold standard in the treatment of obstructive sleep apnea (OSA), its effectiveness depends on the regular use. In this retrospective study, the effectiveness of CPAP with regard to the reduction of the apnea-hypopnea index was calculated based on individual adherence data extracted from a cohort of patients with OSA METHODS: The electronic database was analyzed for follow-up visits of patients receiving CPAP for OSA. The following information was extracted the charts of 750 patients: apnea-hypopnea index (AHI) at diagnosis, AHI with CPAP, duration of therapy, hours of CPAP use, and subjective hours of sleep. Eighty-two successfully treated and stable CPAP patients (AHI/Epworth Sleepiness Scale (ESS) at baseline 35.6 ± 22.1/10.5 ± 5.1) could be further evaluated.

RESULTS

Mean AHI under CPAP was 2.4 ± 2.5 with an ESS of 6.9 ± 4.2. Subjective hours of sleep were 6.5 ± 1.1. The average treatment period was 584.6 ± 566.5 days (3,800 h of sleep). Mean hours of use was 2,712 ± 3,234 (4.69 ± 2.42 per night). This leads to the following calculated measures: hours of sleep without CPAP, 1,088; number of respiratory events with CPAP, 6508.8; number of respiratory events without CPAP, 38,732.8; total number or respiratory events, 45,241.6; average AHI, 11.91.

CONCLUSIONS

Even in an ideal group of patients, CPAP cannot eliminate respiratory events due to limited adherence. Adherence needs to be taken into account when comparing the effects of CPAP on the AHI with alternative treatment methods, especially those with 100% adherence (e.g., surgery).

Awake measures of nasal resistance and upper airway resistance on CPAP during sleep

STUDY OBJECTIVES

Since on CPAP, the nose is the primary determinant of upper airway resistance, we assess utility of noninvasive measures of nasal resistance during wakefulness as a predictor of directly assessed upper airway resistance on CPAP during sleep in patients with obstructive sleep apnea/hypopnea syndrome.

METHODS

Patients with complaints of snoring and excessive daytime sleepiness were recruited. 14 subjects underwent daytime evaluations including clinical assessment, subjective questionnaires to assess nasal symptoms and evaluation of nasal resistance with acoustic rhinometry (AR) and active anterior rhinomanometry (RM) in the sitting and supine positions. Patients underwent nocturnal polysomnography on optimal CPAP with measurements of supraglottic pressure to evaluate upper airway resistance. Comparisons were made between nasal resistance using AR and RM during wakefulness, and between AR and RM awake and upper airway resistance during sleep.

RESULTS

Our study shows that measures of awake nasal resistance using AR and RM had little or no correlation to each other in the sitting position, whereas there was significant but weak correlation in the supine position. Upper airway resistance measured while on CPAP during sleep did not show significant relationships to any of the awake measures of nasal resistance (AR or RM).

CONCLUSION

Awake measurements of nasal resistance do not seem to be predictive of upper airway resistance during sleep on CPAP.

Predictors of continuous positive airway pressure adherence

Continuous positive airway pressure (CPAP) is the leading treatment for obstructive sleep apnoea (OSA), a prevalent disorder of breathing in sleep strongly associated with obesity. OSA has serious adverse health, social and community effects arising from disturbed breathing, loud snoring, poor quality sleep and cardiovascular sequelae. When used appropriately, CPAP treatment is highly effective in normalising breathing and sleep, improving symptoms and lowering adverse event risk. However, patients do not necessarily accept, tolerate or comply with treatment, with many factors influencing CPAP uptake and longer term use. Although knowledge to address challenges affecting CPAP adherence and CPAP mask and machine technologies continue to improve incrementally, optimising CPAP treatment adherence is an ongoing challenge in sleep medicine.

Metabolic effects of the obstructive sleep apnea syndrome and cardiovascular risk

The obstructive sleep apnea syndrome (OSAS) is characterized by collapse of the upper airway during sleep, recurring apneas, intermittent hypoxemia and daytime somnolence. OSAS is often associated with obesity, and its prevalence is expected to rise due to the obesity epidemics worldwide. OSAS is associated with increased cardiovascular risk which appears to be normalized by treatment with nasal continuous positive airway pressure (nCPAP) during sleep, suggesting an independent role of OSAS in accelerating atherosclerosis. Insulin resistance (IR) and the metabolic syndrome (MetS) are often found in OSAS patients, but the relative role played by OSAS and obesity is still unclear. Both OSAS and MetS may exert negative synergistic effects on the cardiovascular system through multiple mechanisms (hypoxemia, sleep disruption, activation of the sympathetic nervous system, inflammatory activation). Besides nCPAP treatment, pharmacologic interventions to treat obesity and the MetS could improve cardiovascular prevention in OSAS.