Obstructive sleep apnea and cardiovascular disease

Prevalence, Risk Factors, and Impact of Obstructive Sleep Apnea in Adults with Congenital Heart Disease

The objective of our study was to determine the prevalence, risk factors, and the impact of obstructive sleep apnea (OSA) in the adult with congenital heart disease (ACHD). One hundred forty-nine consecutive patients seen in our ACHD program were screened for OSA using the Berlin Questionnaire. Demographic and clinical details on subjects were collected through a chart review. Clinical variables were analyzed to determine risk factors for positive OSA screen, as well as associated outcomes. Seventy-seven (52%) of our cohort were females. The median age of the cohort was 33 years (range = 18-74) and median weight was 79 kg (range = 50-145 kg). Overall, 47 (31%) of our cohort were found to have a positive OSA screen using the Berlin questionnaire. Median age of the patients whom tested positive was 34 years. Compared to patients with a negative screen, patients with a positive OSA screen were more likely to be heavier with a median weight of 99 kg vs 71 kg (p < 0.01) and a larger BMI (31 vs 25 kg/m², p < 0.01). Overall, 55% of patients whom screened positive were obese (defined as a BMI > 30) compared to 15% in the negative group (p < 0.02). Patients with a positive screen were more likely to have other co-morbidities including diabetes (p < 0.04), hypertension (p < 0.05), depression (p < 0.002), and were more likely to have decreased exercise capacity (p < 0.01) and a defibrillator (p < 0.007). Our data demonstrates that OSA is common in the ACHD patient and is associated with increasing weight and BMI. Patients with a positive screen are at increased risk for multiple co morbidities including diabetes, hypertension, and depression. We believe our data supports the use of screening protocols for OSA in the ACHD population in effort to identify early, treat, and potentially prevent late complications.

Modafinil and the risk of cardiovascular events: Findings from three US claims databases

PURPOSE

This study examined the potential risk of cardiovascular (CV) events associated with modafinil and the consistency of the risk estimates across databases.

METHODS

A retrospective, inception cohort design of patients who initiated treatment with modafinil between 2006 and 2008 was used in three US health care claims databases. Modafinil users were matched with nonusers. Patients were further divided into two cohorts of obstructive sleep apnea (OSA) and non-OSA (NOSA) cohorts. Endpoints of interest, including myocardial infarction (MI), stroke, CV hospitalizations, and all-cause death, were assessed using incidence rates and Cox proportional hazard ratios (HRs), adjusted for potential confounding factors.

RESULTS

The cohorts included a total of 175 524 patients in MarketScan CM; 77 266-in IMS LifeLink; and 8174-in MarketScan Medicaid. No increased risk for MI in the OSA and NOSA cohorts was observed across all three databases. The risks of CV hospitalization in the OSA and NOSA cohorts were not different between the modafinil users and nonusers, except for IMS LifeLink database where the HR was lower than one in the modafinil users compared with the nonusers (HR, 0.69; 95% confidence interval [CI], 0.54 to 0.87). For OSA patients with prior stroke, an adjusted HR of 1.96 (95% CI, 1.02 to 3.76) was observed for stroke among modafinil users compared with nonusers. Among the NOSA, the HRs for all-cause death in the OSA were inconsistent across databases.

CONCLUSIONS

Except for few CV outcomes, applying one common protocol generated consistent risk estimates of CV events following modafinil use across cohorts and databases.

Role of Oxidative Stress in the Neurocognitive Dysfunction of Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is characterized by chronic nocturnal intermittent hypoxia and sleep fragmentations. Neurocognitive dysfunction, a significant and extraordinary complication of OSAS, influences patients' career, family, and social life and reduces quality of life to some extent. Previous researches revealed that repetitive hypoxia and reoxygenation caused mitochondria and endoplasmic reticulum dysfunction, overactivated NADPH oxidase, xanthine oxidase, and uncoupling nitric oxide synthase, induced an imbalance between prooxidants and antioxidants, and then got rise to a series of oxidative stress (OS) responses, such as protein oxidation, lipid peroxidation, and DNA oxidation along with inflammatory reaction. OS in brain could trigger neuron injury especially in the hippocampus and cerebral cortex regions. Those two regions are fairly susceptible to hypoxia and oxidative stress production which could consequently result in cognitive dysfunction. Apart from continuous positive airway pressure (CPAP), antioxidant may be a promising therapeutic method to improve partially reversible neurocognitive function. Understanding the role that OS played in the cognitive deficits is crucial for future research and therapeutic strategy development. In this paper, recent important literature concerning the relationship between oxidative stress and cognitive impairment in OSAS will be summarized and the results can provide a rewarding overview for future breakthrough in this field.

A novel implantable device for a minimally invasive surgical treatment of obstructive sleep apnea: design and preclinical safety assessment

BACKGROUND

In obstructive sleep apnea (OSA), occlusion of the upper airway by soft tissue causes intermittent hypoxemia and can have serious sequelae. A novel implantable medical device for OSA is composed of a linear silicone elastic element held in an extended state by a bioabsorbable external sheath. The implant is delivered to the tongue base or soft palate via a minimally invasive approach. Normal tissue healing anchors the device at the attachment points before the bioabsorbable material dissolves and the elastic element contracts to stabilize the surrounding tissue.

METHODS

Device prototypes were evaluated in multiple investigations: 1) a finite elements analysis model simulated the movement of the tongue base during sleep with and without the implant; 2) dynamic mechanical testing simulated 10 years' normal use; 3) cadaveric implantations were conducted; 4) an ovine study in which implants of varying design were evaluated via gross pathology and histological assessment; and 5) a canine study in which implants of varying design in the tongue base and soft palate were evaluated via gross pathology and histological assessment.

RESULTS

1) The implant was capable of reducing ~95% of tongue base movement during simulated sleep; 2) implants remained intact throughout the testing with no evidence of creep fatigue or change in dynamic modulus; 3) the device could be reliably deployed in the desired placement locations and was appropriate for various anatomies; and 4) all implants were well tolerated through 1 year, with minimal inflammatory responses.

CONCLUSION

This new minimally invasive device for OSA has been demonstrated, through various bench and animal testing, to be safe, well tolerated, suitable for long-term use, and to function as intended. No adverse health consequences were observed in the animals, and histological evaluation indicated good healing. This study establishes proof of concept and supports human trials.

A novel implantable device for the treatment of obstructive sleep apnea: clinical safety and feasibility

OBJECTIVE

Many cases of obstructive sleep apnea (OSA) involve collapse of the tongue base and soft palate during sleep, causing occlusion of the upper airway and leading to oxygen desaturation. Existing therapies can be effective, but they are plagued by patient adherence issues and the invasiveness of surgical approaches. A new, minimally invasive implant for OSA has been developed, which is elastic and contracts a few weeks after deployment, stabilizing the surrounding soft tissue. The device has had good outcomes in preclinical testing; this report describes the preliminary feasibility and safety of its implementation in humans.

PATIENTS AND METHODS

A prospective, multicenter, single-arm feasibility study was conducted. Subjects were adults with moderate-to-severe OSA who had previously failed or refused conventional continuous positive airway pressure treatment. Intraoperative feasibility data, postoperative pain, and safety information were collected for a 30-day postoperative period.

RESULTS

Forty subjects participated (37 men, three women; average age of 46.1 years); each received two tongue-base implants and two soft-palate implants. Surgical procedure time averaged 43 minutes. Postsurgical pain resolved readily in most cases; at 30 days post implantation, <20% of subjects reported pain, which averaged less than two out of ten. Adverse events were generally the mild and expected sequelae of a surgical procedure with general anesthesia and intraoral manipulation. The device was well tolerated. Implant extrusions were reported with soft-palate implants (n=12), while tongue-base implants required few revisions (n=2). Quantitative and qualitative sleep effectiveness outcomes (including full-night polysomnographic and quality-of-life measures) will be presented in a subsequent report.

CONCLUSION

Implantation of the device was feasible. Although a relatively high rate of extrusions occurred in the now-discontinued palate implants, tongue-base implants were largely stable and well tolerated. The minimally invasive and maintenance-free implant may provide a new alternative to higher morbidity surgical procedures.

Mood Predicts Response to Placebo CPAP

Study Objectives. Continuous positive airway pressure (CPAP) therapy is efficacious for treating obstructive sleep apnea (OSA), but recent studies with placebo CPAP (CPAP administered at subtherapeutic pressure) have revealed nonspecific (or placebo) responses to CPAP treatment. This study examined baseline psychological factors associated with beneficial effects from placebo CPAP treatment. Participants. Twenty-five participants were studied with polysomnography at baseline and after treatment with placebo CPAP. Design. Participants were randomized to either CPAP treatment or placebo CPAP. Baseline mood was assessed with the Profile of Mood States (POMS). Total mood disturbance (POMS-Total) was obtained by summing the six POMS subscale scores, with Vigor weighted negatively. The dependent variable was changed in apnea-hypopnea index (ΔAHI), calculated by subtracting pre- from post-CPAP AHI. Negative values implied improvement. Hierarchical regression analysis was performed, with pre-CPAP AHI added as a covariate to control for baseline OSA severity. Results. Baseline emotional distress predicted the drop in AHI in response to placebo CPAP. Highly distressed patients showed greater placebo response, with a 34% drop (i.e., improvement) in AHI. Conclusion. These findings underscore the importance of placebo-controlled studies of CPAP treatment. Whereas such trials are routinely included in drug trials, this paper argues for their importance even in mechanical-oriented sleep interventions.

Treating obstructive sleep apnea with hypoglossal nerve stimulation

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent pharyngeal collapse secondary to sleep-induced hypotonia of peri-pharyngeal structures. Therapy for OSA is sometimes poorly tolerated and not always effective. The current study reviews a new treatment modality, hypoglossus stimulation, recently evaluated by multiple physiological studies and currently assessed by several clinical studies.

RECENT FINDINGS

A phase-I, implantable hypoglossus nerve stimulation multicenter study was published in 2001. Significant reduction in apnea-hypopnea index (AHI) was reported in seven of the eight implanted OSA patients, but technical faults precluded prolonged follow-up. Over the past 2 years, three new hypoglossus nerve stimulation systems have been evaluated in more than 60 OSA patients. In adequately selected patients, a more than 50% reduction in AHI was observed. Usually, a decrease in OSA severity from moderate-severe to mild-minimal can be achieved.

SUMMARY

Ongoing research, including recent initiation of a large multicenter phase-III study, suggests that hypoglossus nerve stimulators are likely to be available as a new treatment modality within a few years. Additional data are needed to define which OSA patients are most likely to benefit from hypoglossus nerve stimulation. Continuous refinement of electrodes design is likely to improve stimulation efficacy in coming years.