Sex-specific associations between daytime sleepiness, chronic diseases and mortality in obstructive sleep apnea

Objective

Excessive daytime sleepiness (EDS) is common in obstructive sleep apnea (OSA) and has been linked to adverse outcomes, albeit inconsistently. Furthermore, whether the prognostic impact of EDS differs as a function of sex is unclear. We aimed to assess the associations between EDS and chronic diseases and mortality in men and women with OSA.

Methods

Newly-diagnosed adult OSA patients who underwent sleep evaluation at Mayo Clinic between November 2009 and April 2017 and completed the Epworth Sleepiness Scale (ESS) for assessment of perceived sleepiness (N = 14,823) were included. Multivariable-adjusted regression models were used to investigate the relationships between sleepiness, with ESS modeled as a binary (ESS > 10) and as a continuous variable, and chronic diseases and all-cause mortality.

Results

In cross-sectional analysis, ESS > 10 was independently associated with lower risk of hypertension in male OSA patients (odds ratio [OR], 95% confidence interval [CI]: 0.76, 0.69-0.83) and with higher risk of diabetes mellitus in both OSA men (OR, 1.17, 95% CI 1.05-1.31) and women (OR 1.26, 95% CI 1.10-1.45). Sex-specific curvilinear relations between ESS score and depression and cancer were noted. After a median 6.2 (4.5-8.1) years of follow-up, the hazard ratio for all-cause death in OSA women with ESS > 10 compared to those with ESS ≤ 10 was 1.24 (95% CI 1.05-1.47), after adjusting for demographics, sleep characteristics and comorbidities at baseline. In men, sleepiness was not associated with mortality.

Conclusion

The implications of EDS for morbidity and mortality risk in OSA are sex-dependent, with hypersomnolence being independently associated with greater vulnerability to premature death only in female patients. Efforts to mitigate mortality risk and restore daytime vigilance in women with OSA should be prioritized.

Enhancing public health and safety by diagnosing and treating obstructive sleep apnea in the transportation industry: an American Academy of Sleep Medicine position statement

Obstructive sleep apnea (OSA) may lead to serious health, safety, and financial implications-including sleepiness-related crashes and incidents-in workers who perform safety-sensitive functions in the transportation industry. Evidence and expert consensus support its identification and treatment in high-risk commercial operators. An Advanced Notice of Proposed Rulemaking regarding the diagnosis and treatment of OSA in commercial truck and rail operators was issued by the Federal Motor Carrier Safety Administration and Federal Railroad Administration, but it was later withdrawn. This reversal has led to questions about whether efforts to identify and treat OSA are warranted. In the absence of clear directives, we urge key stakeholders, including clinicians and patients, to engage in a collaborative approach to address OSA by following, at a minimum, the 2016 guidelines issued by a Medical Review Board of the Federal Motor Carrier Safety Administration, alone or in combination with 2006 guidance by a joint task force. The current standard of care demands action to mitigate the serious health and safety risks of OSA.

CITATION

Das AM, Chang JL, Berneking M, et al. Enhancing public health and safety by diagnosing and treating obstructive sleep apnea in the transportation industry: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2022;18(10):2467-2470.

Age and weight considerations for the use of continuous positive airway pressure therapy in pediatric populations: an American Academy of Sleep Medicine position statement

This position statement provides guidance for age and weight considerations for using continuous positive airway pressure (CPAP) therapy in pediatric populations. The American Academy of Sleep Medicine (AASM) commissioned a task force of experts in pediatric sleep medicine to review the medical literature and develop a position statement based on a thorough review of these studies and their clinical expertise. The AASM Board of Directors approved the final position statement. It is the position of the AASM that CPAP can be safe and effective for the treatment of obstructive sleep apnea (OSA) for pediatric patients, even in children of younger ages and lower weights, when managed by a clinician with expertise in evaluating and treating pediatric OSA. The clinician must make the ultimate judgment regarding any specific care in light of the individual circumstances presented by the patient, accessible treatment options, patient/parental preference, and resources.

Sleep is essential to health: an American Academy of Sleep Medicine position statement

CITATION

Sleep is a biological necessity, and insufficient sleep and untreated sleep disorders are detrimental for health, well-being, and public safety. Healthy People 2030 includes several sleep-related objectives with the goal to improve health, productivity, well-being, quality of life, and safety by helping people get enough sleep. In addition to adequate sleep duration, healthy sleep requires good quality, appropriate timing, regularity, and the absence of sleep disorders. It is the position of the American Academy of Sleep Medicine (AASM) that sleep is essential to health. There is a significant need for greater emphasis on sleep health in education, clinical practice, inpatient and long-term care, public health promotion, and the workplace. More sleep and circadian research is needed to further elucidate the importance of sleep for public health and the contributions of insufficient sleep to health disparities.

CITATION

Ramar K, Malhotra RK, Carden KA, et al. Sleep is essential to health: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2021;17(10):2115-2119.

Orthogonal pre-use and post-use efficiency testing for single-use anion exchange chromatography

Three efficiency tests for single-use AEX chromatography devices have been developed and applied to six capsule formats of a new, salt tolerant, single-use AEX product. All the tests have been designed to be performed with simple equipment and common reagents. By performing each of the three tests on undamaged capsules and capsules intentionally damaged with small defects, in tandem with Phi-X174 challenges in a high-salt buffer, relationships between test results and viral clearance have been obtained. A pre-use pressure-based installation verification test is simply performed during equilibration of the device and effective at identifying gross bypass defects, for example, due to internal seal breakage. Passing outcomes of a post-use installation validation bubble point test are associated with ≥ 5 log reduction value (LRV) of viral clearance. A new, non-destructive, pre-use AEX capacity test involves challenging the device with chloride ions and is orthogonal to the other two tests in that it can detect chemical defects, as well as mechanical ones. Passing outcomes of this test correspond to > 2 LRV viral clearance and provide in situ assurance of the expected AEX dynamic capacity prior to use. Selection of a pair of pre-use and post-use tests can provide robust risk reduction with respect to viral clearance by single-use AEX devices in biopharmaceutical purifications.

Daylight saving time: an American Academy of Sleep Medicine position statement

None

The last several years have seen intense debate about the issue of transitioning between standard and daylight saving time. In the United States, the annual advance to daylight saving time in spring, and fall back to standard time in autumn, is required by law (although some exceptions are allowed under the statute). An abundance of accumulated evidence indicates that the acute transition from standard time to daylight saving time incurs significant public health and safety risks, including increased risk of adverse cardiovascular events, mood disorders, and motor vehicle crashes. Although chronic effects of remaining in daylight saving time year-round have not been well studied, daylight saving time is less aligned with human circadian biology-which, due to the impacts of the delayed natural light/dark cycle on human activity, could result in circadian misalignment, which has been associated in some studies with increased cardiovascular disease risk, metabolic syndrome and other health risks. It is, therefore, the position of the American Academy of Sleep Medicine that these seasonal time changes should be abolished in favor of a fixed, national, year-round standard time.

Artificial intelligence in sleep medicine: an American Academy of Sleep Medicine position statement

None

Sleep medicine is well positioned to benefit from advances that use big data to create artificially intelligent computer programs. One obvious initial application in the sleep disorders center is the assisted (or enhanced) scoring of sleep and associated events during polysomnography (PSG). This position statement outlines the potential opportunities and limitations of integrating artificial intelligence (AI) into the practice of sleep medicine. Additionally, although the most apparent and immediate application of AI in our field is the assisted scoring of PSG, we propose potential clinical use cases that transcend the sleep laboratory and are expected to deepen our understanding of sleep disorders, improve patient-centered sleep care, augment day-to-day clinical operations, and increase our knowledge of the role of sleep in health at a population level.

Does testing for sleep-disordered breathing pre-discharge versus post-discharge result in different treatment outcomes?

STUDY OBJECTIVES

Treatment of sleep-disordered breathing (SDB) may improve health related outcomes post-discharge. However timely definitive sleep testing and provision of ongoing therapy has been a challenge. Little is known about how the time of testing-during hospitalization vs. after discharge-affects important outcomes such as treatment adherence.

METHODS

We conducted a 10-year retrospective study of hospitalized adults who received an inpatient sleep medicine consultation for SDB and subsequent sleep testing. We divided them into inpatient and outpatient sleep testing cohorts and studied their clinical characteristics, follow-up and PAP adherence, and hospital readmission.

RESULTS

Of 485 patients, 226 (47%) underwent inpatient sleep testing and 259 (53%) had outpatient sleep testing. The median age was 68 years old (IQR=57-78), and 29.6% were females. The inpatient cohort had a higher Charlson Comorbidity Index (CCI) (4 [3-6] vs 3[2-5], p=<0.0004). A higher CCI (HR=1.14, 95%CI:1.03-1.25, p=0.001), BMI (HR=1.03, 95%CI:1.0-1.05, p=0.008) and stroke (HR=2.22, 95%CI:1.0-4.9, p=0.049) were associated with inpatient sleep testing. The inpatient cohort kept fewer follow-up appointments (39.90% vs 50.62%, p=0.03) however PAP adherence was high among those keeping follow-up appointments (88.9% [inpatient] vs 85.71% [outpatient], p=0.55). The inpatient group had an increased risk for death (HR: 1.82 95%CI 1.28-2.59, p=<0.001) but readmission rates did not differ.

CONCLUSIONS

Medically complex patient were more likely to receive inpatient sleep testing but less likely to keep follow-up, which could impact adherence and effectiveness of therapy. Novel therapeutic interventions are needed to increase sleep medicine follow-up post-discharge which may result in improvement in health outcomes in hospitalized patients with SDB.

Contralateral Rerouting of Hypoglossal Nerve Implant Pulse Generator and Stimulation Lead

As use of hypoglossal nerve stimulators has become more widespread in the treatment of obstructive sleep apnea, certain scenarios have dictated alterations to the previously described surgical technique. This report describes a situation in which revision of a hypoglossal nerve stimulator implant was required given the need for breast cancer surgery. It serves as the first description of the contralateral rerouting of a stimulation lead to a left-sided impulse generator and the first description of respiratory sensing lead placement within the left second intercostal space for such a device. Laryngoscope, 131:E2409-E2412, 2021.

Sleep, fatigue and burnout among physicians: an American Academy of Sleep Medicine position statement

None

Physician burnout is a serious and growing threat to the medical profession and may undermine efforts to maintain a sufficient physician workforce to care for the growing and aging patient population in the United States. Burnout involves a host of complex underlying associations and potential for risk. While prevalence is unknown, recent estimates of physician burnout are quite high, approaching 50% or more, with midcareer physicians at highest risk. Sleep deprivation due to shift-work schedules, high workload, long hours, sleep interruptions, and insufficient recovery sleep have been implicated in the genesis and perpetuation of burnout. Maladaptive attitudes regarding sleep and endurance also may increase the risk for sleep deprivation among attending physicians. While duty-hour restrictions have been instituted to protect sleep opportunity among trainees, virtually no such effort has been made for attending physicians who have completed their training or practicing physicians in nonacademic settings. It is the position of the American Academy of Sleep Medicine that a critical need exists to evaluate the roles of sleep disruption, sleep deprivation, and circadian misalignment in physician well-being and burnout. Such evaluation may pave the way for the development of effective countermeasures that promote healthy sleep, with the goal of reducing burnout and its negative impacts such as a shrinking physician workforce, poor physician health and functional outcomes, lower quality of care, and compromised patient safety.

Chronic Opioid Therapy and Sleep: An American Academy of Sleep Medicine Position Statement

None

There is a complex relationship among opioids, sleep and daytime function. Patients and medical providers should be aware that chronic opioid therapy can alter sleep architecture and sleep quality as well as contribute to daytime sleepiness. It is also important for medical providers to be cognizant of other adverse effects of chronic opioid use including the impact on respiratory function during sleep. Opioids are associated with several types of sleep-disordered breathing, including sleep-related hypoventilation, central sleep apnea (CSA), and obstructive sleep apnea (OSA). Appropriate screening, diagnostic testing, and treatment of opioid-associated sleep-disordered breathing can improve patients' health and quality of life. Collaboration among medical providers is encouraged to provide high quality, patient-centered care for people who are treated with chronic opioid therapy.

A Randomized, Placebo-Controlled Trial to Assess the Effects of 8 Weeks of Administration of GSK256073, a Selective GPR109A Agonist, on High-Density Lipoprotein Cholesterol in Subjects With Dyslipidemia

GPR109A (HM74A), a G-protein-coupled receptor, is hypothesized to mediate lipid and lipoprotein changes and dermal flushing associated with niacin administration. GSK256073 (8-chloro-3-pentyl-1H-purine-2,6[3H,7H]-dione) is a selective GPR109A agonist shown to suppress fatty acid levels and produce mild flushing in short-term clinical studies. This study evaluated the effects of GSK256073 on lipids in subjects with low high-density lipoprotein cholesterol (HDLc). Subjects (n = 80) were randomized (1:1:1:1) to receive GSK256073 5, 50, or 150 mg/day or matching placebo for 8 weeks. The primary end point was determining the GSK256073 exposure-response relationship for change from baseline in HDLc. No significant exposure response was observed between GSK256073 and HDLc levels. GSK256073 did not significantly alter HDLc levels versus placebo, but rather revealed a trend at the 150-mg dose for a nonsignificant decrease in HDLc (-6.31%; P = .12) and an increase in triglycerides (median, 24.4%; 95% confidence interval, 7.3%-41.6%). Flushing was reported in 21%, 25%, and 60% of subjects (5, 50, and 150 mg, respectively) versus 24% for placebo. Results indicated that selective activation of the GPR109A receptor with GSK256073 did not produce niacin-like lipid effects. These findings add to the increasing evidence that niacin-mediated lipoprotein changes occur predominantly via GPR109A-independent pathways.

Correlation of the Epworth Sleepiness Scale and Sleep-Disordered Breathing in Men and Women

STUDY OBJECTIVES

To compare Epworth Sleepiness Scale (ESS) scores of men and women and determine if there is a correlation with sleep-disordered breathing (SDB) based on subsequent polysomnography (PSG).

METHODS

Consecutive adult patients were identified who completed ESS and PSG at Mayo Clinic in Rochester, Minnesota, between January 1, 2013, and January 31, 2015. Apnea-hypopnea index (AHI) ≥ 5 events/h was classified as presence of SDB, and increasing values represented greater severity.

RESULTS

Among 6,593 patients with valid ESS scores and timely subsequent PSG, 42% were women. Mean (standard deviation [SD]) age of women was 56.2 (15.2) years; men, 58.5 (15.1) years. Mean (SD) ESS score was 9.5 (5.4) for women and 9.5 (5.3) for men. SDB was present in 83.6% of men and 68.3% of women. Mean (SD) AHI of men was 25.9 (26.7) events/h; women, 16.1 (22.4) events/h (P < .001). Each unit increase in ESS score of men was associated with a 0.51-unit increase in AHI (P < .001); women had a 0.16-unit associated increase (P = .04) (effect ratio, threefold greater for men). PSG demonstrated that women had greater sleep efficiency, less respiratory effort-related arousals, and less hypoxemia (all P < .001). Among women, ESS did not correlate with presence of SDB or mild to moderate SDB. There was a small association in women with severe SDB.

CONCLUSIONS

ESS is not correlated with SDB at mild to moderate levels in women and has a smaller association than in men with severe SDB. Further work is necessary to understand sex-specific differences in patients with SDB.

Practical Implementation of a Single-Night Split-Titration Protocol With BPAP-ST and AVAPS in Patients With Neuromuscular Disease

STUDY OBJECTIVES

At the sleep laboratory, noninvasive positive pressure ventilation titration protocols in patients with neuromuscular disease (NMD) are based on standard pressure cycle devices in a spontaneous/timed mode (BPAP-ST). Experience integrating protocols on average volume-assured pressure support (AVAPS) mode is limited, prompting us to develop a practical single-night titration protocol that provides information to assist clinicians and patients as they decide between BPAP-ST and AVAPS modes.

METHODS

We implemented a sequential titration protocol of BPAP-ST followed by AVAPS during a single-night polysomnography study in patients with NMD and reported polysomnographic and clinical metrics.

RESULTS

There were 27 patients who completed the protocol: 14 (52%) were male with median and interquartile range (IQR) 64 (59 to 70) years of age and body mass index of 29.6 (25.6-32) kg/m². They had median (IQR) maximal percent predicted inspiratory and expiratory pressures, and percent vital capacity of 33 (24 to 54), 34 (22 to 47) and 60 (47 to 74), respectively. At final titration of each device, average tidal volume and nadir non-rapid eye movement sleep oxyhemoglobin saturation (SpO₂) were higher and respiratory rate/tidal volume, transcutaneous CO₂, and arousal index were lower on AVAPS (P < .05) in comparison with BPAP-ST. Full face mask was used in 23 patients (85%). None of the other ventilatory or sleep parameters differed significantly between BPAP-ST and AVAPS (P > .05) sessions.

CONCLUSIONS

A practical single-night split-titration protocol with BPAP-ST and AVAPS can successfully be implemented in patients with NMD, assisting clinicians and patients with the decision on initial treatment modalities and settings.

Clinical Use of a Home Sleep Apnea Test: An Updated American Academy of Sleep Medicine Position Statement

ABSTRACT

The diagnosis and effective treatment of obstructive sleep apnea (OSA) in adults is an urgent health priority. It is the position of the American Academy of Sleep Medicine (AASM) that only a medical provider can diagnose medical conditions such as OSA and primary snoring. Throughout this statement, the term "medical provider" refers to a licensed physician and any other health care professional who is licensed to practice medicine in accordance with state licensing laws and regulations. A home sleep apnea test (HSAT) is an alternative to polysomnography for the diagnosis of OSA in uncomplicated adults presenting with signs and symptoms that indicate an increased risk of moderate to severe OSA. It is also the position of the AASM that: the need for, and appropriateness of, an HSAT must be based on the patient's medical history and a face-to-face examination by a medical provider, either in person or via telemedicine; an HSAT is a medical assessment that must be ordered by a medical provider to diagnose OSA or evaluate treatment efficacy; an HSAT should not be used for general screening of asymptomatic populations; diagnosis, assessment of treatment efficacy, and treatment decisions must not be based solely on automatically scored HSAT data, which could lead to sub-optimal care that jeopardizes patient health and safety; and the raw data from the HSAT device must be reviewed and interpreted by a physician who is either board-certified in sleep medicine or overseen by a board-certified sleep medicine physician.

Polysomnography for Obstructive Sleep Apnea Should Include Arousal-Based Scoring: An American Academy of Sleep Medicine Position Statement

ABSTRACT

The diagnostic criteria for obstructive sleep apnea (OSA) in adults, as defined in the International Classification of Sleep Disorders, Third Edition, requires an increased frequency of obstructive respiratory events demonstrated by in-laboratory, attended polysomnography (PSG) or a home sleep apnea test (HSAT). However, there are currently two hypopnea scoring criteria in The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications (AASM Scoring Manual). This dichotomy results in differences among laboratory reports, patient treatments and payer policies. Confusion occurs regarding recognizing and scoring "arousal-based respiratory events" during OSA testing. "Arousal-based scoring" recognizes hypopneas associated with electroencephalography-based arousals, with or without significant oxygen desaturation, when calculating an apnea-hypopnea index (AHI), or it includes respiratory effort-related arousals (RERAs), in addition to hypopneas and apneas, when calculating a respiratory disturbance index (RDI). Respiratory events associated with arousals, even without oxygen desaturation, cause significant, and potentially dangerous, sleep apnea symptoms. During PSG, arousal-based respiratory scoring should be performed in the clinical evaluation of patients with suspected OSA, especially in those patients with symptoms of excessive daytime sleepiness, fatigue, insomnia, or other neurocognitive symptoms. Therefore, it is the position of the AASM that the RECOMMENDED AASM Scoring Manual scoring criteria for hypopneas, which includes diminished airflow accompanied by either an arousal or ≥ 3% oxygen desaturation, should be used to calculate the AHI. If the ACCEPTABLE AASM Scoring Manual criteria for scoring hypopneas, which includes only diminished airflow plus ≥ 4% oxygen desaturation (and does not allow for arousal-based scoring alone), must be utilized due to payer policy requirements, then hypopneas as defined by the RECOMMENDED AASM Scoring Manual criteria should also be scored. Alternatively, the AASM Scoring Manual includes an option to report an RDI which also provides an assessment of the sleep-disordered breathing that results in arousal from sleep. Furthermore, given the inability of most HSAT devices to capture arousals, a PSG should be performed in any patient with an increased risk for OSA whose HSAT is negative. If the PSG yields an AHI of 5 or more events/h, or if the RDI is greater than or equal to 5 events/h, then treatment of symptomatic patients is recommended to improve quality of life, limit neurocognitive symptoms, and reduce accident risk.

Consumer Sleep Technology: An American Academy of Sleep Medicine Position Statement

ABSTRACT

Consumer sleep technologies (CSTs) are widespread applications and devices that purport to measure and even improve sleep. Sleep clinicians may frequently encounter CST in practice and, despite lack of validation against gold standard polysomnography, familiarity with these devices has become a patient expectation. This American Academy of Sleep Medicine position statement details the disadvantages and potential benefits of CSTs and provides guidance when approaching patient-generated health data from CSTs in a clinical setting. Given the lack of validation and United States Food and Drug Administration (FDA) clearance, CSTs cannot be utilized for the diagnosis and/or treatment of sleep disorders at this time. However, CSTs may be utilized to enhance the patient-clinician interaction when presented in the context of an appropriate clinical evaluation. The ubiquitous nature of CSTs may further sleep research and practice. However, future validation, access to raw data and algorithms, and FDA oversight are needed.

Medical Cannabis and the Treatment of Obstructive Sleep Apnea: An American Academy of Sleep Medicine Position Statement

ABSTRACT

The diagnosis and effective treatment of obstructive sleep apnea (OSA) in adults is an urgent health priority. Positive airway pressure (PAP) therapy remains the most effective treatment for OSA, although other treatment options continue to be explored. Limited evidence citing small pilot or proof of concept studies suggest that the synthetic medical cannabis extract dronabinol may improve respiratory stability and provide benefit to treat OSA. However, side effects such as somnolence related to treatment were reported in most patients, and the long-term effects on other sleep quality measures, tolerability, and safety are still unknown. Dronabinol is not approved by the United States Food and Drug Administration (FDA) for treatment of OSA, and medical cannabis and synthetic extracts other than dronabinol have not been studied in patients with OSA. The composition of cannabinoids within medical cannabis varies significantly and is not regulated. Synthetic medical cannabis may have differential effects, with variable efficacy and side effects in the treatment of OSA. Therefore, it is the position of the American Academy of Sleep Medicine (AASM) that medical cannabis and/or its synthetic extracts should not be used for the treatment of OSA due to unreliable delivery methods and insufficient evidence of effectiveness, tolerability, and safety. OSA should be excluded from the list of chronic medical conditions for state medical cannabis programs, and patients with OSA should discuss their treatment options with a licensed medical provider at an accredited sleep facility. Further research is needed to understand the functionality of medical cannabis extracts before recommending them as a treatment for OSA.

The Risk of Fatigue and Sleepiness in the Ridesharing Industry: An American Academy of Sleep Medicine Position Statement

ABSTRACT

The ridesharing-or ride-hailing-industry has grown exponentially in recent years, transforming quickly into a fee-for-service, unregulated taxi industry. While riders are experiencing the benefits of convenience and affordability, two key regulatory and safety issues deserve consideration. First, individuals who work as drivers in the ridesharing industry are often employed in a primary job, and they work as drivers during their "off" time. Such a schedule may lead to driving after extended periods of wakefulness or during nights, both of which are factors that increase the risk of drowsy driving accidents. Second, these drivers are often employed as "independent contractors," and therefore they are not screened for medical problems that can reduce alertness, such as obstructive sleep apnea. Some ridesharing companies now require a rest period after an extended driving shift. This measure is encouraging, but it is insufficient to impact driving safety appreciably, particularly since many of these drivers are already working extended hours and tend to drive at non-traditional times when sleepiness may peak. Therefore, it is the position of the American Academy of Sleep Medicine (AASM) that fatigue and sleepiness are inherent safety risks in the ridesharing industry. The AASM calls on ridesharing companies, government officials, medical professionals, and law enforcement officers to work together to address this public safety risk. A collaborative effort is necessary to understand and track the scope of the problem, provide relevant education, and mitigate the risk through thoughtful regulation and effective fatigue risk management systems.

Investigating the healing mechanisms of an angiogenesis-promoting topical treatment for diabetic wounds using multimodal microscopy

Impaired skin wound healing is a significant comorbid condition of diabetes that is caused by poor microcirculation, among other factors. Studies have shown that angiogenesis, a critical step in the wound healing process in diabetic wounds, can be promoted under hypoxia. In this study, an angiogenesis-promoting topical treatment for diabetic wounds, which promotes angiogenesis by mimicking a hypoxic environment via inhibition of prolyl hydroxylase resulting in elevation or maintenance of hypoxia-inducible factor, was investigated utilizing a custom-built multimodal microscopy system equipped with phase-variance optical coherence tomography (PV-OCT) and fluorescence lifetime imaging microscopy (FLIM). PV-OCT was used to track the regeneration of the microvasculature network, and FLIM was used to assess the in vivo metabolic response of mouse epidermal keratinocytes to the treatment during healing. Results show a significant decrease in the fluorescence lifetime of intracellular reduced nicotinamide adenine dinucleotide, suggesting a hypoxic-like environment in the wounded skin, followed by a quantitative increase in blood vessel density assessed by PV-OCT. Insights gained in these studies could lead to new endpoints for evaluation of the efficacy and healing mechanisms of wound-healing drugs in a setting where delayed healing does not permit available methods for evaluation to take place.

Clinical Use of a Home Sleep Apnea Test: An American Academy of Sleep Medicine Position Statement

ABSTRACT

The diagnosis and effective treatment of obstructive sleep apnea (OSA) in adults is an urgent health priority. It is the position of the American Academy of Sleep Medicine (AASM) that only a physician can diagnose medical conditions such as OSA and primary snoring. Throughout this statement, the term "physician" refers to a medical provider who is licensed to practice medicine. A home sleep apnea test (HSAT) is an alternative to polysomnography for the diagnosis of OSA in uncomplicated adults presenting with signs and symptoms that indicate an increased risk of moderate to severe OSA. It is also the position of the AASM that: the need for, and appropriateness of, an HSAT must be based on the patient's medical history and a face-to-face examination by a physician, either in person or via telemedicine; an HSAT is a medical assessment that must be ordered by a physician to diagnose OSA or evaluate treatment efficacy; an HSAT should not be used for general screening of asymptomatic populations; diagnosis, assessment of treatment efficacy, and treatment decisions must not be based solely on automatically scored HSAT data, which could lead to sub-optimal care that jeopardizes patient health and safety; and the raw data from the HSAT device must be reviewed and interpreted by a physician who is either board-certified in sleep medicine or overseen by a board-certified sleep medicine physician.

Delaying Middle School and High School Start Times Promotes Student Health and Performance: An American Academy of Sleep Medicine Position Statement

ABSTRACT

During adolescence, internal circadian rhythms and biological sleep drive change to result in later sleep and wake times. As a result of these changes, early middle school and high school start times curtail sleep, hamper a student's preparedness to learn, negatively impact physical and mental health, and impair driving safety. Furthermore, a growing body of evidence shows that delaying school start times positively impacts student achievement, health, and safety. Public awareness of the hazards of early school start times and the benefits of later start times are largely unappreciated. As a result, the American Academy of Sleep Medicine is calling on communities, school boards, and educational institutions to implement start times of 8:30 AM or later for middle schools and high schools to ensure that every student arrives at school healthy, awake, alert, and ready to learn.

The sawtooth sign is predictive of obstructive sleep apnea

BACKGROUND

The sawtooth sign in spirometry is associated with redundant upper airway tissue and snoring, but its predictive value for identifying obstructive sleep apnea (OSA) is disputed. We retrospectively assessed the predictive value of the spirometric sawtooth sign in terms of the odds ratio (OR) of association with a diagnosis of OSA compared to those without the sign.

METHODS

Consecutive spirometry reports showing a sawtooth sign were identified from our laboratory. We identified 50 subjects with sawtooth sign and 100 control subjects without sawtooth sign, matched for age, BMI, and gender. The electronic medical record of each patient was queried for a diagnosis of OSA based on physician-reported diagnoses.

RESULTS

Of the 50 subjects with sawtooth sign, 22 were found to have a current diagnosis of OSA (44%). Twenty-seven of the 100 controls (27%) also had OSA. From logistic regression analysis, sawtooth sign was associated with an increased likelihood of OSA (OR = 2.12, 95% C.I. 1.04 to 4.35). Similar results were obtained after adjustment for age, gender, pack years, and BMI (OR = 2.61, 95% C.I. 1.13 to 6.21).

CONCLUSIONS

Patients with the sawtooth sign have greater odds of having a diagnosis of OSA compared with those without the sign. If prospectively evaluated, as a result of improved identification, we hypothesize that the sawtooth sign may show an even stronger association with OSA. This relatively common finding, which adds no cost to routine spirometry, may serve as an indicator for OSA workup for some individuals not already identified as having OSA.

Putative Metronidazole Neurotoxicosis in a Cat

A presumptive case of metronidazole toxicity in a 3.4-kg adult cat is described. The cat had been treated for suspected inflammatory bowel disease with an anti-inflammatory dose of prednisone and metronidazole (73.5-147 mg/kg PO q24h) for approximately 40 days prior to presentation. Clinical signs were primarily related to the central nervous system, including acute tetraparesis, unresponsiveness, tremors, and vocalization. The patient was euthanatized after 12 days of supportive care. Necropsy revealed no significant macroscopic lesions. Histologic evaluation revealed multifocal, fairly well-demarcated foci of necrosis in the brainstem, extending from the diencephalon to the medulla oblongata. To our knowledge, this is the first report to document histologic lesions associated with metronidazole administration in a cat.

Bacterial Diskospondylitis Associated with Posterior Paresis/Paralysis in North American Farmed Mink (Mustela vison)

Posterior paresis/paralysis in farmed mink is responsible for significant morbidity and mortality, with individual farms reporting the loss of as many as 700 animals each year. Although this disease has been recognized by North American mink farmers for approximately 40 years, there are few published reports focusing on this entity. The objective of this study was to investigate the etiology and pathogenesis of the disease. Complete necropsy examinations were done on 40 clinically affected mink, ranging from 7 to 10 weeks of age, and on three normal animals in the same age range from two mink farms. Thirty-two of the 40 clinically affected animals had an isolated vertebral lesion characterized by bone lysis and proliferation that usually was centered on an intervertebral disk space in the midthoracic area. An inflammatory reaction, composed primarily of neutrophils, was present within the vertebral sections in 25 of the 40 affected animals (62.5%), and the presence of gram-positive cocci was confirmed in 8 of 10 animals (80%) in which bacterial organisms were observed histologically. Bacterial cultures from 15 affected animals yielded Streptococcus sp. from the intervertebral disk space in 13 of 15 (86.7%) animals and from heart blood in 6 of 8 (75%). A farm visit revealed no history or evidence of traumatic wounds as a source of infection in these animals, and the diet appeared to be adequate for skeletal development. We conclude that posterior paresis/paralysis in farmed mink is associated with bacterial diskospondylitis, likely occurring secondary to bacteremia/septicemia.

A 62-year-old man with dyspnea

We describe the case of a 62-year-old man who presented with shortness of breath that had progressed over several years. He had a history of a paralyzed right hemidiaphragm for at least the previous 10 years. He also reported weakness in his proximal legs and daytime sleepiness. On examination, he was found to have thoracoabdominal paradox when in supine position. Pulmonary function testing revealed severe restriction; arterial blood gas showed chronic respiratory acidosis. Electromyography showed chronic phrenic neuropathy bilaterally, with mild proximal myopathy. Serum aldolase level was mildly elevated, but serologic tests for connective tissue disorders were within reference range. After extensive clinical investigations, the patient was found to have severely reduced acid α-glucosidase. Genetic analysis confirmed the diagnosis of adult-onset Pompe disease. The patient started treatment with bilevel positive airway pressure titrated during polysomnography, and acid α-glucosidase enzyme replacement was recommended.

Capacitive Sensing of Intercalated H2O Molecules Using Graphene

Understanding the interactions of ambient molecules with graphene and adjacent dielectrics is of fundamental importance for a range of graphene-based devices, particularly sensors, where such interactions could influence the operation of the device. It is well-known that water can be trapped underneath graphene and its host substrate; however, the electrical effect of water beneath graphene and the dynamics of how the interfacial water changes with different ambient conditions has not been quantified. Here, using a metal-oxide-graphene variable-capacitor (varactor) structure, we show that graphene can be used to capacitively sense the intercalation of water between graphene and HfO2 and that this process is reversible on a fast time scale. Atomic force microscopy is used to confirm the intercalation and quantify the displacement of graphene as a function of humidity. Density functional theory simulations are used to quantify the displacement of graphene induced by intercalated water and also explain the observed Dirac point shifts as being due to the combined effect of water and oxygen on the carrier concentration in the graphene. Finally, molecular dynamics simulations indicate that a likely mechanism for the intercalation involves adsorption and lateral diffusion of water molecules beneath the graphene.

Bone Disease in the Common Marmoset: Radiographic and Histological Findings

The common marmoset (Callithrix jacchus) is a New World primate that is used in biomedical research due to its small size and relative ease of handling compared with larger primates. Although bone disease in common marmosets is well recognized, there are very few detailed descriptions in the literature that cover the range of lesions seen in these animals. For all animals used to model human disease, it is important to be aware of background lesions that may affect the interpretation of study findings. This retrospective study details bone diseases encountered in marmoset breeding colonies at 2 different institutions. Affected marmosets at Johns Hopkins University had lesions compatible with diagnoses of rickets, fibrous osteodystrophy and osteopenia. Affected marmosets at the Wisconsin National Primate Research Center exhibited severe lesions of osteoclastic bone resorption and remodeling that had an unusual distribution and were not easily categorized into a known disease entity. The purpose of this report is to document these naturally occurring skeletal lesions of common marmosets and suggest an approach to evaluating skeletal disease in prospective studies of these animals that will allow the most accurate diagnoses.

Middle ear pressure during sleep and the effects of continuous positive airway pressure

PURPOSE

Prior studies evaluating Eustachian tube physiology, baseline middle ear pressure (MEP), and the effects of continuous positive airway pressure (CPAP) have been performed on awake patients. No study to date has specifically investigated MEP during sleep despite the fact that the average individual spends a third of their lifetime sleeping. The primary objectives of the current study are to quantify normal physiologic MEP during sleep and to evaluate the effects of escalating CPAP levels.

MATERIALS AND METHODS

Prospective observational study at a tertiary academic referral center evaluating serial tympanometry on sleeping adult patients during polysomnography. MEP was recorded awake, at 1-hour intervals during diagnostic polysomnography, and at all CPAP levels during titration. Changes in MEP with duration of sleep and escalating CPAP levels were analyzed.

RESULTS

Ten adults were included (4 females; 6 males; mean age 58years). The mean MEP while awake was 3 decapascals (daPa). The mean MEP during sleep without CPAP rose steadily from 14 daPa at 1hour to 41 daPa at 4hours (r=0.52; p<0.001). The mean MEP during sleep at a CPAP level of 5cm of water was 54 daPa. The mean MEP rose steadily with increasing CPAP levels, and was 104 daPa at 10cm of water, (r=0.82; p<0.001). The mean MEP during sleep without CPAP was 26 daPa, which was significantly lower than the mean MEP during sleep with CPAP between 5-10cm H2O (p<0.01).

CONCLUSIONS

MEP naturally increases with duration of sleep. CPAP therapy causes a supraphysiologic elevation in MEP that rises with increasing pressure levels. These findings may help guide future studies examining the safety of CPAP following otologic surgery and the potential therapeutic benefit in patients with chronic middle ear disease.

Chiari 1 Malformation Presenting as Central Sleep Apnea during Pregnancy: A Case Report, Treatment Considerations, and Review of the Literature

Purpose: Chiari malformation (CM) type-1 frequently causes obstructive or central sleep-disordered breathing (SDB) in both adults and children, although SDB is relatively rare as a presenting manifestation in the absence of other neurological symptoms. The definitive treatment of symptomatic CM is surgical decompression. We report a case that is, to our knowledge, a novel manifestation of central sleep apnea (CSA) due to CM type-1 with severe exacerbation and initial clinical presentation during pregnancy.

Methods: Case report from tertiary care comprehensive sleep medicine center with literature review of SDB manifestations associated with CM type-1. PubMed search was conducted between January 1982 and October 2013.

Results: We report a 25-year-old woman with severe CSA initially presenting during her first pregnancy that eventually proved to be caused by CM type-1. The patient was successfully treated preoperatively by adaptive servoventilation (ASV), with effective resolution of SDB following surgical decompression, and without recurrence in a subsequent pregnancy. Our literature review found that 58% of CM patients with SDB had OSA alone, 28% had CSA alone, 8 (10%) had mixed OSA/CSA, and 6 (8%) had hypoventilation. Of CM patients presenting with SDB, 50% had OSA, 42% had CSA, 8% had mixed OSA/CSA, and 10.4% had hypoventilation. We speculate that CSA may develop in CM patients in whom brainstem compression results in excessive central chemoreflex sensitivity with consequent hypocapnic CSA.

Conclusion: Chiari malformation type-1 may present with a diversity of SDB manifestations, and timely recognition and surgical referral are necessary to prevent further neurological deficits. ASV therapy can effectively manage CSA caused by CM type-1, which may initially present during pregnancy.

Effect of noncovalent basal plane functionalization on the quantum capacitance in graphene

The concentration-dependent density of states in graphene allows the capacitance in metal-oxide-graphene structures to be tunable with the carrier concentration. This feature allows graphene to act as a variable capacitor (varactor) that can be utilized for wireless sensing applications. Surface functionalization can be used to make graphene sensitive to a particular species. In this manuscript, the effect on the quantum capacitance of noncovalent basal plane functionalization using 1-pyrenebutanoic acid succimidyl ester and glucose oxidase is reported. It is found that functionalized samples tested in air have (1) a Dirac point similar to vacuum conditions, (2) increased maximum capacitance compared to vacuum but similar to air, (3) and quantum capacitance "tuning" that is greater than that in vacuum and ambient atmosphere. These trends are attributed to reduced surface doping and random potential fluctuations as a result of the surface functionalization due to the displacement of H2O on the graphene surface and intercalation of a stable H2O layer beneath graphene that increases the overall device capacitance. The results are important for future application of graphene as a platform for wireless chemical and biological sensors.

Factors associated with injury in REM sleep behavior disorder

OBJECTIVE

As factors associated with injury in rapid eye movement (REM) sleep behavior disorder (RBD) remain largely unknown, we aimed to identify such factors.

METHODS

We surveyed consecutive idiopathic (iRBD) or symptomatic RBD patients seen between 2008 and 2010 regarding RBD-related injuries. Associations between injuries and clinical variables were determined with odds ratios (OR) and multiple logistic regression analyses. The primary outcome variables were injury and injury severity.

RESULTS

Fifty-three patients (40%) responded. Median age was 69 years, and 35 (73.5%) were men. Twenty-eight (55%) had iRBD. Twenty-nine (55%) reported injury, with 37.8% to self and 16.7% to the bed partner. 11.3% had marked injuries requiring medical intervention or hospitalization, including two (4%) subdural hematomas. iRBD diagnosis (OR = 6.8, p = 0.016) and dream recall (OR = 7.5, p = 0.03) were associated with injury; and iRBD diagnosis was independently associated with injury and injury severity adjusting for age, gender, DEB frequency, and duration. Falls (p = 0.03) were also associated with injury severity. DEB frequency was not associated with injury, injury severity, or falls.

CONCLUSIONS

Injuries appear to be a frequent complication of RBD, although the relatively low response rate in our survey could have biased results. iRBD patients are more likely to suffer injury--and more severe injuries--than symptomatic RBD patients. In addition, recall of dreams was also associated with injury, and dream enactment behavior (DEB)-related falls were associated with more severe injuries. One in nine patients suffered injury requiring medical intervention. The frequency of DEB did not predict RBD-related injuries, highlighting the importance of timely initiation of treatment for RBD in patients having even rare DEB episodes. Future prospective studies will be necessary to define predictors of injury in RBD.

Multidisciplinary sleep centers: strategies to improve care of sleep disorders patients

Current emphasis on patient outcomes within sleep medicine, with a particular focus on quality improvement and contained costs, calls for sleep specialists to develop innovative models for long-term care and management of sleep disorders patients. Multidisciplinary sleep centers can facilitate highest-quality care that is timely and cost-effective. Effective resource use in a multidisciplinary sleep center can help minimize fragmentation of care, reduce effort duplication, and control costs. Proposed strategies to help achieve a balance between quality of care and cost-effectiveness include: (1) multidisciplinary specialty clinics, (2) optimized use of information technology, and (3) adoption of reliable performance measures.

Effect of recording duration on the diagnostic accuracy of out-of-center sleep testing for obstructive sleep apnea

STUDY OBJECTIVES

This study investigated the minimum recording time needed during out-of-center sleep testing (OCST) to accurately diagnose the presence and severity of obstructive sleep apnea (OSA).

DESIGN AND SETTING

A retrospective analysis was conducted of OCSTs performed from October 2009 to May 2012 at the Mayo Clinic Center of Sleep Medicine using the portable Embletta™ system.

PATIENTS OR PARTICIPANTS

Demographic information was collected for patients who underwent OCSTs during the study period, including presenting symptoms, examination findings, and comorbidities.

INTERVENTION

Each study was divided into 60-, 120-, 180-, 240-, 300-, 360-, and 420-min intervals beginning at the recording start time to determine the respiratory event index (REI) for each of these time intervals. These interval values were then compared to the original REI derived from the total recording time (REITRT) by a paired t-test and concordance correlation coefficient (CCC).

MEASUREMENTS AND RESULTS

There were significant differences between the REITRT and the REI from the 60-min (P < 0.0001), 120-min (0.0001), 180-min (0.003) and 240-min (0.006) intervals with a lack of concordance, suggesting these intervals are poor diagnostic correlates for the REITRT. REIs determined at 300, 360, and 420 min were not significantly different from the REITRT and had highly significant CCCs, 0.963, 0.987, and 0.995, respectively.

CONCLUSIONS

The results suggest that at least 300 min recording time during out-of-center sleep testing is needed for accurate diagnosis of obstructive sleep apnea and determination of obstructive sleep apnea severity.

Bilevel positive airway pressure for obstructive sleep apnea

For most patients with obstructive sleep apnea syndrome (OSA), continuous positive airway pressure (CPAP) is an effective therapy. However, for a subset of individuals, CPAP is either not effective or is poorly tolerated. Bilevel positive airway pressure (BPAP) is potentially capable of treating OSA at a lower mean pressure than CPAP and can help augment ventilation via pressure support. This review summarizes the evidence for the use of BPAP in spontaneous mode in the initial treatment of patients with OSA and in those who are poorly compliant with CPAP therapy. It also examines evidence regarding use of BPAP in OSA with associated hypoventilation, such as in chronic obstructive pulmonary disease or severe obesity. Finally, current clinical guidelines that help determine which patients would be candidates for a BPAP device and how to manually titrate BPAP to determine the optimal settings to be prescribed are also discussed.

Nocturnal Middle Ear Pressure and the Effects of Continuous Positive Airway Pressure

Objectives:

1) Quantify normal middle ear pressure during sleep; 2) Quantify middle ear pressure during sleep in the presence of continuous positive airway pressure (CPAP).

Methods:

A prospective cohort study was conducted on adults without middle ear disease undergoing polysomnography at a tertiary referral sleep medicine center during 2012. Tympanometry was performed on sleeping patients, and middle ear pressure was recorded at 1-hour intervals during diagnostic polysomnography and at all CPAP levels during CPAP titration. Mean middle ear pressures were calculated. Pearson correlation coefficients (r) were used for analysis.

Results:

Ten adults with type A tympanograms and normal otoscopic examinations were included (4 females; 6 males; mean age 58 years). The mean awake middle ear pressure was 3.2 decapascals (daPa). The mean middle ear pressure during sleep without CPAP rose steadily from 14.3 daPa at 1 hour to 41.4 daPa at 4 hours, r = 0.53 ( P < 0.001). The mean middle ear pressure did not change with sleep stages ( P = 0.99). At a CPAP of 5 cm of water, the mean middle ear pressure was 53.7 daPa. The mean middle ear pressure rose with increasing CPAP levels and was 104 daPa at 10 cm of water, r = 0.86 ( P < 0.001).

Conclusions:

In normal ears, middle ear pressure rises with time asleep. CPAP causes a greater than physiologic elevation in middle ear pressure that rises with increasing CPAP levels. These findings may help guide future studies examining the safety of CPAP following ear surgery and potential therapeutic roles for CPAP in patients with middle ear disease.