Beat-to-beat cardiac repolarization lability increases during hypoxemia and arousals in obstructive sleep apnea patients.

Obstructive sleep apnea (OSA) is associated with the progression of cardiovascular diseases, arrhythmias, and sudden cardiac death (SCD). However, the acute impacts of OSA and its consequences on heart function are not yet fully elucidated. We hypothesized that desaturation events acutely destabilize ventricular repolarization, and the presence of accompanying arousals magnifies this destabilization. Ventricular repolarization lability measures, comprising heart rate corrected QT (QTc), short-time-variability of QT (STVQT), and QT variability index (QTVI), were calculated before, during, and after 20,955 desaturations from lead II electrocardiography signals of 492 patients with suspected OSA (52% men). Variations in repolarization parameters were assessed during and after desaturations, both with and without accompanying arousals, and groupwise comparisons were performed based on desaturation duration and depth. Regression analyses were used to investigate the influence of confounding factors, comorbidities, and medications. The standard deviation (SD) of QT, mean QTc, SDQTc, and STVQT increased significantly (P < 0.01), whereas QTVI decreased (P < 0.01) during and after desaturations. The changes in SDQT, mean QTc, SDQTc, and QTVI were significantly amplified (P < 0.01) in the presence of accompanying arousals. Desaturation depth was an independent predictor of increased SDQTc (ß = 0.405, P < 0.01), STVQT (ß = 0.151, P < 0.01), and QTVI (ß = 0.009, P < 0.01) during desaturation. Desaturations cause acute changes in ventricular repolarization, with deeper desaturations and accompanying arousals independently contributing to increased ventricular repolarization lability. This may partially explain the increased risk of arrhythmias and SCD in patients with OSA, especially when the OSA phenotype includes high hypoxic load and fragmented sleep.NEW & NOTEWORTHY Nocturnal desaturations are associated with increased ventricular repolarization lability. Deeper desaturations with accompanying arousals increase the magnitude of alterations, independent of confounding factors, comorbidities, and medications. Changes associated with desaturations can partially explain the increased risk of arrhythmias and sudden cardiac death in patients with OSA, especially in patients with high hypoxic load and fragmented sleep. This highlights the importance of detailed electrocardiogram analytics for patients with OSA.

Thrombolysis treatment protected impairment of functional ability, quality of life and fatigue seven years after stroke.

OBJECTIVES: We studied quality of life, functional outcome, depression, and fatigue of ischemic stroke patients treated with or without thrombolysis seven years post-stroke. MATERIALS AND METHODS: A total of 204 ischemic stroke patients treated with or without thrombolysis during 2013-2015. After seven years the 136 survivors were assessed with telephone interview, which included questions about subjective quality of life (European Quality of Life-5 Dimensions), depression, fatigue with Fatigue Severity Scale, functional ability assessed with Barthel Index and Modified Rankin Scale, living conditions, need of care, and medical aids. RESULTS: At admission patients with thrombolysis had higher National Institutes of Health Stroke Scale scores compared with those not treated with thrombolysis. At seven years post-stroke, 99% of alive patients answered the questionnaires. There were no group differences concerning functional outcome, quality of life, depression, fatigue, or insomnia. The Barthel Index was normal in both groups. The quality of life was good in both groups without group differences in any domains. Of all patients, 68% reported no problems in usual activities, and 61% were without pain. Anxiety or depression were experienced by 19% of all stroke patients, while fatigue was present in 32% of cases. CONCLUSIONS: Seven years post-stroke the quality of life was good and functional outcome remained in good level in both study groups. One third experienced fatigue, while every fifth experienced depression. The thrombolysis treatment seems to protect from decreased quality of life, fatigue, and decreased mobility, self-care, and usual activities despite more severe stroke.

Evolution of sleep-disordered breathing and blood pressure during menopausal transition.

The purpose of this study was to investigate how the blood pressure increase observed during menopausal transition is affected by sleep-disordered breathing and the menopause itself. Further, we aimed to find new sleep-disordered breathing related markers that would predict the development of hypertension. Sixty-four community-dwelling premenopausal women aged 45-47 years were studied. Polysomnography, serum follicle stimulating hormone, forced expiratory volume in 1 s, and a physical examination were performed at baseline and again after 10 years of follow-up. Indices for sleep apnea/hypopnea and inspiratory flow-limitation were determined. Regression models were used to study the relationships between variables. Changes in the apnea-hypopnea index or serum follicle stimulating hormone were not significant for blood pressure change. An increase in morning blood pressure during the follow-up period was associated with a body mass-index increase. An increase in evening blood pressure was associated with an increase in inspiratory flow-limitation during non-rapid eye movement sleep. Incident hypertension during the follow-up was associated with hypopnea (median hypopnea index 7.6/h, p = 0.048) during rapid eye movement sleep at baseline. Users of menopausal hormone therapy had a lower rapid eye movement sleep apnea-hypopnea index (1.6/h vs. 6.9/h, p = 0.026) at baseline whereas at follow-up users and non-users did not differ in any way. The progression of menopause or the use of menopausal hormone therapy had a minimal effect on blood pressure in our population. The effects of inspiratory flow-limitation on blood pressure profile should be studied further.

Lower respiratory tract infections among newly diagnosed sleep apnea patients.

BACKGROUND: Sleep apnea is associated with chronic comorbidities and acute complications. Existing data suggest that sleep apnea may predispose to an increased risk and severity of respiratory tract infections. METHODS: We investigated the incidence of lower respiratory tract infections in the first and second year before and after diagnosis of sleep apnea in a Finnish nationwide, population-based, retrospective case-control study based on linking data from the national health care registers for primary and secondary care from 2015-2019. Controls were matched for age, sex, hospital district, and multimorbidity status. We furthermore analysed the independent effect of comorbidities and other patient characteristics on the risk of lower respiratory tract infections, and their recurrence. RESULTS: Sleep apnea patients had a higher incidence of lower respiratory tract infections than their matched controls within one year before (hazard ratio 1.35, 95% confidence interval 1.16-1.57) and one year after (hazard ratio1.39, 95% confidence interval1.22-1.58) diagnosis of sleep apnea. However, we found no difference in the incidence of lower respiratory tract infections within the second year before or after diagnosis of sleep apnea in comparison with matched controls. In sleep apnea, history of lower respiratory tract infection prior to sleep apnea, multimorbidity, COPD, asthma, and age greater than 65 years increased the risk of incident and recurrent lower respiratory tract infections. CONCLUSIONS: Sleep apnea patients are at increased risk of being diagnosed with a lower respiratory tract infection within but not beyond one year before and after diagnosis of sleep apnea. Among sleep apnea patients, chronic comorbidities had a significant impact on the risk of lower respiratory tract infections and their recurrence.

Metabolic dysfunction in OSA: Is there something new under the sun?

The growing number of patients with obstructive sleep apnea is challenging healthcare systems worldwide. Obstructive sleep apnea is characterized by chronic intermittent hypoxaemia, episodes of apnea and hypopnea, and fragmented sleep. Cardiovascular and metabolic diseases are common in obstructive sleep apnea, also in lean patients. Further, comorbidity burden is not unambiguously linked to the severity of obstructive sleep apnea. There is a growing body of evidence revealing diverse functions beyond the conventional tasks of different organs such as carotid body and gut microbiota. Chronic intermittent hypoxia and sleep loss due to sleep fragmentation are associated with insulin resistance. Indeed, carotid body is a multi-sensor organ not sensoring only hypoxia and hypercapnia but also acting as a metabolic sensor. The emerging evidence shows that obstructive sleep apnea and particularly chronic intermittent hypoxia is associated with non-alcoholic fatty liver disease. Gut dysbiosis seems to be an important factor in the pathophysiology of obstructive sleep apnea and its consequences. The impact of sleep fragmentation and intermittent hypoxia on the development of metabolic syndrome may be mediated via altered gut microbiota. Circadian misalignment seems to have an impact on the cardiometabolic risk in obstructive sleep apnea. Dysfunction of cerebral metabolism is also related to hypoxia and sleep fragmentation. Therefore, obstructive sleep apnea may alter cerebral metabolism and predispose to neurocognitive impairment. Moreover, recent data show that obstructive sleep apnea independently predicts impaired lipid levels. This mini-review will provide novel insights into the mechanisms of metabolic dysfunction in obstructive sleep apnea combining recent evidence from basic, translational and clinical research, and discuss the impact of positive airway pressure treatment on metabolic disorders.

Impact of temperature on obstructive sleep apnoea in three different climate zones of Europe: Data from the European Sleep Apnoea Database (ESADA).

Recent studies indicate that ambient temperature may modulate obstructive sleep apnoea (OSA) severity. However, study results are contradictory warranting more investigation in this field. We analysed 19,293 patients of the European Sleep Apnoea Database (ESADA) cohort with restriction to the three predominant climate zones according to the Köppen-Geiger climate classification: Cfb (warm temperature, fully humid, warm summer), Csa (warm temperature, summer dry, hot summer), and Dfb (snow, fully humid, warm summer). Average outside temperature values were obtained and several hierarchical regression analyses were performed to investigate the impact of temperature on the apnea-hypopnea index (AHI), oxygen desaturation index (ODI), time of oxygen saturation <90% (T90) and minimum oxygen saturation (MinSpO2 ) after controlling for confounders including age, body mass index, gender, and air conditioning (A/C) use. AHI and ODI increased with higher temperatures with a standardised coefficient beta (ß) of 0.28 for AHI and 0.25 for ODI, while MinSpO2 decreased with a ß of -0.13 (all results p < .001). When adjusting for climate zones, the temperature effect was only significant in Cfb (AHI: ß = 0.11) and Dfb (AHI: ß = 0.08) (Model 1: p < .001). The presence of A/C (3.9% and 69.3% in Cfab and Csa, respectively) demonstrated only a minor increase in the prediction of the variation (Cfb: AHI, R2 +0.003; and Csa: AHI, R2 +0.007; both p < .001). Our present study indicates a limited but consistent influence of environmental temperature on OSA severity and this effect is modulated by climate zones.

Positive airway pressure (PAP) treatment reduces glycated hemoglobin (HbA1c) levels in obstructive sleep apnea patients with concomitant weight loss: Longitudinal data from the ESADA.

Patients with obstructive sleep apnea (OSA) are at increased risk of developing metabolic disease such as diabetes. The effects of positive airway pressure on glycemic control are contradictory. We therefore evaluated the change in glycated hemoglobin (HbA1c) in a large cohort of OSA patients after long-term treatment with positive airway pressure. HbA1c levels were assessed in a subsample of the European Sleep Apnea Database [n=1608] at baseline and at long-term follow up with positive airway pressure therapy (mean 378.9±423.0 days). In a regression analysis, treatment response was controlled for important confounders. Overall, HbA1c decreased from 5.98±1.01% to 5.93±0.98% (p=0.001). Patient subgroups with a more pronounced HbA1c response included patients with diabetes (-0.15±1.02, p=0.019), those with severe OSA baseline (-0.10±0.68, p=0.005), those with morbid obesity (-0.20±0.81, p<0.001). The strongest HbA1c reduction was observed in patients with a concomitant weight reduction >5 kilos (-0.38±0.99, p<0.001). In robust regression analysis, severe OSA (p=0.038) and morbid obesity (p=0.005) at baseline, and weight reduction >5 kilos (p<0.001) during follow up were independently associated with a reduction of HbA1c following PAP treatment. In contrast, PAP treatment alone without weight reduction was not associated with significant Hb1Ac reduction. In conclusion, positive airway pressure therapy is associated with HbA1c reduction in patients with severe OSA, in morbidly obese patients. and most obviously in those with significant weight lost during the follow-up. Our study underlines the importance to combine positive airway pressure use with adjustments in lifestyle to substantially modify metabolic complications in OSA.

Pitolisant for Daytime Sleepiness in Patients with Obstructive Sleep Apnea Who Refuse Continuous Positive Airway Pressure Treatment. A Randomized Trial.

Rationale: Excessive daytime sleepiness is a common disabling symptom in obstructive sleep apnea syndrome.Objectives: To evaluate the efficacy and safety of pitolisant, a selective histamine H3 receptor antagonist with wake-promoting effects, for the treatment of daytime sleepiness in patients with moderate to severe obstructive sleep apnea refusing continuous positive airway pressure treatment.Methods: In an international, multicenter, double-blind, randomized (3:1), placebo-controlled, parallel-design trial, pitolisant was individually titrated at up to 20 mg/d over 12 weeks. The primary endpoint was the change in the Epworth Sleepiness Scale score. Key secondary endpoints were maintenance of wakefulness assessed on the basis of the Oxford Sleep Resistance test, safety, Clinical Global Impression of severity, patient's global opinion, EuroQol quality-of-life questionnaire, and Pichot fatigue questionnaire.Measurements and Main Results: A total of 268 patients with obstructive sleep apnea (75% male; mean age, 52 yr; apnea-hypopnea index, 49/h; baseline sleepiness score, 15.7) were randomized (200 to pitolisant and 68 to placebo) and analyzed on an intention-to-treat basis. The Epworth Sleepiness Scale score was reduced more with pitolisant than with placebo (-2.8; 95% confidence interval, -4.0 to -1.5; P < 0.001). Wake maintenance tests were not improved. The Pichot fatigue score was reduced with pitolisant. The overall impact of pitolisant was confirmed by both physicians' and patients' questionnaires. Adverse event incidence, mainly headache, insomnia, nausea, and vertigo, was similar in the pitolisant and placebo groups (29.5% and 25.4%, respectively), with no cardiovascular or other significant safety concerns.Conclusions: Pitolisant significantly reduced self-reported daytime sleepiness and fatigue and improved patient-reported outcomes and physician disease severity assessment in sleepy patients with obstructive sleep apnea refusing or nonadherent to continuous positive airway pressure.Clinical trial registered with www.clinicaltrials.gov (NCT01072968) and EU Clinical Trials Register (EudraCT 2009-017251-94).

The association between high risk of sleep apnea, comorbidities, and risk of COVID-19: a population-based international harmonized study.

PURPOSE: Obstructive sleep apnea (OSA) may increase the risk of severe COVID-19; however, the level of potential modulation has not yet been established. The objective of the study was to determine the association between high risk of OSA, comorbidities, and increased risk for COVID-19, hospitalization, and intensive care unit (ICU) treatment. METHODS: We conducted a cross-sectional population-based web survey in adults in 14 countries/regions. The survey included sociodemographic variables and comorbidities. Participants were asked questions about COVID-19, hospitalization, and ICU treatment. Standardized questionnaire (STOP questionnaire for high risk of OSA) was included. Multivariable logistic regression was conducted adjusting for various factors. RESULTS: Out of 26,539 respondents, 20,598 (35.4% male) completed the survey. Mean age and BMI of participants were 41.5 ± 16.0 years and 24.0 ± 5.0 kg/m2, respectively. The prevalence of physician-diagnosed OSA was 4.1% and high risk of OSA was 9.5%. We found that high risk of OSA (adjusted odds ratio (aOR) 1.72, 95% confidence interval (CI): 1.20, 2.47) and diabetes (aOR 2.07, 95% CI: 1.23, 3.48) were associated with reporting of a COVID-19 diagnosis. High risk for OSA (aOR 2.11, 95% CI: 1.10-4.01), being male (aOR: 2.82, 95% CI: 1.55-5.12), having diabetes (aOR: 3.93, 95% CI: 1.70-9.12), and having depression (aOR: 2.33, 95% CI: 1.15-4.77) were associated with increased risk of hospitalization or ICU treatment. CONCLUSIONS: Participants at high risk of OSA had increased odds of having COVID-19 and were two times more likely to be hospitalized or treated in ICU.

Motor vehicle accidents in CPAP-compliant obstructive sleep apnea patients-a long-term observational study.

PURPOSE: Obstructive sleep apnea (OSA) has been associated with a 2- to 7-fold risk of motor vehicle accidents (MVAs). Continuous positive airway pressure (CPAP) treatment may reduce MVA risk. We further explored this issue in long-term CPAP users and untreated controls. METHODS: We used both before-after and case-control study designs. The observational cohort consisted of CPAP-treated and untreated patients matched for gender, age, and apnea-hypopnea index. All MVAs reported to the police were identified. RESULTS: A total of 2060 patients (75.8% male, mean age 56.0 ± 10.5 years) were included. The CPAP-treated patients (N = 1030) were screened for MVAs for a median of 9.0 years before and after treatment. The median CPAP usage was 6.4 h/day. The control patients (N = 1030) were screened for MVAs for a median of 6.5 years after discontinuation of CPAP. No significant differences were observed between the incidences of MVAs per 1000 person years before treatment (3.2), after treatment (3.9), or in controls (2.6). Compared with controls, patients who had MVA after treatment had a higher body mass index (BMI), but did not differ in terms of other baseline characteristics, sleep study data, or accident conditions. In the majority of these patients, daytime sleepiness was reduced, whereas BMI tended to increase during treatment. CONCLUSIONS: The MVA incidence did not change after CPAP treatment. Among the patients who had MVA, BMI was the only baseline characteristic that differed between the groups and tended to further increase after CPAP treatment. Differences in sleep study data or accident conditions were not observed.

Gender-specific change in leptin concentrations during long-term CPAP therapy.

PURPOSE: Nasal continuous positive airway pressure (CPAP) alleviates sleepiness in patients with obstructive sleep apnoea syndrome (OSAS), but part of OSAS patients keep gaining weight. Leptin and insulin-like growth factor-1 (IGF-1) interact with energy balance, and CPAP therapy has been suggested to influence these endocrine factors. We hypothesised that leptin would decrease during long-term CPAP therapy, and weight gain would associate with OSAS severity, lower CPAP adherence, lower IGF-1, and leptin concentrations. METHODS: Consecutive patients (n = 223) referred to sleep study with suspected OSAS were enrolled. Patients underwent cardiorespiratory polygraphy at baseline. Questionnaires were completed, and blood samples were drawn both at baseline and after 3 years. A total of 149 (67%; M 65, F 84) patients completed the follow-up. Plasma samples were available from 114 patients, 109 of which with CPAP adherence data (49 CPAP users, 60 non-users). RESULTS: At baseline, the CPAP users were more obese and had more severe OSAS than the non-users. Leptin concentrations did not differ. After follow-up, leptin concentrations were higher in CPAP users (30.2 ng/ml vs. 16.8 ng/ml; p = 0.001). In regression analysis, increase in leptin concentrations was independent of age, baseline body mass index (BMI), or the change in BMI. Leptin concentrations increased among females (- 8.9 vs. 12.7 ng/ml; p < 0.001); whereas in men, CPAP did not have an effect, if not opposed the natural decrease in leptin observed in men not using CPAP. Change in IGF-1 levels did not differ. CONCLUSIONS: Our results suggest increase in leptin concentrations during long-term CPAP therapy among females.

Nonfatal and fatal cardiovascular disease events in CPAP compliant obstructive sleep apnea patients.

PURPOSE: Obstructive sleep apnea (OSA) is suggested to predispose to cardiovascular disease (CVD) events. It is uncertain whether compliance to continuous positive airway pressure (CPAP) treatment could attenuate the risk. We explored this issue in long-term CPAP users and untreated controls. METHODS: Retrospective observational cohort of CPAP-treated and control patients were pairwise matched for gender, age, and apnea-hypopnea index (AHI). The study end point was a composite of nonfatal and fatal CVD events. Cox regression model was used to determine the association between CPAP treatment and event-free survival. RESULTS: A total of 2060 patients (75.8% male, mean age 56.0 ± 10.5 years), of which 76.4% had moderate-severe OSA, were included. In the CPAP-treated group (N = 1030), the median use of CPAP was 6.4 h/day during a median follow-up of 8.7 years. The control group (N = 1030) was followed for a median of 6.2 years after the CPAP treatment had ended. The study end point occurred in 14.4% (N = 148) of the CPAP-treated and in 18.8% (N = 194) of the control patients (p = 0.006). Using the Cox regression model adjusted for gender, age, AHI, body mass index, and history of CVD, hypertension, type 2 diabetes, and chronic obstructive pulmonary disease at baseline, a beneficial association between CPAP treatment and CVD risk was observed (hazard ratio 0.64, confidence interval 95% 0.5-0.8, p < 0.001). CONCLUSIONS: CPAP treatment was associated with a decreased risk of nonfatal and fatal CVD events. Majority of the patients were compliant to CPAP. The association was demonstrated independent from common cardiovascular risk factors and AHI.

Stroke Volume Predicts Nocturnal Hypoxemia in the Acute Ischemic Stroke after Intravenous Thrombolysis.

The Goal: The aim of the study was to investigate whether stroke volume or the presence of ischemic stroke lesion on follow-up computed tomography 1 day after admission had association with sleep apnea among ischemic stroke patients undergoing thrombolysis. MATERIALS AND METHODS: We prospectively recruited 110 consecutive ischemic stroke patients and performed computed tomography on admission and after 24 hours after intravenous thrombolysis. Stroke volume was measured from post-thrombolysis computed tomography scans. Unattended cardiorespiratory polygraphy with a 3-channel device was performed during 48 hours after admission. FINDINGS: Of 110 ischemic stroke patients treated with thrombolysis 65.5% were men. Mean age was 65.8 years and body mass index 27.5 kg/m2. The mean Epworth sleepiness scale score was 4.7. Eight patients (12.7%) with visible acute stroke after thrombolysis and none in the other group had hemorrhage as complication (P ˂ .001). Sleep apnea, determined as a respiratory event index greater than or equal to 5/hour, was diagnosed in 96.4% patients. Respiratory event index greater than 15/h was found in 72.8% of patients. Both mean baseline oxygen desaturation index (23.9 versus 16.5, P = .028) and obstructive apneas/hour (6.2 versus 2.7, P = .007) were higher in visible stroke group. Stroke volume (mean 15.9 mL) correlated with proportion of time spent below saturation less than 90%, P = .025. CONCLUSIONS: Acute ischemic stroke patients treated with thrombolysis with visible stroke were more likely to have nocturnal hypoxemia than patients with not visible strokes. Stroke volume correlated with time spent below saturation of 90%.

Telemonitoring of CPAP therapy may save nursing time.

PURPOSE: Telemonitoring might enhance continuous positive airway pressure (CPAP) adherence and save nursing time at the commencement of CPAP therapy. We tested wireless telemonitoring (ResTraxx Online System®, ResMed) during the habituation phase of the CPAP therapy in obstructive sleep apnea syndrome (OSAS). METHODS: In total, 111 consecutive OSAS patients were enrolled. After CPAP titration, patients were followed with the telemonitoring (TM, N = 50) or the usual care (UC, N = 61). The TM group used fixed pressure CPAP device with and the UC group similar device without wireless telemonitoring. Patients and study nurses were unblinded. The evaluated end-points were hours of CPAP use >4 h/day, mask leak <0.4 L/s, and AHI <5/h. Nursing time including extra phone calls, visits, and telemonitoring time was recorded during the habituation phase. CPAP adherence was controlled in the beginning and at the end of the habituation phase and after 1-year of use. RESULTS: TM and UC groups did not differ in terms of patient characteristics. The average length of the habituation phase was 4 weeks in the TM group and fixed 3 months in the UC group. Median nursing time was 39 min (range 12-132 min) in the TM group and shorter compared to that of 58 min (range 40-180 min) (p < 0.001) per patient in the UC group. Both treatment groups had high CPAP usage hours (>4 h/day) and the change in usage at the end of the habituation phase did not differ between the groups (p = 0.39). Patients in both groups were equally satisfied with the treatment protocol. CPAP adherence (6.4 h in TM vs. 6.1 h in UC group, p = 0.63) and residual AHI (1.3 in TM vs. 3.2 in UC group, p = 0.04) were good in both groups at 1-year follow-up. CONCLUSIONS: Wireless telemonitoring of CPAP treatment could be relevant in closing the gap between the increasing demand and available health-care resources. It may save nursing time without compromising short- or long-term effectiveness of CPAP treatment in OSAS.

[Amyotrophic lateral sclerosis and respiratory insufficiency]. / Amyotrofinen lateraaliskleroosi ja hengitysvajaus.

Amyotrophic lateral sclerosis (ALS) is a disease causing degeneration of motor neurons, without any curative treatment. The most common cause of death is respiratory arrest due to atrophy of the respiratory musculature. ALS-associated respiratory insufficiency differs in mechanism from the more common causes of dyspnea, such as diseases of pulmonary or cardiac origin. Recognizing the respiratory insufficiency can be challenging for a clinician. It should be possible to predict the development of respiratory insufficiency in order to avoid leaving the treatment decisions concerning respiratory insufficiency to emergency services. Noninvasive ventilatory support can be used to alleviate the patient's dyspnea. It is actually recommended as the first-line treatment of ALS-associated respiratory insufficiency.

Sleep apnoea severity independently predicts glycaemic health in nondiabetic subjects: the ESADA study.

Obstructive sleep apnoea (OSA) is associated with increased risk of dysglycaemia but the intimate link of these conditions with obesity makes discerning an independent relationship between them challenging. Glycosylated haemoglobin (HbA1c) levels predict adverse cardiovascular outcomes in nondiabetics but there is a lack of population-level data exploring the relationship of HbA1c with OSA. A cross-sectional analysis of 5294 participants in the multinational European Sleep Apnoea Cohort (European Sleep Apnoea Database) study was performed, assessing the relationship of OSA severity with HbA1c levels in nondiabetic subjects, with adjustment for confounding factors. HbA1c levels correlated significantly with OSA severity in univariate analysis. Following adjustment for confounding factors, apnoea-hypopnoea index (AHI) (standardised ß 0.158; p<0.001), along with nocturnal hypoxaemia, predicted HbA1c. Adjusted mean HbA1c levels were lower in the lowest AHI quartile (5.24%, 95% CI 5.21-5.27%) than in the second (5.37%, 95% CI 5.34-5.40%), third (5.44%, 95% CI 5.41-5.47%) or highest (5.50%, 95% CI 5.46-5.53%) quartiles. Subjects in the higher quartiles had significantly greater adjusted odds ratios of HbA1c level ≥6.0% than those in the first quartile. In stratified analyses, OSA severity predicted glycaemic health irrespective of sleep study modality, sex, obesity or daytime sleepiness. OSA severity independently predicts glycaemic health in nondiabetic subjects. Further studies should assess the impact of OSA treatment on glycaemic health and elucidate underlying mechanisms.

Analysis of sleep apnea research with a special focus on the use of positron emission tomography as a study tool.

The quality of sleep plays a significant role in determining human well-being, and studying sleep and sleep disorders using various methods can aid in the prevention and treatment of diseases. Positron emission tomography (PET) is a noninvasive and highly sensitive medical imaging technique that has been widely adopted in the clinic. This review article provides data on research activity related to sleep and sleep apnea and discusses the use of PET in investigating sleep apnea and other sleep disorders. We conducted a statistical analysis of the number of original research articles published on sleep and sleep apnea between 1965 and 2021 and found that there has been a dramatic increase in publications since 1990. The distribution of contributing countries and regions has also undergone significant changes. Although there is an extensive body of literature on sleep research (256,399 original research articles during 1965-2021), PET has only been used in 54 of these published studies, indicating a largely untapped area of research. Nonetheless, PET is a useful tool for identifying connections between sleep disorders and pathological changes in various diseases, including neurological, metabolic, and cardiovascular disorders, as well as cancer. To facilitate the broader use of PET in sleep apnea research, further studies are needed in both clinical and preclinical settings.

Home non-invasive ventilation: An observational study of aetiology, chronic respiratory failure of multiple aetiologies, survival and treatment adherence.

Home non-invasive ventilation (NIV) is used to treat patients with chronic respiratory failure (CRF). However, knowledge on the prevalence and impact of multimorbid aetiology of CRF, patterns of NIV use, and survival of these patients is limited. Our aim was to analyse the multiple aetiologies of CRF, patterns of NIV use and the outcome of those patients. We conducted a retrospective analysis of 1,281 patients treated with home-NIV between 2004 and 2014 in Turku University Hospital, Finland. The patients were divided into nine disease categories: obstructive airways disease (16 %); obesity hypoventilation syndrome (11 %); neuromuscular disease (10 %); chest wall diseases (4 %); sleep apnoea (26 %); interstitial lung diseases (3 %); malignancy (2 %); other (3 %) and acute (8 %), which refers to the patients who did not fulfil criteria of CRF. In addition, multiple aetiologies of CRF were found in 17 %. Mean adherence to home-NIV was 6.0 ± 4.4 h/d and median treatment duration 410 (120-1021) days. Adherence, treatment duration or survival did not significantly differ between patients with either single or multiple causative diseases leading to CRF. Median survival was 4.5 years (95 % CI 3.6 to 5.4). The main reasons for discontinuing NIV were death (56 %) and lack of motivation (19 %). We conclude that home-NIV is used in a variety of diseases. CRF of multiple aetiologies is prevalent and not limited to chronic obstructive lung disease and obstructive sleep apnoea overlap syndrome. However, the adherence to home-NIV or survival did not differ between patients with a single or multiple diseases causing CRF, but the survival of the home-NIV patients differed according to the underlying aetiology of CRF.