Pulse Wave Amplitude Drops Index: A Biomarker of Cardiovascular Risk in Obstructive Sleep Apnea.

Rationale: It is currently unclear which patients with obstructive sleep apnea (OSA) are at increased cardiovascular risk. Objective: To investigate the value of pulse wave amplitude drops (PWADs), reflecting sympathetic activations and vasoreactivity, as a biomarker of cardiovascular risk in OSA. Methods: PWADs were derived from pulse oximetry-based photoplethysmography signals in three prospective cohorts: HypnoLaus (N = 1,941), the Pays-de-la-Loire Sleep Cohort (PLSC; N = 6,367), and "Impact of Sleep Apnea syndrome in the evolution of Acute Coronary syndrome. Effect of intervention with CPAP" (ISAACC) (N = 692). The PWAD index was the number of PWADs (>30%) per hour during sleep. All participants were divided into subgroups according to the presence or absence of OSA (defined as ⩾15 or more events per hour or <15/h, respectively, on the apnea-hypopnea index) and the median PWAD index. Primary outcome was the incidence of composite cardiovascular events. Measurements and Main Results: Using Cox models adjusted for cardiovascular risk factors (hazard ratio; HR [95% confidence interval]), patients with a low PWAD index and OSA had a higher incidence of cardiovascular events compared with the high-PWAD and OSA group and those without OSA in the HypnoLaus cohort (HR, 2.16 [1.07-4.34], P = 0.031; and 2.35 [1.12-4.93], P = 0.024) and in the PLSC (1.36 [1.13-1.63], P = 0.001; and 1.44 [1.06-1.94], P = 0.019), respectively. In the ISAACC cohort, the low-PWAD and OSA untreated group had a higher cardiovascular event recurrence rate than that of the no-OSA group (2.03 [1.08-3.81], P = 0.028). In the PLSC and HypnoLaus cohorts, every increase of 10 events per hour in the continuous PWAD index was negatively associated with incident cardiovascular events exclusively in patients with OSA (HR, 0.85 [0.73-0.99], P = 0.031; and HR, 0.91 [0.86-0.96], P < 0.001, respectively). This association was not significant in the no-OSA group and the ISAACC cohort. Conclusions: In patients with OSA, a low PWAD index reflecting poor autonomic and vascular reactivity was independently associated with a higher cardiovascular risk.

Self-setup of home respiratory polygraphy for the diagnosis of sleep apnea syndrome: cost-efficiency study.

PURPOSE: To evaluate the differences in reliability and costs of home respiratory polygraphy (HRP) when installed by the patient and by a nurse, in order to determine the factors affecting and to consider the possible generalization of self-setup procedure. Several HRP devices have been validated for obstructive sleep apnea (OSA) diagnosis but convenience of a nurse intervention in HRP installation has been scarcely studied. METHODS: This is a prospective and interventional study. About 301 participants were assigned to 2 groups: self-setup and nurse intervention. Sleep study, questionnaires, and diagnostic procedures were performed following the clinical practice in 2016. Signals were considered lost above 3 min, and success of the test was established according to guidelines. Costs were calculated according to a previous multicenter study. RESULTS: Both groups (self-setup and nurse intervention) resulted homogeneous in age, gender, BMI, and final diagnosis of OSA. Signal losses during the test were similar in both groups. Slightly higher percentage of unsuccessful tests were obtained in the self-setup procedure (5.3 vs 2.0%, p = 0.121). The costs were similar (107 vs 105 €) in the self-setup group as compared to the nurse setup group. CONCLUSIONS: The setup of HRP by either the patient or nurse had similar costs and data acquisition. Both installation procedures of HRP were similar regarding test reliability and costs. Main findings are that self-installation by the patient could be similarly reliable and economic as installation by a nurse, as far as consensus guidelines are followed. This study demonstrates that self-setup of HRP is a potentially viable option for the diagnosis of OSA.

Primary Care Physicians Can Comprehensively Manage Patients with Sleep Apnea. A Noninferiority Randomized Controlled Trial.

Rationale: General practitioners play a passive role in obstructive sleep apnea (OSA) management. Simplification of the diagnosis and use of a semiautomatic algorithm for treatment can facilitate the integration of general practitioners, which has cost advantages.Objectives: To determine differences in effectiveness between primary health care area (PHA) and in-laboratory specialized management protocols during 6 months of follow-up.Methods: A multicenter, noninferiority, randomized, controlled trial with two open parallel arms and a cost-effectiveness analysis was performed in six tertiary hospitals in Spain. Sequentially screened patients with an intermediate to high OSA probability were randomized to PHA or in-laboratory management. The PHA arm involved a portable monitor with automatic scoring and semiautomatic therapeutic decision-making. The in-laboratory arm included polysomnography and specialized therapeutic decision-making. Patients in both arms received continuous positive airway pressure treatment or sleep hygiene and dietary treatment alone. The primary outcome measure was the Epworth Sleepiness Scale. Secondary outcomes were health-related quality of life, blood pressure, incidence of cardiovascular events, hospital resource utilization, continuous positive airway pressure adherence, and within-trial costs.Measurements and Main Results: In total, 307 patients were randomized and 303 were included in the intention-to-treat analysis. Based on the Epworth Sleepiness Scale, the PHA protocol was noninferior to the in-laboratory protocol. Secondary outcome variables were similar between the protocols. The cost-effectiveness relationship favored the PHA arm, with a cost difference of €537.8 per patient.Conclusions: PHA management may be an alternative to in-laboratory management for patients with an intermediate to high OSA probability. Given the clear economic advantage of outpatient management, this finding could change established clinical practice.Clinical trial registered with www.clinicaltrials.gov (NCT02141165).

Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea.

BACKGROUND: Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO2) as the main outcome measure. METHODS: Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis. RESULTS: A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO2 of -6 (95% CI -7.7 to -4.2) mm Hg versus -2.8 (95% CI -4.3 to -1.3) mm Hg, (p<0.001) and serum bicarbonate of -3.4 (95% CI -4.5 to -2.3) versus -1 (95% CI -1.7 to -0.2 95% CI)  mmol/L (p<0.001). PaCO2 change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group. CONCLUSIONS: NIV is more effective than lifestyle modification in improving daytime PaCO2, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality. TRIAL REGISTRATION NUMBER: NCT01405976; results.

Efficacy of Different Treatment Alternatives for Obesity Hypoventilation Syndrome. Pickwick Study.

RATIONALE: The incidence of obesity hypoventilation syndrome (OHS) may be increasing in parallel with the present obesity epidemic. Despite extensive noninvasive ventilation (NIV) and continuous positive airway pressure (CPAP) use in patients with OHS, information regarding efficacy is limited. OBJECTIVES: We performed a large, multicenter randomized controlled study to determine the comparative efficacy of NIV, CPAP, and lifestyle modification (control group) using daytime PaCO2 as the main outcome measure. METHODS: Sequentially screened patients with OHS with severe sleep apnea were randomized into the above-mentioned groups for a 2-month follow up. Arterial blood gas parameters, clinical symptoms, health-related quality-of-life assessments, polysomnography, spirometry, 6-minute-walk distance, dropouts, compliance, and side effects were evaluated. Statistical analysis was performed using intention-to-treat analysis, although adjustments for CPAP and NIV compliance were also analyzed. MEASUREMENTS AND MAIN RESULTS: In total, 351 patients were selected, and 221 were randomized. NIV yielded the greatest improvement in PaCO2 and bicarbonate, with significant differences relative to the control group but not relative to the CPAP group. In the CPAP group, PaCO2 improvement was significantly different than in the control group only after CPAP compliance adjustment. Additionally, clinical symptoms and polysomnographic parameters improved similarly with NIV and CPAP relative to the control. However, some health-related quality-of-life assessments, the spirometry, and 6-minute-walk distance results improved more with NIV than with CPAP. Dropouts were similar between groups, and compliance and secondary effects were similar between NIV and CPAP. CONCLUSIONS: NIV and CPAP were more effective than lifestyle modification in improving clinical symptoms and polysomnographic parameters, although NIV yielded better respiratory functional improvements than did CPAP. Long-term studies must demonstrate whether this functional improvement has relevant implications. Clinical trial registered with www.clinicaltrials.gov (NCT01405976).

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

BACKGROUND: Advances in information technology and telecommunications have provided the option of making it easier to diagnose and treat obstructive sleep apnea syndrome (OSAS) using telemedicine techniques. This study assessed the feasibility and reliability of respiratory polygraphy and prescription of treatment by pressure adjustment with auto-continuous positive airway pressure (CPAP) systems, both being transmitted telematically to the Sleep Unit, with teleconsultation as a support method. SUBJECTS AND METHODS: Forty patients were studied from a population 80 km from the Sleep Unit using respiratory polygraphy transmitted in real time. They were divided into two groups: one was seen by conventional consultation, and the other was seen using teleconsultation. We also estimated satisfaction with this system and its costs. RESULTS: The mean patient age was 53 ± 10.3 years, with a body mass index of 31 ± 6.2 kg/m(2) and an Epworth score of 12 ± 5.3. In total, 35 patients were diagnosed with OSAS, with an Apnea-Hypopnea Index of ≥10, and CPAP treatment was started in 16 of them. The agreement in the Apnea-Hypopnea Index, total apneas and hypopneas, mean oxygen saturation, and time with an oxygen saturation <90% was greater than 90% between the studies transmitted in real time and those stored in the polygraph. The level of compliance with CPAP treatment was 85% for the patients who were seen in a conventional clinic and 75% in those seen by teleconsultation. CONCLUSIONS: The use of telematic techniques is useful to establish a diagnostic and therapeutic strategy for OSAS with the creation of a Wide Core Sleep Laboratory as a process controller.