Katrien Hertegonne

The Link Between Obstructive Sleep Apnea and Cardiovascular Disease

Obstructive sleep apnea (OSA) is common in the general population and highly prevalent in patients with cardiovascular disease. In this paper, we review (1) the pathophysiological mechanisms of OSA that may causally contribute to cardiovascular disease; (2) current evidence regarding the association between OSA and hypertension, stroke, ischemic heart disease, heart failure, atrial fibrillation, and cardiovascular mortality; and (3) the impact of continuous positive airway pressure (CPAP) treatment on cardiovascular risk factors and outcomes. We emphasize the importance of obesity as a comorbidity of OSA and a confounder in the association between OSA and cardiovascular disease. We also discuss the importance of addressing obesity in patients with OSA, as a strategy to reduce the burden of cardiovascular risk factors in this population. Implications for the approach of patients’ OSA in clinical practice and future research directions are discussed.

The value of auto-adjustable CPAP devices in pressure titration and treatment of patients with obstructive sleep apnea syndrome

In moderate to severe obstructive sleep apnea syndrome (OSAS), the use of Continuous Positive Airway Pressure (CPAP) is the gold standard therapy. In the last decade, new technologies such as auto-adjustable CPAP (APAP) have been promoted as having an added advantage over CPAP, because of their ability to adapt the pressure level to the patients need at all times. This could logically result in the deliverance of lower pressures, which was hypothesized to improve patient acceptance and compliance for therapy. Several clinical trials have been performed with APAP in different modalities, as a titration tool in attended or unattended conditions, or as a treatment device for chronic use. Comparison of these trials is challenging, since APAP technology is evolving promptly and devices differ not only in how sleep-disordered breathing is detected, but also in how the operational algorithm responds accordingly. Although the question remains whether proof has yet been delivered of the superiority of this technology over CPAP, there is a tendency to accept it as common standard practice in OSAS titration and treatment. This review will bring available evidence on this subject into perspective.

Comfort and pressure profiles of two auto-adjustable positive airway pressure devices: a technical report

STUDY OBJECTIVES The purpose of this study was to compare comfort parameters and pressure profiles of the AutoSet (Resmed) and the SOMNOsmart (Weinmann), two auto-adjustable positive airway pressure (APAP) devices. SETTING The sleep disorders center of a university hospital. DESIGN A single-blind randomized trial protocol was applied. A split night procedure allowed each patient to be treated in a crossover fashion with both APAP devices during one overnight study. PATIENTS AND METHODS Fifty consecutive obstructive sleep apnea (OSA) patients were recruited. Each patient filled out an evaluation form for both devices after the study night. Visual analogue scales were used to score four comfort measures. Three CPAP outcomes generated by the devices (P50, P95 and Pmax) were assessed, compared with each other and correlated with the individually predicted CPAP (Ppred). RESULTS Forty-five males and 5 females, mean age 53.0 years, body mass index 31.0, were included. The mean apnea-hypopnea index was 58.7, the mean arousal index was 54.3. Mean CPAP-compliance before the titration study was 4.9 h per night. Comparison of the two devices regarding the effect on the subjective sleep quality parameters showed no differences. The AutoSet pressure outcomes correlated significantly better with Ppred in comparison with the SOMNOsmart. The P50 and P95 but not the Pmax values were significantly lower in the SOMNOsmart as compared with the AutoSet (P50: 5.1+/-1.3 vs 7.1 +/- 1.9 mbar, P<0.0001; P95: 7.8+/-3.0 vs 9.6+/-1.9 mbar, P<0.0005; Pmax: 10.0+/-3.4 vs 10.8+/-1.8 mbar, NS). CONCLUSION While the subjective tolerance of the two APAP machines was comparable, these devices were characterized by different pressure profiles. The pressure parameters of the AutoSet correlated better with Ppred than those of the SOMNOsmart.

Titration Efficacy of Two Auto-Adjustable Continuous Positive Airway Pressure Devices Using Different Flow Limitation-Based Algorithms

Background: Auto-adjustable continuous positive airway pressure devices are widely used in titration procedures to determine therapeutic pressure levels in obstructive sleep apnea patients. However, differences in operational characteristics may influence the effect on the apnea-hypopnea index (AHI). Objectives: We compared the titration performance of two devices based on detection of inspiratory flow limitation, i.e. the Respironics REMstar Auto™ (RR) and the ResMed Spirit™ (RS). Methods: Fifty obstructive sleep apnea patients were recruited for a double-blind randomized crossover trial. Both devices were employed overnight by means of split-night polysomnography. The primary outcome was the AHI. Secondary outcome measures were the snoring index, pressure profiles and subjective appraisal of sleep quality assessed the morning after the sleep study. The Wilcoxon signed rank test for matched pairs was applied to assess differences between treatment conditions. Results: No significant differences were found in sleep parameters, subjective sleep quality and snoring index. The use of the RR was associated with a significantly lower AHI in comparison with the RS [mean (SD) 6.9 (11.6)/h vs. 9.4 (9.2)/h, p = 0.004]. This result was obtained at significantly lower pressure levels [P95 9.2 (2.3) cm H2O vs. 10.2 (1.5) cm H2O, p = 0.001]. Conclusion: While the RR provided a lower AHI than the RS at lower pressure levels, it could not be assessed whether this difference was relevant for clinical outcomes. However, this face-to-face comparison of Auto-adjustable continuous positive airway pressure devices seems useful for the assessment of titration efficacy.