Cardiopulmonary Phenotyping during Sleep - Innovative Signal Processing for Precision Medicine in Sleep Apnea

Abstract

Background: Obstructive sleep apnea (OSA) is one of the most common sleep disorders with a significant impact on public health. Various studies suggest that the contemporary methods of clinical sleep medicine are insufficient to capture the heterogeneity of OSA. While there is increasing knowledge about the underlying mechanisms and consequences of OSA, their detailed assessment in clinical practice is limited due to complex study protocols. This thesis presents advanced applications of oximeter-based pulse wave analysis and respiratory endotyping for a thorough and accessible assessment of the causes and consequences of OSA in clinical routine. Methods and Results: Studies I and II explored nocturnal finger pulse wave analysis for assessing cardiovascular risk in epidemiological and clinical cohorts. These studies highlighted the ability to evaluate cardiovascular risk beyond established sleep metrics and demonstrated that cardiorespiratory coupling and vascular stiffness are specifically associated with diabetes. Study III analyzed data from a randomized controlled trial involving subjects with moderate to severe OSA to evaluate the clinical utility of pathophysiological endotyping through advanced flow shape analysis. This study demonstrated the feasibility of single-night assessments for endotypic characterizations and provided references for interpreting changes in these traits. Study IV combined the approaches from Studies I-III to fully utilize the potential of integrating pulse wave analysis in the endotypic classification of OSA. Conclusion: Sleep medicine is facing a paradigm shift in how to manage OSA in clinical practice. This thesis highlights the potential of utilizing advanced analysis protocols to assist clinical decision-making, moving away from a one-size-fits-all approach. These accessible and detailed assessments may be implemented to offer more precise diagnostics of the heterogeneity of OSA to enable tailored treatments and improved patient outcomes.