The doctoral dissertation in the field of Applied Physics will be examined at the Faculty of Science, Forestry and Technology, Kuopio campus and online.
What is the topic of your doctoral research? Why is it important to study the topic?
My doctoral dissertation on the detailed characterization of hypoxemia events enhances the assessment of obstructive sleep apnea (OSA) severity. OSA is characterized by frequent nocturnal hypoxemia events, which lead to several OSA-related consequences, such as daytime impaired vigilance and cardiovascular diseases. The present diagnostic metric for OSA, the apnea-hypopnea index (AHI), shows a poor correlation with most OSA-related consequences. Therefore, it is essential to investigate and characterize oxygen desaturation events in OSA patients, as they correlate more closely with OSA-related outcomes. Our findings demonstrate the association of hypoxic load with impaired daytime vigilance and lung-to-finger circulation time (LFCt).
What are the key findings or observations of your doctoral research?
A key observation of my research is that the hypoxic load is significantly associated with daytime impaired vigilance in OSA patients, and this association remains consistent in males in sex-stratified analysis. Furthermore, prolonged LFCt is significantly associated with higher hypoxic load, even in OSA patients with milder respiratory events. These novel hypoxic load-based metrics could be used as markers for patients in the most urgent need of treatment. Supplementing the current OSA diagnostic metrics with our novel metrics would enable timely and efficient treatment, improving patients' overall well-being while alleviating the direct and indirect socioeconomic burden of OSA.
How can the results of your doctoral research be utilised in practice?
Our research provides novel insights into oxygen desaturation characteristics, daytime vigilance, respiratory event severity, and LFCt in OSA patients. The proposed hypoxic load metrics are more strongly linked to impaired vigilance and prolonged LFCt than the AHI. Therefore, incorporating the presented and readily available pulse-oximetry-derived hypoxic load-based metrics alongside the conventional diagnostic metrics could enhance the clinical assessment of OSA severity and treatment prioritization. This approach would enable limited treatment resources to be allocated in a tailored, patient-specific manner.
What are the key research methods and materials used in your doctoral research?
The retrospective dataset included 912 pairs of polysomnography and psychomotor vigilance task recordings from suspected OSA patients at the Sleep Disorders Centre of Princess Alexandra Hospital in Brisbane, Australia. The first comparative study analyzed quartiles of OSA patients with and without impaired vigilance, and a similar analysis was conducted separately for males and females. Additionally, we investigated the connection between LFCt, respiratory events, and hypoxic load. The significance of the results was assessed using statistical tests and regression model analysis, and their impact was evaluated from both research and clinical perspectives.
The doctoral dissertation of Purbanka Pahari, ME, entitled Detailed characterization of hypoxemia events enhances assessment of obstructive sleep apnea severity will be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus. The opponent will be Professor Danny Eckert, Flinders University, Australia, and the custos will be Associate Professor Timo Leppänen, University of Eastern Finland. Language of the public defence is English.
For more information, please contact:
Purbanka Pahari, purbanka.pahari@uef.fi, tel.+358 40 356 3960, X: @PurbankaPahari
