Scientific Reports

Identification of arterial oxygen intermittency in oximetry data

Paulo P Galuzio, Alhaji Cherif, Xia Tao, Ohnmar Thwin, Hanjie Zhang, Stephan Thijssen, Peter Kotanko


In patients with kidney failure treated by hemodialysis, intradialytic arterial oxygen saturation (SaO2) time series present intermittent high-frequency high-amplitude oximetry patterns (IHHOP), which correlate with observed sleep-associated breathing disturbances. A new method for identifying such intermittent patterns is proposed. The method is based on the analysis of recurrence in the time series through the quantification of an optimal recurrence threshold ([Formula: see text]). New time series for the value of [Formula: see text] were constructed using a rolling window scheme, which allowed for real-time identification of the occurrence of IHHOPs. The results for the optimal recurrence threshold were confronted with standard metrics used in studies of obstructive sleep apnea, namely the oxygen desaturation index (ODI) and oxygen desaturation density (ODD). A high correlation between [Formula: see text] and the ODD was observed. Using the value of the ODI as a surrogate to the apnea-hypopnea index (AHI), it was shown that the value of [Formula: see text] distinguishes occurrences of sleep apnea with great accuracy. When subjected to binary classifiers, this newly proposed metric has great power for predicting the occurrences of sleep apnea-related events, as can be seen by the larger than 0.90 AUC observed in the ROC curve. Therefore, the optimal threshold [Formula: see text] from recurrence analysis can be used as a metric to quantify the occurrence of abnormal behaviors in the arterial oxygen saturation time series.

About the Contributors

Hanjie Zhang, MSc, PhD

Supervisor of Biostatistics and Applied Artificial Intelligence /Machine Learning

Hanjie joined RRI in 2014. She received a master’s degree in statistics from Columbia University, New York, and a PhD in medical science from the University of Maastricht, The Netherlands. Hanjie has been involved in the design of several large cluster-randomized clinical trials and complex statistical analyses in collaboration with the Medical Office, FMCNA...

Stephan Thijssen, MD

Vice President, Applied and Basic Research

Prior to coming to New York, Stephan worked in the Nephrology Department at the University Hospital Homburg, Germany. He joined RRI in 2005. Stephan brings more than one and a half decades of research experience to the RRI team, covering laboratory research, clinical research, epidemiology research, and mathematical modeling. He has written and published an extensive number of scholarly articles in leading national and international peer-reviewed scientific journals and published several book chapters.

Dr. Peter Kotanko, MD

RRI Research Director

SVP, Corporate Research & Development

Peter Kotanko, MD, is Research Director at the Renal Research Institute (RRI), New York. Prior to joining RRI, from 1997 to 2007 he served as vice chair of a department of internal medicine at an academic teaching hospital in Graz, Austria. Prior to moving to Graz in 1989, he worked from 1982 to 1989 in the Department of Physiology and the University Clinic of Internal Medicine in Innsbruck, Austria. From 1995 to 1996 he trained in nephrology at the Hammersmith Hospital, London, United Kingdom.