Hemodialysis International

Interactions between intradialytic central venous oxygen saturation, relative blood volume, and all-cause mortality in maintenance hemodialysis patients

Priscila Preciado, Laura Rosales, Hanjie Zhang, Jeroen P. Kooman, Frank M. van der Sande, Peter Kotanko


Introduction: In maintenance hemodialysis (HD) patients, low central venous oxygen saturation (ScvO2 ) and small decline in relative blood volume (RBV) have been associated with adverse outcomes. Here we explore the joint association between ScvO2 and RBV change in relation to all-cause mortality.

Methods: We conducted a retrospective study in maintenance HD patients with central venous catheters as vascular access. During a 6-month baseline period, Crit-Line (Fresenius Medical Care, Waltham, MA) was used to measure continuously intradialytic ScvO2 and hematocrit-based RBV. We defined four groups per median change of RBV and median ScvO2 . Patients with ScvO2 above median and RBV change below median were defined as reference. Follow-up period was 3 years. We constructed Cox proportional hazards model with adjustment for age, diabetes, and dialysis vintage to assess the association between ScvO2 and RBV and all-cause mortality during follow-up.

Findings: Baseline comprised 5231 dialysis sessions in 216 patients. The median RBV change was -5.5% and median ScvO2 was 58.8%. During follow-up, 44 patients (20.4%) died. In the adjusted model, all-cause mortality was highest in patients with ScvO2 below median and RBV change above median (HR 6.32; 95% confidence interval [CI] 1.37-29.06), followed by patients with ScvO2 below median and RBV change below median (HR 5.04; 95% CI 1.14-22.35), and ScvO2 above median and RBV change above median (HR 4.52; 95% CI 0.95-21.36).

Discussion: Concurrent combined monitoring of intradialytic ScvO2 and RBV change may provide additional insights into a patient's circulatory status. Patients with low ScvO2 and small changes in RBV may represent a specifically vulnerable group of patients at particularly high risk for adverse outcomes, possibly related to poor cardiac reserve and fluid overload.

Keywords: central venous oxygen saturation; hemodialysis; patient outcomes; relative blood volume; ultrafiltration rate.

© 2023 The Authors. Hemodialysis International published by Wiley Periodicals LLC on behalf of International Society for Hemodialysis.

About the Author

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.

Laura Rosales, MD, MPH

Director, Research Medical Education & Information

Laura obtained her MD degree from the Central University in Quito, Ecuador, and a master’s degree in public health from Columbia University, New York. She was a research fellow for Beth Israel Medical Center in partnership with RRI and was the Research Associate Lab Director at RRI for several years. Laura is an accomplished scientist with ample experience in clinical research for more than 16 years and has authored and co-authored numerous publications in peer-reviewed journals.

Hanjie Zhang, MSc, PhD

Supervisor of Biostatistics and Applied Artificial Intelligence /Machine Learning

Hanjie joined the 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...