title: Intradialytic Hypoxemia and Clinical Outcomes in Patients on Hemodialysis.
abstract: OBJECTIVE
  Intradialytic hypoxemia has been recognized for decades, but its associations with outcomes have not yet been assessed in a large patient cohort.
  
  
  METHODS
  Our retrospective cohort study was conducted between January of 2012 and January of 2015. We recorded blood oxygen saturation every minute during hemodialysis in patients with arteriovenous access. A 6-month baseline period with at least 10 treatments with oxygen saturation measurements preceded a 12-month follow-up. Patients were stratified by the presence or absence of prolonged intradialytic hypoxemia defined as oxygen saturation <90% for at least one third of the treatment time. Demographic, laboratory, and treatment data and hospitalization and mortality rates were compared between the groups. Multivariate Cox regression analysis was used to assess baseline predictors of all-cause mortality during follow-up.
  
  
  RESULTS
  In total, 100 (10%) of 983 patients had prolonged intradialytic hypoxemia. These patients were older (+3.6 years; 95% confidence interval, 0.8 to 6.3), had longer dialysis vintage (+1.2 years; 95% confidence interval, 0.3 to 2.1), and had higher prevalence of congestive heart failure (+10.8%; 95% confidence interval, 1.6 to 20.7) and chronic obstructive pulmonary disease (+13%; 95% confidence interval, 5 to 21.2). They also resembled an inflammatory phenotype, with lower serum albumin levels (-0.1 g/dl; 95% confidence interval, -0.2 to 0) and higher neutrophil-to-lymphocyte ratios (+1; 95% confidence interval, 0.5 to 1.6). They had lower hemoglobin levels (-0.2 g/dl; 95% confidence interval, -0.4 to 0) and required more erythropoietin (+1374 U per hemodialysis treatment; 95% confidence interval, 343 to 2405). During follow-up, all-cause hospitalization (1113 hospitalizations; univariate hazard ratio, 1.46; 95% confidence interval, 1.22 to 1.73) and mortality (89 deaths; adjusted hazard ratio, 1.98; 95% confidence interval, 1.14 to 3.43) were higher in patients with prolonged intradialytic hypoxemia.
  
  
  CONCLUSIONS
  Prolonged intradialytic hypoxemia was associated with laboratory indicators of inflammation, higher erythropoietin requirements, and higher all-cause hospitalization and mortality.
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Anna
authors.initials: A
authors.lastname: Meyring-Wösten
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Hanjie
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Ye
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Doris H
authors.initials: DH
authors.lastname: Fuertinger
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, New York;
authors.forename: Lili
authors.initials: L
authors.lastname: Chan
authors.affiliation: Institute for Mathematics and Scientific Computing, University Graz, Graz, Austria; and.
authors.forename: Franz
authors.initials: F
authors.lastname: Kappel
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Mikhail
authors.initials: M
authors.lastname: Artemyev
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Nancy
authors.initials: N
authors.lastname: Ginsberg
authors.affiliation: Department of Statistics and Applied Probability, University of California, Santa Barbara, California.
authors.forename: Yuedong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Renal Research Institute, New York, New York;
authors.forename: Stephan
authors.initials: S
authors.lastname: Thijssen
authors.affiliation: Renal Research Institute, New York, New York; Icahn School of Medicine at Mount Sinai, New York, New York; pkotanko@rriny.com.
authors.forename: Peter
authors.initials: P
authors.lastname: Kotanko
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Cohort Studies; Humans; erythropoietin; hospitalization; hypoxia; inflammation; mortality; oxygen saturation; prolonged intradialytic hypoxemia; renal dialysis