Assessing Extracellular Volume in Hemodialysis Patients Using Intradialytic Blood Pressure Slopes

Hao Liu, Rong Lu, Shani Shastri, Mark Sonderman, Peter Noel Van Buren

Research output: Contribution to journalArticle

Abstract

Background/Aims: Extracellular volume (ECV) overload is a mortality risk factor in hemodialysis patients, but no standard approach exists to objectively assess this clinically. We aimed to quantify relationships between slopes of repeated intradialytic blood pressure (BP) measurements and ECV. Methods: In a cross-sectional study of 71 hemodialysis patients, we calculated BP slopes from all intradialytic measurements using Gaussian regression. We measured extracellular and total body water (TBW) with bioimpedance spectroscopy. We analyzed unconditional and conditional associations between BP slope and volume metrics with mixed linear models and sensitivity analyses using non-linear intradialytic BP trajectory. Results: Mean systolic intradialytic BP slope (IBPS) was –0.06 (0.1) mm Hg/min. Post-dialysis extracellular water (ECW)/weight was the volume metric mostly strongly associated with slope (r = 0.34, p = 0.007 for unconditional analysis; β = 1.45, p = 0.001 for conditional analysis). Among subjects with post-dialysis systolic BP ≥130 mm Hg, the association strengthened (r = 0.40, p = 0.006; β = 1.42, p = 0.003). ECV was more strongly associated with the BP slope than with pre-dialysis, post-dialysis, or delta systolic BP (r = –0.07, 0.19, 0.28; p = 0.6, 0.1, 0.03). In nonlinear models, BP trajectory also had the strongest association with post-dialysis ECW/body weight (p < 0.001). Conclusions: In hypertensive hemodialysis patients, measurements of ECV excess are more strongly associated with IBPSs than with pre-dialysis, post-dialysis, or change in systolic BP. Among varying volume metrics, post-dialysis ECW/weight has the strongest association with these slopes. Determining IBPS is a novel method to optimize clinical assessment of ECV in hemodialysis patients.

Original languageEnglish (US)
JournalNephron
DOIs
StateAccepted/In press - Feb 13 2018

Fingerprint

Renal Dialysis
Blood Pressure
Dialysis
Water
Weights and Measures
Nonlinear Dynamics
Body Water
Blood Volume
Linear Models
Spectrum Analysis
Cross-Sectional Studies
Body Weight
Mortality

Keywords

  • Bioimpedance spectroscopy
  • Extracellular volume
  • Hemodialysis
  • Hypertension
  • Intradialytic blood pressure slopes

ASJC Scopus subject areas

  • Physiology
  • Nephrology
  • Urology
  • Physiology (medical)

Cite this

Assessing Extracellular Volume in Hemodialysis Patients Using Intradialytic Blood Pressure Slopes. / Liu, Hao; Lu, Rong; Shastri, Shani; Sonderman, Mark; Van Buren, Peter Noel.

In: Nephron, 13.02.2018.

Research output: Contribution to journalArticle

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abstract = "Background/Aims: Extracellular volume (ECV) overload is a mortality risk factor in hemodialysis patients, but no standard approach exists to objectively assess this clinically. We aimed to quantify relationships between slopes of repeated intradialytic blood pressure (BP) measurements and ECV. Methods: In a cross-sectional study of 71 hemodialysis patients, we calculated BP slopes from all intradialytic measurements using Gaussian regression. We measured extracellular and total body water (TBW) with bioimpedance spectroscopy. We analyzed unconditional and conditional associations between BP slope and volume metrics with mixed linear models and sensitivity analyses using non-linear intradialytic BP trajectory. Results: Mean systolic intradialytic BP slope (IBPS) was –0.06 (0.1) mm Hg/min. Post-dialysis extracellular water (ECW)/weight was the volume metric mostly strongly associated with slope (r = 0.34, p = 0.007 for unconditional analysis; β = 1.45, p = 0.001 for conditional analysis). Among subjects with post-dialysis systolic BP ≥130 mm Hg, the association strengthened (r = 0.40, p = 0.006; β = 1.42, p = 0.003). ECV was more strongly associated with the BP slope than with pre-dialysis, post-dialysis, or delta systolic BP (r = –0.07, 0.19, 0.28; p = 0.6, 0.1, 0.03). In nonlinear models, BP trajectory also had the strongest association with post-dialysis ECW/body weight (p < 0.001). Conclusions: In hypertensive hemodialysis patients, measurements of ECV excess are more strongly associated with IBPSs than with pre-dialysis, post-dialysis, or change in systolic BP. Among varying volume metrics, post-dialysis ECW/weight has the strongest association with these slopes. Determining IBPS is a novel method to optimize clinical assessment of ECV in hemodialysis patients.",
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AU - Van Buren, Peter Noel

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N2 - Background/Aims: Extracellular volume (ECV) overload is a mortality risk factor in hemodialysis patients, but no standard approach exists to objectively assess this clinically. We aimed to quantify relationships between slopes of repeated intradialytic blood pressure (BP) measurements and ECV. Methods: In a cross-sectional study of 71 hemodialysis patients, we calculated BP slopes from all intradialytic measurements using Gaussian regression. We measured extracellular and total body water (TBW) with bioimpedance spectroscopy. We analyzed unconditional and conditional associations between BP slope and volume metrics with mixed linear models and sensitivity analyses using non-linear intradialytic BP trajectory. Results: Mean systolic intradialytic BP slope (IBPS) was –0.06 (0.1) mm Hg/min. Post-dialysis extracellular water (ECW)/weight was the volume metric mostly strongly associated with slope (r = 0.34, p = 0.007 for unconditional analysis; β = 1.45, p = 0.001 for conditional analysis). Among subjects with post-dialysis systolic BP ≥130 mm Hg, the association strengthened (r = 0.40, p = 0.006; β = 1.42, p = 0.003). ECV was more strongly associated with the BP slope than with pre-dialysis, post-dialysis, or delta systolic BP (r = –0.07, 0.19, 0.28; p = 0.6, 0.1, 0.03). In nonlinear models, BP trajectory also had the strongest association with post-dialysis ECW/body weight (p < 0.001). Conclusions: In hypertensive hemodialysis patients, measurements of ECV excess are more strongly associated with IBPSs than with pre-dialysis, post-dialysis, or change in systolic BP. Among varying volume metrics, post-dialysis ECW/weight has the strongest association with these slopes. Determining IBPS is a novel method to optimize clinical assessment of ECV in hemodialysis patients.

AB - Background/Aims: Extracellular volume (ECV) overload is a mortality risk factor in hemodialysis patients, but no standard approach exists to objectively assess this clinically. We aimed to quantify relationships between slopes of repeated intradialytic blood pressure (BP) measurements and ECV. Methods: In a cross-sectional study of 71 hemodialysis patients, we calculated BP slopes from all intradialytic measurements using Gaussian regression. We measured extracellular and total body water (TBW) with bioimpedance spectroscopy. We analyzed unconditional and conditional associations between BP slope and volume metrics with mixed linear models and sensitivity analyses using non-linear intradialytic BP trajectory. Results: Mean systolic intradialytic BP slope (IBPS) was –0.06 (0.1) mm Hg/min. Post-dialysis extracellular water (ECW)/weight was the volume metric mostly strongly associated with slope (r = 0.34, p = 0.007 for unconditional analysis; β = 1.45, p = 0.001 for conditional analysis). Among subjects with post-dialysis systolic BP ≥130 mm Hg, the association strengthened (r = 0.40, p = 0.006; β = 1.42, p = 0.003). ECV was more strongly associated with the BP slope than with pre-dialysis, post-dialysis, or delta systolic BP (r = –0.07, 0.19, 0.28; p = 0.6, 0.1, 0.03). In nonlinear models, BP trajectory also had the strongest association with post-dialysis ECW/body weight (p < 0.001). Conclusions: In hypertensive hemodialysis patients, measurements of ECV excess are more strongly associated with IBPSs than with pre-dialysis, post-dialysis, or change in systolic BP. Among varying volume metrics, post-dialysis ECW/weight has the strongest association with these slopes. Determining IBPS is a novel method to optimize clinical assessment of ECV in hemodialysis patients.

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KW - Hypertension

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