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Abstract: TH-PO202

Impact of Extracellular Volume Overload on Ambulatory Blood Pressure in Hemodialysis Patients with and Without Intradialytic Hypertension

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • McAdams, Meredith, UTSW, Dallas, Texas, United States
  • Gregg, L Parker, University of Texas Southwestern, Dallas, Texas, United States
  • Concepcion, Michael Lopez, Dallas Veterans Hospital, Dallas, Texas, United States
  • Lederer, Swati, VA North Texas, Dallas, Texas, United States
  • Penfield, Jeffrey G., VA North Texas Health Care System, Terrell, Texas, United States
  • Van Buren, Peter N., UT Southwestern, Dallas, Texas, United States
Background

Hemodialysis (HD) patients with recurrent intradialytic hypertension (IH) have higher ambulatory blood pressure (BP) and atypical ambulatory BP patterns compared to HD controls. Recurrent IH is also associated with increased extracellular volume (ECV) and intradialytic vasoconstriction surges. We examined how these variables influence ambulatory BP in HD patients with and without IH.

Methods

In a case-control study of recurrent IH patients (systolic pre to post-HD BP increase >10 mmHg in 4/6 treatments) and hypertensive HD controls we obtained pre and post-HD ECV/weight with bioimpedance spectroscopy and total peripheral resistance index (TPRI) with a cardiac output monitor. Linear regression measured associations of peridialytic variables on 44-hr ambulatory BP measurements.

Results

There were 18 IH subjects and 57 controls. Those with IH had higher ECV than controls (0.27±0.04 L/kg vs. 0.23±0.04, p=0.002) and different intradialytic TPRI changes than controls (385±840 dyn/sec/cm2/m2 vs.-478±700, p=0.001). Mean ambulatory BP was nonsignificantly higher in IH subjects (147±13 mmHg vs. 142±14, p=0.1), and BP slopes were different in hours 1-24 (-0.14±0.9 mmHg/hr vs. 0.42±0.9, p=0.04) but not hours 1-44. ECV/weight was associated with mean ambulatory BP in IH subjects and ambulatory BP slope in controls (Table). Post-HD BP associated with ambulatory BP in both groups.

Conclusion

Chronic ECV overload is a primary factor associated with ambulatory BP in IH patients, but interdialytic weight gain and intradialytic vasoconstriction surges are not. In controls, ECV overload is associated with a blunted ambulatory BP rise. Intra- and interdialytic BP patterns may help guide diagnosis and management strategies of ECV in HD patients.

Regression Coefficients and P-values for Variables Using Mean Ambulatory Blood Pressure and Ambulatory Blood Pressure Slope as Dependent Variables in Subjects With and Without Intradialytic Hypertension
 Dependent Variable: Mean Ambulatory Systolic BPDependent Variable: Ambulatory Systolic BP Slope (Hours 1-44)
 Intradialytic Hypertension (n=18)Controls (n=57)Intradialytic Hypertension (n=18)Controls (n=57)
 βp-valueβp-valueβp-valueβp-value
Post-HD Extracellular Water/Body Weight (L/kg)314<0.00149.40.50.030.9-4.560.04
Intradialytic Change in Total Peripheral Resistance Index (dyn/sec/cm2/m2)-0.0020.20.0040.3-0.00020.20.000020.9
Post-HD Systolic BP (mmHg)0.240.0020.30.02-0.0050.5-0.0020.001
Interdialytic Weight Gain (% of dry weight)-1.30.070.550.7-0.130.20.090.1

Funding

  • NIDDK Support