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Abstract: SA-PO589

Association of Bioimpedance Parameters with Changes in Blood Pressure During Hemodialysis: A Secondary Analysis of the Frequent Hemodialysis Network (FHN) Daily Trial

Session Information

Category: Dialysis

  • 801 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Sayed, Enass, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Farag, Youssef MK, Bayer US, New Jersey, New Jersey, United States
  • Ravi, Katherine Scovner, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Chertow, Glenn, Stanford University School of Medicine, Stanford, California, United States
  • McCausland, Finnian R., Brigham and Women's Hospital, Boston, Massachusetts, United States
Background

Intra-dialytic hypertension (IDHyper) affects 5-15% of patients and is associated with cardiovascular and all-cause mortality. Hypervolemia is thought to be a major etiological factor, yet the association of objective measures of volume with IDHyper is not well described.

Methods

In post hoc analyses of the FHN Daily Trial (n=234), using data from baseline, 1, 4, and 12 months (n=800), random effects regression was used to assess the association of bioimpedance measures of volume and general health (vector length and phase angle) with post-HD SBP (continuous) and any increase in SBP (categorical) from pre- to post-HD. Models were adjusted for randomized group, age, sex, race, BMI, vascular access, HD vintage, hypertension, heart failure, diabetes, residual urea clearance, pre-HD SBP, hemoglobin, phosphorus, and eKt/V.

Results

Mean age was 50 ±14 years; 39% were female; 43% were Black. Shorter vector length (per 50 Ω/m) was associated with higher post-HD SBP (3.1 mmHg; 95%CI 2.0, 4.2; Fig. 1) and higher odds of IDHyper (OR 1.64; 95%CI 1.13, 2.39). The lowest tertile of vector length (vs. highest) was associated with higher post-HD SBP (6.3 mmHg; 95%CI 3.3, 9.3) and a trend toward higher odds of IDHyper (OR 2.09 95%CI 0.81, 5.35). Narrower phase angle (per 1 degree) was associated with higher post-HD SBP (1.0 mmHg; 95%CI 0.3, 1.6), and higher odds of IDHyper (OR 1.33; 95%CI 1.03, 1.72). The lowest tertile of phase angle (vs. highest) was associated with higher post-HD SBP (5.5 mmHg; 95%CI 2.6, 8.4) and higher odds of IDHyper (OR 2.74; 95%CI 1.11, 6.76).

Conclusion

Bioimpedance measures of volume status are independently associated with higher post-HD SBP and risk of IDHyper. Incorporation of bioimpedance measurement at individual HD sessions may help identify a subgroup of patients at risk of IDHyper.

Mean vector length and mean post-HD SBP

Funding

  • NIDDK Support