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Hemodynamic and Volume Changes during Hemodialysis
Author(s) -
Lindsay Robert M.,
Shulman Tanya,
Prakash Suma,
Nesrallah Gihad,
Kiaii Mercedeh
Publication year - 2003
Publication title -
hemodialysis international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.658
H-Index - 47
eISSN - 1542-4758
pISSN - 1492-7535
DOI - 10.1046/j.1492-7535.2003.00041.x
Subject(s) - medicine , hemodialysis , blood volume , hematocrit , body water , extracellular fluid , hemodynamics , intravascular volume status , body fluid , cardiology , hypervolemia , vascular resistance , cardiac output , blood pressure , volume overload , fluid compartments , dialysis , body weight , heart failure , extracellular , chemistry , biochemistry
Background: Volume overload is a factor in the hypertension of hemodialysis (HD) patients. Fluid removal is therefore integral to the hemodialysis treatment. Fluid removal by hemodialysis ultrafiltration (UF) may cause intradialytic hypotension and leg cramps. Understanding blood pressure (BP) and volume changes during UF may eliminate intradialytic hypotension and cramps. Studies (S1, S2, and S3) were carried out to determine the amount and direction of changes in body fluid compartments following UF and to determine the relationships between BP, changes in blood volume (ΔBV), central blood volume (CBV), cardiac output (CO), peripheral vascular resistance (PVR) plus total body water (TBW), and intra‐ and extracellular fluid volumes (ICF, ECF) in both the whole body and body segments (arms, legs, trunk).Methods: Indicator dilution technology (Transonic) was used for CBV, CO, and PVR; hematocrit monitoring (Crit‐Line) was used for ΔBV segmental bioimpedance (Xitron) for TBW, ICF, and ECF.Results: S1 (n = 21) showed UF sufficient to cause ΔBV of −7% and lead to minor changes (same direction) in CBV and CO, and with cessation of UF, vascular refilling was preferential to CBV. S2 (n = 20) showed that predialysis HD patients are ECF‐expanded (ECF/ICF ratio = 0.96, controls = 0.74 [P < 0.0001]) and BP correlates with ECF (r = 0.47, P = 0.35). UF to cause ΔBV of −7% was associated with a decrease in ECF (P < 0.0001) and BP directly (r = 0.46, P = 0.04) plus ΔBV indirectly (r = −0.5, P = 0.024) correlated with PVR, while CBV and CO were maintained. S3 (n = 11) showed that following UF, total‐body ECF changes were correlated with leg ECF (r = 0.94) and arm ECF (r = 0.72) but not trunk ECF. Absolute ECF reduction was greatest from the legs.Conclusions: Predialysis ECF influences BP and UF reduces ΔBV and ECF, but CBV and BP are conserved by increasing PVR. ECF reduction is mainly from the legs, hence may cause cramps. Intradialytic hypotension is caused by failure of PVR response.