Abstract

Osmotic changes in plasma are assumed to cause cerebral swelling in hemodialysis patients. We investigated the acute effect of low-flux hemodialysis (HD) (removal of small molecules) and pre-dilution hemodiafiltration (pre-HDF) (additional removal of larger molecules) on cerebral compartment volumes using quantitative magnetic resonance imaging (MRI) in chronic uremic patients. Twelve patients underwent a session of HD and pre-HDF in a randomized crossover study with equal ultrafiltration. MRI was performed immediately before and after dialysis. A linear correlation was found between changes in gray matter and plasma osmolarity (HD: r² = 0.83; HDF: r² = 0.73) but not between changes in white matter volume and plasma osmolarity (HD: r² = 0.02; HDF: r² = 0.004). Total brain volume increased by 1.8 ± 1.7% (18.7 ± 17.4 mL) (mean ± SD) during HD and 2.0 ± 0.9% (22.3 ± 10.7 mL) during pre-HDF. Gray matter volume increased: HD 3.8% (from –3.6 to 9.7) and pre-HDF 4.2% (from –2.8 to 14.3). White matter volume did not change significantly. Reduction ratio of urea (molecular weight (MW) 0.06 kDa) (HD: 68%; pre-HDF: 69.7%) and β2-microglobulin (MW 11.7 kDa) (HD: –13.7%; pre-HDF: 67.2%) separated the treatments. This study showed that HD and pre-HDF caused equal acute cerebral swelling of the grey matter. This appeared to be driven by small solute change in plasma interacting linearly with gray matter volume regardless of additional removal of larger molecules or ultrafiltration.


Author Details

Authors

• Niels Johansen¹
• Krista Dybtved Kjaergaard¹
• Christian Daugaard Peters¹
• Michael Pedersen²
• Bente Jespersen¹
• Jens Dam Jensen¹

Departments

• ¹ Department of Renal Medicine, Aarhus University Hospital, and
• ² Comparative Medicine Lab, Institute of Clinical Medicine, Aarhus University, Denmark

Address

Jens Dam Jensen, MD, PhD
Department of Renal Medicine
Aarhus University Hospital
Palle Juul-Jensens Boulevard 99

8200 Aarhus N, Denmark

Email: [email protected]

Citation