ON HEMODIALYSIS-INDUCED HYPOTENSION

One common misconception on hypotension during hemodialysis is naive thinking that induction of intravascular volume depletion by rapid ultrafiltration causes the problem. But in actuality it is not the only mechanism as patients can tolerate same rate of fluid removal with pure hemofiltration.

 During conventional hemodialysis, the rapid diffusive removal of urea results in a reduction of the plasma osmolality. This creates two processes simultaneously. Firstly, water moves osmotically into the cells. Secondly, the rapid fall in plasma osmolality causes hemodynamic instability by interfering with sympathetic responsiveness to volume depletion.

Reference:

Bergstrom J, Asaba H, Furst P, Oules R. Dialysis, ultrafiltration, and blood pressure. Proc Eur Dial Transplant Assoc 1976; 13:293.