What is dialysis disequilibrium syndrome and when does it occur?

• A. Cerebral edema caused by rapid removal of urea at dialysis initiation; more common in new patients.
• B. Hypotension during dialysis.
• C. Hyperkalemia after dialysis.
• D. Infection at the dialysis access site.

Answer: (A)

Dialysis disequilibrium syndrome happens when solutes like urea are removed from the blood faster than the brain can adjust, creating an osmotic difference that pulls water into brain tissue and leads to cerebral edema. This is most likely during the first dialysis treatments in patients who are new to dialysis or have very high urea levels, because the rapid clearance creates a steep osmotic gradient. Early signs are neurological—headache, nausea, vomiting, restlessness, or changes in mental status—and in more severe cases seizures or coma can occur during or soon after dialysis. Prevention focuses on starting with gentler, slower dialysis sessions and gradual solute removal to let the brain adapt and avoid rapid osmotic shifts. The other options describe different dialysis-related problems (hemodynamic instability like hypotension, post-dialysis hyperkalemia, or access-site infection) and do not involve the rapid brain osmolality change that causes DDS.