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On the nephrology service, so let’s talk very briefly about something I had never heard of before, but makes complete sense when you think about it for a moment...
Disequilibrium Syndrome
#DavidLearns
Disequilibrium Syndrome
#DavidLearns
The crux of this condition is that chronically uremic patients will build up increasing amounts of urea in cerebral tissues.
Recall that urea is an osmotically active compound that contributes to plasma osmolarity along with sodium and glucose
Recall that urea is an osmotically active compound that contributes to plasma osmolarity along with sodium and glucose
Late stage CKD patients and ESRD patients develop chronically elevated BUN levels, but these individuals can tolerate high BUN that would otherwise be very symptomatic if they were to occur acutely.
As mentioned earlier, urea is osmotically active and over time there is a balance reached between intracellular solutes and the extra cellular plasma wherein both compartments have significantly elevated BUN
Disequilibrium syndrome occurs when a patient like this suddenly initiates hemodialysis and has a significant amount of their plasma urea filtered and removed, but none of their intracellular urea changes in its concentration.
Urea does not readily diffuse across cell membranes, so what happens instead is osmosis, wherein water from the intravascular space floods cells in order to reach a new similar equilibrium following dialysis.
This in turn causes swelling of brain parenchyma and cerebral edema.
This in turn causes swelling of brain parenchyma and cerebral edema.
Symptoms of disequilibrium syndrome are predominantly neurologic and in increasing severity include headaches, nausea, confusion, visual disturbances, seizures and coma.
There is unfortunately no good treatment for disequilibrium syndrome.
Primary prevention is the best course of action including gradual initiation of hemodialysis in an ESRD patient who has previously never had iHD.
Primary prevention is the best course of action including gradual initiation of hemodialysis in an ESRD patient who has previously never had iHD.
In the event that a patient does develop signs/symptoms of dialysis disequilibrium syndrome, the first course of action should be to stop dialysis.
As mentioned above, the symptoms typically occur in an order proportional to the degree of cerebral edema, so early symptom detection is of crucial importance.
As well, mannitol can be used for treatment of cerebral edema as it is an osmotically active molecule that remains confined to the intravascular space and can thus reverse brain swelling by drawing fluid back into the vascular compartment.
