A 22-year-old patient is admitted with an acute traumatic brain injury with raised intracranial pressure. They also have a severe acute kidney injury requiring renal replacement therapy (RRT). Outline the potential issues of providing RRT, including your management of the issues
This question is a reworded version of Question 21 from the first paper of 2018, which means readers can go there to see what the official college answer would likely have been.
|Access||Avoid internal jugular lines||Promote venous drainage from the brain|
|Modality||Prefer CRRT||Produces a more gradual solute clearance;
less likely to produce cerebral oedema
|Low efficiency IHD/SLED|
|Frequency||Daily, if not continuous||Daily treatments decrease the fluctuations of urea|
|Blood flow||Start low, increase slowly||Minimise haemodynamic effects|
|Dialysate flow||Start low, increase slowly||Minimise solute clearance|
|Dose||Under-dialyse (by half)||Minimise solute clearance per unit time|
|Solute clearance||Pre-dilution haemofiltration||Minimise urea clearance: decrease the resulting urea gradient between brain parenchyma and blood, minimising cerebral oedema|
|Filtration||Low volume fluid removal||Minimise dialysis-associated hypotension to prevent cerebral hypoperfusion|
|Anticoagulation||Regional, or none||Prevent cerebral haemorrhage extension due to anticoagulation. Minimal anticoagulation is recommended for 2 weeks following TBI.|
|Dialysate||Add sodium||Minimise the hyponatremia which develops due to exposure to hyponatremic dialysate (to keep sodium around 145-150 mmol/L)|
|Add urea||Minimise urea clearance|
|Minimise bicarbonate||Prevent intracellular acidosis (may be hypthetical)|
|Fluid warmer||Temperature matching||Maintain therapeutic hypothermia if this is being used for ICP control|
Davenport, Andrew. "Renal replacement therapy in the patient with acute brain injury." American journal of kidney diseases37.3 (2001): 457-466.
Davenport, Andrew. "Renal replacement therapy for the patient with acute traumatic brain injury and severe acute kidney injury." Acute Kidney Injury. Vol. 156. Karger Publishers, 2007. 333-339.
Davenport, Andrew. "Practical guidance for dialyzing a hemodialysis patient following acute brain injury." Hemodialysis International 12.3 (2008): 307-312.
Yeh, Shih-Hao, Chen-Yu Wang, and Chien-Min Lin. "Preventing intracranial pressure fluctuation in severe traumatic brain injury during hemodialysis." Journal of Medical Sciences 36.4 (2016): 152.