Final answer:
For a hemodynamically unstable patient with acute kidney injury after a motor vehicle accident, Continuous venovenous hemodialysis (CVVHD) is the recommended renal replacement therapy due to its gentle and continuous process, suited for managing hypervolemia and hyperkalemia.
Step-by-step explanation:
The most suitable renal replacement therapy for a hemodynamically unstable patient with acute kidney injury would be Continuous venovenous hemodialysis (CVVHD). Hemodialysis may be too rigorous for a patient with unstable blood pressure, as it requires rapid blood processing and can lead to hemodynamic instability. On the other hand, CVVHD operates continuously, making it more gentle and better tolerated by patients who are hemodynamically unstable.
It provides slower fluid removal and cardiovascular stability, making it an ideal choice in this scenario. Peritoneal dialysis may not be suitable due to the risk of infection and abdominal pressure in a recently traumatized patient. Plasmapheresis is primarily used for diseases related to antibodies and plasma components, not typically for managing hypervolemia and hyperkalemia associated with kidney failure.
The patient's best-tolerated therapy for managing hypervolemia and hyperkalemia while being hemodynamically unstable is Continuous venovenous hemodialysis (CVVHD). CVVHD allows for more stable and gradual fluid removal and solute control in critically ill patients.