Hemodialysis Principles and Practices Flashcards

What is the purpose of the venous pressure monitor in the hemodialysis blood circuit?

Answer: To detect access recirculation or obstruction in the return line

The venous pressure monitor measures pressure in the return (venous) line. Rising venous pressure may indicate a clot, needle malposition, or access stenosis; falling pressure may indicate needle dislodgement.

Which dialysis modality is specifically designed for patients with acute kidney injury in an ICU setting due to its slow, continuous fluid removal?

Answer: Continuous Renal Replacement Therapy (CRRT)

CRRT is used in hemodynamically unstable ICU patients. It runs 24 hours/day and removes fluid slowly, minimizing cardiovascular stress compared to conventional intermittent hemodialysis.

What causes dialysis disequilibrium syndrome?

Answer: Rapid removal of urea causes an osmotic gradient that draws water into brain cells, causing cerebral edema

Dialysis disequilibrium syndrome occurs when BUN drops rapidly, creating an osmotic gradient. Urea acts as an idiogenic osmole in brain cells, drawing water in and causing cerebral edema with symptoms of nausea, headache, and seizure.

A hollow-fiber dialyzer contains thousands of hollow fibers through which blood flows. What is the primary advantage of this design?

Answer: It provides a large surface area for diffusion in a compact device

Hollow-fiber dialyzers pack thousands of tiny capillary fibers into a small cartridge, providing a surface area of 0.8–2.1 m² for solute and fluid exchange. This design optimizes clearance efficiency in a small footprint.

In hemodialysis, what does the term 'recirculation' refer to and why is it problematic?

Answer: When dialyzed blood re-enters the arterial line instead of returning to systemic circulation, reducing treatment efficiency

Access recirculation occurs when treated blood re-enters the extracorporeal circuit. This dilutes the incoming blood with already-dialyzed blood, reducing urea clearance and dialysis adequacy (Kt/V).

Which parameter must be confirmed before connecting a patient to the hemodialysis machine to ensure the machine is ready for treatment?

Answer: Conductivity and temperature of the dialysate are within prescribed limits

Before connecting a patient, the technician must confirm dialysate conductivity (reflecting sodium/electrolyte concentration) and temperature are within safe limits. Out-of-range conductivity can cause fatal electrolyte imbalances.