Continuous arterial-venous hemodiafiltration in critically ill patients

Area of Science:

• Nephrology
• Intensive Care Medicine

Background:

• Critically ill patients often experience circulatory instability and hypotension during intermittent hemodialysis, hindering fluid removal.
• Acute renal failure in critically ill patients, particularly those with septic shock, presents significant management challenges.

Purpose of the Study:

• To evaluate the safety and efficacy of slow, continuous arterial-venous hemodiafiltration (CAVHD) in critically ill patients with acute renal failure.
• To compare CAVHD with intermittent hemodialysis in terms of fluid removal, urea clearance, and patient outcomes.

Main Methods:

• CAVHD was initiated in 17 critically ill patients with acute renal failure, 13 of whom had septic shock.
• Dialysate flow rates were adjusted (800 ml/h and 1600 ml/h) to assess urea clearance.
• Serum sodium levels were monitored and adjusted using different dialysate fluid compositions.

Main Results:

• Five patients (29%) survived, and renal function recovered in six (35%) after an average treatment of 15 days.
• A dialysate rate of 1600 ml/h provided sufficient urea clearance, negating the need for intermittent hemodialysis.
• Hyponatremia was common, particularly with lower sodium dialysate, but manageable with higher sodium content; thrombocytopenia occurred in 76% of patients.

Conclusions:

• CAVHD is a safe and potentially superior alternative to intermittent hemodialysis for critically ill patients.
• CAVHD facilitates adequate fluid removal and urea clearance, even in hemodynamically unstable patients.
• Careful monitoring and adjustment of dialysate composition are necessary to manage electrolyte disturbances like hyponatremia during CAVHD.