Continuous arterial-venous hemodiafiltration in critically ill patients

Intermittent hemodialysis in critically ill patients is often accompanied by circulatory instability and hypotension. This may hamper the removal of fluid. Therefore, slow, continuous arterial-venous hemodiafiltration (CAVHD), using the patient's arterial-venous pressure difference, was developed. In 17 critically ill patients with acute renal failure, CAVHD was initiated. Most patients (n = 13) suffered from septic shock. Five (29%) patients survived and in six (35%), renal function was recovered. Average length of treatment was 15 days. The filter life was 52 h. When a dialysate rate of 1600 ml/h was employed, urea clearance was sufficient and hemodialysis was no longer needed as compared with a dialysate rate of 800 ml/h. Hyponatremia developed in all but one patient, but was more severe in the group treated with a dialysate fluid containing 132 mmol/L Na. After using a dialysate with a higher Na content of 140 mmol/L, the average serum Na concentration was 131 mmol/L. Convective Na transport by ultrafiltration was probably responsible for most of the Na loss. In 13 (76%) patients, thrombocytopenia was present. In one patient a hematoma developed in the groin, but could be controlled by local pressure. It is concluded that CAVHD is a safe technique that might replace intermittent hemodialysis in critically ill patients.