Continuous arteriovenous hemofiltration: a comparison with hemodialysis in acute renal failure

Continuous arteriovenous hemofiltration (CAVH) is increasingly used in treatment of acute renal failure. There are no clinical comparisons to acute hemodialysis (HD). We studied control of uremia, electrolyte and fluid balance, and incidence of bleeding, hypotension, and tachyarrhythmia in 4 patients randomly alternated between CAVH and HD. The side effects both during and 4.3 hrs after each HD (total 88 + 97 = 187 hrs) were analyzed to allow time comparison. Five CAVH treatments (total 187 hrs) where 147 L BUN clearance and 10.9 kg net ultrafiltration (UF) occurred; and 23 HD (88 hrs) where 790 L BUN clearance and an UF of 34 kg were compared. Uremia and fluid and electrolyte control were achieved by all treatments except one CAVH session. Two patients had bleeding episodes on CAVH, and none on HD, despite careful minimal heparinization. There were 2 episodes of sudden hypotension on CAVH versus 6 on or after HD. Per unit time, there were 3 times as many episodes of hypotension with HD. Four episodes of sustained tachyarrhythmia occurred on CAVH, and 5 occurred on or after HD. When these side effects were more meaningfully normalized to BUN clearance, there were twice as many hypotensive events and 4 times as many tachyarrhythmic episodes on CAVH as on HD, although UF rate was 7 times faster on HD. CAVH is simple to do, but has more clinical ill effects than HD when normalized to treatment efficiency. The continuous heparinization necessary for CAVH is potentially dangerous, despite careful monitoring. The clinical safety of CAVH has probably been over-rated, and it best may be suited to patients with acute renal failure who do poorly on HD.