Hypotension during acetate and bicarbonate dialysis in patients with acute renal failure

Bicarbonate dialysate is claimed to be superior to acetate for both chronic and acute hemodialysis. We compared acetate and bicarbonate dialysates in 30 acute renal failure patients during 120 dialyses. 4 patients were diabetic and 2 had liver failure. Patients were dialyzed alternating acetate and bicarbonate dialysate in a double-blind cross-over manner; each patient was his own control. BUN, creatinine, Na+, K+, osmolality, delta osmolality, % ultrafiltration, arterial blood gases, pre, post and lowest dialysis mean arterial blood pressure, dialysis with hypotensive episodes and symptoms of hypotension were recorded. The measurements obtained for each patient during dialyses with acetate and bicarbonate were compared. There was no difference in predialysis chemistries, osmolality or osmolality fall, no change in mean arterial blood pressure or hypotensive episodes and symptoms and ultrafiltration. PCO2 and pH were slightly lower for the acetate group at the 2nd h but not at the end of dialysis. 4 patients had serum acetate determinations, all metabolized acetate normally. These findings contradict recent suggestions that severely ill patients should not be dialyzed against acetate. Since acetate is technically much easier to use and has no clinical drawbacks, it does not need to be replaced with bicarbonate in acute patients. Other factors must be more important than acetate in generating hypotension during acute dialysis.