Effects of bicarbonate- and lactate-buffered replacement fluids on cardiovascular outcome in CVVH patients

Background Bicarbonate-buffered replacement fluid (RF-bic) in continuous ve novenous hemofiltration (CVVH) may be superior to lactate-buffered replacem ent fluid (RF-lac) in acute renal failure. In an open, randomized, multicen ter study, we investigated the effects of RF-bic and RF-lac on cardiovascul ar outcome in patients requiring CVVH following acute renal failure. Methods. One hundred seventeen patients between the age of 18 and 80 years were randomized to CVVH either with RF-bic (N = 61) or RF-lac (N = 56). Pat ients were treated with CVVH for five days or until either renal function w as restored or the patient was removed from the study. Data were analyzed o n day 5 or according to the "last observation carried forward" (LOCF) optio n. Adverse events were classified according to the WHO-Adverse Reaction Ter minology system. Results. Blood lactate levels were significantly lower and blood bicarbonat e levels were significantly higher in patients treated with RF-bic than in those treated with RF-lac (lactate, 17.4 +/- 5.5 vs. 28.7 +/- 10.4 mg/dL, P < 0.05; bicarbonate, 23.7 +/- 0.4 vs. 21.8 +/- 0.5 mmol/L, P < 0.01). The number of hypotensive crises was lower in RF-bic-treated patients than in R F-lac-treated patients (RF-bic 14 out of 61 patients, RF-lac in 29 out of 5 6 patients; 0.26 +/- 0.09 vs. 0.60 +/- 0.31 episodes per 24 h, P < 0.05). N ine out of 61 patients (15%) treated with RF-bic and 21 out of 56 patients (38%) treated with RF-lac developed cardiovascular events during CVVH thera py (P < 0.01). A multiple regression analysis showed that the occurrence of cardiovascular events was dependent on replacement fluid and previous card iovascular disease and not on age or blood pressure. Patients with cardiac failure died less frequently in the group treated with RF-bic (7 out of 24, 29%) than in the group treated with RF-lac (12 out of 21, 57%, P = 0.058). In patients with septic shock, lethality was comparable in both groups (RF -bic, 10 out of 27, 37%; RF-lac, 7 out of 20, 35%, P = NS). Conclusions. The results show that the administration of RF-bic solution wa s superior in normalizing acidosis of patients without the risk of alkalosi s. The data also suggest that the use of RF-bic during CVVH reduces cardiov ascular events in critically ill patients with acute renal failure, particu larly those with previous cardiovascular disease or heart failure.