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

Background

Bicarbonate-buffered replacement fluid (RF-bic) in continuous venovenous hemofiltration (CVVH) may be superior to lactate-buffered replacement fluid (RF-lac) in acute renal failure. In an open, randomized, multicenter study, we investigated the effects of RF-bic and RF-lac on cardiovascular outcome in patients requiring CVVH following acute renal failure.

Methods

117 patients between the age of 18 and 80 years were randomized to CVVH either with RF-bic (N = 61) or RF-lac (N = 56). Patients were treated with CVVH for 5 days or until either renal function was restored or the patient was removed from the study. Data were analyzed on day 5 or according to the 'last observation carried forward' (LOCF) option.

Results

Blood lactate levels were significantly lower and blood bicarbonate levels were significantly higher in patients treated with RF-bic than in those treated with RF-lac (lactate, 17.4 ± 8.5 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 RF-lac-treated patients (RF-bic 14 out of 61 patients, RF-lac in 29 out of 56 patients; 0.26 ± 0.09 vs 0.60 ± 0.31 episodes per 24 h, P < 0.05). Nine 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 therapy (P < 0.01). A multiple regression analysis showed that the occurrence of cardiovascular events was dependent on replacement fluid and previous cardiovascular 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 was superior in normalizing metabolic acidosis without the risk of alkalosis. The use of RF-bic during CVVH reduced cardiovascular events in critically ill patients with acute renal failure, particularly in those with pre-existing cardiovascular disease or heart failure.