Normal citratemia and metabolic tolerance of citrate anticoagulation for hemodiafiltration in severe septic shock burn patients

Abstract

Anticoagulation during renal replacement therapy remains an important challenge for burn patients due to their high risk of bleeding. In this study we compared the efficacy and safety of citrate anticoagulation to heparin anticoagulation for hemodiafiltration (HDF) in severe burn patients, focusing on metabolic tolerance and handling of citrate. Retrospective observational study (January 2000-December 2007) at a university teaching hospital. Among 548 patients admitted with burns, 70 severe burn septic shock patients (median age 57.5 years, interquartile range 42-76 years; median burned surface area 40%, interquartile range 30-60%) who underwent HDF for more than 24 h were included. Of the 70 HDF patients, 31 at high risk of bleeding were treated with citrate and 39 with heparin, with a mortality rate of 70.9 and 71.8%, respectively. In continuous venovenous hemodiafiltration (CVVHDF), the filter survival was higher with citrate, and hemorrhagic complications were lower (0.035 vs. 0.145 episodes/day, respectively). During citrate CVVHDF [median delivered dialysis dose: 578.9 ml kg(-1) day(-1) (461.5-769.2 ml kg(-1) day(-1))] in catecholamine-supported patients (norepinephrine 0.53 μg kg(-1) min(-1)), no metabolic derangements in pH, bicarbonates, Na+, K+, Ca++, and ionized calcium were observed. Systemic citratemia was within the normal range (<0.4 mmol/l) and was associated with a marked citrate removal in the effluent (5 patients, 36-60% of infused amount). In septic shock burn patients, citrate for CVVHDF was efficient and safe, and superior to heparin for hemorrhagic complications and filter survival. Observed metabolic stability was most likely due to a marked loss of citrate in effluent volume and subsequent low total citrate load for the patient.