Efficacy and safety of a citrate-based protocol for sustained low-efficiency dialysis in AKI using standard dialysis equipment

Abstract

Background and objectives: A simple anticoagulation protocol was developed for sustained low-efficiency dialysis (SLED) in patients with AKI, based on the use of anticoagulant citrate dextrose solution formulation A (ACD-A) and standard dialysis equipment. Patients' blood recalcification was obtained from calcium backtransport from dialysis fluid.

Design, setting, participants, & measurements: All patients treated with SLED (8- to 12-hour sessions) for AKI in four intensive care units of a university hospital were studied over a 30-month period, from May 1, 2008 to September 30, 2010. SLED interruptions and their causes, hemorrhagic complications, as well as coagulation parameters, ionized calcium, and blood citrate levels were recorded.

Results: This study examined 807 SLED sessions in 116 patients (mean age of 69.7 years [SD 12.1]; mean Acute Physiology and Chronic Health Evaluation II score of 23.8 [4.6]). Major bleeding was observed in six patients (5.2% or 0.4 episodes/100 person-days follow-up while patients were on SLED treatment). Citrate accumulation never occurred, even in patients with liver dysfunction. Intravenous calcium for ionized hypocalcemia (< 3.6 mg/dl or < 0.9 mmol/L) was needed in 28 sessions (3.4%); in 8 of these 28 sessions (28.6%), low ionized calcium was already present before SLED start. In 92.6% of treatments, SLED was completed within the scheduled time (median 8 hours). Interruptions of SLED by impending/irreversible clotting were recorded in 19 sessions (2.4%). Blood return was complete in 98% of the cases. In-hospital mortality was 45 of 116 patients (38.8%).

Conclusions: This study protocol affords efficacious and safe anticoagulation of the SLED circuit, avoiding citrate accumulation and, in most patients, systematic calcium supplementation; it can be implemented with commercial citrate solutions, standard dialysis equipment, on-line produced dialysis fluid, and minimal laboratory monitoring.

Figure 1.

Systemic ACT values. Systemic ACT values at 0, 2, 4, 6, and 8 hours of SLED in patients with a MELD score below (left panel) and equal to or above (right panel) the median value of 25. The total number of ACT values used for the plot is 2892. The numbers in percentages reported on the top of each panel represent the proportion of ACT values >300 seconds at each time point. ACT values are plotted on a log-scale. ACT, activated clotting time; SLED, sustained low-efficiency dialysis; MELD, Model for End-Stage Liver Disease. The dots represent outside values, defined as values that are larger than the upper quartile plus 1.5 times the interquartile range, or values that are smaller than the lower quartile minus 1.5 times the interquartile range.

Figure 2.

Citrate levels in the blood before the filter at 2, 4, 6, and 8 hours of SLED with ACD-A infusion rates of 200 ml/h, 300 ml/h, and 400 ml/h. The total number of citrate measurements used for the plot is 166. SLED, sustained low-efficiency dialysis; ACD-A, anticoagulant citrate dextrose-formulation A. The dots represent outside values, defined as values that are larger than the upper quartile plus 1.5 times the interquartile range, or values that are smaller than the lower quartile minus 1.5 times the interquartile range.

Figure 3.

Systemic citrate levels stratified by MELD score. Systemic citrate levels at 0, 2, 4, 6, and 8 hours of SLED in patients with a MELD score below (left panel) and equal to or above (right panel) the median value of 25, receiving ACD-A infusion rates of 200 ml/h, 300 ml/h, and 400 ml/h. There were no citrate levels available in the patients with MELD score above the median receiving an intermediate infusion rate of ACD-A (300 ml/h). The total number of citrate measurements used for the plot is 290. SLED, sustained low-efficiency dialysis; MELD, Model for End-Stage Liver Disease; ACD-A, anticoagulant citrate dextrose-formulation A. The dots represent outside values, defined as values that are larger than the upper quartile plus 1.5 times the interquartile range, or values that are smaller than the lower quartile minus 1.5 times the interquartile range.