HEmoFiltration With Citric Acid Anticoagulation
Condition: Acute Kidney Injury; Acute Kidney Failure; Renal Replacement Therapy; Hemofiltration
MeSH terms: Acute Kidney Injury; Renal Insufficiency
Study type: Observational

Summary: 
      Prospective observational study of all consecutive cardio-vascular surgical patients treated
      with post-dilution hemofiltration with regional citrate anticoagulation as first-choice
      anticoagulation method. The filter life-span was assessed in the context of postoperative
      cardiac surgical antithrombotic prophylaxis. Reasons for termination of hemofiltration
      sessions were assessed. The second aim of this study was to assess the influence ACD-A based
      anticoagulation protocol on acid-base and ion homeostasis in cardiac surgical patients with
      acute renal failure.
    

Detailed description: 
      All consecutive cardio-vascular surgery patients treated with post-dilution hemofiltration
      with regional citrate anticoagulation (HF RCA) from August 2015 through November 2017 were
      included to prospective audit. Indication to hemofiltration treatment was based on clinical
      assessment of patients renal function and clinical status by attending physician and
      conformed conventional indications to renal replacement therapy (RRT) in intensive care unit
      (ICU). Severe chronic liver disease or acute liver injury with INR > 2 and refractory shock
      with lactate increasing above 8 mmol/L were considered as contraindication to RCA.

      Initially set blood flow was 5 times higher than filtrate flow, which makes filtration
      fraction of 20%. To reduce the risk of metabolic alkalosis, ACD-A citrate solution was
      proposed instead of most commonly used trisodium citrate solution, and relatively low target
      citrate concentration (2.8 mmol/L) was adopted. In case of pH increase above 7.5 or
      bicarbonate concentration above 40 mmol/L filtrate flow was decreased from initial 35
      ml/kg/hour down to 25 ml/kg/hour which should reduce bicarbonate synthesis by 25%. If
      metabolic alkalosis persisted, the second step involved reduction of blood flow from initial
      5 times down to 4 times filtrate flow, which reduced citrate flow by the same factor.

      In order to avoid hypomagnesemia resulting from magnesium binding to citrate, and its removal
      with ultrafiltrate not balanced with magnesium content in replacement fluid, the original
      protocol was modified by connecting magnesium sulfate solution 2g/50 ml 0.9% NaCl at the flow
      1 mL/hour.

      All sessions stopped due to patients death before 48 hours of HF treatment were excluded from
      the analysis. Similarly, all cases where hemofiltration session was stopped before 48 hours
      of treatment due to organizational reasons, recovery of renal function, change of therapy,
      and when patients were treated with heparin infusion due to surgical indications were
      excluded from further circuit survival analysis.

      Blood gas parameters together with pH, bicarbonate concentration, Na, Cl, K, Ca, hemoglobin
      concentration, hematocrit, lactate, and anion gap were analyzed every 6 hours. Post filter
      ionized calcium concentration was not assessed. Serum phosphate, magnesium and total calcium
      was assessed every 24 hours during hemofiltration treatment with RCA.
    

Intervention name(s): Hemofiltration with regional citrate anticoagulation
Intervention type(s): Procedure
Intervention description(s): To reduce risk of metabolic alkalosis during hemofiltration treatment, ACD-A citrate solution was proposed instead of most commonly used trisodium citrate solution and relatively low target citrate concentration (2.8 mmol/L) was adopted. In case of pH increase above 7.5 or bicarbonate concentration above 40 mmol/L filtrate flow was decreased from initial 35 ml/kg/hour down to 25 ml/kg/hour which reduced bicarbonate delivery by 25%. If metabolic alkalosis persisted, the second step involved reduction of blood flow from initial 5 times down to 4 times filtrate flow, which reduced citrate flow by the same factor.
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        All consecutive cardio-vascular surgery patients treated with post-dilution hemofiltration
        with regional citrate anticoagulation from August 2015 through November 2017