HEmoFiltration With Citric Acid Anticoagulation

Study Overview
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Brief Summary
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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
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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.

Official Title
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Evaluation of Safety and Efficacy of a Regional Anticoagulation Protocol for Continuous Renal Replacement Therapies.

Conditions
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Hemofiltration, Acute Kidney Injury, Acute Kidney Failure, Renal Replacement Therapy

Intervention / Treatment
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* Procedure: Hemofiltration with regional citrate anticoagulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: cardiac and vascular surgery patients treated with continuous hemofiltration with regional citrate anticoagulation Exclusion Criteria: severe chronic liver disease, acute liver injury with INR > 2, and refractory shock with lactate increasing above 8 mmol/L

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| HF RCA<br>Cardiovascular surgery patients treated with hemofiltration with regional citrate anticoagulation | Procedure: Hemofiltration with regional citrate anticoagulation<br>* 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.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hemofiltration circuit survival time | in hours | up to 120 hours from the beginning of hemofiltration session | 
| Incidence of metabolic alkalosis | Arterial blood pH>7.5 or BE > 40 mmol/L | From the beginning of hemofiltration session until 6 hours after its end | 
| Incidence of hypernatremia and hyponatremia | Incidence of hypernatremia> 150 mmol/L and hyponatremia < 130 mmol/L in arterial blood sample | From the beginning of hemofiltration session until 6 hours after its end | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of citrate accumulation | Incidence of total to ionized calcium ratio > 2,5 in arterial blood sample | From the beginning of hemofiltration session until 24 hours after its end |