Evaluation of a Simplified Protocol for Regional Citrate Anticoagulation in Continuous Venovenous Hemodiafiltration

June 2, 2008 updated by: University of Alberta

Dialysis requires thinning of the blood to prevent clotting in the dialysis machine. Thinning of the blood is necessary but some forms of blood thinners may cause bleeding. Therefore, researchers are seeking ways to minimize bleeding risks and ensure effective dialysis.

One medication used to thin the blood in the dialysis machine is citrate. Citrate has the advantage of having its blood-thinning properties quickly reversed by calcium in the patient's blood. As a consequence, only the blood in the machine is thinned, greatly reducing the risk of bleeding when dialysis is carried out using other blood thinners. Until now, most patients who received citrate for dialysis were administered the citrate in a separate infusion through an IV pump into the dialysis machine. This method requires complex monitoring and calculations. This study is about Prismocitrate which is a dialysis fluid very similar to the regular dialysis fluid that is used in this intensive care unit, except that this fluid already contains exactly the correct amount of citrate. Thus, this method does not require a separate pump for citrate and calculations to pump the citrate into the blood as it goes through the kidney machine. Having the citrate already contained in the dialysis fluid simplifies the procedure and reduces the possibility of calculation errors.

This study seeks to determine if this simplified means of providing blood thinning in the kidney machine also results in the correct balance of blood salts.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Acute renal failure is common among the critically ill [1-3] , and is an independent contributor to morbidity and mortality [4,5]. Continuous renal replacement therapy (CRRT) is commonly used for renal replacement in this group. This requires an extracorporeal circuit, the maintenance of which requires anticoagulation. Heparin has been the most common anticoagulant used with CRRT. However, heparin exposure for CRRT is major risk after surgery or trauma. Citrate has been used as a regional anticoagulant for plasmapheresis and chronic dialysis for many years [12,13], and is increasingly being used for CRRT. Regional anticoagulation refers to the provision of anticoagulation within the extracorporeal circuit without any alteration in coagulation in the patient's systemic circulation. Calcium is a co-factor in coagulation. Citrate reduces levels of ionized calcium in blood of the extracorporeal circuit to levels where coagulation cannot occur. Once the blood is returned to the patient's systemic circulation, the calcium levels are restored and coagulation can occur again. Renal replacement solutions for CRRT using citrate anticoagulation, should be calcium-free. [14-19] Despite a reduced risk of bleeding, widespread adoption of citrate regional anticoagulation has been limited by a lack of commercially available calcium-free solutions and the complexity of many protocols. Part of this complexity is the requirement for a separate citrate infusion into the extracorporeal circuit to achieve regional anticoagulation. This simplified protocol provides citrate in the replacement fluid infused prefilter as both anticoagulant and as buffer.

To predict appropriate replacement rates, Hospal Gambro scientific laboratories have developed a calculation model to predict the physiological interactions between the components of the administered replacement- and hemodialysis fluids and the patient's complex metabolic system. These interactions are influenced, in large part, by systemic parameters such as blood-flow and ultrafiltration rates, and patient parameters, such as acid base-status and liver function. This calculation model needs clinical validation in respect to its ability to predict the outcome and narrow the margin of metabolic disturbances caused by the administration of citrate anticoagulation. A previous study of a similar replacement fluid using citrate 8 mmol/L and citric acid 4 mmol/L resulted in mild metabolic acidosis of minimal clinical significance in some subjects and so this study will evaluate a modified version of fluid containing citrate 10 mmol/L and citric acid 2 mmol/L which has been calculated to provide optimal metabolic balance.

Subjects:

Twenty patients in the General Systems ICU at the University of Alberta Hospital treated with CVVHDF using a Prisma-CFM machine will be studied.

Inclusion criteria:

  1. Male or female between 17 and 80 years of age.
  2. Intensive care unit patient.
  3. Renal failure requiring CVVHDF.
  4. Likely to survive for at least 72 hours.

Exclusion criteria

  1. Age > 80 years
  2. Need for systemic anticoagulation, fibrinolytic therapy or activated protein C
  3. Acute or chronic hepatic failure

Patients are treated by regular CVVHDF setting in pre-dilution mode. The replacement flow-rate for the citrate replacement fluid depends on the blood pump speed [fixed ratio, see 9.3 and table below]. Mean dialysate flow is between 100 ml/hr and 2500ml/hour in accordance to the desired base-equivalent intake. Access pressure is kept between -100 and 150mmHg. Access and return pressure are monitored. Specially formulated replacement- and dialysate fluids are used.

Citrate anticoagulation Published literature data show that a mean citrate-dosage of 3.5 to 4mmol/l of undiluted blood is necessary to decrease the level of ionized serum calcium below 0.4mmol/l which provides sufficient anticoagulation to maintain an extracorporeal circuit. A minimum citrate concentration of 3.5 mmol/l blood will be used in this protocol. The infused citrate replacement fluid contains trisodium citrate and citric acid in a mixture (10mmol/l tri-sodium citrate plus 2 mmol/l citric acid). Preliminary results proved that the anticoagulation potency of this mixture is similar to a plain 12 mmol/l tri-sodium citrate solution. Therefore a fixed ratio of citrate replacement fluid will be infused in pre-pump predilution mode per 1 liter of effective blood flow.

Calcium replacement:

The loss of calcium- and magnesium-citrate in the ultra-filtrate via the hemofilter needs to be compensated to avoid systemic hypocalcemia and hypomagnesemia. Calcium replacement solution is prepared by removing 300 mls from a 1000 mls bag of 0.9% saline and subsequently adding 200 mls of 10% calcium gluconate to this bag. This calcium gluconate solution is infused via a central line at an initial infusion rate of 60 ml/hr. Ionized calcium levels are monitored every 6-8 hours and corrected by changing of flow rate of the infusion.

Potassium replacement:

Potassium is added into the replacement and dialysate fluid based on clinical requirement.

Sodium-bicarbonate adjustment:

The sodium bicarbonate level is influenced by the flow-rate of the replacement fluid (citrate intake) and the dialysate flow (bicarbonate intake). It is monitored every 6 hours and is corrected during treatment by altering the dialysate flow. Reducing the flow rate lowers bicarbonate intake in case of metabolic alkalosis, raising flow increases the bicarbonate intake in case of metabolic acidosis. If these adjustments are not successful, further corrections can be done by adding bicarbonate into the next dialysate fluid bag, when it is changed:

Consent procedure Subjects will be identified, recruited and informed consent obtained by the principal investigator, co-investigator or research co-ordinators.

Study benefits The study renal replacement solution includes all elements required for safe use. It does not require custom preparation by hospital personnel. This will minimize risk of error and increase patient safety. It is hoped this study will eventually enable the general use of a simple safe technique for citrate regional anticoagulation during continuous renal replacement therapy.

Adverse effects CVVHDF using citrate regional anticoagulation using any protocol may be associated with hypocalcemia, metabolic alkalosis or acidosis, hypernatremia or hyponatremia. In anticipation of this, all protocols including this one use extensive metabolic monitoring and algorithmic responses to abnormalities. This simplified protocol minimizes the potential for complication.

Adverse effects would be notified to patient or family, investigator, and HREB committee.

Privacy Patient data will be anonymized to prevent identification. Gambro Canada (study sponsor) will have access to anonymized case report forms and aggregate report.

Study Type

Observational

Enrollment (Actual)

20

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Alberta
      • Edmonton, Alberta, Canada, T6G 2B7
        • General Systems Intensive Care Unit, University of Alberta Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

17 years to 80 years (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

  1. Male or female between 17 and 80 years of age.
  2. Critically ill intensive care unit patient.
  3. Renal failure requiring continuous venovenous hemodiafiltration.
  4. Likely to survive for at least 72 hours

Description

Inclusion Criteria:

  • Male or female between 17 and 80 years of age.
  • Intensive care unit patient.
  • Acute renal failure requiring continuous venovenous hemodiafiltration.
  • Likely to survive for at least 72 hours

Exclusion Criteria:

  • Age > 80 years
  • Need for systemic anticoagulation, fibrinolytic therapy or activated protein C
  • Acute or chronic hepatic failure

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
A
Critically ill patients with acute renal failure requiring continuous renal replacement therapy
Drug: Regional citrate anticoagulation
Continuous venovenous hemodiafiltration with regional anticoagulation using dilute trisodium citrate. This requires the use of a continuous renal replacement therapy (CRRT) machine in venovenous hemodiafiltration mode. Anticoagulation and buffer are provided by the use of a dilute solution of trisodium citrate in the replacement fluid which is infused in a predilution mode. Standard bicarbonate containing dialysate is used.
Other Names:
  • Prismocitrate - the study fluid
  • Prismocal - the commercially available dialysate

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
metabolic stability
Time Frame: 24, 48 and 72 hours
24, 48 and 72 hours

Secondary Outcome Measures

Outcome Measure
Time Frame
Hemofilter survival
Time Frame: 24, 48 and 72 hours
24, 48 and 72 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Alberta

Collaborators

Gambro Renal Products, Inc.

Investigators

  • Principal Investigator: Noel Gibney, MB BCh BAO, University of Alberta

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

April 1, 2005

Primary Completion (Actual)

March 1, 2008

Study Completion (Actual)

March 1, 2008

Study Registration Dates

First Submitted

December 20, 2007

First Submitted That Met QC Criteria

December 20, 2007

First Posted (Estimate)

December 31, 2007

Study Record Updates

Last Update Posted (Estimate)

June 4, 2008

Last Update Submitted That Met QC Criteria

June 2, 2008

Last Verified

June 1, 2008

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 5793

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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