Replacement post-filter (ml/hr) Blood flow (ml/min) Dialysate (ml/hr) Weight (kg)

Transcription

1 404FM.1 CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) USING CITRATE Target Audience: Hospital only ICU (Based on Gambro and Kalmar Hospital protocols) CRRT using regional citrate anticoagulation This is a therapy which is used in Critical Care as a supportive mechanism for those patients who have developed an acute kidney injury (AKI). AKI is characterised by a rapid reduction in kidney function resulting in a failure to maintain fluid, electrolyte and acid-base homoeostasis (Lewington and Kanagasundaram, 2011). The aim of therapy is to replace normal glomerular filtration by: Relieving hypervolaemia and maintaining fluid balance. Removing excess urea and creatinine. Correcting and maintaining metabolic and electrolyte balance. This continuous technique was developed as critically ill patients with AKI, who were treated with conventional dialysis, frequently became unstable during their treatment due to the short intense duration of dialysis over a three to four hour period. CRRT allows fluid and waste products to be removed. 1. SET-UP Before starting treatment Check the daily blood results before the start of treatment, to include: Total calcium (not the corrected value) Magnesium and potassium levels Ionised calcium (arterial blood gas) Calcium levels, as well as potassium and magnesium levels, should be corrected prior to treatment. APTT levels will NOT be required for citrate anticoagulation. Equipment needed 1 ST150 Prismaflex kit 1 CA250 calcium line 1 50 ml Luer lock syringe 1 bag of 5 litre Prismocitrate 18/0 (citrate used as pre-dilution) 1 bag of 5 litre Prism0cal B22 (dialysate)(calcium-free solution) 1 bag of 5 litre Phoxilium for replacement (post-dilution) 1 litre 0.9% sodium chloride (priming solution) 30 mmol calcium chloride made up to 50 ml with 0.9% sodium chloride Setting up and priming circuit Choose the option CVVHDF. Choose citrate calcium via the Prismaflex syringe pump. Follow the installation steps on the screen. Install Prismocitrate 18/0 on the white scale (PBP = pre-blood pump). Install Prism0cal B22 on the green scale (Dialysate). Guideline 404FM.1 1 of 5 Uncontrolled if printed

2 Install Phoxilium on the purple scale (Replacement). Ensure that the Replacement Solution screen indicates calcium concentration of 1.25 mmol/l. If not, call shift coordinator. Prime the ST150 circuit with 1 litre of 0.9% sodium chloride (NO heparin required). Install the calcium chloride syringe into the Prismaflex syringe pump. This should be a Terumo 50 ml Luer lock syringe. Leave calcium line unclamped and do not connect to the patient at this stage. Ensure fluid loss/gain limit is set to 400 ml/3 h. (Default setting do not change.) Starting parameters Mode: CVVHDF Starting citrate dose: 3.0 mmol/l blood Starting calcium compensation: 100% Based on actual body weight Weight (kg) Blood flow (ml/min) Dialysate (ml/hr) Replacement post-filter (ml/hr) Actual treatment dose obtained (ml/kg/hr) For the higher blood flow rates, you may want to start at a lower rate and build up if the patient is haemodynamically stable. If starting at a lower blood flow rate than that suggested above, the replacement and dialysate flow rates should still be according to the table for the patient s weight. 2. If starting at a lower blood flow rate, wait for 1 hour after achieving the desired blood flow rate before measuring calcium levels. 3. Actual treatment dose is effluent minus 15% downtime. Connection Ensure flow test is performed by shift co-ordinator. Do not start treatment if there is a flow problem. Flow rate should be adequate to withdraw 20 ml of blood in 6 seconds or less. 1. Connect access line to patient (red). 2. Connect blue return line to the blue vascath port. 3. Connect yellow line to effluent bag. 4. Connect calcium line to central line. A large-bore cannula can be used in the short term, but a central line must be used as soon as possible. 5. Unclamp all lines. 6. START treatment. 7. Once patient is stable, increase blood pump speed to required level as above. 8. Set patient fluid removal as required. Guideline 404FM.1 2 of 5 Uncontrolled if printed

3 2. TREATMENT MONITORING i) Ionised calcium post-filter and patient One hour after treatment is initiated and blood flow established, make two ionised calcium checks (one from the blue port on the set and another from the patient s arterial line) and alter according to the following table: Filter Ca 2+ >0.5 Filter Ca Filter Ca 2+ <0.25 Patient Ca 2+ <1.0 Citrate dose increased increased by 10% Calcium compensation increased by 10%. Patient Ca Citrate dose increased NORMAL IDEAL VALUES. Patient Ca 2+ >1.3 Calcium compensation Check post-filter ionised calcium and patient calcium levels hourly until ideal values have been established. Once two consecutive measurements are within the normal range, check the post-filter ionised calcium four times a day (every 6 hours). Increase back to hourly should values alter to outside the normal ideal values. (NEED A PLACE ON CHART FOR THIS OR BLOOD RESULTS SHEET.) Do not take any blood for analysis from the filter set, other than for calcium. Do not make any adjustments to therapy unless confirmed by the shift co-ordinator or ICU consultant. If the citrate dose is reduced, the pre-blood pump flow and hence total effluent dose will also fall. If the total effluent dose falls below 30 ml/kg/h, increase the replacement flow until a dose of 30 ml/kg/h is achieved. If there are any changes in citrate dose or blood flow rate, hourly checks need to be carried out again. Action <2.5 Check twice daily Consult medical staff and consider the following: Aim post-filter calcium of 0.4 to 0.5 mmol/l by reducing citrate dose in 0.2 mmol/l increments until this range is achieved. >2.5 If ratio remains above 2.5 despite post-filter calcium of 0.4 to 0.5 mmol/l then consider: DO ONE AT A TIME 1. Double baseline dialysate flow (will increase citrate clearance) 2. Reduce blood pump speed (will reduce total administered citrate dose) 3. Stopping citrate and use an alternative anticoagulation or no anticoagulation Guideline 404FM.1 3 of 5 Uncontrolled if printed

4 ii) Total calcium/ionised calcium ratio monitoring Measure blood total calcium level at 6 hours (easiest to send with ). Divide the patient s total uncorrected calcium by the patient s ionised calcium (total Ca/ionised Ca). The ratio is to be calculated every 12 hours, and documented on the blood results flow chart. Increasing requirements for calcium compensation could indicate citrate accumulation. Calcium monitoring Initally And then: Post-filter ionised calcium (blood gas from circuit) Target 0.25 to 0.50 mmol/l Patient systemic ionised blood calcium (blood gas from patient) Target 1.0 to 1.3 mmol/l Patient total calcium (not corrected calcium) Target 2.20 to 2.50 mmol/l Calcium ratio (Total Ca/patient's systemic ionised Ca) Target ratio <2.5 iii) Frequency of blood tests Hourly until stable within normal values Hourly until within normal values After 6 hours After 6 hours 6 hourly 6 hourly 12 hourly with 12 hourly with Test Potassium Glucose FBC Magnesium and phosphate Frequency 6 hourly initally. 12 hourly when stable. At least 6 hourly. More frequent if unstable. At least 6 hourly. More frequent if unstable. 12 hourly with 12 hourly with iv) The Phoxilium solution is particularly used to treat critically ill patients with acute kidney failure having: A normal concentration of potassium in the blood (normal kalaemia) or A normal or low concentration of phosphate in the blood (normal or hypophosphataemia). BEFORE YOU USE PHOXILIUM Do not use Phoxilium on patients with any of the following three conditions: A high concentration of potassium in the blood (hyperkalaemia). A high concentration of bicarbonate in the blood (metabolic alkalosis). A high concentration of phosphate in the blood (hyperphosphataemia). 3. FREQUENTLY ASKED QUESTIONS Q. How do I deal with acid-base issues? Aim for a ph of i) Metabolic acidosis Most patients in renal failure will have a degree of metabolic acidosis on commencing CVVHDF. This should improve with treatment over hours. If the base excess or bicarbonate do not improve towards normal, consider: 1. Reducing dialysate flow by 50% (more citrate will reach patient). 2. Increasing blood pump speed (delivers more citrate to patient). 3. Giving systemic NaHCO 3 to the patient (e.g. 100 ml of 8.4% NaHCO 3 IV). These will have differing effects on clearance, potential for citrate toxicity and cardiovascular status and should not be undertaken without prior discussion with the shift co-ordinator or ICU consultant. Guideline 404FM.1 4 of 5 Uncontrolled if printed

5 ii) Metabolic alkalosis Consider: 1. Increasing dialysate flow by double baseline rate. 2. Reducing blood pump flow. These changes may affect clearance and filter life and should not be undertaken without prior discussion with the shift co-ordinator or ICU consultant. Q. What do I do if I want to increase clearance? Depending on solute to be removed, either increase replacement flow or alternatively move patient up to the next weight bracket. Q. My calcium compensation is very high. Is that normal? There are lots of reasons why the patient s calcium needs can increase but if calcium compensation is above 150% this could indicate citrate accumulation (citrate is not being metabolised and calcium is not being released). Other signs of citrate accumulation include a persistently low systemic ionised calcium and a raised total:ionised calcium ratio - if >2.5, see the guidelines above. Title of Guideline Continuous Renal Replacement Therapy (CRRT) using Citrate Guideline Number 404FM Version 1 Effective Date February 2015 Review Date February 2018 Original Version Published February 2015 Approvals: Formulary Management Group 22 nd October 2014 Clinical Guidelines Subgroup 12 th February 2015 Author/s Lucy Bull SDU(s)/Department(s) responsible Critical Care for updating the guideline Uploaded to Intranet 23 rd February 2015 Buckinghamshire Healthcare NHS Trust Guideline 404FM.1 5 of 5 Uncontrolled if printed