Continuous Renal Replacement Therapy Guidelines

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there has recently been some debate in our unit about Continuous Renal Replacement Therapy (CRRT) Guidelines.

Topics raised include;

- which therapy is the most effective? CVVH / CVVHDF and why ? and should we have a protocol to decide which one to use ?

- potassium supplementation and should we be using more formal guidelines / protocols when adding potassium to substitution bags to prevent hypokalemia ?

- vascular access and what is best practice when line not in use hep-lock or citrate-lock ?

- whether regular flushing of vascular access may prevent problems with access and return pressures during treatment ?

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Specializes in ICU.

Isn't much of that up the renal MD?

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Specializes in ACNP-BC, Adult Critical Care, Cardiology.

- which therapy is the most effective? CVVH / CVVHDF and why ? and should we have a protocol to decide which one to use ?

Doesn't Nephrology decide on this based on the goal of therapy, i.e., fluid removal vs solute removal or both, desired rate of acidosis correction.

- potassium supplementation and should we be using more formal guidelines / protocols when adding potassium to substitution bags to prevent hypokalemia?

Again, Nephrology makes that decision where I work and writes those orders.

- vascular access and what is best practice when line not in use hep-lock or citrate-lock ?

We only use Trialysis Catheters by Bard now. As someone who inserts these catheters routinely in the ICU, I can tell you they are harder to insert than the older Quintons or Vas-caths (guidewire bends easily, odd shape of catheter at its diameter). But they have the advantage of having the extra port that's compatible with the PSI requirements of IV contrast administration for CT Scans. We use Heparin as a rule, Citrate only if the patient has HIT.

- whether regular flushing of vascular access may prevent problems with access and return pressures during treatment ?

Don't know the answer to this.

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on our unit the nurses do most of the therapy the doctors say they want it and a general target in terms of fluid loss and then the nursing staff set it up, administer it and decide on exchange rates, pre and post dilution values, usually we only use CVVH but i have read a few articles suggesting CVVHD is also beneficial and am trying to see if it would be worth suggesting its implementation on the unit hence asking for advice on here.

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there has recently been some debate in our unit about Continuous Renal Replacement Therapy (CRRT) Guidelines.

Topics raised include;

- which therapy is the most effective? CVVH / CVVHDF and why ? and should we have a protocol to decide which one to use ?

They all have their own uses.

There are two processes in dialysis. Fluid removal and solute removal. Here is a Baxter page which explains it: http://www.baxter.com/healthcare_professionals/therapies/renal/acute_kidney_treatment/continuous_renal_replacement_therapy.html

Then there are four modes for CRRT to accomplish this. (depending on your machine).

SCUF - ultrafiltration only - removes fluid no dialysis

CVVH - removes solutes through convection - slow to remove solutes but good for someone who needs fluid off but also needs a little bit of filtration.

CVVHD - This moves solutes through diffusion. You can vary the amount of solutes by increasing your replacement fluid flow. You get more dialysis with this.

CVVHDF - combines both convection and diffusion. Most efficient in removing solutes and correcting pH problems.

The cost is that as you become more efficient with the dialysis, your cost and nursing time goes up. In CVVH the nurses change the dialysate bag around every four hours and the waste bag around every two. In CVVHDF they are changing both bags every hour or more. You can usually tell these patients by the cases of dialysate stacked up outside the door. The cost also goes up dramatically.

We use both nxstage and prismaflex dialysis machines. Our older nxstage doesn't have CVVHDF but our prismaflex does.

- potassium supplementation and should we be using more formal guidelines / protocols when adding potassium to substitution bags to prevent hypokalemia ?

We have replacement protocols for dialysis patients that are different from non-dialysis patients. The potassium is also determined by the bath (dialysate). This should be specified in the order. Most patients should be on a 4k bath which will keep potassium pretty normal. If they have severe hyperkalemia we will occasionally order a 2k or 0k bath. This is usually reserved for patients with lifethreating hyperkalemia with symptoms.

- vascular access and what is best practice when line not in use hep-lock or citrate-lock ?

We hep lock our lines with 1:1000 vascath solution. Citrate only for HIT positive.

- whether regular flushing of vascular access may prevent problems with access and return pressures during treatment ?

The flushing is machine dependent. On the nxstage the nurses have to flush (usually 100ccs every 1 or 2 hours). The prismaflex takes care of this automatically.

I am guessing that you are either outside the US or have very lazy nephrologists. In the US dialysis is a medical device and all the parameters must be ordered by a provider. You can't just write an order to do some dialysis and take fluid off. That would be like me writing an order to give the patient some antibiotics.

We have an order set where the nephrologists basically go through and check off what they want. Then nurse then sets things up according to the order. If I don't agree with whats going on, I call the nephrologist to get the order changed. Thats the way things should work any way.

For a more comprehensive guide, this Australian guide is pretty in depth (ignoring the weird spelling): http://intensivecare.hsnet.nsw.gov.au/five/doc/education_packages/nepean/nepean_CRRT_2009.pdf

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We only use Trialysis Catheters by Bard now. As someone who inserts these catheters routinely in the ICU, I can tell you they are harder to insert than the older Quintons or Vas-caths (guidewire bends easily, odd shape of catheter at its diameter). But they have the advantage of having the extra port that's compatible with the PSI requirements of IV contrast administration for CT Scans.

We use Schoen dialysis catheters for the most part. If a patient is sick enough to get a dialysis catheter then they have a CVL which are all pressure compatible. We occasionally put in the trialysis catheters on someone who is getting better and needs IV access and dialysis access (so we can pull the central line). If I have one around sometimes I use them for large volume resuscitation. I can't remember the brand we have (we "borrow" them from IR). But they have a really slick peal away sheath that makes them super easy to put in. Generally our nephrologists don't like them compared to the Shoens because they don't have as much flow and have more clotting problems.

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Specializes in Surgery, Trauma, Medicine, Neuro ICU.

We pretty much only run CVVHDF.

We have an order set with guidelines for potassium, magnesium and calcium replacement and we run all our electrolytes by our nephrologist for other tweaking as needed.

We also use ACDA almost exclusively for anticoagulation on the machine, with the CaCl gtt to go along with it. I'm not sure I've ever used heparin as an anticoagulant on the machines.

We only use the Bard Trialysis as well, hep-locked/packed when not in use. And we don't flush routinely during treatment unless there is a problem!

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I just run the machine, the renal doc gets the big bucks to decide what I run through it.

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