What is the significant sign for clotting dialyser?

[NurseRies, BSN, RN]

You're right. TMP can be high or low, indicating clotting. Venous pressure gradually increasing usually indicates either the venous chamber or dialyzer is clotting. You can always flush with 100cc to assess situation. If the filter looks clear, could be a machine issue or an access issue. Which machine do you use? The Fresenius K never had a specific alarm that indicates clotting, but TMP is the best sign.

[Chisca, RN]

A/V pressures are going to indicate flow through the circuit. If there is a clot in either the venous or arterial chamber then yes you would see this reflected in A/V pressures as this is impeding flow. Clotting in the dialyser is occuring on the surface of the dialyser and since it has such a large surface area it really doesn't impede blood flow to and from the patient until very late in the clotting process. TMP is the relationship between pressure on the venous side of the blood circuit and the pressure on the dialysate side of the artifical kidney. A low or positive TMP means that little to no solutes are being removed from the blood. As that process continues eventually you would see alteration in the A/V pressures but by that time your TMP would be so unstable the machine would be continually alarming.

[Hoosier_RN, MSN]

I will suggest to look at the whole circuit, especially chambers and dialyzer, after rinseback. See if you are able to visualize clots anywhere in the system

[SmilingBluEyes]

Also watch the dialyzer for marked streaking, another possible sign. I agree; always look at the circuit, don't rely just on the machine and its numbers to tell you that clotting is occuring. Look at your KECN as well, if they go precipitously down, you likely have a clotting issue.

[Zeek, LPN]

Others that have posted here are correct about the venous pressure staying the same or similar.  Here is why:  TMP (Transmembrane Pressure) is calculated by using the current venous pressure and the dialysate pressure (which, if pulling fluid should always be less than the venous pressure).  This creates the hydraulic pressure difference to remove fluid.  When your dialyzer (filter) is clotting, the resistance of the blood moving through the tubing into the venous drip chamber doesn't change.  The pressure in the DIALYZER changes which affects TMP.  If your venous pressure changes then look at the drip chamber and line as others have noted.  Note that your dialysate pressure will fluctuate based on current UF rate.  If you use a profile (start high, end lower, etc.) watch the TMP throughout the run.  It should decrease as well.  If you have a negative TMP, verify your venous pressure is correct for that patient (no clotting, transducers OK, Pods OK on the Streamline tubing etc).  At least on the machines I have used, TMP is never negative without clotting, BUT I have not used all the machines out there.  All of the same things above will apply.

Also remember that TMP is what helps us remove fluid.  It only affects solutes (waste) with convection or solute drag which enhances the dialysis process.  Chisca RN above is correct if she means that by the clotting in the dialyzer we are removing fewer solutes.  Mostly the solutes are removed through diffusion.  

Sorry for the long post, but TMP is something people don't teach enough about in my opinion!!

[uae808]

We are using Braun machine, I am strange if dialyser clotted, why V and A pressure all stable within the normal range?

[Lizzy19684]

What causes a negative TMP? is this an indication that the system will be clotting?

[Chisca, RN]

Negative or positive not so important as stability. A fluctuating TMP that won't stay stable is your clue. Wet transducers, either from blood or saline are also going to give you unstable TMP.