CRRT: negative patient fluid removal

Specialties MICU


  • by Kate96
    Specializes in critical care.

Hey Everyone! I am fairly new to CRRT and had an issue come up one night. I was having problems with my access pressure being extremely negative. I was troubleshooting and ultimately my Vas Cath location was just not going to work anymore. I tried to return the blood before my filter clotted off and I was able to. However, when I went to do my I & Os for that hour the actual CRRT fluid removed was a negative number (-127). I understand that because I was having so much trouble with my access I was not able to pull anything so this accounts for delivery of fluid. But I am just confused by how I delivered so much? Also what was the fluid being delivered? Was it just the NS from the filter when I delivered the blood? Or is this the replacement fluid? I guess I am confused how and where this number came from. Thank you to anyone who has any help!

Specializes in Critical Care, Capacity/Bed Management.

Sounds like the patient had an unintended fluid gain, this can come from the post filter fluid if you are running CVVH, CVVHD, or CVVHDF and are having access issues with frequent alarms stopping therapy. It can also come if you return more fluid than blood during the blood return. For example, if your filter holds 150ml of blood, but you decided you want to get every last RBC and hold down the manual return button then you can hit a fluid gain situation after the 150ml of blood the machine has accounted for. 

I don't know what CRRT machine your facility uses, but my experience is with Baxter's PrismaFlex and PrisMax machines. They have a hard stop of unintended fluid gain/loss of I think 400ml/3h. If we have a lot of access issues we are allowed to switch the access and return lines as long as we inform nephrology about it. The catheter gets changed out ASAP though in those situations. If I remember correctly site selection for catheter placement is as follows: Right IJ > Left IJ > Femoral > Subclavian

Specializes in ICU.

A lot of times these catheters can give us trouble. In my experience, I have switched the return and access lines to promote better blow flow of the catheters. If the catheters cannot be manipulated and are just positional, it can be an issue with where the access is placed itself. The PCP might want an xray to assess if the access is still viable - or just might want a new catheter inserted all together.


In addition, let's say the patient is not getting much fluid. 0 in subtracted by a net negative goal of 200 will provide the patient will a -200 return. This is completely okay, and the nephrologist will be extremely happy with you keeping the goal in place. However, as critically thinking RNs - we also have to be cognizant of the patients pressure. If BP is going down, the nephro's removal goal might have to be changed. Obvi once asking them first.


Please feel free to reach out w other MICU questions! 🙂

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