Dandy-Walker; ICP monitoring

[BBQvegan]

Hi all,

I wasn't sure whether to post here or in Neuro ICU, so I posted in both. I am a nursing student in the pediatric rotation. I cared for a 2 y.o. child with Dandy Walker syndrome who had just had a 3rd ventriculostomy. No shunt was placed, but an ICP catheter was placed and hooked to an art line and monitor. This was a closed system that was hooked to a plastic contraption where the physician could withdraw CSF for analysis. Otherwise, there was no drainage; only monitoring of ICP.

I understand this is the system of ICP monitoring that was available before the newer technology. Do many hospitals have this system? What is the name for it? Why was it hooked to an art line? How does it work? Is there anything else I should know about it?

I also want to understand his CSF lab results. RBCs 1600 (normal = 0-10). And neutrophils 100 (normal = 0-6). Is this due to the trauma/inflammation caused by the burr hole and ventriculostomy? What else might we expect to see?

In this case, I have identified main nursing priorities:

1. Monitor and maintain ICP levels below 25 mm Hg.

2. Administer antibiotics and observe for signs of infection.

3. Control pain and nausea.

4. Provide comfort and emotional support to pt and mother.

Are there other important interventions I am overlooking? And anything else I need to consider?

Thank you so much!

[NotReady4PrimeTime, RN]

The system you're describing is called an external ventricular drain. It can be used for drainage, pressure monitoring or both. It isn't attached to an art line. If it's used for pressure monitoring it will have a transducer identical to the ones used for art lines and a pressure cable connected to your monitor. This system allows the monitor to do the calculation of cerebral perfusion pressure (CPP=mean arterial pressure minus intracranial pressure). Every hospital that does neurosurgery will have these systems; the newer technology like the Camino or Codman fiber optic catheters have limitations. You cannot drain cerebrospinal fluid with them to help regulate ICP and they don't interface with the monitor so you have to do the CPP calculation yourself. Also there's no easy way to tell if the catheter tip has migrated into the parenchyma. It cannot be recalibrated once it's placed, unlike the EVD, which can be recalibrated whenever.

Your analysis of the CSF labs is what I'd expect. The neutrophils should fall fairly quickly; if they don't it could mean ventriculitis or meningitis. Bad.

Your nursing interventions are appropriate. You could also add monitoring urine output and urine electrolytes and osmolarity, since tinkering with the third ventricle can precipitate diabetes insipidus. The treatment is administration of IV DDAVP and judicious urine replacement. Some craniotomy patients require an infusion of 3% saline to help maintain normal ICPs and electrolytes.

I admitted a patient from the OR post op third ventricle tumor resection four hours ago.

[BBQvegan]

Thanks, janfrn, for that very thorough explanation! I am beginning to understand!

[NotReady4PrimeTime, RN]

You're most welcome.

I just thought of something to add when discussing ventriculostomy. An EVD serves as a very good canary-in-the-coal-mine post-operatively because if the CSF draining from it becomes more sanguinous (signalling new bleeding), you'll notice pretty quickly and be able to intervene. It's normal for the CSF to be quite pink initially, but over several hours it should become the usual straw color. The fiber optic catheters can't give you that kind of feedback.

Some other little tidbits about EVDs: The pressure level will be ordered by the surgeon and the order might read, "EVD at 15 cm open continuously", or "EVD at 10 cm. Open for 5 minutes if ICP >20 for >5 minutes". This level is where the top part of the chamber is positioned (see drawing below) in relation to the third ventricle (no matter why the EVD was placed) and your landmark for this is the tragus of the ear if the patient is supine and the bridge of the nose if they're side-lying. The higher the level, the greater the pressure required for CSF to drip into the chamber (gravity!). We used specially designed laser levels that attach to the back of the sliding collection chamber set-up right at the zero reference, which then attaches the set to the pole. It's vitally important to ensure the level is maintained and that the collecting system is secured tightly to the pole with both the screw clamp and the hanging cord. Just imagine what would happen if the set fell while the drain was open! Of course, any intervention with an EVD requires scrupulous aseptic technique. The transducer should be calibrated every four hours, or according to hospital policy. Oh, and once you're duly licensed and are within your scope of practice to sample the CSF, make sure you NEVER aspirate it from any point between the patient and the transducer. The only one who should be drawing fluid proximal to the brain is the surgeon.

[BBQvegan]

Fantastic information. Thanks!