EVD

Background

Watch this NEJM video https://www.nejm.org/doi/full/10.1056/NEJMvcm1805314

Indications for EVD placement

1. ICP monitoring

2. CSF Diversion to treat hydrocephalus

3. Clearance of blood products (IVH) or Infectious Debris (severe meningitis/shunt infection)

4. Post-intra-op dural defect (skull base/posterior fossa procedure), need to promote healing

Steps when EVD is Decided

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This is the exact order of operations to take when you know a patient is getting an EVD.

Check labs and order CBC/Coags/T&S if any of it is missing - call nurse immediately, this is #1 hold-up

Order Ancef 2g ASAP (takes a long time from the pharmacy)

Check for SQL/SQH administration - some attendings care about this a lot

If patient is on AC/AP, make sure they are being reversed

Order K centra as needed

Order platelets if patient is on aspirin or possibly on aspirin

if you're in the ED, they actually have their own blood bank and will get it directly from there, but confirm with nurse that it's on the way and verbalize that you need it. Ask for 2 units by default, can always return the second one.
if you're in ICU, you need to call the PUH blood bank 412-647-5850 too. Ask charge in the ICU exactly what needs to be done. Don't assume it's on the way STAT.

Order post-placement CTH while you have the chart open already

Place the EVD order (set it at 10AMB and then just verbal change it once you confirm level later); can put in comments "ok to clamp while transporting to scan"

Print an EVD & Blood consent and get family phone number from chart.

also print all anticipated procedure consents e.g. Crani/Blood/Angio for a ruptured aneurysm

Call the appropriate (ICU fellow/ED attending) to discuss and plan for sedation.

Gather all supplies as listed below.

Supplies Needed and where to get them

Items	Where to get in PUH	Notes
Cranial Access kit OR Phasor Drill	All ICUs should have If all else fails, go to OR center aisle (kindly ask front desk)	• phasor is better for left-sided EVDs as it's less awkward than hand-drilling on the left side of the head if you're right handed. • Kindly ask ICU nurse to get this for you (this you can trust they should know)
EVD catheter	All ICUs should have If all else fails, go to OR center aisle (kindly ask front desk)	• Almost always it's a red antibiotic impregnated one OR less commonly the clear large bore one. Ask your senior which is indicated for the pathology in question. • Just personally make sure you get the right one early on in this process.
Clipper	ICUs will all have these	Ask for this early, as they are sometimes hard to find.
• 2 large chloro prep sticks • gown + hat • sterile flushes / 1L sterile water • Telfa • Stapler + remover • 3 nylon ties • 2 silk ties (2-0, not 4-0) • Ruler + marker	ICU Supply Rooms /ICU carts
Green chuck Blue pad	patient's room	Ask nurse to get this Green chuck is to elevate head/neck as needed Blue pad is to place under patient's head as shit will get bloody

NOTE: on 4G/4F/5F, you can possibly trust nurses to get you everything, but on 6FG you can only trust them to get you a cranial access kit, just save yourself the time and get everything else yourself up front.

Steps for EVD Placement

Position the patient

Take the time to do this right. Be efficient but don't rush this step, you will pay for it later.

Make HOB flat (do this quickly as ICP will be rising)

Rotate patient so that whole body is midline on the bed (yes it matters for your own orientation even if you're just at the head)

Move patient north in the bed until head is creeping about 2-3 inches above the top edge (don't worry they'll slide back down)

Re-elevate HOB to 30˚ while lifting feed up so that they don’t slide down.

Adjust height of whole bed to make it ergonomic and comfortable for yourself

Pre-procedural

Administer 2g Ancef - can also be given up to 1 hour AFTER skin is cut (don't let this delay you)

Administer platelets if needed

Start sedation: if not intubated then ICU attending/fellow must be present and you cannot start without them, otherwise just need a nurse titrating drips if they’re intubated.

Prepare your table (in sterile manner)

Use the craniostomy kit box to prop open the garbage and throw packaging away as you open things up.

Setting the table with sterile gloves as nurses prime EVD / CCM prepares sedation.

Open your gown and gloves you will use during procedure like this and place on window

Place prep and shaver on bottom of bed so they don’t get lost.

Position and Measure - take the time to do this right, be efficient but don’t rush or you will pay for it later!

HOB flat (quickly do this as ICP will rise)

Bump the patient to top of bed

Rotate/move their hips so the whole body is midline on bed (yes it matters for your own orientation, even though you are working at head only)

Move patient north to bed until head is creeping 2-3 inches over the edge

HOB back to 30, elevate feet so they don’t slide

Place two green chucks below neck to secure head

Bring entire bed all the way down to make it more ergonomic to pass

Find Kocher's point

Verify you are mid-pupillary

Prep

Shave only up to Kocher's point and posteriomedially for an exit site.

Chloroprep x 2 (WIDELY), watch the dripping into eyes/ears

Drape w/ plastic cover, staple white sheets under plastic (be careful if patient is on an airbed, staple the plastic drape to white sheet, not to bed!)

Inject lidocaine at Kocher's point and at exit site posteriomedially

Re-measure after injecting lido, the bubble will displace your prior marking

Prep widely, after draping, must drape with blue towels both for sterility and to lay your instruments on more easily for economy of motion

Craniostomy

Knife down to bone

Dissect under pericranium around 1-2 cm in every direction around your incision

Stick caterpillar clamp in there

REMEASURE - don't be afraid to extend incision and reposition if you find that you need to at this step, that is the whole point of remeasuring

Have a headholder be ready, tell them to reach under the plastic drapes (don't assume they know it's sterile)

EVD PLACEMENT

Drill perpendicular to bone

Laterally: Aim for contralateral canthus
Anterior-posterior: Tilt back to an angle until your catheter is parallel to ear
If all else fails, just go perpendicular to skull
Tactile changes you will fell from superficial to deep as you approach brain:

outer table = cortical bone (tough)
cancellous bone (becomes easy)
inner table = cortical bone (again tough)

Use a curved kelly to dig out bone chips

Flush

Catheter Insertion

Pierce dura with weapon in a cruciate fashion (two punctures)

Before pass catheter through dura, ask for BP < 140

Go slowly with the literal pass, this is the only thing you can do to prevent tract hemorrhages

Go down until you see the string (at 6.5) at the OUTER table

Tie-down

Retention loop and closing

Random Tips:

When you are doing an EVD replacement and/or placing a contralateral EVD, you need to prep and drape thoughtfully.

use the plastic clear drape but then use your scissors to expand the circle to be big enough for two EVDs if needed

drape copiously with blue towels in all sides

try to keep midline visible without covering with blue towels, for your orientation (see below)

When the phasor stops drilling, it's because bone dust is inhibiting it. Use a raytech and rub it off.

The large bore catheters do not come with a cap. You need to open a regular bore EVD just to steal the red cap (shown below) from it.

Dealing with venous bleeding - cover the craniostomy with a 4x4 and just tamponade with flush

Connect to monitor

Post-placement scans

window CTH to bone to see holes and make sure they are in vents

Exchanging an EVD

Prep differences

Use betadine

Procedural differences

EVD Leveling

Remember EVD levels are set according to height of water in centimeters (cmH2O), different then height of mercury in millimeters (mmHg). Generally speaking the settings are used as follows

EVD level	mmHg	Setting	Typical uses
5 cm H2O	3.7	low	Encourage drainage (hydro, clearance of debris/blood)
10 cm H2O	7.4	moderate	ICP monitor w/ little bit of drainage
15-20cm H2O	11-14	high	Weaning the EVD (i.e. before you clamp it next) Before aneurysm is secured Posterior fossa mass (to prevent upward herniation)

Troubleshooting

During Placement

Not draining after initially seeing CSF

Always check if you are air-locked. Just very gently suction in and out.

After Placement

"The EVD is not working" / "The EVD is not tidaling"

Re-level the EVD (laser to tragus), i.e. re-calibrate your 0 to be MB as you define it
Clamp proximally (i.e. open to transducer, insert picture)
zero it on the monitor and then rescale

'ICP is really high"

Make sure you are clamped, transducer does not give accurate ICP measurement while EVD is opened!