External Ventricular Drainage Weaning Protocol [Neurosurgery Wiki]

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====== External Ventricular Drainage Weaning Protocol ======

**J. Sales-Llopis**  

''Neurosurgery Department, General University Hospital of Alicante, Spain''
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Structured approach to evaluate readiness for **external ventricular drain (EVD)** removal and minimize risk of **hydrocephalus relapse** or **shunt dependency**.

===== ✅ Indications to Start Weaning =====
  * Resolution of acute condition (e.g., stabilized IVH or ICH)
  * **Neurologically stable** for ≥ 24–48 hours
  * Controlled **ICP (< 20 mmHg)** with minimal or no CSF drainage
  * No evidence of active infection or new hydrocephalus on imaging

===== 🔁 Stepwise Weaning Protocol =====

==== 📍 Step 1: Elevation of Drainage Level ====
  * Raise drain to **+20 cmH₂O** above EAM
  * Monitor for 24 hours
  * If no CSF drainage and patient stable → proceed to next step

==== 📍 Step 2: EVD Clamping Trial ====
  * **Clamp EVD completely** (closed system, monitor ICP)
  * Monitor for:
    - ↑ ICP (> 20–25 mmHg)
    - ↓ consciousness or new symptoms
    - New ventricular enlargement on CT

  * Duration: **24–72 hours**, depending on risk and tolerance
  * If tolerated → CT scan → consider EVD removal

==== ❌ Failure Criteria ====
  * ICP spikes > 25 mmHg (sustained)
  * Neurologic deterioration
  * New or worsening hydrocephalus on CT
  * Symptomatic bradycardia, vomiting, headache

===== 🧾 If Weaning Successful =====
  * Unclamp EVD and **drain 10–15 mL slowly before removal** (optional)
  * Remove catheter under sterile conditions
  * Apply occlusive dressing and monitor site
  * Monitor patient closely for 48–72 h post-removal

===== 🧠 If Weaning Fails =====
  * Re-open EVD and reassess need for:
    - **Repeat weaning trial** after 48–72 h
    - **Permanent CSF diversion** (e.g., ventriculoperitoneal shunt)

===== ⚠️ Pearls & Precautions =====
  * Do not rush clamping in unstable or comatose patients
  * Ensure no **obstruction** before concluding tolerance (a dry EVD can be blocked)
  * Always confirm with **neuroimaging** before final removal

====== 🔁 When to Convert EVD to VP Shunt ======

Clinical criteria and decision-making pathway to determine when a patient with an **external ventricular drain (EVD)** requires **permanent CSF diversion** via ventriculoperitoneal (VP) shunt.

===== ✅ Indications for VP Shunt Conversion =====
  * Persistent **hydrocephalus** despite EVD > 7–10 days
  * **Weaning failure** after ≥2 trials (clamping intolerance or ICP crisis)
  * **Recurrent CSF drainage need** (e.g., > 150–200 mL/day to maintain ICP < 20 mmHg)
  * New or worsening **ventricular enlargement** on imaging
  * Clinical deterioration when EVD is clamped
  * Known **obstructive hydrocephalus** (e.g., aqueductal stenosis, post-SAH, IVH with cast)
  * Recurrent **intraventricular hemorrhage**, chronic communicating hydrocephalus
  * Recovery phase of **poor-grade SAH or IVH** with persistent CSF resorption failure

===== 🔍 Additional Considerations =====
  * Perform **repeat CT scan** after EVD clamping trial
  * Confirm **no CSF infection** (send CSF culture, cell count)
  * Rule out **reversible causes** (e.g., meningitis, elevated protein > 150 mg/dL)
  * For IVH patients: delay shunting if active **blood clearance** is ongoing

===== 🛠️ Pre-Shunt Planning =====
  * Normalize coagulation parameters
  * Decide on **programmable vs fixed-pressure valve**
  * Consider **endoscopic third ventriculostomy (ETV)** as alternative in non-communicating cases
  * Confirm **no active infection or sepsis**
  * Discuss **shunt dependency risk** with patient/family

===== ❌ Contraindications to Shunt Placement =====
  * Active CSF infection (e.g., ventriculitis)
  * Uncontrolled systemic sepsis
  * Very high protein or debris in CSF
  * Unstable patient not yet optimized for surgery

===== 🧪 How Many Negative CSF Cultures Are Required? =====

To safely remove an **external ventricular drain (EVD)** or convert to a **ventriculoperitoneal (VP) shunt**, the following microbiological criteria must be met:

==== ✅ Recommended: 2–3 Consecutive Negative CSF Cultures ====
  * Ideally spaced **24–48 hours apart**
  * Collected **after antibiotic therapy** is completed or near completion
  * **No growth** on culture
  * Normalizing **CSF cell count and protein** (↓ WBC, ↓ neutrophils, ↓ protein)

==== 📋 Rationale ====
  * One negative culture may **miss low-level or biofilm infections**
  * Shunting in presence of infection → ↑ risk of:
    - Shunt infection
    - Shunt malfunction
    - Recurrent ventriculitis or abscess

==== 🧠 Practice Summary Table ====
^ Scenario ^ Recommended Cultures Before Shunt/Removal ^
| **Documented ventriculitis** | ≥ 3 negative cultures |
| **No prior infection** | 1–2 negative samples may suffice |
| **SAH / IVH patients** | Prefer 2–3 negative cultures |

==== ❗ Important ====
  * Always evaluate **CSF glucose, protein, cell count** along with culture
  * Avoid CSF sampling unless clinically indicated to **reduce infection risk**

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