EVD Management and Troubleshooting

CSF BASICS:

  • CSF production ~0.2–0.4 mL/min or 500–600 mL a day

 

MANAGEMENT OF EVD:

  • INITIAL SET UP
  • Determine height of EVD collecting system
  • Adjust height of EVD
    • pressure transducer in line with Foramen of Monro (external auditory meatus in supine and between eyebrows in lateral position)
    • Use Carpenter’s level or laser leveling device to zero drain
    • Unsecured aneurismal SAH
      • initial height set “high” so CSF not drained too quickly to avoid rapid change in transmural pressure across aneurism wall, which predisposes to rebleeding
      • Negative level of drainage may be encountered in negative pressure HCP or massive IVH
  • Set drainage
    • continuous set level
    • fixed volume per desired time
    • as needed according to ICP elevations
  • NOTES:
    • At prescribed height, CSF will drain whenever intraventricular pressure exceeds that set by the height of the collection system.
    • If transducer is above Foramen of Monro, falsely low ICP and insufficient drainage of CSF may occur, and intracranial hypertension would go undetected.
    • Clamp drain during transfer and transport.
  • Inspect ICP tracing.
    • If EVD is open with continuous drainage – turn stopcock at level of transducer “off” to drain and “open” to transducer. ICP waveform takes 30s to stabilize and should appear pulsatile.
    • Normal ICP waveform has 3 peaks, decreasing in height.
    • In intracranial HTN or failing compliance, amplitude of all 3 peaks increase followed by elevation of second over first.
  • ACCESSING EVD:
    • indications:
      • withdraw CSF for cultures or obtaining malignant cells
        • Do not collect samples from collection bag – rapid degradation of cellular components.
        • Aspirate from proximal port.
        • Aspirate slowly (no more than 1 ml/min). If resistance is met, abort procedure and inform MD.
      • instill medications
        • tPA for IVH or ABx for ventriculitis
        • clamp EVD x 1 hour.
  • Other nursing management:
    • 1. Monitoring for ICH
    • 2. Inspecting entire EVD systemand insertion site for CSF leak
    • 3. Noting quantity, color and clarity of CSF
      • increase in hourly output signals ICH
      • bright red bloody CSF indicate aneurysm rupture
      • cloudy CSF indicate presence of infection

 

TROUBLESHOOTING THE EVD:

  • Causes of obstruction of a ventriculostomy catheter
    • cellular debris, (blood clots / tissue fragments).
    • Mechanical kinking of tubing, failure of any part of the system, migration of EVD catheter
    • Physiologic factors such over drainage or tight ventricles or CSF leak
  • Technique:
    • FIXED OBSTRUCTION
      • clues:
        • Dampening of the ICP waveform
        • reduction or absence of CSF flow
        • lack of pulsation of the CSF meniscus in drain tubing with respiration
      • change EVD collection system
    • NO FIXED OBSTRUCTION
      • Lower drainage system briefly to see if CSF flow ensues (no fixed obs)
      • cellular debris = catheter irrigation with small volume (less than 2 ml) sterile isotonic normal saline
        • flush distal port first
        • flush proximal port (potentially result in increased ICP in patients with preexisting intracranial hypertension and/or poor intracranial compliance)

 

EVD RELATED INFECTION

  • Risk factors
    • systemic infection, depressed skull fracture, lack of tunneling of EVD catheter, site leak, catheter irrigation, frequency of CSF sampling and possibly duration of EVD placement
  • Techniques to reduce infection
    • Prophylactic IV antibiotics – develop resistant organisms
    • Antibiotic-impregnated and ionized silver particle coated EVD catheters – same, costly
    • Sample EVD only when infection suspected
    • Monitor EVD dressing site for CSF leak
    • Maintain collection system in upright position
    • Do not routinely change drain tubing

 

Reference

Muralidharan, Rajanandini. “External Ventricular Drains: Management And Complications”. Surgical Neurology International 6.7 (2015): 271. Web.

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