External Ventricular Drain (EVD)

1. External ventricular drain
Department of Neurosurgery
Dr RE Anto

2. Introduction
• An EVD (external ventricular drain) is the temporary drainage of CSF
from the fluid filled cavities (ventricles) to a closed collection system
outside the body.

3. Standardized approach
• Common procedure
• Often done by junior staff
• Emergency/After hours
• First time is most important to avoid
complications
• Proper care of EVD

4. Indications
• To relieve raised ICP
• Divert infected CSF
• Divert blood stained CSF
• For ICP monitoring
• Intra-operative brain relaxation

5. Catheters
• Ventricular catheters (5-7 days)
• Antibiotic coated catheters
(Bactiseal) (10-12 days)
• orange in colour
• has 0.15% clindamycin and
0.054% rifampicin infused into
silicone matrix at molecular level

6. Drainage system
1
2
3
4

7. Planning
 Review imaging studies
 Identify landmarks
 Coagulation parameters
 OR with tunnelled distal system
 Future shunt placement

8. Anaesthetics
• Local anaesthesia (1% Lignocaine)
• Short acting anaesthesia
• (assess neurological status post EVD)
• IV Antibiotics
• Covering skin flora
• EVD duration

9. Frontal approach
• Right side (non dominant hemisphere > 90%)
• Shave appropriately
• Entry point on scalp is marked with pen and ruler
• Clearly define midline.
• Also place ECG sticker on nasion
• Local anaesthesia (tunnelling exit)
• Appropriate size Drill-bit

10. Entry site
• Kocher’s Point
• Anterior to motor strip
• Posterior to the forehead
• Lateral to SSS and large bridging veins
• Location
• Burrhole perpendicular to bone
• Dural opening

11. Trajectory

12. Depth of catheter
• 5-6cm from the outer table of skull – soft pass further 1cm to
Foramen of Monroe

13. Posterior (Occipital) approach
• Position
• Supine with ipsilateral shoulder roll and head turned fully
toward contralateral shoulder
• HOB can be elevated 15- 20°

14. Entry points
• Fraziers burrhole
• 6-7 cm superior to inion and 3-4 cm
off midline
• Parietal boss
• 3 cm above and 3 cm posterior to auricle
tip.
• Dandy’s Point
• 3 cm superior to inion and 2 cm off
midline
• Higher risk of visual pathway damage

16. Trajectory
• Always check imaging for
individual anatomy
• Aim for medial ipsilateral canthus
• May deflect to temporal horn
• Choroid plexus obstruction
• With stylet 6cm
• CSF flow – soft pass till 10-12 cm
(8 cm for kids)
• Tip – frontal horn in front of
Foramen of Monro

17. Secure drain to scalp
• Tunnel the catheter atleast 5cm
away from burrhole
• Use figure of 8 stitch around drain
and loop it around the catheter
and tie it off.
• Avoid multiple stitches to scalp
• Apply sterile occlusive dressing

18. Maintenance and care
• Ensure zero point is accurate
• External auditory meatus
• Document Pressure level
• Amount of CSF per hour
• Characteristics of CSF
• Avoid aspirating EVD

19. Drainage
• Hourly documentation
• CSF produced continuously by choroid plexus
• 20-25ml/hour
• 500ml/day
• Drainage of more than 50ml/hr - excessive

20. No CSF in chamber
• Observe movement of CSF
• Pulsations
• Ensure not kinked/clamped
• Lower the chamber
• Opening pressure (?low)
• Repeat imaging
• Malpositioned

21. Clamping the EVD
• Not for more than 30 min at a time
• Reposition or move the patient
• Transfer pt
• Pre-operatively to enlarge ventricles for easier access

22. Removing the EVD
• Clamp and close neuro-observation
• Any changes – immediately unclamp
• Repeat imaging after 24 hours
• Removed aseptic technique
• Send tip for culture

23. Complications
• Overdrainage
• Obstruction
• Infection
• Haemorrhage
• Risk of bleeding 7%
• Significant bleed 0.8%
Remove EVD as soon as clinically not indicated

24. References
• Winn H.R. Youmans & Winn Neurological Surgery. Elsevier;
Amsterdam, The Netherlands: 2017.
• Handbook of Neurosurgery, 9th edition
• Lozier A.P., Sciacca R.R., Romagnoli M.F., Connolly E.S., Jr.
Ventriculostomy-related infections: A critical review of the
literature. Neurosurgery. 2002;51:170–181
• Edwards N.C., Engelhart L., Casamento E.M., McGirt M.J. Cost-
consequence analysis of antibiotic-impregnated shunts and external
ventricular drains in hydrocephalus. J. Neurosurg. 2015;122:139–147.