The Cell Index in Ventriculitis

Summarizing an old article on the CSF Cell Index published in 2004, study has not been validated, but information is “nice to know.”

The CSF cell index is a ratio between the blood cells in the ventricles (in intracranial hemorrhage) and the peripheral blood.  At the time of bleeding, blood in the ventricles is diluted within the CSF, and the relationship between WBC:RBC should equal that in the peripheral blood.  This ratio, called the CSF cell index, should approximate 1 in the absence of infection.

The CSF cell index is calculated using to the following formula:


This study reported that the cell index rises 3 days before diagnosis of a catheter-related ventriculitis, and proper antimicrobial treatment led to a rapid decrease of the cell index.  The study concluded that a significant increase in the cell index is highly indicative of nosocomial EVD-related ventriculitis in patients with IVH, and that the increase of the cell index usually precedes diagnosis by conventional means by 3 days.





Pfausler, B. et al. “Cell Index ? A New Parameter For The Early Diagnosis Of Ventriculostomy (External Ventricular Drainage)-Related Ventriculitis In Patients With Intraventricular Hemorrhage?”. Acta Neurochirurgica 146.5 (2004): 477-481.

Subarachnoid Hemorrhage and Ventriculitis

Clinical signs of ventriculitis are difficult to recognize in SAH patients who are sedated, who have recently undergone neurosurgery, or have a sterile inflammatory response in the CSF due to the SAH.  Clinical symptoms of SAH (headache, nuchal rigidity, AMS) closely resemble bacterial ventriculitis.

Suspect with:
  • new fever
    • Fever occurs in 40 % after SAH +/- infection
  • new nuchal rigidity


What to do?

Exclude other causes of infection

  1. physical examination
  2. blood / sputum / urinary cultures
  3. CXR

Exclude other causes of AMS (HCP and ischemia)

  • Neuroimaging with plain CT scan
  • Serum:  CRP WBC glucose
  • CSF analysis (cell count, GS / CS, glu / protein)
    • Interpretation of CSF WBC problematic; CSF RBC causes aseptic ventriculitis
    • CSF cell count  helpful but low sensitivity and specificity
      CSF RBC higher in CSF culture-negative bacterial ventriculitis
    • cell index for EVD-related ventriculitis with IVH (formula proposed, but not yet validated)
  • Blood cultures
  • CSF lactate, cytokine levels, and serum procalcitonin
    • Also disturbed after SAH
    • procalcitonin discriminates between SIRS and systemic infection but value for aseptic vs bacterial ventriculitis is limited
  • CSF PCR for bacterial pathogens – low sensitivity in EVD related bacterial ventriculitis and aseptic ventriculitis after surgery
Case definitions:
  1. Clincally suspected bacterial ventriculitis – empirical antibiotic treatment for bacterial ventriculitis, but negative CSF cultures
  2. Confirmed Bacterial ventriculitis – (+) CSF culture for bacteria; if staph epidermidis – needs 2 consecutive positive cultures to rule out contamination
  • No good discriminative tests, treatment initiated on first suspicion
  • Antibiotic regimen for bacterial ventriculitis
    •  ceftriaxone 2 g BID + vancomycin 2 g BID
    •  ceftazidime 2 g TID + vancomycin 2 g BID if external CSF catheter in place
  • Duration
    • culture negative – discontinue ABx (after 72h)
    • culture positive – 2 weeks


  1. Physical Examination
  2. Assessment:
    • clinically suspected bacterial ventriculitis
    • confirmed bacterial ventriculitis
  3. Blood work:
    • CBC (WBC)
    • BMP (glucose)
    • Blood cultures x 2
    • CRP
    • Procalcitonin
  4. sputum cultures
  5. urinalysis with reflex to urine culture if (+)
  6. CXR
  7. Plain CT scan
  8. CSF studies
    • cell count
    • Gram stain and culture
    • CSF glucose
    • CSF protein
    • calculate cell index
    • CSF lactate
    • *CSF cytokine levels
    • *CSF PCR for bacterial pathogens
  9. Treatment x 2 weeks
    • ceftriaxone 2 g BID + vancomycin 2 g BID
    • ceftazidime 2 g TID + vancomycin 2 g BID if (+) EVD
    • discontinue within 72 hours if cultures are negative



Hoogmoed, J. et al. “Clinical And Laboratory Characteristics For The Diagnosis Of Bacterial Ventriculitis After Aneurysmal Subarachnoid Hemorrhage”. Neurocritical Care (2016): 1-9.

EVD Bundle (Placement)

Elements of EVD infection control protocol for EVD placement.

  1. wide clipping of head – enough to fit a medium-sized Tegaderm
  2. apply chlorhexidine-alcohol – first skin prep
  3. full draping followed by second chlorhexidine-alcohol skin preparation with the surgeon wearing gown, gloves, cap, and mask and full barrier precautions used throughout
  4. minocycline/rifampin antibiotic-impregnated EVD catheter tunneled 3 to 5 cm; secured with curvilinear line of surgical staples
  5. apply benzoin tincture to skin broadly and fully dry
  6. apply biopatch over exit site (not wrapping around catheter)
  7. apply medium-sized transparent dressing film
  8. secure borders of transparent dressing film and catheter with adhesive strips



<click here for MS Powerpoint File>



Flint, Alexander C. et al. “A Simple Protocol To Prevent External Ventricular Drain Infections”. Neurosurgery 72.6 (2013): 993-999. Web.

EVD Weaning Protocols

10cm H20 prior to weaning

Initiation of weaning left to discretion of attending neurosurgeon.


  1. raise drain height by 5 cm q24h to final level of 25 cm H20
  2. on Day 4, close the drain
  3. reopen if:
    1. ICP>20mm H20 x >5 minutes
    2. neurologic deterioration
    3. CT next day shows hydrocephalus

RAPID WEANING (within 24 hours)

  1. close drain immediately
  2. reopen if:
    1. ICP>20mm H20 x >5 minutes
    2. neurologic deterioration
    3. CT next day shows hydrocephalus

Failure of weaning = VP shunt insertion

**No differnece in incidence of HCP / need for VP shunting (62.5 vs 63.4% p=0.932)

**gradual weaning group spent 2.8 more days in the ICU (p=0.0002)

Neurocritical Care Society Guideline:

EVD weaning should be accomplished as quickly as is clinically feasible so as to minimize the total duration of EVD monitoring and VRI risk.

Two main methods to select those who will need permanent CSF diversion: clamping trial vs progressive wean.1. Clamping Trial: clamp EVD and monitor ICP, clinical status, ventricle size – determine whether VPS is required2. Progressive wean – progressively increase level of ventricular drainage (usually 5mm Hg/d) while monitoring ICP, clinical status, ventricular size, drainage volume Only 1 RCT (Klopfenstein, see reference listed) comparing the two methods. Clamping trial associated with shorter duration of EVD and ICU and hospital LOS with similar clinical outcomes.Currently decision to shunt is based on clinical deterioration. There is little information about the effects of subclinical hydrocephalus on cognitive function, chronic headache and fatigue. Studies have shown decrease in CBF in NPH, correlating with cognitive dysfunction.


Fried, Herbert I. et al. “The Insertion And Management Of External Ventricular Drains: An Evidence-Based Consensus Statement”. Neurocritical Care 24.1 (2016): 61-81. Web.

Klopfenstein, Jeffrey D. et al. “Comparison Of Rapid And Gradual Weaning From External Ventricular Drainage In Patients With Aneurysmal Subarachnoid Hemorrhage: A Prospective Randomized Trial”. Journal of Neurosurgery 100.2 (2004): 225-229. Web.

Rabinstein, A. and Lanzino, G. (2018). Aneurysmal Subarachnoid Hemorrhage. Neurosurgery Clinics of North America, 29(2), pp.255-262.

Grading of EVD Placement

  1. Grade I
    • optimal placement in the ipsilateral frontal horn or third ventricle
  2. Grade 2
    • functional placement in the contralateral ventricle or noneloquent (parenchyma)
  3. Grade 3
    • suboptimal placement in the eloquent cortex [(parenchyma) or nontarget CSF space, with or without functional drainage


Kakarla, Udaya K. et al. “Safety and accuracy of bedside external ventricular drain placment”. Operative Neurosurgery 63 (2008): ONS162-ONS167.


Ghajar Guide

The Ghajar guide is a device used to improve the accuracy of external ventricular drain (EVD) insertion.  The EVD catheter is traditionally inserted blindly by the neurosurgeon, based on anatomical landmarks (s.a. Kocher’s point).

The Ghajar device is a tripod that is mounted on the skull surface, which guides the path of entry of the EVD catheter.  The investigators of this device noted fewer passes and better accuracy with the use of this device.  Of note, the Neurocritical Care Society guidelines for EVD mentions the Ghajar guide in passing, but recommends the use of Kocher’s point and a trajectory perpendicular to the skull or targeting the contralateral medial canthus as landmarks during EVD insertion.

This device was invented by Jamshid B. G. Ghajar.  See url below for patent details.





Fried, Herbert I. et al. “The Insertion And Management Of External Ventricular Drains: An Evidence-Based Consensus Statement”. Neurocritical Care 24.1 (2016): 61-81. Web.


Elements of the external ventricular drain (EVD) infection control protocol for EVD placement.

  • A wide area of the patient’s hair (A) is clipped to an area large enough to eventually dress with a medium-sized transparent dressing film.
  • Chlorhexidine-alcohol is then applied in a first skin preparation (A, left).
  • Full patient draping is followed by a second chlorhexidine-alcohol skin preparation with the surgeon wearing gown, gloves, cap, and mask (A, center), and full barrier precautions are used throughout (A, right).
  • A minocycline/rifampin antibiotic-impregnated EVD catheter is tunneled 3 to 5 cm and then secured with a curvilinear line of surgical staples (B).
  • After Benzoin tincture is applied to the skin broadly and allowed to fully dry, a chlorhexidine-eluting patch is applied over the exit site (without wrapping the patch around the catheter), and a medium-sized transparent dressing film is applied (B).
  • The borders of the transparent dressing film and the catheter are further secured with adhesive strips (B).
  • Additional information on placement and dressing available at:



Elements of the external ventricular drain (EVD) infection control protocol for EVD manipulation (cerebrospinal fluid draws or flushing). Supplies are arranged outside the sterile field (A): 70% isopropyl alcohol, a kidney basin, and several 10- mL vials of sterile, preservative-free normal saline. Supplies are then opened onto a sterile field created with a large sterile drape over the patient (B): several chlorhexidine-alcohol swabs, several sterile 10-mL syringes, a surgical sponge, and sterile Luer-fitting port caps. Before gowning and gloving, the 3-way stopcock on the EVD port is turned to 45 (“off” to all directions) and submerged in 70% isopropyl alcohol solution (C). (This step is not performed on the sterile field.) The intensive care unit (ICU) nurse holds the EVD line over the sterile field without allowing the tubing to contact the field (D), and the physician dons cap, mask, sterile gown, and sterile gloves. The physician then cleanses the entire region of the port with a chlorhexidine-alcohol swab. The old port cap is discarded; the port is inverted; and fluid in the port is shaken out onto a surgical sponge (E). The port is cleaned again and then filled with chlorhexidine-alcohol solution (F). The port is inverted, and chlorhexidine-alcohol solution is shaken out onto the surgical sponge (G). Steps F and G are repeated several times. The physician uses the sterile 10-mL syringes to draw up sterile, preservative-free normal saline in sterile fashion from the ICU nurse. The port is rinsed with sterile, preservative-free normal saline, and the port is inverted to discard (H). The rinse step is repeated several times. A sterile 10-mL syringe is then attached to the port for CSF draw or flushing (I). Additional information about EVD manipulation techniques available at:


External Ventricular Drain Infection Control Protocol




Flint, Alexander C. et al. “A Simple Protocol To Prevent External Ventricular Drain Infections”.Neurosurgery 72.6 (2013): 993-999. Web.