External ventricular drainage

The purpose of this guideline is to provide guidance about external ventricular drainage (EVD) at Great Ormond Street Hospital (GOSH).

EVD is a treatment that allows the temporary drainage of cerebrospinal fluid (CSF) from the ventricles of the brain, relieving raised intracranial pressure (Cartwright and Wallace 2007).

Patients with an EVD must only be cared for by nursing staff competent to do so.

The following wards are able to take patients with an EVD:

  • Koala Ward
  • Bumblebee Ward
  • Paediatric Intensive Care
  • Neonatal Intensive Care (Rationale 1)

It is the responsibility of all nursing staff caring for a patient with an EVD to ensure that they are competent to do so (Rationale 2).

The clinical practice guidelines refer to both children and young people. The term ‘child’ incorporates young people.

The EVD is inserted in theatre by a neurosurgeon. The procedure is done under a general anaesthetic.

Indications for EVD are:

  • to relieve raised intracranial pressure (RICP)

  • to divert infected CSF

  • to divert bloodstained CSF following neurosurgery/haemorrhage

  • to divert the flow of CSF (Nielsen et al 2007)

Two types of EVD system may be inserted:

  1. If a child has an existing ventriculoperitoneal shunt system, this may be externalised at the distal end and connected to an external drainage system. This shunt system will contain a pressure valve, which controls the amount of drainage from the ventricles (Smith and Martin 2009). Externalised shunt systems should not be aspirated. Please contact Koala Ward if CSF sampling is required.  

  2. More commonly a new catheter is placed into the lateral ventricle through a burr hole made in the skull. Once inserted, the scalp incision is sutured and covered with a sterile dressing. The new catheter is tunnelled under the skin, exiting on the abdominal wall and connects to an external drainage system. This system does not have a pressure valve so drainage depends upon gravity. The exit site must be planned carefully to prevent an unsightly scar, reduce the risk of infection and reduce risk of accidental removal (Smith and Martin 2009; Cartwright and Wallace 2007). 

The ventricular catheter is connected to an external drainage system in the operating theatre (Rationale 3). The system has several components:

  • a sampling/access port

  • an anti-reflux collection chamber

  • a drainage bag

  • a pressure scale

External ventricular drainage
External ventricular drainage

A blue or pink stopcock protection box must be placed over the access port. The sponge can be removed from the box to ensure a good fit. The box must then be labelled with the green external ventricular drain stickers (Rationale 4). 

Photographs with kind permission of Medtronic Ltd (EVD) and Integra Neurosciences (Stopcock Protection Box).

Silver clamps, gauze and a 2% chlorhexidine wipe (eg Clinell®) must be kept with the set to enable the system to be clamped if the drainage system accidentally becomes disconnected.

The system should ONLY be changed every 24 hours if organisms are present in the CSF (according to microbiological advice) until the CSF is free of organisms on microscopy. The system can then be used for up to two weeks.

The drainage bag should be changed when it is about three quarters full as overfilling the drainage bag may impair drainage (Cartwright and Wallace 2007).

It is the responsibility of the neurosurgeon to give instructions on the level at which the drain is to be set or the amount of drainage required each hour and document in the patient’s medical records (Rationale 5). 

Inform the child and family

Explain the entire procedure and management to the child and family avoiding medical and nursing jargon and language. Information must be given according to the child’s age, condition and developmental understanding. 

Explain the following:

  • why the EVD is necessary

  • the reason for the EVD

  • what it entails

  • the likely length of placement of an EVD (Rationale 6)

If appropriate provide play preparation, involving the play specialist (Smith and Martin 2009). Consider involvement of a clinical psychologist if appropriate, particularly if previous procedures have been stressful for the child or if the child is known to have, or exhibits signs of, anticipatory anxiety or distress (Smith 2009).

Neurological assessment

The following observations should be carried out on return from theatre.

A full set of neurological observations must be performed at least one to four hourly depending on the condition of the child (Cartwright and Wallace 2007). They may need to be performed more frequently depending on the condition of the child and if the height of the drain is altered (Rationale 7).

When performing the hourly EVD checks (see management section), a visual assessment of the child should be made and a set of neurological observations performed in conjunction with CEWS.

Observe for a change in the child’s neurological condition by assessing the following:

  • level of consciousness 

  • pupil reaction (sluggish reactions or unequal reactions may indicate raised intracranial pressure (RICP))

  • limb movement and strength

  • heart rate (bradycardia is a sign of RICP)

  • blood pressure (hypertension is a late and ominous sign of RICP) 

  • respiratory rate

  • a change in body temperature

  • amount of CSF drainage

Observe for under-drainage of CSF:

  • bulging of fontanelle in infants

  • headaches

  • vomiting

  • irritability

  •  lethargy

Observe for over-drainage of CSF:

  • dipping of fontanelle in infants

  • headaches

  • irritability

  • pallor

  • tachycardia

The frequency, duration and severity of any headaches should be monitored.

The family should be included in general observation of child. Often families will have a better understanding of their child's baseline neurology and can indicate a deviation from the norm.

Drain management: positioning of drain

The system must be positioned accurately (Rationale 8).

The EVD set should not be placed horizontally on the bed or trolley unless the drip chamber has been emptied and the EVD clamped. This is to prevent the filters within the drip chamber becoming wet which could affect the efficiency of the drainage (Czosnyka 2003).

It is the responsibility of the neurosurgeon to give instructions on the level at which the drain is to be set or the amount of drainage required each hour and document in the patient’s medical records.

The level of the ventricles must be estimated to create a zero reference point:

  • Draw an imaginary line between the outer aspect of the child’s eye and the external auditory meatus (Cartwright and Wallace 2007).

  • The midpoint of this line is the zero point for the EVD system (0cm).
  • Position the pressure level arrow at the top of the drip chamber at the prescribed height, eg +5, +10 (above) or -2 cmsH²O (below) the zero point/the ventricles and secure with the locking screw.

The difference in height between the child’s ventricles and the drip chamber creates both a pressure gradient and a safety valve. The height of the drip chamber equates to the pressure inside of the head or intracranial pressure (ICP). This pressure must be reached before any CSF will drain into the drip chamber (Cartwright and Wallace 2007).

The position of drain should be indicated on the child’s fluid chart.

When moving or repositioning the child:

  • clamp drain
  • re-zero drain
  • unclamp drain immediately (Rationale 9)

Parents should be taught the following care of the drain:

  • To clamp the drain if:  

    • moving their child

    • if their child is crying excessively

  • To ask for the assistance of a health care professional who is competent in EVD management, to re-zero/reposition the drain once their child has been moved (Cartwright and Wallace 2007)(Rationale 9).

  • That the drain should never be clamped for longer than one hour, less if the CSF is heavily bloodstained (Rationale 10).

Drain management: drainage

Once the drain is positioned an initial assessment of CSF drainage should be made.

Subsequently hourly checks should be made of (Cartwright and Wallace 2007):

  • amount of drainage

  • colour of CSF – should be colourless

  • exit site (redness, inflammation, oozing of blood or leakage of CSF)

  • visual assessment of the child's neurological status

Record hourly on the child’s fluid balance chart:

  • the amount of CSF drainage

  • the position of the EVD

The Neurosurgeon will have prescribed the height for the drain. This should not be altered without discussion with the neurosurgical team unless the neurosurgeon has indicated that a specific amount of CSF should be drained each hour. Only if this is the case should a nurse change the drain height independently.

If the child is crying excessively the drain should be clamped off (Rationale 9).

It must never be clamped off for more than one hour (Rationale 10).

Contact the neurosurgical SPR on bleep 0001 or neurosurgical nurse practitioners on bleep 0983/2058 or ext 1612 if there are concerns about:

  • the amount of drainage
  • the condition of the child

Drain management: connecting or changing the system

Newly inserted EVDs will be connected to the drainage system in theatres (Smith and Martin 2009).

If the system needs changing or the catheter is accidentally disconnected or damaged then it should be replaced by, or under the supervision of, a health care professional who is competent. Two practitioners may be required, one to perform the sterile procedure and the other to assist.

Inform the child and family that the procedure is to be performed.

Prepare equipment:

  • dressing trolley

  • clamps and gauze

  • a pair of sterile gloves and an apron

  • EVD system

  • sterile scissors (if accidental disconnection has occurred)

  • 2% chlorhexidine solution in 70% isopropyl alcohol % or 2% chlorhexidine in 70% isopropyl alcohol wipe (eg Clinell®) 

  • sterile dressing pack

  • non dissolvable suture

To change the drainage system:

  • Clamp catheter close to patient using non-sterile gauze and clamps.

  • Wash hands.

  • Open equipment onto sterile field.

  • Put on apron and perform a hand wash.

  • Put on sterile gloves.

  • Assemble drainage set closing clamps.

  • The 'sterile' practitioner disconnects the old system and cleans the newly exposed catheter end with 2% chlorhexidine in 70% isopropyl solution or alcohol wipe (eg Clinell®) for 30 seconds using friction and allow to dry naturally.

If accidental disconnection or damage has occurred then 1-2cm of catheter should be cut off using sterile scissors. If the catheter has split less than 10cm from the exit site then the neurosurgical SPR on call (bleep 0001) should be consulted.

  • Place new connector if accidental disconnection has occurred and secure by tying with a suture.

  • Connect new system.

  • Check connections.

  • Position system as prescribed by the neurosurgeon.

  • Release clamps on new system and those close to the patient.

  • Clear away equipment according to Waste Policy.

  • Wash hands.

Record the procedure in the child’s health care records.

Drain management: patency of drain – general

Observe the CSF drainage hourly to ensure the drain is patent (Cartwright and Wallace 2007; Smith and Martin 2009).

The volume of CSF drainage and drain position must be recorded on the child’s fluid balance chart hourly (Cartwright and Wallace 2007).

If there is no CSF in chamber:

  • observe for movement of CSF in system

  • ensure system is not clamped or kinked

  • lower chamber momentarily below head level to check patency of EVD. CSF should be seen moving along the line

  • advise medical team if no drainage

Drain management: patency of a drain – unblocking a catheter

If a catheter appears to be blocked:

  • exclude damage to the EVD system

  • lower drain and observe for CSF movement

  • change EVD drainage set if competent to do so

If the EVD will still not drain then this constitutes a neurosurgical emergency and the neurosurgical SPR on call (bleep 0001) or neurosurgical nurse practitioners (bleep 0983/2058 or ext 1612) must be contacted urgently.

They may attempt aspiration of the catheter; if aspiration is unsuccessful the EVD should be flushed. This must only be done by a neurosurgeon or neurosurgical nurse practitioner. 

To flush the EVD  

This is an aseptic procedure.

  • Wash hands and put on apron.

  • Prepare sterile field.

  • The neurosurgeon/nurse practitioner should draw up 4mls of 0.9% sodium chloride into a syringe.

  • Remove stopcock protection box.

  • Open access port.

  • Clean with 2% chlorhexidine in 70% isopropyl alcohol wipe (eg Clinell®) for 30 seconds using friction and allow to dry naturally.

  • Insert syringe into the access port, close clamp to EVD set.  

  • Gently attempt to inject the sodium chloride.

  • Place a needle free access device on access port.

  • Open clamp to EVD set and observe for drainage.

  • Replace stopcock protection box.

Continue after aspirating and/or flushing by:

  • discard syringe 

  • position system as instructed by the neurosurgeon 

  • clear away equipment according to Waste Policy 

  • wash hands 

Record the procedure in the child’s health care records.

If the EVD continues to not drain, the child may need to return to theatre for a new drain to be inserted. The frequency of observations increased (every fifteen minutes may be required dependant on the child's neurological status). Any changes in neurological status must be highlighted to the neurosurgical team promptly.

Drain management: fluid and electrolyte balance

CSF contains approximately 120mmol/l of sodium. The child should have their electrolytes measured regularly, daily if losses are significant for the child's size (Nielsen et al 2007). Replacement is usually given in the form of 0.9 per cent sodium chloride intravenously – this can often be achieved with the flushing and dilution of intravenous antibiotics. Otherwise for older children oral sodium supplements may suffice, some will not require any replacement (Nielsen et al 2007).

Cerebrospinal Fluid (CSF) losses and intravenous fluid replacement should be recorded hourly on a fluid balance chart and reviewed every shift by the nurse in charge.

Accessing the drain: CSF sampling

Routine sampling of CSF from EVDs is not advised due to the risk of introducing infection to an otherwise sterile circuit. 

CSF samples should be taken according to the following guidance:

  • Every 24 hours IF organisms are present in the CSF, according to microbiological advice, until the CSF is free of organisms on microscopy.
  • Every 24 hours for CSF antibiotic levels if on intraventricular antibiotics. 
  • At the request of the neurosurgeon based on the condition of the child or planned procedure for example – to check CSF protein levels before a new ventriculoperitoneal shunt is placed. 
  • As part of a septic screen should the child become febrile. 

The amount of CSF that can be sampled is the same for all ages including neonates.

Gather the following equipment:

  • sterile field or dressing pack

  • 2% chlorhexidine in 70% isopropyl alcohol wipe (eg Clinell®)

  • two 10ml syringes

  • two universal containers – one for protein count, one for MC&S +/- antibiotic levels

  • glucose specimen bottle (yellow)

  • sterile gloves and an apron

  • one needle free access port

  • computer-generated request forms

CSF samples should be obtained by, or under the supervision of, a health care professional who is competent.

To obtain a CSF specimen

  • Close clamps on drainage system close to injection port. 

  • Wash hands and put on apron.

  • Prepare sterile field.

  • Perform a hygienic hand wash and put on gloves.

  • Remove the stopcock protection box.

  • Remove injection port on EVD and clean opening with 2% chlorhexidine in 70% isopropyl alcohol wipe (eg Clinell®) for 30 seconds using friction and allow to dry naturally.

  • Insert a 10ml syringe into the port.

  • Slowly withdraw 2ml of CSF, remove syringe and discard.

  • Insert second syringe into port.

  • Slowly withdraw 2ml of CSF.  

  • Place 0.5ml of CSF into the glucose specimen container and 0.5ml into one universal specimen container and 1ml into the other universal specimen container.

  • Open clamps on drainage system close to injection port.

  • Replace the stopcock protection box.

  • Label samples at the child's bedside and send them with completed request forms to the correct laboratory in accordance with local policy.

  • Dispose of all used equipment according to Waste Policy.

  • Wash hands according to hospital policy.

Record the procedure in the child’s health care records.

Accessing the drain: giving intraventricular drugs

Intraventricular drugs, eg antibiotics, are administered to enable local treatment of the CSF.

Antibiotic levels should be as follows:

  • Vancomycin: less or equivalent to 15mg/litre

  • Gentamicin: less than 3mg/litre

Intraventricular antibiotics must only be administered by a suitably trained health care professional. The medicine should be checked in accordance with the Trust Medicine Administration Policy. 

Gather the following equipment:

  • sterile gloves and an apron

  • sterile field or dressing pack

  • 2% chlorhexidine in 70% isopropyl alcohol wipe (eg Clinell®) or 2% chlorhexidine in 70% isopropyl alcohol solution

  • Intrathecal drug (NB if the medicine is not prepared by CIVAs; it should be administered using a 10ml syringe. If the quantity of the medicine is small, this will need to be prepared in an appropriate size, smaller syringe and then decanted into a 10ml syringe for administration)

  • three 10ml syringes

  • blue needle

  • prescribed antibiotics

  • sodium chloride 0.9% for injection

  • child's prescription chart

To administer intraventricular antibiotics

  • Close clamp on drainage system close to access port.

  • Put on apron and wash hand.

  • Prepare sterile field.

  • Perform a hygienic hand wash and put on gloves.

  • Check drugs according to hospital Medicine Administration Policy.

  • Prepare drugs using aseptic technique.

  • Check patient’s identity according to the Patient Identification Policy.

  • Remove stopcock protection box.

  • Clean port/needle-free access device opening with 2% chlorhexidine in 70% isopropyl alcohol wipe for 30 seconds using friction and allow to dry naturally.

  • Insert a 10ml syringe and slowly withdraw 4ml of CSF, remove syringe and discard.

  • Insert syringe containing the antibiotic into the catheter opening.

  • Inject antibiotic according to manufacturer’s guidelines.

  • Remove syringe.

  • Insert syringe containing 0.9% sodium chloride into catheter opening and gently flush catheter with 4mls 0.9% sodium chloride.

  • Remove syringe.

  • Replace stopcock protection box.

  • Keep drainage system clamped for one hour only.

  • Dispose of all used equipment according to Waste Policy.

  • Wash hands according to hospital policy.

Record the procedure in the child’s health care records.

Exit site care

Photo of dry dressing
Photo of dry dressing

The child will return from theatre with a dressing over the exit site. 

Hair must be clipped for short tunnelled EVD (exiting at the head) for adherence of dressing.

EVD exit dressings should follow the same protocol as for central venous access device (CVAD) dressings. The post-op dressing should be changed at 24 hours (if necessary) using ANTT, incorporating a sterile field and gloves and 2% chlorhexidine in 70% isopropyl alcohol solution % to clean the site. The EVD should be looped and secured with steri strips and covered with opsite or IV 3000®. Following this the dressing should be changed weekly or more often if soiled. Dressing must remain intact at all times.

Photo of leaky dressing
Photo of leaky dressing

If there is ooze from the exit site then a swab should be taken and the exit site redressed as previously including an absorbent dressing (eg Solvaline ®N). The neurosurgeon should be informed if the exit site appears infected. If there is CSF leakage from the exit site the neurosurgeon or nurse practitioner (via the cisco phone: 1612 or bleep 0983/2058) should be informed, this may require suturing.

Removal of the drain

EVD placement should be reviewed on Day 10. After this time the entire system may need to be removed or changed in theatre. 

Pre-operatively, the nurse may be asked to clamp the drain for a specified time prior to surgery. If the child’s condition deteriorates due to clamping pre-operatively, unclamp the drain and contact the neurosurgical team.

Post-operatively, assess the child and observe for any CSF leak from the wound site and carry out neurological observations between one to four hourly as appropriate.

Rationale

Rationale 1: External Ventricular Drainage is a high risk procedure due to the potential of raised ICP or over-drainage.
Rationale 2: Nurses must recognise and work within the limits of their competence (NMC 2015).
Rationale 3: This is a sterile environment.
Rationale 4: This is to prevent accidental administration of intravenous medication.
Rationale 5: The height at which the EVD is set will determine the child's ICP. Miscalculation of this height can have devastating consequences for the child.
Rationale 6: To enable parents/child to give informed consent.
Rationale 7: The height at which the EVD is set will determine the child's ICP, therefore any change in the drain height may alter the child's conscious level.
Rationale 8: The height at which the EVD is set will determine the child's ICP.
Rationale 9: To prevent over or under drainage of CSF.
Rationale 10: To prevent the catheter becoming occluded. 

References

Reference 1:
Cartwright C and Wallace D (2007) Nursing Care of the Pediatric Neurosurgery Patient. Berlin, Springer.

Reference 2:
Czosnyka M, Czosnyka ZH, Richards HK, Pickard JD (2003) Hydrodynamic properties of extraventricular drainage systems. Neurosurgery 52 (3): 619-23; discussion 623.

Reference 3:
Neilsen N, Pearce K, Limbacher E & Wallace DC (2007) Hydrocephalus Cartwright CC and Wallace D In: Nursing Care of the Pediatric Neurosurgery Patient. Berlin, Springer.

Reference 4:
Nursing and Midwifery Council (NMC) (2008) The Code: Professional standards of practice and behaviour for nurses and midwives. London, NMC.

Reference 5:
Smith J & Martin C (2009) Paediatric Neurosurgery for Nurses. London, Routledge.

Document control information

Lead Author(s)

Jody O'Connor, Neurosurgical Nurse Practitioner, Neurosciences

Document owner(s)

Jody O'Connor, Neurosurgical Nurse Practitioner, Neurosciences

Approved by

Guideline Approval Group

Reviewing and Versioning

First introduced: 
31 May 1999
Date approved: 
28 April 2015
Review schedule: 
Three years
Next review: 
28 April 2018
Document version: 
4.0
Previous version: 
3.0