External Ventricular Drains - Best Practice Guidelines
|Next review: 01/09/2025|
|Approved By: Trust Clinical Guidelines Group|
|Copyright© Leeds Teaching Hospitals NHS Trust 2022|
This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
Please check the patients allergy status, as they may be allergic to Chlorhexidine, and alternative ( Providine iodine) solution will be required.
Be aware: Chlorhexidine is considered an environmental allergen.
Refer to the asepsis guidance.
External Ventricular Drains - Best Practice Guidelines
- Ventricular system anatomy
- Effects of CSF on intracranial pressure
- Insertion of external ventricular drainage
- Lumbar drain insertion
- Insertion of an EVD and consent
- Nursing care and management of the patient with an EVD
- Positioning of the EVD and CSF drainage
- Complications associated with EVD
- CSF drainage
- Clamping the EVD
- Patient positioning and safety
- Neurological observations
- Intracranial pressure
- Removal of EVD
- Summary of nursing care
- Medical responsibility
- Appendix 1: CSF Flow
- Appendix 2: Medical Guidelines
- Appendix 3: Competency
- Appendix 4 - Lumbar drain disconnection
An external ventricular drain (EVD) is a temporary system, which allows drainage of cerebrospinal fluid (CSF), from the lateral ventricles of the brain. EVD’s are commonly used within the Neurosciences Unit for the management of patients requiring drainage of CSF in order to control raised intracranial pressure associated with head injury, subarachnoid haemorrhage, acute hydrocephalus secondary to cerebral aqueduct obstruction, posterior fossa tumours or purulent meningitis.
Following the opening of the Neuro Intensive care unit (NICU) in September 1997, standardised guidelines were produced in order to promote best practice, and maintain the safety of patients with EVDs.
The guidelines have been reviewed and updated for this 7th edition.
There are four ventricles, which comprise the ventricular system within the brain, the largest of which being the two lateral ventricles. These lateral ventricles are situated deep within the subcortical tissue one on each side of the midline. Each lateral ventricle communicates with the third ventricle through the intraventricular foramina (foramen of Monro); this third ventricle communicates with the fourth ventricle, located in the medulla, through the aqueduct of Sylvius. There are two lateral foramina (foramina of Luschka), and one median foramina (foramen of Magendie) located in the roof of the fourth ventricle which communicate with the subarachnoid space beneath the arachnoid membrane. The floor of the fourth ventricle is continuous with the central spinal canal.
CSF is produced continuously by the choroid plexus of the two lateral ventricles at a rate of approximately 20-25ml per hour, or 500mls per day (Hickey, 1992). At any one time, approximately 100-150mls of CSF are contained within the cerebral ventricles and spinal cord. Once produced it flows through the interventricular foramina of Monro into the third ventricle and then through the single aqueduct of Sylvius into the fourth ventricle.
Once in the fourth ventricle the CSF then flows through the two foramina of Luschka and the single foramen of Magendie at which point it enters the subarachnoid space. The foramina of Luschka allows CSF to flow around the brain and the foramen of Magendie directs CSF to the spinal cord.
An obstruction at any point in the flow of CSF will result in dilation of the cerebral ventricles and a condition known as hydrocephalus.
Appendix 1 illustrates a simplified flow diagram of the route CSF takes following its production in the lateral ventricles.
CSF has a number of functions; it provides buoyancy and support to the brain and spinal cord as well as maintaining a constant extracellular fluid composition for central nervous system metabolic activity. It also provides a medium for unnecessary substances and metabolites to be drained away from the neurones (Jones & Cayard, 1982). CSF is a modified form of plasma consisting of water, glucose, protein, minerals and a few lymphocytes.
Normal values of CSF
|White blood cells||none|
|Lymphocytes||less than 5|
Effects of CSF on intracranial pressure
The Monro-Kellie hypothesis states that the skull is a rigid compartment filled to capacity with essentially incompressible substances – blood, brain matter and CSF. As such an increase in one or more of the components will result in an increase in the overall pressure within the skull unless, another component decreases in volume reciprocally (Lindsey, Bone & Callendar, 1991).
Intracranial pressure (ICP) is thus affected directly by any changes in volume of CSF within the brain. These changes in volume may be the result of:
- Change in the rate of production of CSF
- Obstruction to CSF flow within the ventricular system
- Change in the rate of absorption of CSF
Problems associated with production, flow or absorption of CSF can cause increased ICP and may be indication for EVD.
EVD’s are inserted by a Neurosurgeon in the operating department, under sterile aseptic conditions.
In exceptional circumstances there may be occasions when insertion of the EVD is required to take place in an ICU environment. In these circumstances, the decision will be made by the patient’s Consultant following a detailed risk assessment having been carried out. Maximum sterile and environmental precautions must be adhered to if insertion is to occur in the ICU. Grade and experience of the surgeon intending to insert the EVD in an ICU environment must be taken into consideration (Wong as cited in Mayhall, 1999).
Infection Prevention guidance recommends the Operating Theatre as the ideal environment for insertion of an EVD. Evidence suggests this is due to a higher risk and incidence of hospital acquired infection in the ICU compared to other clinical environments (Weber et al., 1999) and an associated poor outcome for patients with nosocomial CNS infections (Gantz and Tkatch, 1999).
For audit purposes, where EVD insertion occurs outside of the operating theatre department these incidences will be reviewed at the Neurosurgery Clinical Governance Forum.
Generally the site chosen will be 1cm anterior to the coronal suture, 2-3cm from the midline over the non-dominant hemisphere (Rockoff & Kennedy, 1983). The site is clipped removing as much hair as possible with single use clippers (Pratt et al, 2004) with the skin being cleaned with a chlorhexidine 0.5% in 70% alcohol solution, which is allowed to dry, a recommended time of no more then 2 minutes before incision.
Currently there is no safety data for 2% chlorhexidine for any procedure where there can be potential contact with CSF/neural tissues and 0.5% chlorhexidine in 70% alcohol solution has been recommended for both spinal drains and EVDs.
Following an initial incision, a drill is used to create a small burr hole opening in the skull. The dura is opened and the arachnoid and pia membranes are cauterized. A stylet is used to introduce the ventricular catheter into the frontal horn of the lateral ventricle. The stylet is removed once the catheter is in place and this may then be sutured at the insertion site or tunnelled beneath the galea for at least 5cm and exit at a separate scalp site.
In adults, the catheter usually sits within the ventricles at a depth of approximately 5-6cm. The catheter is then connected to the drainage system, the incision site sutured and the area covered with an appropriate interactive dressing.
A lumbar drain is inserted in the operating theatre usually under local anaesthetic following strict aseptic techniques and strict adherence to the LTHT hand hygiene and standard precaution policies.
In exceptional circumstances there may be occasions when insertion of the lumbar drain is required to take place in an ICU environment. Maximum sterile and environmental precautions must be adhered to if insertion is to occur in the ICU.
Prior to insertion the skin is cleaned with a Chlorhexidine 0.5% in 70% alcohol which is allowed to dry, a recommended time of no more than 2 minutes before insertion. A spinal needle is inserted into the subarachnoid space in the lumbar region below L2. The needle is removed once the catheter is in place and then the catheter is connected to the external drainage system.
Ideally consent for the procedure should be sought from the patient by the clinician performing the procedure. Where an adult patient lacks the mental capacity (either temporarily or permanently) to give or withhold consent for themselves, no-one else can give consent on their behalf (DOH, 2001). However, it is viewed as best practice to seek ‘assent’ from the family members and complete a Consent Form 4. In circumstances where an EVD needs to be inserted urgently, treatment may be given without consent or family ‘assent’ if it is in the best interests of the patient, as long as it has not been refused in advance in a valid and applicable advance directive. Family should be informed of the reasons for inserting the EVD at the earliest opportunity.
Once the EVD has been inserted, the operating surgeon will connect the external draining system to the EVD before the patient returns to the ward. It is the responsibility of the operating surgeon to ensure the patency of the drain at this point, before the patient has returned to the ward.
In cases where the patient is transferred directly from the operating theatre to the ICU, the operating surgeon should accompany the patient, position the external drainage system at the required level and height, ensure its patency and inform the nursing staff of any specific instructions (which should also be clearly documented on the operating note).
Nursing care and management of patients with EVD’s is predominantly aimed at preventing the occurrence of complications. Collaboration with the medical teams is essential to establish prescribed parameters which are based on individual assessment of the patient’s clinical status. These guidelines for nursing care must therefore be used in conjunction with the medical guidelines included in Appendix 2. All new starters to the Leeds Centre for Neuroscience will be supported through the competency for the Management of CSF drainage systems - External Ventricular drains and lumbar drains included in Appendix 3.
Below is a diagram showing the EVD system and the CSF drainage. The Institute for Neurosciences currently use the CODMAN EDS 3TM CSF External Drainage System. It is a closed sterile system that allows CSF to drain freely into a sliding graduated flow chamber that can be adjusted to a prescribed level. The whole system is then attached to a collection drainage bag.
The CODMAN EDS 3TM CSF External Drainage System does not have a pressure valve and as such the drainage of CSF depends upon gravity, i.e. the level of the flow chamber will determine the amount of CSF drained. The zero point for the external drainage system is the location of the foramen of Monro which is estimated at the anatomical landmark of the ‘External auditory meatus (EAM) or ear hole. To ensure accuracy of establishing the zero point, this is measured using a spirit level.
The flow chamber is then positioned at a prescribed distance in cm H2O above this zero point.
The level at which the EVD is to be set should be documented clearly in the operative note and any subsequent changes should be clearly documented in the medical notes.
This prescription should also be clearly written within the patient’s nursing care plan, ICU chart and fluid balance chart. The level of the flow chamber in relation to the zero point will determine the amount of CSF drainage; for example, if the drain is set at 15cm H2O and the intra cranial pressure (ICP) is less than 15cm H2O then there will be no drainage. If however the level is 15cm H2O and the ICP is greater than 15cm H2O the system will drain to maintain the pressure ordered.
Positioning the flow chamber above the level of the foramen of Monro will lead to insufficient drainage of CSF and an increase in ICP with potentially devastating consequences relating to increased ICP. If the flow chamber is placed below the level of the foramen of Monro, it can lead to excessive drainage of CSF and subsequent collapsing of the ventricles (German & Ladd, 1990).
The EVD system is suspended by an adjustable cord from an IV drip stand placed at the head of the bed. The system is then clamped to the drip stand for stability, with the flow chamber facing the foot of the bed, thus being visible to the nurse at the bedside at all times.
In case of lumbar drains, the zero point is also at the level of the foramen of monro unless otherwise documented in the medical notes. Examples of alternative zero points for lumbar drains include point of catheter entry or shoulder level. The neurosurgeon must be consulted to determine the zero point for each individual patient and this must be documented in the medical notes and the patient’s care plan.
The height of the drain should not be altered unless the neurosurgery team has requested that they would like a certain amount of CSF draining per hour. In this instance the amount of CSF to be drained per hour must be documented clearly in the medical notes and on the fluid chart. This is the only time the level of the drain can be changed by a qualified nurse independently.
Inadequate drainage of CSF may cause the ventricles to enlarge with subsequent rises in ICP.
This may occur if:
- The EVD system is placed too high above the level of the foramen of Monro thus minimising CSF drainage.
- CSF drainage is obstructed. This may occur if the tubing is kinked or inadvertently clamped, the three-way tap is turned the wrong way, the drainage bag is full or tissue/thick CSF blocks the system.
Excessive drainage of CSF may also occur if the system is placed too far below the level of the foramen of Monro. This excessive drainage may cause the ventricles to collapse and pull the brain tissue away from the dura. This can cause tearing of the blood vessels and result in a subdural or subarachnoid haemorrhage (Bracke et. al., 1978).
Tentorial herniation may be caused by either excessive or insufficient drainage of CSF. Symptoms include:
- Severe headache
- Sluggish pupillary responses
- Abnormal reflexes
- Changes in BP and heart rate
All of the above signs and symptoms require prompt intervention (Scheinblum and Hammond, 1990).
CSF drainage must be observed at least hourly (having the flow chamber facing the nurse at the bedside will ensure regular observation), and recorded on the fluid balance chart. Significant changes must always be reported to a neurosurgeon.
Drainage of more than 50mls/hour is considered excessive; however this may be acceptable in patients with gross hydrocephalus (each patient must be considered individual and a general trend must be taken into account). CSF is normally clear and colourless; the presence of blood may indicate haemorrhage. The sudden presence of blood in the EVD must be reported to a neurosurgeon immediately. The colour and consistency of CSF in the EVD flow chamber must be noted at the beginning of each shift to detect changes and thereafter at hourly intervals. There are three ways to describe the colour of CSF, which should be documented on the ICU/HDU chart, nursing care plan or fluid balance chart: -
- Clear and colourless
- Xanthochromic – discoloured CSF usually yellow, orange or brown due to the breakdown of red blood cells from previous haemorrhage
- Blood stained – as a result of recent haemorrhage or surgery
CSF may also be described as turbid (cloudy) which occurs due to the presence of increased WBC’s as a result of CNS infection e.g. Meningitis.
The entire drainage tubing including the three-way ports must be checked for patency at the beginning of each shift and again at hourly intervals thereafter. In order to check patency of the EVD, observe the tubing to establish whether the level of CSF in the tube is oscillating. If the level is not oscillating, the flow chamber may be dropped to below the foramen of Monro for a brief period only to check whether CSF drains into the chamber. Once this has been observed, the flow chamber must be re-aligned to prevent over-drainage of CSF.
In the case of lumbar drains the level does not usually oscillate within the tube, therefore the method of lowering the drain below the zero reference point may be used to check the patency of these drains.
If at any time EVD/lumbar drains appear to be blocked (i.e. there is no observed oscillation or drainage of CSF), a neurosurgeon must be contacted immediately as it may be necessary to flush the system.
There have been occasions where an EVD has remained ‘closed’ at a three-way port due to lack of inspection. It is therefore crucial that the entire external drainage system is inspected at the start of a nursing shift as well as at hourly intervals and all three-way ports are ‘open’ to drainage.
If there is a blockage, there are two points to consider; drains that need flushing distally because of distal blockage, and those requiring flushing proximally due to proximal blockage.
Only qualified medical staff that have received the relevant training and deemed competent can flush an EVD. This should be done under a strict aseptic technique with a strict adherence to the LTHT hand hygiene and standard precautions policies. Normal saline solution should be used as much as is needed to flush the blockage if necessary.
Proximal flushing is potentially very high risk if the site of the catheter is unknown, if you inject fluid and cannot re-aspirate then potentially can exacerbate intracranial pressure. This should be performed by neurosurgical doctor who has the relevant training and competence.
Clamping the external drainage system may result in inadequate CSF drainage and subsequent rise in ICP, however there are occasions when it may be necessary to clamp the system for short periods. An example of such an occasion is during the moving and handling or repositioning of patients.
The decision to clamp the EVD must be made following assessment of the patient’s clinical condition and neurological status; it must be clamped for no more than 30-45 minutes at a time.
It may be necessary to transfer the patient with the EVD to another clinical area or to CT scan. In these situations the EVD may be left open but this must be first discussed with the medical staff and as previously stated must take into consideration the patient’s neurological status.
If it is necessary to maintain CSF drainage during the transfer, the patient must be closely monitored to prevent accidental disconnection or any alteration in position, which may affect CSF drainage.
For the duration of the transfer the external drainage system must be attached to a drip stand at the head of the patient’s bed and zeroed to the level of the external auditory meatus.
As previously stated the EVD system must be securely clamped to an IV drip stand at the head of the patients’ bed with the flow chamber facing the foot of the bed. This securing of the chamber will reduce the risk of accidental disconnection and is particularly important in the case of restless or agitated patients. In the case of ambulant patients, the EVD may be clamped for short periods to enable the patient to walk about. The system must be immediately unclamped once the patient has returned to bed. It is the responsibility of the qualified nurse to ensure that the system is re-aligned and unclamped.
If at any time accidental disconnection should occur, the ventricular catheter should immediately be clamped and the patient nursed in a supine position. A neurosurgeon must be contacted immediately for review and assessment of the situation.
The EVD system must be re-aligned (the 0cm H2O mark corresponds with the foramen of Monro) following re-positioning of the patient. Caution must be taken when raising or lowering the bed for moving and handling/cleaning purposes. Physiotherapists, Radiographers and Ward Housekeepers attending the patient must be informed that the patient has an EVD insitu and that care must be taken during any procedures which may affect the patient, or bed position, to safeguard the correct alignment of the EVD.
One of the major complications of having an EVD is infection. Numerous studies are available, reporting infection rates relating to ICP monitoring. In light of limited evidence in relation to EVD’s and infection prevention, principles from the Epic Project (DOH, 2001 and 2007) have been adopted for the Neuroscience’s Unit at the LGI.
Maintenance of a closed system is essential, and irrigation of the EVD should only be performed if necessary. Any maintenance must encompass a strict aseptic technique (Wisinger & Mest-Beck, 1990, Bader et. al., 1995) with strict adherence to both the LTHT hand hygiene and standard precaution policies. Before accessing any part of the EVD system the external hub and any connections must be decontaminated using a 0.5% Chlorhexidine in 70% isopropyl alcohol solution which is left to dry for no more than 2 minutes before withdrawing any CSF for sampling or injection of intrathecal antibiotics (DOH, 2001 and 2007). A qualified member of the medical team who is trained and competent must perform both of these practices. The EVD tubing must not be irrigated or manipulated unless necessary.
An appropriate interactive dressing should be applied over the insertion site it is essential that the ventricular catheter and EVD tubing are free from traction and kinks. Within the Neuroscience’s Unit it is advocated that the ventricular catheter and the connection between the catheter and the EVD tubing is carefully coiled and secured with an appropriate interactive dressing to prevent this occurring.
The nurse at the bedside must observe the EVD for evidence of CSF leakage. Leakage is suspected if the dressing is wet, and a neurosurgeon must be informed. It can also occur at any connection ports throughout the system and a routine check of these must be made at least once per shift.
The EVD drainage bag must be changed when the bag becomes ¾ full. This must be done under a strict aseptic technique with strict adherence to the LTHT hand hygiene and standard precautions policies.
Some authors recommend the use of prophylactic antibiotics until the catheter is removed (Wisinger & Mest-Beck, 1990, Bader et. al., 1995). This practice is not advocated within the unit at the LGI. CSF should be sampled for glucose, cell count and culture only when an infection is suspected, there is no evidence to suggest routine of daily sampling is needed as this practice may carry the risk of introducing contamination in the system. CSF sampling is the responsibility of qualified medical staff who have had the relevant training and been deemed competent. Any sampling from any port must be conducted using a strict aseptic technique with strict adherence to both the LTHT hand hygiene and standard precautions policies. Before accessing any part of the EVD system the external hub and any connections must be decontaminated using a and 0.5% chlorhexidine in 70% isopropyl alcohol and left to dry, no more than a recommended time of 2 minutes. (DOH, 2001 and 2007)
Mayhall et al. (1984) demonstrated that catheter insertion of 5 days or greater and opening of the ventriculostomy for irrigation were significant factors in contributing to the increased risk of catheter related infections. They recommend that the ventricular catheter is removed after 5 days and a new one replaced at a different site. It is current practice within the Neuroscience’s Unit at the LGI that the EVD is changed in the event of malfunction or suspected infection. However, the unit advocates the need for the EVD to be reviewed 5-10 days after insertion.
If an EVD infection is suspected, urgent CSF sample for cell count and gram stain would be critical. If preliminary results suggest infection, IT Vancomycin may be prescribed pending an EVD change. Prescribing Vancomycin before CSF sampling may lead to false negative cultures.
When prescribing IT antibiotics, the first dose should be prescribed on the stat part of drug chart, subsequent doses prescribed and administered within working hours. All antibiotics will be stored in a designated IT fridge on the ward. Antibiotics must be checked and the one with the shortest expiry date be used first, allowing stock to expire will cause unnecessary delay in administration as replacement stock will have to be ordered. The Medicine Code Policy for LTHT must be adhered to when administering IT antibiotics in respect to administering the drug at the correct prescribed time and signing after administration occurs.
The IT antibiotics must be second checked by medical personnel or by a qualified nurse who has an awareness of IT drugs and both signatures must be on the eMeds drug chart and be given at the time of prescription.
Only qualified medical staff who have received the relevant training and deemed competent can administer IT antibiotics, again using a strict aseptic technique with strict adherence to LTHT hand hygiene and standard precautions policies. Before accessing any part of the EVD system the external hub and any connections must be decontaminated using 0.5% chlorhexidine in 70% isopropyl alcohol and left to dry, no more than a recommended time of 2 minutes. (DOH, 2001 and 2007).
Following administration of IT antibiotics, the CODMAN EDS CSF external drainage system drip chamber is raised to 27cmh20 by the person administrating the antibiotics. This is for a duration of 45-60 minutes only (to allow the drug to remain within the ventricular system for absorption. It is the responsibility of the qualified nurse at the bedside to consult with a member of the medical team regarding this and to lower the chamber back to its original pressure setting as instructed. On lowering the drip chamber, it is the responsibility of the qualified nurse to ensure the drain remains patent.
If IT antibiotics need to be administered via two drains into non - communicating ventricles, the dose must be split equally between ventricles (e.g. 10mg Vancomycin per drain prepared in separate syringes.)
Please refer to LTH Antimicrobial guideline via the following link, http://nww.lhp.leedsth.nhs.uk/antimicrobials/policies.aspx
Vital signs and neurological observations, in patients who are not sedated, must be recorded at least hourly for a patient with an EVD in the acute phase of the illness. In the ward environment observations should be performed in accordance with observations frequency for post operative neurosurgical patients. After the acute phase the need for continued neurological observations is reviewed according to the patient’s clinical condition, however it should be noted that the frequency of neurological observations must be increased following lowering or raising of the EVD. Lumbar drains may be insitu for prolonged periods therefore neurological and other observations are also performed according to the patient’s clinical condition. Over-drainage or under-drainage of CSF may create a neurosurgical emergency, which demands immediate attention.
The symptoms of excessive drainage include:
- Slurred speech
If drainage is insufficient the patient will develop signs of increased intracranial pressure with changes in conscious level.
It is possible to monitor intracranial pressure through the ventricular catheter using a continuous closed monitoring system with a non-flush transducer device.
In some patients, CSF drainage will gradually reduce as blocked arachnoid villi re-open and CSF is absorbed into the venous system.
Once the patients’ clinical condition and neurological status has stabilized, instructions may be given to raise the EVD prior to removal (i.e. the drip chamber is set at a pressure of 27cmh20). The same procedure may apply for lumbar drains. The patient’ neurological status must be closely monitored during the period when the drain is raised.
The EVD is removed by a trained medical healthcare professional. The skin must be sutured at the insertion site using an aseptic technique, with strict adherence to LTH Hand Hygiene, Standard Precautions and Asepsis policies and covered with an appropriate interactive dressing and the stitch removed after 5 days.
Tips should only be sent for culture if infection suspected. For EVD’s and lumbar drains that have had a long duration of insertion and any clinical concerns regarding fever/headache, both CSF and tip should be sent for culture. On removal of the EVD, the patients’ neurological observations must be monitored closely. It is recommendation of the people reviewing the guidelines that the Glasgow Comma Score assessment be recorded hourly for 4 hours, and then reduced once the patients’ condition is stable.http://nww.lhp.leedsth.nhs.uk/common/guidelines/detail.aspx?ID=702
A neurosurgeon must be informed immediately if the patients’ condition deteriorates or if there is any CSF leakage.
In the event of an EVD or LD disconnection, the neurosurgical team must be informed immediately and are required to attend for review on an urgent basis.
The on-call neurosurgical registrar must be informed of this event and following a clinical review, a decision on further management will be instated. This may involve removal of the drain with or without replacement (depending on the clinical situation).
See Appendix 4 for a flow chart on management of a disconnected lumbar drain.
All patients should have mechanical thromboprophylaxis (unless contra-indicated) commenced on admission.
Current recommendations are for the medical team to perform a risk versus benefit analysis for venous thromboembolism in every patient with an EVD or lumbar drain. The presence of an indwelling CSF drain does not represent an absolute contraindication to LMWH prophylaxis. Whilst an EVD or lumbar drain remains in-situ, the current recommendation is to commence prophylactic pharmacological thromboprophyalxis the following day.
However, the initiation of pharmacological thromboprophylaxis in patients with EVD or lumbar drains in-situ must be discussed with a neurosurgical registrar or above. The administration of any form of blood thinning agents must also be discussed with the neurosurgical registrar.
LMWH prophylaxis should be omitted the evening before (and morning of, if a BD dosage) planned drain removal.
- Flow chamber must be positioned at the prescribed distance in cm above the 0cm pressure level, ensure this level is prescribed in the patients’ notes and is clearly documented on the ICU / HDU chart, fluid balance chart and nursing care plan.
- The anatomical reference or zero point is the location of the foramen of Monro, which is estimated at the external auditory meatus in the supine patient. With a lumbar drain this is also at the foramen of monro, unless otherwise documented in the medical notes.
- A spirit level is used to determine the zero point.
- The EVD system must be securely clamped to a drip stand at the head of the bed with the drip chamber facing the foot of the bed.
- Observe the tubing at least hourly for patency/kinking and that the CSF level is oscillating.
- Ensure that the tubing has not been clamped and that all three way taps are open.
- Record CSF drainage hourly on output charts. Report excessive drainage/sudden cessation of drainage to a neurosurgeon immediately.
- Observe CSF for colour and consistency. Report if cloudy, milky or xanthochromic. Colour and consistency of CSF should be clearly documented in the patients care plan.
- In the acute phase monitor the patient’s neurological status and pupillary responses in accordance with local procedure for post – operative observations and report any significant changes to a neurosurgeon.
- The EVD may be clamped for short periods if necessary, for example during transfer and patient positioning. The EVD must be unclamped as soon as possible or if the patients’ neurological condition deteriorates.
- GCS and pupillary response must be monitored hourly for at least 4 hours following removal.
- Frequency of neurological observations must be increased following raising of the level or clamping of the EVD (especially when the drain has been clamped for theatre)
- Apply an appropriate interactive dressing to the EVD insertion site (See insertion site management section). Report CSF leakage to a neurosurgeon.
- Observe the site for signs of infection and monitor temperature. Report pyrexia to medical staff.
- Change the collection bag when ¾ full using an aseptic technique.
- Use extreme caution when moving and repositioning patients’ to ensure the EVD is maintained at the correct zero point.
Management of Insertion Site
- The recommended dressing for EVD and lumbar drain insertion sites is op- site visible, so visualisation of the wound can be achieved.
- Initially the dressing should be applied in theatre then left in place for 5 to 7 days.
- Dressings should be removed/changed prior to this time if the occlusive seal is breached (e.g. through patient showering) or the amount of exudate is causing pooling of fluid over the wound.
- If you have difficultly sealing the dressing then it is recommended to press the dressing down with your hand to warm the dressing, using an aseptic technique at all times
- If you still continue to have difficultly in sealing the dressing on the EVD/ lumbar drain site then Cavalon spray is recommended to seal the dressing, this is to be used after the other practice of sealing has failed.
- It is the responsibility of the medical staff to obtain consent for the procedure of inserting the EVD or when this is not possible ensuring that the reasons for the procedure are explained to the patient and/or family at the earliest possible time.
- Instructions for positioning of the EVD and pressure settings on the external drainage system as well as any other specific instructions such as required hourly drainage need to be clearly documented on the operative note or medical notes.
- EVD tubing must not be irrigated, changed or manipulated unless absolutely necessary.
- If a CSF leak is suspected the junior doctor must consult with a Registrar at all times.
- A strict aseptic technique must be used during any sampling or maintenance procedures.
- Before any sampling or injection ports must be decontaminated using 0.5% Chlorhexidine in 70% isopropyl alcohol solution and left to dry for 2 minutes.
- The EVD is removed under strict aseptic technique by a neurosurgeon.
- GCS and pupillary response must be monitored hourly for at least 4 hours following removal.
If any assistance is required with regard to these guidelines please contact Clinical Practice Educator for The Institute of Neurosciences on Ext 28347
|Objective:||External Ventricular Drains (EVDs) are commonly used within the Neurosciences Unit for the management of patients requiring drainage of CSF in order to control raised intracranial pressure associated with head injury, subarachnoid haemorrhage, acute hydrocephalus secondary to cerebral aqueduct obstruction, posterior fossa tumours or purulent meningitis.|
|Target patient group:||Neurosurgical|
|Target professional group(s):||Secondary Care Doctors
Secondary Care Nurses
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Trust Clinical Guidelines Group
LHP version 3.0
FLOW OF CSF
Foramen of Monro (Interventricular foramen)
Aqueduct of Sylvius
Foramen of Magendie and Luschka
An external ventricular drain (EVD) is a tube, which conducts cerebrospinal fluid from the ventricle to an external collection system. It is used to remove CSF when production, drainage or absorption is abnormal. Hourly measurements are recorded to enable a trend to be established. As drainage reduces the need for the device should be questioned.
- EVD is inserted aseptically in theatre unless a risk assessment has been made otherwise.
- Zero should be level with the Foramen of Monro (EAM in supine patients)
- Drainage usually set at 10cm H2O initially, reassess level depending on pathology and drainage
- EVD drainage is recorded hourly
- CSF sample aseptically by medical staff for glucose, cell count and culture if any infective processes are suspected, CSF from the most proximal port.
- Suspected CSF leak must be reported to a Neurosurgery Registrar immediately.
- Prescription of EVD/ lumbar level should be clearly documented in the medical notes.
- After five days the need for the drain must be evaluated daily
- EVD tips must be sent for culture following removal only if an infection is suspected.
- Skin preparation used for EVD insertion and spinal insertion should be 0.5% chlorhexidine in 70% alcohol.
- Only qualified medical staff can flush, take CSF samples and administer IT antibiotics ( at the prescription time) if trained and deemed competent.
- A strict aseptic technique must be used for accessing the EVD
- Patients who have had their EVD clamped for theatre should receive increased observations.
Equity and Diversity
The Leeds Teaching Hospitals NHS Trust is committed to ensuring that the way that we provide services and the way we recruit and treat staff reflects individual needs, promotes equality and does not discriminate unfairly against any particular individual or group.