External ventricular / lumbar drain (EVD / LD)
A temporary tube draining CSF to an external chamber, set to a height above a fixed zero point. The twin dangers: over-drainage if the drain is too low (collapse, bleed) and raised ICP if it blocks - and you clamp it before moving the patient.
Also called: EVD, external ventricular drain, ventriculostomy, lumbar drain, LD, CSF drain, extraventricular drain, spinal drain
What it is
An external ventricular drain (EVD) or lumbar drain (LD) is a temporary catheter draining CSF out of the body into a collection chamber at the bedside, used for acute hydrocephalus, raised intracranial pressure, CSF infection or a CSF leak. Unlike a shunt, it is external and the drainage rate depends on the height of the chamber relative to a fixed zero point on the patient.
That height-dependence is the whole safety story. The drain is levelled to a reference (for an EVD, the tragus) and set a prescribed distance above it. If the patient is sat up or the chamber dropped, CSF siphons out too fast (over-drainage); if the patient is laid flat or the chamber raised, it drains too little (under-drainage / rising ICP). The standard is explicit that misuse of an EVD because of a lack of proficiency in their use can lead to serious infections, over drainage, underdrainage and death
- which is why any movement, transfer or position change means clamping the drain first.
How to recognise it
- A tube leaving the head (EVD, usually a dressing on the scalp) or the lower back (lumbar drain), running to a graduated burette/collection chamber mounted on a drip stand at a set height.
- A marked zero/reference point and a prescribed height; for an EVD
The zero level of the drain should be set at the level of the tragus
. - A three-way tap on the line used to open, clamp or sample; an hourly CSF volume chart.
- A patient who should be under neurosurgical/critical-care management - EVDs are managed in neuro theatres, recovery, the neuro ward or neuro ICU, not general wards.
What it gets confused with
An EVD/LD is external and temporary, draining to a visible bedside chamber; a shunt is internal and permanent with no external collection. If CSF is draining into a chamber on a drip stand, it is an external drain.
What goes wrong
Over-drainage
The chamber too low relative to the patient (or the patient sat up with the drain open), draining a large volume of CSF; the patient becomes headachey, pale, clammy, drowsy, or deteriorates suddenly.
Red flag
Rapid over-drainage collapses the ventricles and can cause subdural/intracranial haemorrhage or upward herniation. Clamp the drain, lie the patient flat, and call neurosurgery; do not simply reopen it without instruction.
Under-drainage / blockage (rising ICP)
No CSF draining and no fluid-level swinging in the line, with the signs of raised ICP returning - headache, falling GCS, pupillary change.
Red flag
A blocked or wrongly-high EVD lets ICP climb. Check the system is open and correctly levelled, look for kinks and clot, and escalate to neurosurgery urgently; flushing/unblocking is a neurosurgical task, not an ED one.
Drain-associated infection (ventriculitis)
Fever, declining GCS, new headache, and cloudy CSF in the chamber in a patient with a drain in for days.
Red flag
EVD-associated ventriculitis is a serious infection. Do not break the closed system; sampling is done by competent neuro staff. Discuss antibiotics and sampling with neurosurgery/micro.
Accidental disconnection, over-drainage during movement, or dislodgement
The line disconnected, the patient moved or transferred with the drain open, or the catheter pulled.
Red flag
An open drain at the wrong height during a position change dumps CSF fast. Clamp before any move; for disconnection, clamp and call neurosurgery (infection risk); for a dislodged catheter, cover the site and escalate - ICP is now unprotected.
The first ten minutes
- Before a position change, transfer or laying the patient flat, close the drain. For a simple position change (lying to sitting) switch off the three-way tap; before a transfer or laying flat, empty the drip chamber first, then close the tap. Re-level and reopen only on instruction - an open drain at the wrong height is how over-drainage happens. A clamped drain also leaves ICP unprotected, so check GCS more often while it is closed and get neurosurgical instruction on how long it may stay clamped.
- Check the zero and the height. Confirm the drain is levelled to its reference (tragus for an EVD) and set at the prescribed height; a drain that is too low over-drains, too high under-drains.
- If the patient is over-draining or deteriorating, clamp the drain and lie them flat, then call neurosurgery.
- If the drain is not swinging/draining and ICP is rising, check for kinks and clamps and escalate - do not flush it yourself.
- Keep the system closed - do not disconnect or sample it; infection (ventriculitis) is a major risk.
- For transport, if it cannot be kept upright and level, follow the standard:
the drip chamber should be emptied and the drain turned off at the patient-line stopcock port
, and move with someone competent in EVD care.
Do not
Who owns it
Neurosurgery and neuro critical care own the drain. Tell them the drain type (EVD vs lumbar), the prescribed height and whether it is pressure- or volume-led, whether it is draining and swinging, the CSF appearance, the current GCS, and what has changed.
Who to call
The team and the criteria are national. The phone number is local, and this tool does not know it. Find it once, now, and write it on the department's own card — that is the part no website can do for you.
- Say the device name first
- Open with laryngectomy, LVAD, shunt — the single word changes who comes and what they bring. Do not bury it in the history.
- Say what you have already established
- Whether the device is patent, whether it has been removed or disturbed, and what you have already tried. The specialist is deciding whether to walk or run.
- Ask who owns it out of hours
- Device ownership and the on-call route often differ from the implanting specialty, and it is frequently a regional centre rather than your own hospital.
- The patient's own team is a resource, not an afterthought
- Named nurse specialists, home-care companies and device helplines answer questions nobody else can, and the patient usually has the number.
When the device is not the problem
A patient with a device gets pneumonia, sepsis, pulmonary oedema and myocardial infarction at the same rate as everybody else. The device is the most visible thing about them and it attracts the whole assessment.
- The NTSP says it out loud
- The project's own manual warns that
patients with tracheostomies can become unwell with all the problems that other patients get too. It is easy to become fixated with the tracheostomy.
The same sentence applies to every device in this tool. - Clear the device, then leave it
- Establish that the device is doing its job — the stoma is patent, the line draws back, the pump is running — and then assess the patient as you would anyone else.
- The anchoring runs both ways
- The opposite error is treating a device complication as a medical illness: a blocked gastrostomy read as vomiting, a baclofen pump failure read as sepsis.
- NTSP manual — Red flags · read in full
What the patient will be carrying
These patients are inpatients under neurosurgical/critical care; the owning team, the prescribed drain height and drainage parameters are in the notes and on the bedside chart, not on a patient-held card.
Scope of this page
This page covers the safe handling and troubleshooting of an external CSF drain encountered in the ED or on transfer: clamp before moving, keep it correctly levelled, recognise over- and under-drainage and infection, and keep the system closed. It does not teach EVD insertion, flushing, CSF sampling or drain removal - advanced neurosurgical/neuro-nursing competencies. The cited standard of practice is the adult EVD standard; lumbar-drain specifics (different parameters, and pneumocephalus / herniation risks) and paediatric drains follow local neurosurgical and paediatric protocols. External CSF drains are used in adults and children under specialist care.