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Clinical Practice Keywords /Brain ventricles/Drainage/Haemorrhage Review This article has been Neurology double-blind peer reviewed In this article... ● Cerebrospinal fluid production and circulation, and causes of ● Indications for external ventricular drains, components and complications ● Practical points for safe nursing care of patients with external ventricular drains

Caring for neurosurgical patients with external ventricular drains

Key points Author Emily Humphrey is staff nurse (mental health), neurosciences department, Hydrocephalus, surgical division, Nottingham University Hospitals Trust. an excess of cerebrospinal fluid, Abstract External ventricular drains are life-saving devices used in neurosurgical is a medical patients with hydrocephalus (excessive amounts of cerebrospinal fluid). The fluid is emergency as it produced in the brain ventricles and circulates around the brain and , raises intracranial protecting them from injury and supplying brain cells with nutrients. Hydrocephalus pressure can occur due to impaired circulation or malabsorption and is a medical emergency, which can lead to raised . Nurses are responsible for the care of Excess fluid can be patients who have external ventricular drains. This article explains how the drains removed from the work and discusses key nursing considerations for their management. brain by an external ventricular drain Citation Humphrey E (2018) Caring for neurosurgical patients with external ventricular drains. Nursing Times [online]; 114: 4, 52-56. Patients with EVDs need to have cerebrospinal ydrocephalus is a medical Before entering the subarachnoid output monitored emergency and its treatment space, CSF travels through the ventricles hourly involves inserting an external (Waugh and Grant, 2014), four specialised Hventricular drain (EVD) into cavities in the brain: one in each of the two EVDs carry a high one of the lateral ventricles of the brain to cerebral hemispheres (left and right lateral risk of infection, remove excess cerebrospinal fluid (CSF). ventricles) plus two additional ones. The so nurses need to This article discusses the essentials of fluid is constantly produced and reab- maintain asepsis nursing care for patients with EVDs. sorbed, so while 500ml is produced daily, and regularly assess only around 150ml is in circulation at any patients CSF circulation one time in healthy patients (Hickey, Cerebrospinal fluid is a clear, odourless 2009). On average, 125ml of CSF is present Assessing patients’ liquid containing substances that bathes in the subarachnoid space and 25ml in the consciousness is the brain and spinal cord, providing ventricles of the brain (Sakka et al, 2011). crucial to identify energy to the working brain cells (neu- The route of CSF circulation is as fol- neurological rons), such as glucose, oxygen and electro- lows: most is produced in the blood vessels deterioration early lytes (Hickey, 2009). It travels around the lining the two lateral ventricles (choroid brain and spinal cord within the subarach- plexus) (Sakka et al, 2011). The fluid passes noid space, an enclosed area that sits from the lateral ventricles into the intra- between two of the three outer protective ventricular foramina, a narrow descending layers () that envelop the brain passageway, before entering the third ven- and spinal cord (Fig 1). tricle. It then passes into the cerebral aque- From outer to inner layers, the order of duct, a longer and narrower descending the meninges and subarachnoid space is: passageway, to reach the fourth ventricle, l Dura mater; from where it enters the subarachnoid l Arachnoid mater; space through the median aperture (Sakka l Subarachnoid space; et al, 2011). While CSF moves in one direc- l Pia mater. tion when passing through the ventricles,

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Fig 1. Subarachnoid space, ventricles and meninges

Skull Choroid plexus Scalp Pia mater (produces CSF) Meninges of Arachnoid the brain Left lateral mater (which also ventricle (hiding envelop the right lateral Dura mater spinal cord) ventricle)

Front anterior horn of lateral ventricle Subarachnoid space (contains CSF)

Third ventricle Light blue = CSF circulation

Fourth Red = CSF production CSF = cerebrospinal fluid ventricle

it moves in several different directions the arachnoid villi. Secretion is not in l Tumours of the choroid plexus, which within the subarachnoid space (Sakka et equilibrium with absorption, and CSF are rare, can cause overproduction of al, 2011). It is eventually absorbed by the builds up. CSF (Woodward and Mestecky, 2011). arachnoid villi (protruding structures that Hydrocephalus can have many causes: line the subarachnoid space) and leaves the l Following subarachnoid haemorrhage, A medical emergency subarachnoid space to enter the venous blood in the subarachnoid space makes Hydrocephalus, from any cause, needs to bloodstream (Waugh and Grant, 2014). it harder for the CSF to reach the be treated urgently as it can cause arachnoid villi and slows down or increased pressure in the ventricles (either CSF functions prevents its absorption (Bowles, 2014); by build-up of CSF around an obstruction The CSF cushions the brain and spinal cord, l Following intraventricular or by blood increasing the overall circu- acting as a shock absorber and reducing the haemorrhage, blood in the ventricles lating volume in the ventricles and suba- impact of outside knocks and jolts. It also can enter the subarachnoid space and rachnoid space). Increased ventricular keeps the brain buoyant by reducing its den- impair CSF absorption (Muralidharan, pressure equates to increased intracranial sity, thereby preventing its circulation being 2015); pressure (ICP) in the overall (Sakka et cut off by the impact of its weight (Wood- l Tumours near the third and fourth al, 2011). ward and Mestecky, 2011). In addition, CSF ventricles can obstruct CSF flow Raised ICP is critical because it reduces enables homoeostasis by delivering impor- (Woodward and Waterhouse, 2009); blood flow to the brain, starving it of tant substances – such as hormones, oxygen l Exudate from infection (such as oxygen, glucose and other vital sub- and nutrients – to brain cells and removing or encephalitis) can block stances. Due to the limited space in the waste (Waugh and Grant, 2014). the cerebral aqueduct and therefore skull, untreated ICP will eventually lead to These functions rely on a constant flow obstruct CSF flow (Woodward and , a medical emergency in of CSF being produced and absorbed in the Waterhouse, 2009); which the brain shifts into any available correct amounts. However, sometimes l Genetic disorders, such as: aqueduct space – usually downwards. It descends there is excessive CSF in circulation: this is stenosis (abnormally narrow cerebral into the opening at the base of the skull, known as hydrocephalus. aqueduct); Dandy-Walker crushing the structures of the brain stem malformation (several abnormal brain and impeding the vital functions they con- Causes of hydrocephalus structures including a dilated fourth trol, such as respiration and heart rate Hydrocephalus is a broad term for any ventricle); and Arnold Chiari (Woodward and Mestecky, 2011). situation where there is too much CSF in malformation (where the base of the circulation, for example because the cho- brain pushes through the opening of EVD insertion roid plexus secretes too much, there is an the skull and protrudes into the spinal Hydrocephalus is temporarily treated by obstruction somewhere on its route, or canal) can impair CSF circulation insertion of an EVD. Also known as an

PETER LAMB PETER there are problems with its absorption by (Woodward and Waterhouse, 2009); external (Hammer et al,

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Fig 2. External ventricular drain The collection chamber and pressure scale hang side by side. Pressure is measured

in millimetres of water pressure (cmH20). The scale includes both positive and nega- tive measurements; zero corresponds to the Pressure setting for pressure where the catheter enters the ven- drainage of CSF tricle, and should always be horizontally Collection level with the tragus of the patient’s ear (Fig chamber 4) (Woodward and Waterhouse, 2009). When the patient is lying on one side, this anatomical reference point becomes the bridge of the nose (Woodward and Mestecky, 2011). It is a key nursing respon- sibility to ensure that zero on the pressure scale is level with the patient’s tragus at all Zero on times (Woodward et al, 2002). pressure scale The number above (or below) the zero must be point is the prescribed pressure level of the horizontally level EVD determined by the neurosurgical with tragus of the ear team (Woodward et al, 2002). In the Lateral ventricle patient’s brain, this pressure level corre- sponds to the amount of pressure that must be inside the ventricles before the CSF drains into the catheter. In the Drainage bag for CSF external drainage system, it corresponds to the height at which the collection chamber hangs. If the collection chamber hangs from a higher point, it will drain CSF from a CSF = cerebrospinal fluid higher pressure in the ventricles than one hanging from a lower point. The pre- scribed pressure level must be docu- mented, and the collection chamber must 2016), the EVD is a small soft catheter Monitoring CSF drainage be checked frequently to ensure it is nei- inserted directly into one of the lateral ven- Outside the skull, the catheter is connected ther too high (which would cause under- tricles (Hickey, 2009), usually of the right to a drainage system consisting of a collec- drainage of CSF) nor too low (which would hemisphere, to drain excess CSF (Fig 2). tion chamber hanging from an intrave- cause over-drainage) (Woodward and The right hemisphere is the non-dominant nous (IV) pole attached to the bed, a pres- Waterhouse, 2009). hemisphere for language (Grandhi et al, sure scale (also hanging from the IV pole) 2015), so insertion into the right lateral and a drainage bag (Fig 2). Stopcocks “External ventricular ventricle reduces the risk of language dys- between the collection chamber and drains can appear function. Box 1 lists the clinical indications drainage bag allow control of the entry of daunting, but they are for EVD insertion CSF and its drainage (Fig 3). To reduce the risk of infection, the cath- a rewarding aspect of eter is initially tunnelled a few centimetres Box 1. Indicators for external patient care” under the scalp before entering the skull. It ventricular drain insertion is then inserted into the anterior horn of Problems associated with EVDs the ventricle (the large C-shaped structure l Monitoring intracranial pressure Infection at the front) by drilling a small hole in the l Treating hydrocephalus, including The insertion of an EVD is a highly invasive skull (burr hole) and incising the negative-pressure hydrocephalus, procedure and carries a significant risk of meninges. The skin incision is then where pressure level is set below zero, infection (Muralidharan, 2015; Chatzi et al, sutured, the catheter is sutured to the correcting intracranial hypertension 2014; Wong, 2011); this risk increases the scalp and the wound covered with a sterile l Administering medication for more frequently it is accessed by health occlusive dressing (Woodward et al, 2002). intraventricular haemorrhage or professionals to obtain CSF samples (Jam- Patients requiring ongoing CSF ventriculitis joom et al, 2017), and the longer the EVD is drainage will have a cerebral surgi- l Diverting infected or bloodstained kept in situ (Camacho et al, 2010). Touching cally inserted. Shunts are thin tubes that cerebrospinal fluid, preventing its EVD components, such as the stopcock or drain CSF to other parts of the body such absorption by the arachnoid villi drainage bag, must be an aseptic proce- as the abdomen, heart or lung for absorp- l Treating hydrocephalus secondary dure and handling must be kept to a min- tion. A valve can be set at the desired pres- to aneurysmal subarachnoid imum (Woodward and Waterhouse, 2009). sure to allow CSF to escape whenever the haemorrhage or a tumour A sterile, closed drainage system should

PETER LAMB PETER pressure level is exceeded. be maintained and the entry site dressing

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Fig 3. Stopcock positioning

Collection chamber

Stopcock pointing north (turned upwards) Stopcock pointing west indicates EVD is ‘off’ indicates EVD is ‘on’ Stopcock Stopcock CSF will remain in CSF will drain from collection chamber and collection chamber into not enter drainage bag drainage bag

Turn stopcock to this Turn stopcock back to position before nursing this position after intervention involving intervention is finished movement

Drainage bag

CSF = cerebrospinalCSF = cerebrospinal fluid; EVD = fluid;external EVD ventricular = external drain ventricular drain

Fig 4. Ear pierced at the and respirations; cloudiness or debris in ventricle, pulling the brain tissue away tragus previously clear CSF indicates infection and from the dura, tearing cortical veins and should be reported to the neurosurgical leading to subdural haematoma (Wood- team (Woodward and Waterhouse, 2009). ward and Waterhouse, 2009). Over- Patients might need to be monitored more drainage can be prevented by ensuring frequently depending on the stability and that the CSF is not draining at a lower pres- status of their neurological and vital obser- sure than that set by the neurosurgeon. vations, so this requires clinical judgement. Over-drainage of CSF can be caused by increased pressure inside the ventricles. Over- and under-drainage Straining to pass faeces can increase intra- It is crucial to monitor EVDs meticulously, ventricular pressure, so it is important to ensuring the zero point on the scale is hor- ensure patients with EVDs maintain reg- izontally level with the patient’s tragus and ular bowel habits using stool softeners. that the prescribed pressure level is cor- Drainage should be turned off at the col- rect. If CSF drains at a higher pressure it lection chamber before any intervention will cause under-drainage and lead to involving patient movement, such as suc- raised ICP, signs of which include: tioning, walking, physiotherapy and repo- l Reduced level of consciousness sitioning in bed – all of which can increase indicated by a decline in Glasgow intraventricular pressure. Coma Scale score; Drainage at the collection chamber is should only be changed if it becomes l New weakness in any of the limbs; turned off by turning the stopcock so that soiled or loose. The neurosurgical team l ; it points ‘north’ (upwards). It can be should be informed as soon as possible if l Changes in pupil size and equality; helpful to visualise the stopcock as the dressing may be wet from CSF leakage l Vision changes (including double or obstructing CSF flow into the drainage bag (Woodward et al, 2002) as this poses an blurred vision); when it is pointing north and associate infection risk. The drainage bag should be l Oedema of the optic disc (papilloedema); ‘off’ with the stopcock pointing north. As changed when it is three-quarters full, as l Changes in vital signs (Woodward and soon as the intervention is finished, the too much weight could disrupt drainage Mestecky, 2011). stopcock should be turned to point ‘west’, (Woodward et al, 2002). Neurological and vital signs should be turning the drainage system back on again The integrity of the entire EVD system observed at least every four hours as above (Fig 3). Drainage should not be turned off must be checked at a minimum of every and CSF output documented hourly on a for longer than needed, as this can cause four hours, and damage or disconnection fluid balance chart (Woodward et al, 2002). the catheter to block. of any of the components reported as an Signs of under-drainage should be reported Early signs of over-drainage include emergency. Patients must also be checked immediately to the neurosurgical team. , and the neurosurgical team every four hours for early signs of infection Equally damaging for the patient is should be notified urgently if the rate of

PETER LAMB PETER such as an increase in temperature, pulse over-drainage, which can collapse the drainage exceeds 10ml per hour or a total

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Box 2. Monitoring and Nurses need to be vigilant for signs of References trauma, which is another reason why neu- Bowles E (2014) Cerebral aneurysm and documentation aneurysmal subarachnoid haemorrhage. Nursing rological and vital observations should be Standard; 28: 34, 52-59. l On pressure scale, check prescribed performed frequently. They also need to: Camacho EF et al (2011) Infection rate and risk pressure level is correct and zero is in l Alert the neurosurgical team factors associated with infections related to line with tragus immediately if previously clear CSF external ventricular drain. Infection; 39: 1, 47-51. l Document amount of cerebrospinal is blood-stained; Chatzi M et al (2014) Bundle of measures for external cerebral ventricular drainage-associated fluid (CSF) drained per hour on fluid l  Cohort or provide one-to-one care to ventriculitis. Critical Care Medicine; 42: 1, 66-73. balance chart confused or agitated patients to prevent Dash C et al (2016) Massive life-threatening l Check catheter is oscillating and accidental removal of the EVD; bifrontal epidural hematoma following placement not kinked l Regularly check that the catheter is of an external ventricular drain. Child’s Nervous l Monitor colour of CSF and alert swinging: a patent catheter will gently System; 32: 2, 237-239. Grandhi R et al (2015) Iatrogenic pseudoaneurysm the neurosurgical team immediately swing but a catheter that is not swinging of the middle meningeal artery after external if it changes at all could indicate that it is blocked by ventricular drain placement. Journal of l Monitor clarity of CSF and alert the clotted blood or tissue debris; ; 25: 1, 140-141. neurosurgical team immediately if l Regularly check that the catheter is not Hammer C et al (2016) Decreased CSF output as a cloudiness and/or debris appear kinked: this can cause a blockage. clinical indicator of cerebral vasospasm following aneurysmal . Clinical l Check dressing is intact, clean and dry A blocked catheter needs immediate Neurology and ; 144: 101-104. medical attention; the neurosurgical team Hickey JV (2009) The Clinical Practice of may need to irrigate it, remove any haema- Neurological and Neurosurgical Nursing (6th edn). of more than 30ml drains in one hour toma or remove the EVD altogether. Philadelphia, PA: Lippincott Williams and Wilkins. (Woodward et al, 2002). Due to the risks of intracranial haemor- Jamjoom AAB et al (2018) Prospective, multicentre study on external ventricular When the patient is being transferred, rhage (haemorrhage anywhere in the brain), drainage-related infections in the UK and Ireland. the EVD system must remain in an upright prophylactic anticoagulants prescribed for Journal of Neurology, Neurosurgery and position and not be left lying flat on the deep vein thrombosis may be contraindi- Psychiatry; 89: 2, 120-126. bed, as this will impair drainage (Wood- cated in patients with an EVD in situ. Nurses Lewis A et al (2015) Predictors for delayed ward and Waterhouse, 2009). must check the local policy and raise any ventriculoperitoneal shunt placement after concerns with the neurosurgical team. external ventricular drain removal in patients with subarachnoid hemorrhage. British Journal of Trauma and haemorrhage Neurosurgery; 29: 2, 219-224. Although they are life-saving devices, Conclusion Muralidharan R (2015) External ventricular drains: EVDs are not without risk. Lewis et al Box 2 lists what to monitor and document, management and complications. Surgical (2015) suggest there is a link between EVDs while Box 3 features a range of competen- Neurology International; 6 (Suppl 6): S271-S274. and delayed hydrocephalus in patients cies relating to the safe care and manage- Sakka L et al (2011) Anatomy and physiology of cerebrospinal fluid. European Annals of with subarachnoid haemorrhage, arguing ment of patients with an EVD in situ. Otorhinolaryngology, Head and Neck Diseases; 128: that the drain may interrupt CSF flow and Although these drains can appear 6, 309-316. slow down clearance of debris from daunting, with an understanding of their Waugh A, Grant A (2014) Anatomy and Physiology bleeding, which can impair CSF absorp- key elements and functioning they are a in Health and Illness (12th edn). Edinburgh: Churchill Livingstone. tion by the arachnoid villi. rewarding aspect of patient care. NT Wong FW (2011). Cerebrospinal fluid collection: a EVDs themselves can cause trauma and comparison of different collection sites on the therefore lead to haemorrhage in the ven- Box 3. Competencies for external ventricular drain. Dynamics; 22: 3, 19-24. tricles (intraventricular haemorrhage), or Woodward S, Mestecky AM (eds) (2011) managing patients with Neuroscience Nursing: Evidence-Based Practice. in functioning brain tissue (parenchymal external ventricular drains haemorrhage) (Dash et al, 2016), as well as Oxford: Wiley-Blackwell. Woodward S, Waterhouse C (eds) (2009) Oxford l  to aneurysm rupture (when a weakened Know infection control policies Handbook of Neuroscience Nursing. Oxford: part of a cerebral blood vessel bursts) about handling, monitoring and Oxford University Press. (Muralidharan, 2015). cleaning medical devices Woodward S et al (2002) Benchmarking best Placement of the drain can cause the l Know how to assess patients practice for external ventricular drainage. British dura mater to pull away from the for infection Journal of Nursing; 11: 1, 47-53. overlapping skull bones and Dash et al l Be able to apply principles of asepsis (2016) report the case of a patient devel- l Understand how external ventricular Nursing Times oping a haematoma above the dura (epi- drains (EVDs) work and appreciate Self-assessment dural haematoma) after EVD placement. importance of maintaining alignment Grandhi et al (2015) report a case of EVD with tragus Test your knowledge with placement causing a pseudoaneurysm l Know the ‘on’ and ‘off’ positions of Nursing Times Self- (where blood collects between the two stopcock assessment after reading this article. If outer layers of an artery) of a major cere- l Be able to identify indications for you score 80% or more, you will receive bral artery; they also cite evidence that and complications of EVDs a personalised certificate that you can EVDs can cause arteriovenous malforma- l Know how to manage complications download and store in your NT tions (AVMs), which are abnormal connec- l Be able to use the Glasgow Coma Portfolio as CPD or revalidation tions between arteries and veins. Aneu- Scale to detect early neurological evidence. Visit nursingtimes.net/ rysms and AVMs carry a major risk of deterioration NTSAVentricular to take the test. rupture and bleeding.

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