Ventriculoperitoneal shunt problems

Disclaimer

These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.

Read the full CAHS clinical disclaimer.

Aim

To guide the PCH ED with the assessment and management of ventriculoperitoneal shunt problems.

Definition

Ventriculoperitoneal (VP) shunt complications include blockage and infection. Early and prompt detection of shunt dysfunction is vital as delay can lead to markedly raised intracranial pressure, coning and death.

All patients with suspected VP shunt dysfunction should be discussed with neurosurgery.

Background

VP shunts are inserted for treatment of hydrocephalus. Hydrocephalus is not a single disease entity. It is either due to subnormal CSF re-absorption, obstruction along the flow pathways or very rarely increased production. It may be:

Congenital (e.g. myelomeningocele, Dandy Walker syndrome, stenosis of the aqueduct of Sylvius) or
Acquired (e.g. post meningitis, post haemorrhagic, obstruction due to tumour).

Treatment options include:

Insertion of a CSF temporary diversion shunt (external ventricular drain) or a permanent diversion shunt (VP shunt) – the main treatment modality
Endoscopic third ventriculostomy (internal diversion via perforating the floor of the third ventricle allowing CSF to flow from the 3rd ventricle directly to the cortical subarachnoid space).

Assessment^1,2

The following signs suggest a dangerously elevated intracranial pressure which constitutes a neurosurgical emergency:

Impaired or falling Glasgow Coma Scale
Bradycardia
Hypertension
Papilloedema
Sun setting eyes

Immediate mandatory referral to the on-call neurosurgery team via Switch or Vocera.

If, in the event of such an emergency, there is an issue in obtaining the neurosurgery team, contact the on call neurosurgery consultant for advice.

History

Parents may know the usual symptoms for their child in the event of a shunt blockage. Do not ignore the concerns of the child’s parents or carers, particularly if they have had shunt dysfunction in the past.

History and symptoms may be variable

Drowsiness
Headache
Vomiting
Irritability.

The presence of drowsiness, headache and vomiting together make it very likely that the patient has shunt dysfunction.

Less commonly

Seizures
Any new neurological symptoms
Abdominal problem (tenderness, distension or peritonism)
Fever (suggestive of shunt infection)
Lethargy
Intermittent shunt dysfunction/blockage or low pressure may lead to a more protracted time course with chronic headaches
Always suspect shunt dysfunction in any patient with a VP shunt and no alternative explanation for the presenting symptoms.

Examination

Shunt evaluation (pressing the valve) is diagnostically unreliable and can potentially cause shunt dysfunction. Do not press the valve without prior discussion/direction from the neurosurgical team.
Any abnormal shunt findings should be discussed with the neurosurgical team.
Examine for new focal neurological signs.
Examine for conscious state, pupillary size/reactivity, papilloedema.
In a child with an open fontanelle, this should be soft and pulsatile.
A sunken fontanelle may be due to low pressure.
Fluid tracking along subcutaneous shunt tubing may indicate shunt blockage.
Erythema, tenderness along shunt tubing and fever suggest infection.
Examine shunt surgical wounds if implanted.

Investigations

Investigations that aid in diagnosis are:

Brain CT – to detect ventricular size
- Enlarged ventricles may imply shunt obstruction.
- A scan showing obviously dilated ventricles when compared with previous scans is a definite indication of shunt blockage/hydrocephalus.
- A 'normal' looking CT scan without a previous scan does not reliably exclude the diagnosis of a shunt blockage/hydrocephalus. (as in slit ventricle syndrome)
- Consider ultrasound in an infant with an open fontanelle.
Plain X-ray / shunt series – may demonstrate a disconnection.
CSF sampling – this should only to be done by the neurosurgical team or after consultation with neurosurgery.
Full blood picture (FBC) and C-reactive protein (CRP) may help in elucidating infection/ shunt dysfunction.

Differential diagnoses

In any unwell child with a VP shunt, shunt dysfunction must be a differential and not excluded until proven otherwise – early consultation with the neurosurgical team is advised if suspected.

Management^3,4,5,6

Maintain a low threshold for contacting the neurosurgery team for advice
If blocked or infected, the shunt will require revision/removal – urgent consultation with the neurosurgical team is required.
In the event that herniation (coning) is imminent and/or neurosurgical intervention will be delayed, institute steps to maintain / restore cerebral perfusion pressure including:
- Reducing brain bulk and cerebral blood volume:
  - Anaesthesia
  - Intubation
  - Hyperventilation (End tidal Carbon Dioxide (ETCO2) 28-35mmHg)
  - Mannitol 20%: IV bolus 1 gram/kg (equivalent to 5mL/kg) over 20 minutes³or
  - Sodium chloride 3% (hypertonic saline): IV bolus 5mL/kg over 10-20 minutes.6
  - Needling of the shunt and removal of cerebral spinal fluid. (always to be done by someone who is familiar with the procedure or under guidance from neurosurgery)
  - Increasing cerebral perfusion pressure using inotropes such as a noradrenaline infusion.

Advice on this support can be provided by contacting the PCH Paediatric Critical Care Unit.

Child with CSF shunt who presents unwell
No signs and symptoms of raised intracranial pressure (ICP) or no new neurological findings	Raised ICP or history comparable to a previous episode of blocked shunt
Consult with Neurosurgeon Observe and investigate for other problems Treat as appropriate	If very unwell consult with the neurosurgeon and PCC immediately Arrange CT head +/- shunt series X-rays Minimum of hourly observations: pulse rate, respiratory rate, blood pressure, neurological observations and continuous oxygen saturation monitoring Discuss findings of CT scan with neurosurgeon Initiate treatment as prescribed by the neurosurgeon.

Nursing

Observations

Record baseline observations heart rate, respiratory rate, blood pressure, oxygen saturations, temperature and neurological observations on the observation and response tool, neurological observations chart and the clinical comments chart.
Minimum of hourly neurological observations (including BP) along with general observations until definite diagnosis is made
Any significant changes must be reported immediately to the medical team.

References

Barnes NP, Jones SJ, Hayward RD, Harkness WJ, Thompson D. Ventricularperitoneal shunt block: what are the best predictive clinical indicators? Arch Dis Child 2002; 87:198-201.
Watkins L, Hayward R, Andar U, Harkness W. The diagnosis of blocked cerebrospinal fluid shunts: a prospective study of referral to a paediatric neurosurgical unit. Childs Nerv Syst 1994; 10:87-90
AMH Children’s Dosing Companion (2021) Australian Medicines Handbook Pty Ltd Mannitol Updated July 2021 [Cited 9 December 2021] Available from: Mannitol - AMH Children's Dosing Companion (health.wa.gov.au)
Stevens RD, Shoykhet M, Cadena R, Emergency Neurological Life Support: Intracranial Hypertension and Herniation. Neurocrit Care 2015 23:S76-S82
Brophy GM, Human T, Shutter L, Emergency Neurological Life Support: Pharmacotherapy. 2015 23:S48-S68
Tasker R., Elevated intracranial Pressure (ICP) in children: Management [Internet] Uptodate; 2021. [cited 13 January 2022] Available from: Elevated intracranial pressure (ICP) in children: Management - UpToDate

Endorsed by:	Drugs and Therapeutics Committee	Date:	Mar 2022
		Review date:	Jan 2025

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