Compare and contrast the intraventricular catheter and the intra-parenchymal fibre- optic transducer for intracranial pressure monitoring in critically ill patients.

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College Answer

Intraventricular catheters

Intra – parenchymal devices

Gold standard for ICP monitoring

Not a gold standard though fairly accurate

Catheters are Surgically placed into the
ventricular system and affixed to a drainage bag and a pressure transducer with a three way stopcock

Thin cable with an electronic fibre-optic
transducer at the tip placed in the cerebral parenchyma

Can be rezeroed (re-calibrated)after
insertion on a regular basis

Not possible to re-calibrate after insertion

Accurate provided catheter patent

Drift leading to inaccuracy particularly after 5 to 7 days

Can drain CSF to treat raised ICP

No ability to drain CSF

Ventriculitis - a serious life threatening
difficult to treat complication. Higher risk after 5 days.

Lower risk of Infection

Blocked Catheter and intra-cerebral or intra-ventricular haemorrhage other complications.

Solid state systems. Less chance of haemorrhage.

Requires special expertise for insertion

Easier to place

Difficult to insert in patients with collapsed ventricles due to severe cerebral oedema
– DAI in a young patient

Can be inserted in these patients easily

Other indication – Subarachnoid
haemorrhage with hydrocephalus

Other indications ( controversial) –
meningitis , acute liver failure

Coagulopathy – absolute contraindication

Coagulopathy – relative contraindication

Cheap

Expensive

Discussion

The college table is fairly comprehensive. One cannot add very much to this list of advantages and disadvantages.

A discussion of EVDs and the indications/contraindications of ICP monitoring can be found here:

Specifically, methods of ICP monitoring are discussed, and a table similar to the above is constructed on the basis of published data. This table is reproduced below:

A Comparison of ICP Monitoring Equipment
EVD Codman Microsensor
Gold standard of ICP monitoring Similar accuracy to EVD
Pressure is transmitted to a Wheatsone bridge transducer via fluid-filled non-compressible tubing Piesoelectric strain gauge pressure sensor is intracranial; connected to the monitor via fiberoptic cable
Requires a certain expertise to place correctly. About 12% areplaced into an inappropriate position. Requires less expertise to place (however, this should still be done by somebody with neurosurgical experience)
More traumatic owing to depth of insertion and diameter of catheter Less traumatic, because the catheter placement is not as deep, and the catheter tip is finer. The Codmans typically sits about 2cm below the cerebral surface.
CSF can be drained though the EVD CSF cannot be drained or sampled
The catheter can become blocked by clots or debris The catheter cannot block
Measures intraventricular pressure, which is thought to be representative of the pressure within the intracranial CSF Measures local parenchymal pressure
Can be re-zeroed to atmorpsheric pressure Cannot be re-zeroed after insertion; calibration tends to drift after 72 hours
Insertion is impossible if the ventricles are collapsed Does not rely on venticular placement, and thus is the only option in a patient with small collapsed ventricles
Dangerous in coagulopathy. Even when non-coagulopathic, the risk of haemorrhagic complications is around 5-7% on average Coagulopathy is only a relative contraindication; hemorrhagic complications are infrequent. One study puts the rate of bleeding at 1.1%.
Places the patient at risk of ventriculitis after 5 days. Bacterial colonisation rates range up to 27%, but studies vary in their definition of what a clinically significant infection actually is. Less likely to become infected; highly unlikely to cause ventriculitis, as it does not communicate with the entricles.
One study puts the infection rate at 0.6%.
Cheap Expensive

References

Brean, A., P. K. Eide, and Audun Stubhaug. "Comparison of intracranial pressure measured simultaneously within the brain parenchyma and cerebral ventricles." Journal of clinical monitoring and computing 20.6 (2006): 411-414.

Raboel, P. H., et al. "Intracranial pressure monitoring: invasive versus non-invasive methods—a review." Critical care research and practice 2012 (2012).

Lozier, Alan P., et al. "Ventriculostomy-related infections: a critical review of the literature." Neurosurgery 51.1 (2002): 170-182.

Saladino, Andrea, et al. "Malplacement of ventricular catheters by neurosurgeons: a single institution experience." Neurocritical care 10.2 (2009): 248-252.

Bekar, A., et al. "Risk factors and complications of intracranial pressure monitoring with a fiberoptic device." Journal of Clinical Neuroscience 16.2 (2009): 236-240.

Khan, S. H., et al. "Comparison of percutaneous ventriculostomies and intraparenchymal monitor: a retrospective evaluation of 156 patients."Intracranial Pressure and Neuromonitoring in Brain Injury. Springer Vienna, 1998. 50-52.