Question 27.2

College Answer

a) List the indications for the use of this device in traumatic brain injury.

1.  Intracranial pressure monitoring in patients with traumatic brain injury associated with an initial non-sedated Glasgow Coma Score > 8 prior to non-surgical resuscitation
a.   AND an abnormal CT scan associated with trauma:
i.  Diffuse axonal injury grade II – IV or ii.   Mass lesions with midline shift > 5mm
b.  AND in the following patients with a normal CT Scan

i.  Age >40
ii.  Lateralising signs

iii.  Hypotension
iv.  Significant extra-cranial trauma

b) List 3 important principles of measurement/management of this device

1.  Attached flushed transducer to fluid-filled catheter – do not inject
2.  Set transducer to reference level (EAM or aortic root)
3.  Attach drainage manometer and set at 10-20 cm H2O at level of EAM.
4.  Monitor ICP continuously with intermittent drainage (hourly) unless clinically
indicated, for which drainage may be increased in frequency or continuously.
5.  Septic surveillance of CSF daily.

Discussion

Methods of intracranial pressure monitoring and indications for intracranial pressure monitoring are discussed elsewhere.

The modern indications for ICP monitoring come from the Brain Trauma Foundation  (4th edition), which are simply  "anyone with an abnormal CT and GCS 3-8 gets ICP monitoring".

The setup of the EVD, its waveforms, and various other tidbits all have their own chapter.

In short, the normal principles of ICP measurement are:

• Inserted into the lateral ventricle, about 2.5 centimetres left or right from the midline, 11cm posterior to the junction between the frontal bone and the nasal bones.
• The drain connects to the transducer via a three-way tap
• The connecting tubing is incompressible, and primed with saline
• The transducer is zeroed to atmospheric pressure at the level of the tragus.
• The height of the drain is set to a certain specified height (in cm) above the patients tragus; lets say, 15cm
• The ICP is measured continuously; drainage occurs hourly, or sporadically.
• Daily CSF samples are sent for protein, glucose, cell count, Gram stain and culture.

Chawla, Lakhmir S., et al. "Lack of equivalence between central and mixed venous oxygen saturation." CHEST Journal 126.6 (2004): 1891-1896.