How can drainage of CSF be controlled using an EVD?

  • CSF drainage can be controlled by changing the height of the EVD measuring cylinder above the zero set point:
    • Set a prescribed distance in cm above the zero-point
    • Requires the pressure of CSF in cmH2O to equal the set height before it will drain (a drain set at a height of 15cm will require an intracranial pressure (ICP) >15cm H2O) before CSF will drain
  • The level at which the EVD flow chamber should be set is usually determined by the neurosurgical team