External drainage and monitoring is the temporary drainage of cerebrospinal fluid (CSF) from the lateral ventricles of the brain, or the lumbar space of the spine, into an external collection bag. An external ventricular drainage (EVD) system drains CSF by using a combination of gravity and intercerebral pressure. The drainage rate depends on the height at which the EVD system is placed relative to the patient’s anatomy.

EVDs are used in neuro critical care situations to:

• Relieve elevated intracranial pressure (ICP)
• Drain infected CSF
• Drain bloody CSF or blood after surgery or hemorrhage
• Monitor the flow rate of CSF

The physician attaches the drainage system and indicates its level. A qualified critical care nursing professional maintains the system. Management of the patient with an external ventricular drain requires constant assessment and intervention.