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External ventricular drainage (EVD)

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External ventricular drainage (EVD) is performed to drain the cerebrospinal fluid (CSF) temporarily into an external collection bag from the lateral ventricles of the brain or the lumbar space of the spine. An EVD system uses a combination of gravity and intracerebral pressure to drain CSF. The drainage rate depends entirely on the height of the EVD system and the patient’s anatomy. EVD’s are used in neurocritical care situations to relieve elevated intracranial pressure, drain infected CSF, drain bloody CSF or blood after surgery or hemorrhage, or monitor the flow rate of CSF.