External Ventricular Drain (EVD)

What is it?

EVD stands for external ventricular (ven-TRICK-you-ler) drain. It is a small tube. Some people have too much fluid in the brain. The extra fluid puts pressure on the brain. This is called intracranial (in-truh-KRAY-nee-ol) pressure. To reduce the pressure, the doctor can insert an EVD into the brain to drain the extra fluid. The part of the brain where the tube is placed is called the ventricle (VEN-trick-ol).

How does an EVD work?

The fluid flows from the brain, through the EVD, and into a bag. The bag hangs on the head of the patient’s bed or on an IV pole. The doctor and nurse check how much fluid drains into the bag. The EVD has a device that helps measure pressure in the brain. It lets the doctor and nurse know if the pressure is decreasing. The EVD is used for while and then is removed.

When is an EVD needed?

Too much pressure in the brain may cause symptoms. When a patient has symptoms, an EVD may be needed. Symptoms may include:

  • Headache

  • Nausea and vomiting

  • Becoming less alert or less awake

What causes extra brain fluid?

These conditions may cause an increase of brain fluid:

  • A bulge in a blood vessel (aneurysm) that breaks open

  • A tumor

  • A stroke

  • A serious head injury

What precautions are needed?

The patient must do exactly what the doctor or nurse says about changing position. This is very important. While you have an EVD:

  • You must never get out of bed without calling the nurse, even to go to the bathroom

  • You must call the nurse for help to change the bed position. This includes moving the head of the bed up or down.

Note: Changing position without help can cause you serious harm.

Can there be problems?

Having an EVD may cause other problems. These problems are called complications. Some potential problems are:

  • Bleeding inside the brain or where the tube enters the head

  • Infection of the brain fluid or of the brain itself

The doctors and nurses will watch closely for any sign of these problems.