What Is an External Ventricular Drain?

An external ventricular drain is a medical device that can direct Cerebrospinal Fluid (CSF) from inside the brain to a bag outside the body. Gravity and the pressure inside the head typically help to drain the CSF, which can build up as a result of injury, infection, surgery, or other conditions. Cells inside the brain produce this fluid, filling cavities called ventricles as well as the space around the spinal cord. The fluid is normally secreted and absorbed into the blood at the same time, typically at the same pace. A drain is usually inserted when too much builds up and creates pressure, and can remain there until the CSF is made and absorbed at normal rates.

The fluid around the brain and spinal cord can act as a cushion and also has nutrients that are absorbed by nerve cells. If too much is produced, pressure can build up in the skull. This can be extremely painful as well as cause damage to the brain and spinal cord. An external ventricular drain can drain excess CSF as well as that which is infected or mixed with blood. In the process, intracranial pressure is often relieved, which can prevent more serious health conditions from occurring.

Parts associated with an external ventricular drain typically include a drainage system and a bag. A flexible tube typically makes up the device, which is inserted through the bone of the skull and into a ventricle. There are four ventricles in the brain that the device can be placed in. The drainage is usually monitored closely to determine the level of fluid that comes out. An external ventricular drain usually requires constant adjustment as pressure levels change.

Surgical procedures such as a ventriculostomy, when a path is created between the ventricles if there is a blockage, are sometimes associated with an external ventricular drain. The drain can be placed after an injury that causes brain swelling, if a shunt becomes infected, or if one needs surgery to remove a tumor. If used for an infection, the drain may be required for up to 10 days. It typically stays in place, however, until the pressure is relieved and physicians determine that CSF production is normal.

A patient with an external ventricular drain must generally lie in bed and stay in a specific position for CSF to drain properly. Sometimes the medical equipment needs adjustment, but it can be very dangerous for someone other than a nurse or doctor to tamper with it. Moving a patient should usually be done with the help of a nurse.