An external ventricular drain (EVD), also known as a ventriculostomy, is a device used in neurosurgery that relieves raised intracranial pressure and hydrocephalus when the normal flow of cerebrospinal fluid around the brain is obstructed. These are 10 French tubes placed by neurosurgeons and managed by ICU nurses to drain fluid from the ventricles of the brain, and thus keep them decompressed, as well as to monitor intracranial pressure.
The tube is most frequently placed in Kocher's point with the goal of having the catheter tip in the frontal horn of a lateral ventricle. The catheter is normally inserted on the right side of the brain. An EVD (also called an intraventricular catheter, or IVC) is used to monitor pressure in patients with brain injuries, intracranial bleeds or other brain abnormalities that lead to increased fluid build-up. In draining the ventricle it can also remove blood from the ventricular spaces. This is important because blood is an irritant to brain tissue and can cause complications such as vasospasm.
If the EVD becomes occluded, clogged, or obstructed, as it often does with fibrinous or clot like material, the brain can swell due to pressure build up in the ventricles and permanent brain damage can occur. Nurses and neurosugeons often have to adjust or flush these small diameter catheters to manage medical tube obstructions and occlusions at the intensive-care bedside[1]. Pressure settings are generally measured in cmH2O. The equilibrium pressure of the EVD apparatus is adjusted based on cerebrospinal fluid output, ICP waveform, imaging including CT or MRI of the brain, and clinical response.