How Intracranial Pressure Monitors Work

Intracranial pressure (ICP) monitors are probes inserted into the ventricle -- or tissue -- of the brain to monitor pressure inside the skull. They're commonly used on patients who have experienced severe head trauma or brain hemorrhages, as well as for aftercare following brain surgery. The probes are used to monitor the pressure of cerebral spinal fluid (CSF) inside the skull, which is important because excessive pressure can impair brain function and cause damage to the tissue.

Procedure

• The ICP monitor is a small tube inserted into the cranium -- the hard shell of bone that protects the brain -- using a small burr hole drilled into the skull. A burr hole is a medical term used to describe a hole placed in the skull that penetrates the brain's outer layer, or dura mata. Today burr holes and burr drills are as small as 5 millimeters (mm) in diameter, and usually not larger than 20mm. Once in position, the tube is connected to a monitoring device or integrated into the patient's bedside monitor. This can be done as part of scheduled surgery in the case of brain tumors or disorders, as well as take place in the intensive care unit in case of emergency head trauma.

Pump

• According to the New South Wales Department of Health, some ICP monitors also have a small pump built in to remove excess blood or CSF from the cranium. CSF is a clear liquid that encases the brain and protects it from the hard shell of the cranium. This procedure is necessary if pressure is too high inside the cranium to allow proper insertion of the ICP monitor.

Does it Hurt?

• In most cases, a patient is completely unconscious during the insertion of an ICP monitor, but the procedure can also be performed using a sedative and local anesthetic while the patient is awake. If the doctor is interested in monitoring brain functions and conscious vital signs, only a mild sedative is administered to keep the patient conscious while monitoring intercranial pressure.

Complications

• As with any form of surgery, there is a risk of infection associated with ICP monitors. In addition, brain hemorrhaging can occur if the tube is not inserted properly, or if pressure in the cranium is too high. A skilled neurosurgeon can mitigate both these risks.