Intracranial Pressure (ICP) is the total pressure within the cranium at a given time. The ICP is the accululative pressure that the vasculature or blood, brain and cerebral spinal fluid (CSF) places on the inside of the cranium. Resting ICP is generally around 5-18 mmHg in the normal healthy adult at rest and supine; however, this pressure normally decreases up to negative 10 mmHg in a patient who is vertical.
ICP is important for paramedics who are treating patients who have had a head injury. This is because any trauma to the head may cause changes in the brain, such as internal bleeding, which will increase the ICP. If the ICP is allowed to continuously increase, it will force the brain tissue downards, damaging the brain stem, and eventually cause the brain stem and other apsects of the brain to be forced downdwards and through the foramen magnum (the big hole that the spinal cord uses to enter the cranium). This will lead to severe brain damage and death.