 Hi, welcome to the nursing school explained in this video on intracranial pressure as well as cerebral profusion pressure. Now, in order to really understand the concept of increased intracranial pressure and how it relates to head injuries, it is very important to first understand what intracranial pressure and cerebral profusion pressure mean and how the body really regulates the two of them. So, intracranial pressure is basically the hydrostatic pressure that we can measure in the CSF compartment of the head and it is influenced by the arterial pressure, the venous pressure, as well as intra-abdominal and introthoracic pressures, the patient's posture, the body temperature and then blood gasses, specifically CO2. And over here I have drawn out the skull and as you can see inside that cranial cavity, inside the skull we have three things, number one the brain, number two blood vessels and number three CSF. And remember that the body can adjust things as needed and I'll go over this in a moment here. Now, intracranial pressure is normally 5 to 15 millimeters of mercury, anything above 20 must be treated because it can be life-threatening. Now, typically our bodies have great ability to compensate for any kind of changes that occur and so what happens because we have these three major compartments the body can increase or decrease the production and or absorption of cerebral spinal fluid which basically means it could regulate to push more CSF down into the spinal cord which is also covered in CSF if you remember that. It can also auto-regulate the blood compartments of the skull by increasing or decreasing the vessel diameter, so dilating or constricting the blood vessels to make more space inside that cranial cavity. And then actually the brain itself can extend the dura mater which is the protective lining of the brain or it can slightly compress the brain tissue if there is a need to do that when there would be increased intracranial pressure. But if the body is unable to compensate or there is too much pressure in that intracranial cavity then the brain gets compressed and ischemia occurs because now we have no blood flow and then eventually self-death will occur. Now over here cerebral perfusion pressure is calculated by the mean arterial pressure minus the intracranial pressure and recall that the map or mean arterial pressure is systolic blood pressure plus two times diastolic blood pressure divided by three that can be very easily obtained with a very simple calculation. In cerebral perfusion pressure normally is 60 to 100 but anything less than 50 means ischemia and the neurons are starting to die and anything less than 30 is incompatible with life so we really have to be very careful in regulating this. And then cerebral auto-regulation is another mechanism that our bodies are equipped with by basically again the ability to base a dilate and constrict to ensure cerebral perfusion with changing blood pressures because depending on what's going on in our lives on our activity on our underlying conditions comorbidities the blood pressure changes on a day to day sometimes even a minute by minute or second to second basis but the brain takes up about 20 percent of the entire blood volume of the human body and about 25 percent of its glucose that's how important it is to our bodies to support and supply the the brain with the oxygen and the nutrients that it needs and ideally this auto-regulation works best when the map is 70 to 150. Now that is a pretty wide range so actually a pretty wide range of systolic and diastolic blood pressures will accommodate this but it's ideal with 70 to 150. Now with this calculation here this cerebral perfusion pressure between 60 and 100 it all depends on the map and the ICP but we want to make sure that we maintain that and keep in mind that we want to maintain the CPP and that we don't want it to get too low with the ICP we don't want to get too high. And then really the only thing that we can measure here or in this formula is the map and the ICP the map already told you how to calculate this and the ICP is monitored by putting a monitor into the patient's ventricles into that CSF compartment that's a very specialized procedure of course to monitor the ICP by a certain gauge and of course that's done in the intensive care unit. So now we have the two components that we need we have the main arterial pressure we have the ICP and now we can calculate the patient's cerebral perfusion pressure and then make adjustments as needed to prevent the ceschemia and your own death that might lead to the patient's being brain dead. So I hope that this has helped you on understanding these concepts between intracranial pressure and cerebral perfusion pressure and how they really relate to each other and all the mechanisms that our brain is equipped with to physiologically compensate and also auto-regulate that it's that it receives the blood supply that it needs. Please also watch my other video where I go about what happens or how do we treat increased intracranial pressure that can occur due to a variety of things such as epidural or subdural hematomas as well as strokes or aneurysms or really strokes ischemic as well as hemorrhagic strokes or any kind of other brain injuries. Thanks for watching this video see you soon here on Nursing School Explained.