Intracranial pressure (ICP) monitoring and CPP . PREPARED BY Fatima Hirzallah MISS. Intracranial pressure (ICP): . The main components inside the cranium are: - brain tissue (80%), blood (10%), and cerebrospinal fluid (CSF (10%).
Fatima Hirzallah MISS
The main components inside the cranium are: - brain tissue (80%), blood (10%), and cerebrospinal fluid (CSF (10%).
So that any increase in the size of brain tissue or increase in the volume of the CSF or problem in the blood vessel (E.g. bleeding into the cranium) will cause increase in the ICP.
The normal ICP in patients should be less than
The effect of increase in ICP will cause neurological deficit (sensory, motor, level of consciousness) or other problem such as seizure so that it is important in some patient to monitor ICP.
1- patients with severe head injury ( GCS≤ 8 after cardiopulmonary resuscitation).
A- with abnormal admitting head CT.
B- normal CT but with more or equal to 2 of the risk factor which include( age > 40, SBP< 90, decerebrate or decorticate posturing on motor exam unilateral or bilateral).
2- Multiple system injured with altered level of consciousness
3- Subsequent to removal of intracranial mass.
1-awake patient, we will follow neurological exam.
2-Coagulopathy( e.g. DIC ), if ICP monitoring is essential; consider taking steps to correct coagulopathy by using fresh frozen plasma and platelet and plan for subarachnoid bolt or epidural ( but intravantricular or intraparanchymal is contraindicated.
*Remove monitor when ICP become normal for 48-72 hours after withdrawal from ICP monitor
1-Intraventricular space: -
*This approach is accomplished through placing a small catheter into the ventricular system (ventriculostomy).
*The catheter inserted through burr hole under local or general anesthesia into the anterior horn of the lateral ventricle, also the preferred side to insert the catheter is the nondominent hemisphere.
ICP is accomplished through a placing a small hollow bolt or screw into the subarachnoid space.
It is inserted through burr hole, usually located in the front of the skull behind the hairline.
The normal cerebral blood flow (CBF) is 50ml / 100g of brain tissue.
Although brain makes up to 2% of the body weight but it required 15% to 20 % of the resting cardiac output and 15% of the total body’s oxygen demands.
1- Acidosis (caused by hypoxia, hypercapnia, and ischemia), which result vasodilation by the effect of carbon dioxide, which lead to increase in CBF.
2- Alkalosis (caused by e.g. hypocapnia) which will result cerebral vasoconstriction, which lead to cerebral ischemia
3- Reduction in the metabolic rate (e.g. from hyporthermia or barbiturate).
4-Increase in the metabolic rate (e.g. hyperthermia).
A sustained CPP 30 mmHg or less usually results in neuronal hypoxia irreversible neurologic damageand death.