ICP / ICT Monitoring

Definition:      The primary goals of intracranial pressure (ICP) monitoring are identification of intracranial pressure trends and evaluation of therapeutic interventions in order to minimize ischemic injury in the brain-injured patient. Intracranial hypertension (sustained ICP equal to or greater than 15 mm Hg) results when the brain's protective mechanisms to shunt cerebrospinal fluid (CSF) to the subarachnoid space or to vasoconstrict cerebral arterioles fail to maintain the ICP below 15 mm Hg. Intracranial hypertension compromises the relationship between systemic blood pressure and the resistance that must be overcome to accomplish cerebral perfusion. When cerebral perfusion pressure (CPP), calculated by subtracting the ICP from the mean arterial pressure, falls below 50 mm Hg, secondary brain ischemia, herniation, and, ultimately, brain death occur. ICP monitoring allows for early detection of intracranial hypertension and subsequent aggressive management.

            ICP monitoring is accomplished by the use of a fluid-filled monitoring system attached to an intraventricular catheter. The ICP waveform resembles a dampened arterial blood pressure waveform and is considered normal when the pressure is between 0 and 15 mm Hg. In addition, a stopcock within the system allows for therapeutic drainage of CSF and for sampling for infection surveillance.

Indications

1- Severe traumatic brain injury

2- Intracranial hemorrhage

3- Cerebral edema

4- Post-craniotomy

5- Space-occupying lesions such as epidural and subdural hematomas, tumors, abscesses, or aneurysms which occlude the CSF pathway

6- Reye syndrome patients who develop coma, posturing, and abnormal responses to obnoxious stimuli

7- Encephalopathy from lead ingestion, hypertensive crisis, or hepatic failure

8- Meningitis/encephalitis resulting in malabsorption of CSF

Contraindications

1.                     1-Central nervous system infection

2- Coagulation defects

3- Anticoagulant therapy

4- Scalp infection

5- Severe midline shift resulting in ventricular displacement

6- Cerebral edema resulting in ventricular collapse

Complications

`1- Intracranial infection

2- Intracerebral hemorrhage

3- Air leakage into the ventricle or subarachnoid space

4- CSF leakage

5- Overdrainage of CSF leading to ventricular collapse and herniation

6- Loss of monitoring or drainage capabilities due to the occlusion of the catheter with brain tissue or blood

                7- Inappropriate therapy because of erroneous ICP readings due to dampened waveforms,      electromechanical failure, or operator error (i.e. inappropriate leveling)