Definition: pressure exerted by intracranial volume of: 1- Brain 2- Blood 3- CSF Normal ICP: 1 - 15 mm Hg. Increased ICP: >20 mm Hg. Intracranial Pressure Monitoring
- Understanding the Determinants of Intracranial Pressure - Intracranial Contents: 1- 80% brain tissue 2- 10% blood 3- 10% cerebrospinal fluid An increase in the volume of any of these intracranial contents causes increased intracranial pressure - The brain can swell (edema) - Excess blood can accumulate due to hemorrhage - Cerebrospinal fluid can accumulate due to blockage of outflow
Causes of Sustained Increases in ICP Increased Brain Volume Increased CSF Increased blood volume cerebral edema from trauma or hypoxia, infectious process, tumor decrease fluid absorption due to meningitis, obstruction of CSF flow due to hydrocephalus or tumor aneurysm, intracranial hemorrhage
Measuring Intracranial Pressure Procedure: Indication: To measure ICP, which allows for calculation of cerebral perfusion pressure (CPP). CPP is an important indicator of cerebral blood flow. ICP monitoring may be useful in patients with sever head injury. Normal range of CPP : 60 - 70
ICP Review CBF is a factor of CPP –If CPP , then CBF CPP = Mean arterial pressure (MAP) - ICP –MAP = systolic BP+2 (Diastolic ) divided on 3.
EXAMPLE CEREBRAL PERFUSION PRESSURE (CPP) The following assessment is made: BP = 130/82; ICP=15; MAP = 98 MAP- ICP = CPP 98 -15= 83 (>60 indicates the brain is being perfused) MAP 100 and/or ICP >20 impairs cerebral perfusion
SITES FOR ICP MONITORING Epidural Subarachnoid Intraventricular
Equipment: - Hair clippers. - Antiseptic solution. - Sterile drapes and towels. - No. 11 scalpel. - Local anesthetic. - 10-ml syringe, 18, 25, and 27-G needles for local anesthesia (optional). - Twist drill. - Nonbacteriostatic saline.
- Explain procedure to the patient. - A conscious patient requires sedation or analgesia. - Neurological assessment. - Using restraints. - Calibrate the monitoring equipment according to the manufacturer's recommendations. - Place the patient in a supine position. - Cleanse the site with an antiseptic solution. - Shave or clip hair.
Infiltrate the site with a local anesthetic. Implementation: - Incise down to the skull. Use a small twist drill to make a hole in the skull. Place the monitor as follows: a-Ventricular catheter: -Penetrate the dura and, -Insert the ventricular catheter with the stylet in place through the brain tissue until it is in the ventricle. -Remove the stylet. Free flow of CSF confirms placement. b-Subarachnoid bolt: - Insert the bolt into the subarachnoid space. c- Epidural monitoring: - Place the epidural sensor between the skull and the dura.
- Irrigate the wound gently. - Attach the device to the calibrated monitoring system. - Once a good waveform is established, assist with wound closure. - Apply an antibiotic ointment. - Apply a sterile occlusive dressing. - Document the initial ICP. - Calculate cerebral perfusion pressure (CPP).
Post care: Patient: - Remain in a supine position so the monitor functions accurately. Nurse: - Hand wash. Environment: - Return equipment. Documentation: - Neurological assessment. - Initial ICP measuring. - Quality of the waveform. - Appearance of the CSF.
Complication: - Epidural hematoma. - Occlusion of a ventricular catheter by blood or brain tissue can occur. - Infection. - Headache and Seizures.