EEG And ICP Monitoring Flashcards
How much energy does the cerebrum require?
3-5 ml O2/min/100g tissue
Normal Cerebral Blood Flow is ___.
50 ml/min/100 g tissue 750 ml/min for brain Delivers 150 ml O2/min
O2 extraction from cerebral blood flow is:
35-50%
What is the equation for Cerebral Perfusion Pressure (CPP)?
CPP = MAP - ICP
Cerebral blood flow is:
- Tightly regulated except post-trauma
Cerebral blood flow stays around ____, as long as MAP is between _____ mm Hg.
50 ml/100g/min , 50-100
CBF is reduced by
- Head injury 2. Intracranial hypertension 3. Hypotension 4. Hyperventilation 5. Vasospasm
Ways of directly monitoring ICP:
- Ventricular catheters 2. Subdural/subarachnoid bolts 3. Epidural transducers 4. Intraparenchymal fiber optic devices
What is the Monroe-Kellie hypothesis:
The skull is a fixed volume. If one or more of these components increases, ICP rises: - Blood - CSF - Brain
ICP determined by:
- Brain mass (80%) - Blood flow (10%) - CSF volume (10%)
ICP monitoring physical set up
- Connection of device to transducer 2. Watertight fluid interface 3. Deformation of transducer membrane converted to electrical pulsations and amplified and displayed as a waverform
Zeroing of ICP Monitors requires:
- Zeroing to room air - Catheter tip transducers only zeroed prior to insertion - External transducers can be zeroed anytime
Indication for ICP monitoring:
-GCS < 8 (or higher if CT of concern {Hematoma, Edema, Contussion, etc}) -Normal CT with GCS 40 2. Posturing 3. SBP < 90 mm Hg -Sedation precluding clinical assessment
ICP monitoring is useful in:
- Head injury 2. Poor grade SAH 3. Intracerebral hematoma 4. Meningitis 5. Stroke 6. Allows calculation of CPP 7. Info on intracerebral compliance
ICP Values:
Normal: 7-15 mm Hg Abnormal: > 20 mm Hg If > 25 mm Hg, aggressive management indicated
High ICP:
will cause internal or external herniation of the brain, distortion and pressure on cranial nerves and vital neurological centers
When ICP is elevated cerebral perfusion will be:
Impeded and operating conditions difficult or impossible
When brain volume increases
loss of CSF and reduction of venous blood volume act to compensate
Subdural hematoma can lead to:
Tentorial herniation
Hemorrhage can lead to:
Subfalcine herniation
Devices to measure ICP:
What is the Gold Standard of ICP measuring?
Intraventricular drain and transducer b/c you can control ICP by CSF drainage and zero externally
What are the contraindications of intraventricular drain and transducer?
- Bleeding
- Blockage
- Infection risk
- Insertion difficulties
Which ventricle is the intraventricular catheter placed?
Lateral ventricle (frontal horn)
