Acute Intracranial Problems Notes Flashcards
3 essential volume components of the skull
Brain Tissue
Blood
Cerebrospinal Fluid (CSF)
Primary Injury
Occurs at the initial time of injury
Secondary Injury
Effects of the primary injury that can appear in a few hours to a few days.
Intracranial Pressure (ICP)
Pressure of CSF fluid within the brain.
Factors that influence ICP
Arterial Pressure Venous Pressure Intraabdominal Pressure Posture Temperature Blood Gases
Monro-Kellie Doctrine
The 3 components must stay in a constant volume overall.
Only affects when the skull is closed.
Brain compensates in any component if one component is displaced more than others.
Normal ICP ranges
5-15 mmHg
Cerebral Blood Flow (CBF)
Blood supply given to the brain in any given time period, usually 1 minute.
Cerebral Autoregulation
Automatic adjustment that the brain does to maintain a constant blood flow when arterial BP changes.
Normal MAP
60-100 mmHg
Most people have 70mmHg
Critical to maintain MAP when ICP is increased
Cerebral Perfusion Pressure (CPP)
Pressure needed to ensure blood flow to the brain.
Normal CPP
60-100 mmHg
How to calculate MAP
(SBP+2(DBP))/3
How to calculate CPP
CPP=MAP - ICP or
CPP= Flow x Resistance
Factors Affecting Cerebral Blood Flow
CO2
O2
Hydrogen ions (H+)
Why is it critical to maintain CBF?
To preserve tissue and minimize secondary injury.
Prevent brainstem compression and brain herniation.
3 Types of Cerebral Edema:
Vasogenic
Cytotoxic
Interstitial
Vasogenic Cerebral Edema
Most common type
Characterized by leakage of large molecules from capillaries into surrounding extracellular space.
Cytotoxic Cerebral Edema
The cell membrane breaks and moves fluids and proteins into cells.
Interstitial Cerebral Edema
Result of hydrocephalus (buildup of brain fluid)
C/M on Increased ICP
Changes in LOC - most reliable indicator of neuro status
Cushing’s Triad - MEDICAL EMERGENCY
Compression of Cranial Nerve III - fixed unilateral dilated pupils - MEDICAL EMERGENCY
Blurred vision, diplopia, and extraocular eye movements
Compression of Cranial Nerves II, IV, and VI.
Contralateral hemiparesis or hemiplegia
Decorticate or Decerebrate posturing
Headache
Unexpected vomiting
Projectile Vomiting
Cushing’s Triad
MEDICAL EMERGENCY
Systolic HTN with widening pulse pressure
Bradycardia with bounding peripheral pulses
Irregular Respirations
Which is worse: decorticate or decerebrate
Decerebrate
Why do we have to monitor for headache?
Headache may appear benign but that’s an early symptom of cerebral edema and increase ICP that can lead to coma and death
2 Major Complications:
Cerebral Perfusion
Cerebral Herniation
Tentorial Herniation
Mass lesion in the cerebrum forces brain to herniate downwards
Uncal Herniation
Lateral and downward herniation
Cingulate Herniation
Lateral displacement of brain tissue under falx cerebri (dura wall that separate’s 2 cerebral hemispheres)
Diagnostic Studies
CT and MRI Cerebral angiography EEG PET Transcranial Doppler Studies Infrascanner - detects life-threatening intracranial bleeding ECG Lumbar Puncture (LP) Lab Studies
Why should you not perform a LP when an ICP is suspected?
Possible cerebral herniation can occur when the pressure is released during a LP.
Indications for Intracranial Pressure Monitoring
Hemorrhage Stroke Tumor Infection Traumatic Brain Injury (TBI) Pts with GCS < 8 Abnormal CT or MRI scan
Ventriculostomy Nursing Management
Gold Standard for monitoring ICP
A specialized catheter is inserted into the lateral ventricle with an external transducer.
Make sure the transducer is in the same level as foramen of Monro
Document ICP every hour
Turn and reposition the patient every 2 hours.
Check capillary blood glucose level every 6 hours.
Monitor cerebrospinal fluid color and volume hourly.
Fiberoptic Catheter
A sensory transducer is found within the catheter tip.
Sensor tip is placed within the brain tissue and ventricle.
It gives a direct measurement of brain pressure.
Air pouch/Pneumatic technology
Air-filled pouch at the tip of the catheter that maintains a constant volume.
How do you get an accurate reading of ICP with CSF device in place?
Close drain for 6 minutes
Monitor ICP waveform and mean ICP
Major Complication for ICP monitoring?
Infection
Intermittent Drainage
Open the system at indicated ICP and allow to drain for 2-3 minutes. Then close it after draining
Continuous Drainage
Monitor for drained CSF volume
Strict aseptic technique
LICOX and Neurovent catheters
Placed in healthy white matter of the brain
Measure brain oxygenation and temperature.
Jugular Venous Bulb Oximetry
Measures oxygen in jugular vein using a catheter
SjvO2 should be 60-75%
Mannitol (Osmitrol)
decreases ICP via plasma expansion and osmotic effect
Monitor fluid and electrolyte status
Contraindicated by renal disease
Hypertonic Saline
Shifts fluids out of brain cells and into blood vessels.
Frequent monitoring of BP and serum sodium levels
Corticosteroids
Treat vasogenic edema around tumors and abscess
Improves CBF and restores autoregulation.
Monitor fluid intake and sodium levels
Monitor blood glucose
Give antacids, histamine blockers or PPI to prevent GI ulcers and bleeding
Barbituates
Reduces cerebral metabolism
Monitor pt’s ICP, blood flow and EEG
Ventriculostomy Indications
Hydrocephalus
Cerebral Edema
Increased ICP
Decorticate Posturing
Flexor position
Flexion position of arms, wrists, and fingers with adduction in upper extremities: extension, internal rotation and plantar flexion in lower extremities
Nursing Management of ICP
GCS
Neuro Assessments include Assessing CN III, CN IV, and CN VI
