Unit 1: Increased Intracranial Pressure Flashcards
Monro-Kellie Doctrine
3 components (brain tissue, blood, and cerebrospinal fluid) occupy a rigid box, the skull -When one of these 3 increases, the other components must decrease to maintain equilibrium, preventing further injury to the brain through compression of the tissue within the fixed box (skull)
What 3 components occupy the skull?
- Brain tissue (80%)
- Blood (10%)
- Cerebrospinal fluid (CSF) (10%)
Intracranial Compliance
ability of the body to compensate by adjusting the levels of the components (brain tissue, blood, and CSF)
Brain Tissue
composed primarily of water
-makes up 80% of the intracranial components
Blood + Cerebrospinal fluid (CSF)
each make up 10% of the remaining contents within the cranium
Normal ICP
0-15
Herniation Syndromes
classified according to the region of tissue that is displaced
- brain shifts
- can occur with continued addition of volume
- S/S: “Cushings Triad”: increased SBP w/ widening pulse pressure, bradycardia, and irregular respirations
Cushings Triad
-Increased Systolic BP w/ widening pulse pressure
-Decreased HR (bradycardia)
-Irregular Respirations
>late sign of Increased ICP
>occurs late in the herniation process as the brainstem is compressed
Increased ICP Assessment Findings
- Increased confusion
- Progressive lethargy
- Sluggish pupils
- Motor Weakness
- Vomiting
- No change in vital signs
Herniation Assessment Fidnings
- Unresponsive (GCS <8); coma
- Unilateral or Bilateral pupillary dilation
- Contralateral (opposite side) Hemiparesis
- Flexor or Extensor posturing
- Positive Babinski reflex (toes flare out)
- Cushings Triad
Glasgow Coma Scale
-Best Eye Opening (1-4)
-Best Motor Response (1-6)
-Best Verbal Response (1-5)
>15 highest score
>3-8= coma
What is the most sensitive indicator of increased ICP?
decreased LOC
How to detect Increased ICP?
-neurological assessments
-elements of wakefulness
-arousal
-cranial nerves
-motor function
>establish an accurate baseline of functioning from which to judge deterioration
Management of Increased ICP
- Decreasing the volume of brain water, blood, or CSF in the intracranial space
- Emergency management: airway management and therapies to decrease intracranial contents (osmotic diuretics, hyperventilation)
- Vigilant monitoring (neurological status)
Management of Increased ICP: Vigilant monitoring
- To identify neurological deterioration that places a patient at risk for increased ICP and cerebral herniation syndrome
- Assess oxygenation, ventilation, and hemodynamic parameters to optimize therapy and prevent or mitigate brain injury
- Full systems assessment to identify signs of complications/ conditions that may negatively impact the patient w/ increased ICP, such as respiratory compromise
- Assess laboratory values (serum electrolytes, serum osmolality) to detect electrolyte imbalance and dehydration, which can lead to renal insufficiency or failure
Diagnosis of Increased ICP
- CT Scan to determine the cause of increased ICP (e.g. collection of blood, cerebral edema)
- Laboratory testing (serum osmolality, ABGs) to guide medical treatments
CT Scan
uses x-rays to obtain many cross-section/ slices of the head and brain
- allows detailed views of the skull, brain structures and tissue, facial bones, or sinuses
- performed quickly
- w/ or w/o contrast
- first performed w/o contrast to visualize brain structures and detect bleeding (contrast and blood appear the same color (white) in the brain tissue)
- images obtained after contrast if a mass (brain tumor, abscess) is suspected b/c IV contrast travels into brain tissue where the blood brain barrier has been disturbed; a mass “lights up” on a contrast CT scan b/c the BBB has been disrupted and the contrast has infiltrated the interstitial space in and around the mass
Nursing Considerations for CT scan
- Transport of the pt w/ increased ICP performed with the right team depending on stability of the pt (providers, nurse practitioners, or respiratory therapists; to ensure continuity of care from ICU to procedure area
- Assess for contrast-induced nephropathy; hypotension, diabetes, and chronic kidney disease
- Serum creatinine (within 24 hours of test) b/c contrast can damage the kidney
- Serum Creatinine monitored at least once after the contrast administration and more often if acute kidney injury is suspected; an increase of at least 0.5 mg/dL is expected, will decrease over 24-48 hours
- Pregnancy test performed prior
- Assess ability to remain still
- Patients with increased ICP may be confused, restless, or agitated, requiring sedation or anxiolysis
- Assess ability to lie flat during the scan
- Assess allergy to iodine or shellfish
- Assess IV access
Medications used to decrease cerebral edema
-Osmotic Diuretics (Mannitol)
-High concentration sodium chloride
>these medications are used to increase the osmolality of the blood (increase solute in the blood) in order to pull water from the interstitial space of the brain and other tissues into the vascular space; area from low concentration (brain tissue) to high concentration (blood)
Osmotic Diuretic: Mannitol (Osmitrol)
pulls water from the interstitial spaces into the vascular space, and then diuresis occurs at the level of the kidney
- IV fluid should be administered to replace fluid losses
- Side Effects: hyponatremia, hyperkalemia, acute kidney injury
- Assess BUN and Creatinine
- Monitor Electrolytes
High Concentration Sodium Chloride
pull water from the interstitial spaces into the vascular space w/o the dramatic fluid shifts caused when osmotic diuretics are utilized
Physical Interventions for Increased ICP
- Raise HOB to 30-45 degrees
- neck in neutral position
- hip flexion minimized
- hyperventilation
- external drainage of CSF
Surgical Management: Hemicraniectomy w/ a durotomy
removal of a section of the cranium and dura in order to create space for the swelling brain
- removal of a section of the skull and opening of the dura
- the skull is removed and stored in a tissue bank or tissue pocket within the patients abdomen
- dura is replaced w/ synthetic material that allows for brain tissue expansion and watertight closure of the meningeal layer
Intracranial Pressure Monitoring
ICP can be monitored using a catheter or sensor placed in one of the lateral ventricles of the brain, in the brain tissue/ parenchyma, or in the subarachnoid space
- used for pt’s w/ a traumatic brain injury (TBI) or GCS of <8
- can increase risk of infection; risk of bleeding along catheter tract
- an accurate ICP can be monitored only when the drainage system is closed to CSF drainage
- drainage system must be correctly leveled after the HOB is repositioned to safely drain CSF
- maintain system as a closed system to prevent infection
