Intracranial Pressure - Exam 6 Flashcards
What is blood brain barrier?
Physiologic barrier between blood capillaries and brain tissue
What is the monroe-kellie docterine?
Within closed space (skull) there must be a constant volume of 3 components within the skull: brain tissue, blood, CSF. If this fails, increase ICP results
The adult skull is a rigid box containing brain tissue, cerebral spinal fluid and blood. When the volume or amount of one of these substances changes there must be changes in the others to compensate.
What is cerebral perfusion pressure?
CPP=MAP-ICP
Normal = 60-100
If ICP is too high, patient’s brain will herniate through formen magnum. If CPP is too low, patient will suffer anoxic brain injury. MAP must be enough to keep perfusing, even with increased ICP.
The amount of pressure needed to adequate perfuse brain tissue (provides adequate O2 and nutrients, removes wastes)
What is cerebral edema?
Swelling/edema of the brain
Fluid volume overload, hyponatremia
3 types: vasogenic, interstitial, cytotoxic
What is brain (tentorial) herniation?
The brain presses into places it should not
What is ventriculostomy/intracranial pressure monitoring?
- To drain CSF out
- Measure ICP
- Instill intraventricular medication
mannitol (Osmitrol)
Classification: diuretic
Mechanism of action: plasma expander, osmotic response. Plasma expanding effect lowers HCT and blood viscosity and increases CBF and O2 delivery. The osmotic gradient created moves fluid from tissue into blood vessels
Use: cerebral edema, increased intraocular pressure
Side/Adverse effects: Increased UO, tachycardia, seizures, rebound increased ICP
Nursing Implications:
- I/O
- BP
- Electrolytes (K, NaCl)
- BUN/Cr
- Neuro checks
- Seizure precautions
- Do not use if patient has kidney disease
- Often given with lasix
- Osmolality
dexamethasone (Decadron)
Classification: Corticosteroid
Mechanism of action: Decreases inflammation by controlling vasogenic edema surrounding tumors/abscesses. Not recommended for use in head injury due to increased mortality risk.
Use: brain tumors (edema around tumor), inflammation, cerebral edema
Side/adverse effects: poor wound healing, increased risk of infection, hyperglycemia, GI hemorrhage, mood changes, psychosis, insomnia, seizures, osetoporosis
Nursing Implications:
- I/O
- Monitor for s/sx of increasing edema
- Daily weights
- S/sx of infection
- Mental status changes
- BG should be monitored
What breathing patterns may be seen with increased ICP?
- Cheyne-Stokes
- Central neurogenic hyperventilation
- Apneustic breathing
- Cluster breathing
- Ataxic breathing
What is cheyne-stokes breathing?
Cycles of hyperventilation and apnea
Location: bilateral hemispheric disease of metabolic brain dysfunction
What is central neurogenic hyperventilation?
Sustained, regular rapid and deep breathing
Location: brainstem between lower midbrain and upper pons
What is apneustic breathing?
Prolonged inspiratory phase or pauses alternating with expiratory pauses
Location: mid or lower pons
What is cluster breathing?
Clusters of breaths follow each other with irregular pauses between
Location: medulla or lower pons
What is ataxic breathing?
Completely irregular with some breaths deep and some shallow. Random, irregular pauses, slow rate.
Location: reticular formation of the medulla
Risk for ineffective cerebral tissue perfusion
Risk for decrease in cerebral tissue circulation
Defining Characteristics:
- Reduction of venous/arterial blood flow and cerebral edema as evidenced by
- CPP <60mm Hg
- GCS <8
- Altered mental status
- Behavioral changes
- Motor dysfunction
Nursing Interventions:
- Neuro checks
- GCS
- NIH stroke score
- Papillary response
- Montor function
- Aphasia
- VS
- I/O
- Electrolytes
- O2 sat
- Fall precautions
- Seizure precautions
- Monitor ICP
- Notify MD of any changes
- End tidal CO2
- Calculate CPP
- HTN with volume expansion, positive intotropic or vasoconstrictive agents to maintain hemodynamic parameters and optimize CPP
- Neurological status to evaluate O2 of brain
- Normovolemia and assess effects of diuretics/corticosteroids
- Safety measures
Decrease intracranial adaptive capacity
Intracranial fluid dynamic mechanism that normally compensates for increase in intracranial volumes are compromised, resulting in repeated disproportionate increase in ICP in response to a variety of noxious and nonnoxious stimuli
Defining characteristics:
- Decreased cerebral perfusion
- Sustained ICP
- Changes in ICP
- Increased BP
- Decreased HR
- Decreased RR
Nursing Interventions:
- Neuro checks
- VS
- Prevent hyperthermia (sometimes induced hypothermia)
- Decrease environmental stimuli
- HOB at 30 degrees to improve venous drainage
- Suctioning as needed for shortest amount of time possible
- Glycemic control (CO2 increased = vasodilation)
- Maintain normal fluid volume
- Sedate patient
- Consider hypothermia as decreased ICP
- Manage pain
What is a major objective when taking care of a patient with ICP or potential for increased ICP?
Protect the patient at risk from sudden icnreases in intracranial pressure
What should you do regarding baseline neurological signs?
Assess baseline neurological signs with periodic reassessment and comparison to previous findings. Assess LOC, pupillary size and reaction to light, eye movement, and motor/sensory function.
Subtle changes in neurological signs can indicate deterioration or improvement in the neurological status. These changes can only be detected by frequent monitoring and comparison with previous findings.