Disorders of Circulation in CNS Flashcards
Ischemia
Obstructed blood vessels
drops blood flow in brain
Increased Pressure w/in Skull Caused By
hematoma
excessive production of cerebral spinal fluid
blockage of duct system conveying cerebral spinal fluid
Brain & Spinal Cord FX
detect/transmit/analyze sensory information
generate signals to autonomic/motor pathways
orchestrate endocrine functions/coordination/movement
Major Disorders
Transient ischemic attack (TIA)
Stroke
Subdural/Spinal Cord Hemorrhage
Transiet Ischemic Attack
brief appearance of symptoms resembling stroke
generally resolve w/in 24 hours
Stroke
brain attack
enduring disruption of speech/motor/communication/accompanied by cognitive deficits
Cerebrospinal Fluid Pruduced
in choroid plexi of ventricles
CSF Flows Through
ventricular system of brain
subarachnoid space surrounding brain & spinal cord
CSF FX
resorbed into venous dural sinuses via arachnoid villi
balance between production & absorption is critical
CSF Made
constantly
blockage = over-accumulation
increases pressure against brain
Blood-BrainBarrier About
specialized endothelium in brain capillaries
permits selective entry of substances into CNS
tight junctions between endothelial cells
active transport
BBB Transport (Direct)
highly lipophilic substances
BBB Transport (Simple Diffusion)
water
BBB Transport (Facilitated Diffusion)
most nutrients
Meds that typically cross BB
small weight anti-psychotics
sleep aids
antidepressants
98% cannot
Cerebral Autoregulation
maintains steady flow of blood to brain/spinal chord
Cerebral Blood Flow Increased BP Decreased BP Increased PaCo2 Decreased PaCo2
arteries respond to pH/Co2/O2 constricted cerebral capillaries dilated capillaries dilated vessels constricted cerebral vessels
If Autoregulatory Mechanisms Fail
loss of match between oxygen supply/demand of tissues
Intracrainial Pressure
pressure exerted by contents of cranium
compensatory relationship maintains cerebral compliance in response to changes in volume
Injured Brain Tissue
cytotoxic edema vasogenic edema
clearance of brain tissue swelling
Hydrocephalus
excessive accumulation of CSF in cranial vault that compresses surrounding structures
Hydrocephalus Causes
lesions that obstruct CSF flow
problems with resorption
Intracranial Pressure (ICP) NV
5-15 mmHG
Increased ICP Causes
trauma hemorrhage growths/tumors hydrocephalus edema inflammation in brain
Increased ICP Effects
impeded circulation to brain
impeded absorption of CSF
impacts fx of nerve cells
leads to brainstem compression/deat
Neuro Assessment
Altered level of consciousness (earliest sign of increased ICP) pupillary changes fever headache nausea vomitting abnormal respirations
Later Signs of Neurological Changes
elevated SBP widened pulse pressure bradycardia LATE changes in motor function positive babinski (toes extended) decorticate (Cs inward) decerebrate(Es outward) seizures
Glasgow Coma Scale uses
gauge impact of acute brain trauma vascular injury/infection hepatic/renal failure hypoglycemia diabetic ketoacidosis
Glasgow Coma Scale
Severe
Moderate
Mild
<8
9-12
13-15
Elevated ICP Intervenions
avoid increasing intra pressure (straining/coughing/blowing nose) head of bed 30-40 degrees head in neutral position avoid flexion of neck/hips minimal stimuli bring items closer to prevent reaching
Hydrocephalus Etiology/Patho
imbalance of I/O CSF flow blockage of CSF through ventricles Inhereted genetic abnormalities/developmental disorders (ex spina bifida) complications of premie birth intraventricular hemorrhage meningitis tumors traumatic head injury subarachnoid hemorrhage
Hydrocephalus Infants S/s
rapid increase of head circumference unusually large head size vomiting sleepiness irritability downward deviation of eyes (sun setting) seizures
Hydrocephalus Adults s/s
skulls cannot expand headache w/ vomiting nausea blurred/double vision sun setting balance issues poor coordination gait disturbance urinary incontinence slow/loss of development lethargy drowsiness irritability personality/cognition changes memory loss
Hydrocephalus TX
Ventriculoperitoneal (VP) shunt placed CT scan for FX/malfunction medication (controversal) only temporary acetazolamide furosemide
Carbonic Anhydrase Inhibitor (class/ex/moa/actions)
anticonvulsant
acetazolamide
inhibits carbonic anhydrase from catalyzing hydration/de of CO2 to carbonic acid
controls fluid secretions
promotes diuresis in abnormal fluid retention
used in glaucoma tx
acetazolamid SE/BBW/Contra/Intx/Preg
Stevens-Johnson syndrome toxic epidermalnecrolysis (TEN) acidosis agranulocytosis hepatic necrosis NONE cirrhosis, hypokalemia, hyponatremia, renal dysfunction, suprarenal gland failure can inhibit renal excretion of basic drugs/promote acidic drug release, increase salicylate toxicity (acidosis) C
Brain use of Total Cardiac Output/Body’s Oxygen Consumption
15%
20%
Cerebral Blood Flow
Cerebral Vascular Resistance (CVR) x Cerebral Perfusion Pressure (CPP)
Mitochondrial Dysfunction
leads to infarction/tissue death
anaerobic glycolytic pathways initiated
Energy Deprivation/Loss of Ion Homeostasis
cells can’t maintain negative membrane potential
excitatory amino acids in extracellular space
glutamate/influx of CA ions
apoptosis
Cerebral Hemorrhage in Sepsis
immune cells activated
leukocytes enter brain
inflammatory agents contribute to brain inflammation
nitric oxide/nitric oxide synthetase pathway
mitochondrial dysfunction/apoptosis
Stroke (Ischemic vs Hemorrhagic)
interruption in blood supply to region of the brain or bleeding in vessel resulting in tissue damage or infarction
87% vs 13%
Stroke s/s
sudden onset of focal neurologic deficit persisting for at least 24 hours
depend on area affected
Stroke Patho/Causes
partial or complete occlusion of cerebral blood flow due to thrombus/embolus
atherosclerosis
cardiac disorders
thrombotic strokes (internal carotid artery, middle cerebral artery, basilar artery)
Stroke Hemorrage Causes
burst blodo vessel (intracerebral/intraventricular/extracerebral) subarachnoid hemorrhage cerebral aneurysm ischemic conversion arteriovenous malformations (aVMs)
Ischemic Stroke TX
restoration of blood flow/reduce area effected supplemental o2 glycemic control fibrinolytic therapy antihypertensive therapy aspirin 325 mg hypothermia blood pressure control
Hemorrhagic Stroke TX
osmotic diuretics blood pressure control surgical evacuation craniotomy w/ aneurysm clipping endovascular therapy w/ coil embolization delayed cerebral ischemia (DCI)
Penumbra
tissue surrounding infartction
Osmotic Agent (class/ex/moa/actions)
Diuretic mannitol promotes diuresis by increase ECF osomolarity tx cerebral edema/acute glaucoma increase in plasma oncotic pressure
Mannitol (SE/BBW/Contra/In/Preg)
GI symptoms Dizziness CHF Compartment Syndrome injection site extravasation Fluid/Elec Imbalance Acute injury of Kidneys Pulmonary Edma Coma Seizures ^ Dose = ^ risk of kidney disease/fluid overload (life-threatening pulmonary edema) [Severe Bronchospasms] anuria/aortic&cerebral aneurysm/uncontrolled HTN/recent MI or CVA/severe hypovolemia/dehydration/active intracranial bleed/pulmonary edema Tobramycin = ototoxicity fetal risk can't be ruled out
Fibrinolytic Therapy
clot removal w/in 24-48 hrs of formation
Tissue Plasminogen activator (TPA) alteplase (Activase)
TPA converts plasminogen to plasmin
Plasmin digests fibrin strands restoring circulation
regulates unwanted clots, fibrin remains
Blood Modifier Agent (Class/ex/Moa/Actions)
Tissue plasminogen activator
alteplase
enhances conversion of plasminogen to plasmin biding to fibrin (initiating fibrinolysis)
TX acute MI/ischemic, acute CVA/pulmonary embolism/central venous catheter occlusion
Alteplase (SE/BBW/Contra/IX/Preg)
Can Cause intercranial Hemorrhage (frequent neuro checks 15 min/signs of increased ICP like headache)
Angioedema/allergic rx
Once started do not insert additional IV/catheter
NONE
active internal bleeding/intracranial hemorrhage, AVM, bleeding diathesis, severe uncontrolled HTN/subarachnoid hemorrhage/within 3 months of cranial or spinal surgery or serious head trauma
anticoagulants/antiplatlets = increased risk of bleeding
ace-inhibitor = angioedma
fetal risk cannot be ruled out
Anti-Platelet Therapy (moa/primary use/medications/nursing)
alters plasma membrane of platelets so they cannot aggregate
prevent thrombi formation after stroke of MI
aspirin clopidogrel
monitor for bleeding/prolonged pressure needed w/ puncture sites
Clopidogrel (moa/uses)
inhibits platelet aggregation by selectively bonding to receptors on platelets
prevents thrombi formation after stroke or MI
Clopidogrel (SE/BBW/Contra/INtX/Preg)
bleeding (can be fatal)
epistaxis
hematuria
bruising
ulcers
TTP
[diminished antiplatelet effect if 2 loss of function alleles of CYP2C19 gene]
active bleeding, peptic ulcer, intracrainial hemorrhage
omeprazole (cyp2c19 inhibitors), NSAIDs/warfarin/SSRIs/SNRIs
Fetal risk can’t be ruled out
Transient Ischemic Attack (TIA) CAuse
temporary episodes of neurologic dysfunction
focal brain/spinal cord/retinal ischemia wout acute infarction
TIA s/s
facial dropping arm/leg weakness on one side of body speech difficulty sudden trouble seeing in one or both eyes difficulty walking w/ dizziness lack of balance/coordination severe headaches
TIA Risk Factors
age family prior TIA/stroke race sex sickle cell MODIFIABLE: cardiovascular disease carotid artery disease diabetes excess weight high blood pressure high cholesterol smoking heavy drinking physical inactivity poor nutrition use of birth control pills
TIA DX/TX
exclusion of conditions that mimic TIA BG/blood tests to rule out electrocardiography noncontrast CT MRI w/ diffusion-weighted imaging CT angiogrpahy/magnetic resonance angiography carotid doppler
Subdural Hematoma
bleeding from bridging veins between dura mater/arachnoid membrane
Subdural Hematoma Patho Causes
trauma from high-speed impact to skull
spontaneous
acute (bleeding identified immediately after injury)
chronic (brain atrophy)
Subdural Hematoma s/s
headache confusion changes in behavior dizziness nausea vomiting lethargy excessive drowsiness weakness apathy seizures
Subdural Hematoma TX
surgery
Spinal Cord Hemorrhage Patho
rare trauma vascular malformation bleeding disorders epidural/subdural/subarachnoid/intramedullary
Spinal Cord Hemorrhage s/s
sudden/severe back pain w/ or w/out radiculopathy
headache
neck stiffness
photosensitivity
irreversible sensory loss below level of bleed
Spinal Cord Hemorrhage TX
subdural: surgical decompression
subarachnoid: surgical resection
catheter-based interventional techniques
focal radiation w/ gamma knife/cold photon knife
First Question to ask
When was the last well?
Hypoglycemia can
Mimic the s/s of a stroke
24 Hours post Ischemic Stroke
TPA cannot be used for fear of causing a hemorrhagic stroke
