Neuro Emergencies Flashcards
Monroe-Kellie Hypothesis
“We have a perfect environment inside our cranium”
Cranial vault is a fixed space. If we had any increase in one component(blood, brain, CSF) there has to be a decrease in another component.
Normal ICP measurement
0-15mmHg
What is CBF
Cerebral Blood Flow- requires 15-20% of cardiac output to meet metabolic demands and is maintained by cerebral autoregulation
What is CPP
Cerebral Perfusion Pressure- Gradient that drives CBF and is calculated as follows: CPP=MAP-ICP
Normal CPP 60-80mmHg
Brain requires 60-70 for optimal CBF
Adult goal = >70mmHg
Peds goal = >60mmHg
CPP <50mmHg = infarction
MAP and Pulse pressure calculations
MAP=[(DBPx2)+SBP]/3
Pulse pressure= SBP-DBP
How to maintain CBF
increase MAP and decrease ICP
*CO2 affects chemical regulation is cerebral vascular resistance
Hypocapnia will cause Vasoconstriction(could lead to infarct)
Hypercapnia will cause Vasodilation(causes an increase in ICP)
**New standard is to prevent the 3 H’s( Hypoxia, Hypotension, Hyperventilation)
Causes of secondary TBI
Hypoxia, Hypo/Hypertension, Hypo/Hypercapnia, Ischemia, Edema, Vasodilation, and increased ICP
Signs of increased ICP
Change in LOC, pupil size/reaction, motor response, signs of herniation(decorticate/decerebrate/blown pupils), and Cushings Triad( HTN/widening pulse pressure, bradycardia, Cheyne-Stokes respirations) Standard ICP patient will initially see tachycardia instead of brady.
Elevated ICP treatment
limit suction, noise, and atmospheric pressure changes.
Fluid balance
Normothermia
Normal electrolytes
Sedation and analgesia(consider long acting paralysis)
head to bed elevated to 30 degrees
Osmotherapy with mannitol or hypertonic saline
Concave vs Convex CT head scans
Concave always means an Epidural bleed.
Convex is always a Subdural bleed.
Subdural bleed
40-60% mortality rate.
VENOUS BLEED
Causes: HTN, ruptured aneurysm, and trauma.
Occurs between dura and arachnoid.
typically have immediate LOC
Subdural bleed treatment
advanced airway management(maintain ETCO2 35-50mmHg)
adeqaute fluid resuscitation
osmotherapy (mannitol, lasix, 3% saline)
maintain serum Na+ at upper limit of 155mEq/L
higher serum osmolarity(<320mOsm)
anticonvulsants for seizure prevention
CT findings
If the bleed is lighter in color(white) then its fairly new. Darker in color(grey or black) its an older bleed
Epidural Bleed
ARTERIAL BLEED(usually from middle meningeal artery) temporal lobe damage(side of the head)
occurs between cranium and dura
often associated with skull Fx
**classic presentation is initial LOC with a lucid interval, followed by neurological deterioration
causes rapid compression of the brain stem
Epidural Bleed treatment
Decrease ICP
Evacuate bleed ASAP
Low mortality if treated in timely fashion