What are three types of cerebral edema?
1. vasogenic 2. cytotoxic 3. interstitial
What is interstitial edema associated with?
seen in acute obstructive hydrocephalus; as the CSF is forced by hydrostatic pressure to move from the ventricular spaces to the interstitium of the parenchyma
What is vasogenic edema?
an extracellular accumulation of fluid that is usually associated with a disruption in the BBB
What is cytotoxic edema?
intracellular accumulation of fluid due to hypoxic-ischemic insult leading to depletion of ATP and subsequent failure of the Na+K+ ATPase, causing an alteration in the selective permeability of cellular membranes. This leads to intracellular edema
What is the goal target for therapeutic hypothermia and how long do you maintain it for?
32 to 34 degrees Celsius and for 12 to 24 hours
The evidence supports hypothermic therapy in cardiac arrest associated with what particular arrhythmias?
cardiac arrest from VF; limited evidence in the setting of non-VF rhythms, including PEA or asystole
What are potential complications for hypothermic therapy? (4)
1. coagulopathy 2. arrhythmias 3. electrolyte abnormalities 4. risk of infections
Uncal herniation presents with what 3 findings caused by compression of what 3 structures?
1. compresses parasympathetic fibers that mediate miosis resulting mydriasis (fixed dilated pupil localizes the side of the uncal herniation) 2. if uncus compresses ipsilateral cerebral peduncle - contralateral hemiparesis 3. compression of PCA - infarction
What is the normal ICP range?
general txt of ICP (6)? specific txt of ICP (9)?
General txt: 1. head of the bed at 30 degrees 2. maintain normothermia 3. glucose control 4. BP control 5. adequate nutrition 6. prevention of complications specific txt: 1. hyperventilation 2. osmotic agents (ie mannitol) 3. hypertonic solutions 4. corticosteroids in select cases (ie brain tumor) 5. CSF drainage 6. surgical decompression in select cases 7. barbiturate coma 8. pharmacologic ppx 9. hypothermia
How long does the effect of hyperventilation on ICP last for?
10 - 20 hours and subsequently a rebound phase with increased ICP may be seen
How does hyperventilation work to decrease ICP?
hyperventilation --> reduction in partial pressure of CO2 --> hypocapnia --> cerebral vasoconstriction --> decrease cerebral blood vol --> reduction in ICP
What is the target pCO2 in hyperventilation?
a reduction of pCO2 by 10 mmHg and or to a target of 30mm Hg
How does mannitol work? What is the dose and the target serum osmolarity?
-raises the serum osmolarity producing an osmotic gradient that drives water from the interstitium to the intravascular compartment -boluses of 0.5 to 1.5g/kg -target level no higher than 320 mOsm/L
Prolonged infusion of sodium nitroprusside can lead to what kind of toxicity? What is the treatment?
-cyanide and thiocynate toxicity (metabolites toxicity) txt: -sodium thiosulfate transform cyanide into thiocynate -although thiocynate is still toxic, it can be excreted by the kidneys -thus can also be treated with dialysis
What is the appearance of SDH on head CT?
crescent or concave shape
What causes SDH?
trauma that produces an acceleration force that causing tearing/rupture of the surface bridging veins
When is surgical evacuation indicated for SDH?
if the SDH is more than 1 cm or if there is midline shift
What is the appearance of epidural hematoma on head CT?
lenticular shaped or biconvex
What causes epidural hematomas?
rupture of the middle meningeal artery (usually associated with a skull fracture)
Describe Lundberg A, B waves, anc C waves in ICP monitoring. What is the significance of these waves, duration, and amplitude?
-Lundberg A waves are pathological; associated with decrease intracranial compliance, intracranial hypertension, with risk of ischemia. Also known as plateau waves. Duration 5 to 20 minutes. Amplitude ranges from 50 mmHg to 100 mmHg.
-B waves are normal; duration 1 -2 minutes; amplitude 20 to 50 mmHg
-C waves are normal; duration 4 to 5 minutes; amplitude < 20 mmHg
What is the initial management of SAH? (5)
1. if cannot protect airway - intubate 2. avoid hypertension/control BP (one aneurysm is secured then you can be more liberal with BP) 3. aggressive isotonic fluids 4. ppx AED 5. mild sedation/optimize pain control
What is the CCB of choice that has been shown to improve outcomes from vasospasm? What is the dose and duration of therapy?
Nimodipine; 60mg Q 4hours for 21 days
What is triple H therapy?
hypervolemia, hypertension, hemodilution Recommended for treatment of vasospasm
What are the risks of triple H therapy?
1. rebleeding from unsecured aneurysm 2. pulmonary edema 3. congestive heart failure 4. cerebral edema
What is apneusis and where does it localize to?
respiratory pause at full inspiration and occurs from bilateral pontine lesions
What is Cheyne-Stoke respiration? Where does it localize to?
hyperpnea alternates with apnea and depth of breathing increases and decreases gradually -poorly localizing; can be seen with forebrain impairment in the setting of intact brainstem respiratory reflexes, but also present in severe cardiopulmonary disease
What is ataxic breathing and where does it localize to?
irregular respiratory pattern (gasping respiration) seen with lesion damaging the respiratory rhythm generator in the upper medulla
What is the treating of ICH in the setting of Warfarin with an INR of 6?
1. withhold warfarin
2. give vitamin K dependent factors (FFP or prothrombin complex concentrates)
3. IV Vitamin K