Term
| What are the two most common causes of spontaneous subarachnoid hemorrhage? |
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Definition
1. Aneurysm
2. AV maformation |
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Term
What is a common complaint of someone with a subarachnoid bleed?
What percentage of these folks die regardless of treatment? |
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Definition
"Worst headache of my life"
50% |
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Term
| Besides headache, what are some symptoms of SAH? |
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Definition
Pupil changes and fundoscopic hemorrhage or edema with photophobia.
Also, 20% have evidence of myocardial ischemia due to the very high circulating catecholamines. |
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Term
| What is an intracerebral hematoma, and what is the treatment? |
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Definition
| Bleeding directly into brain tissue. If large, they may be evacuated, but they are usually treated medically. |
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Term
When will an ICP monitor be used?
When are ICPs usually treated? |
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Definition
If the GCS is 3-8 after adequate resuscitation of shock, if they are >40 years, if the SBP < 90, and/or posturing
Treatment when ICP 20-25 |
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Term
| Besides keeping the ICP down, what is the goal for CPP? What can make this difficult? |
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Definition
CPP > 60-70
Other injuries resulting in hemorrhage (intra-abdominal, thoracic, vascular and orthopedic injuries) |
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Term
Where do aneurysms typically occur?
If an aneurysm ruptures, resulting in SAH, how many of those pts will die? |
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Definition
Anterior Circle of Willis
2/3 of pts |
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Term
| What is vasospasm, and when is it most likely to occur? |
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Definition
| An intractable constriction of cerebral blood vessels due to free oxyhemoglobin which releases vasoactive substance and free radicals. Most likely to occur post bleed or clipping between days 4-14 |
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Term
| Preventing vasospasm is critical. What measures do we employ to do that? |
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Definition
1. Hypervolemia (CVP > 12, PAP > 18 with fluids and colloids)
2. Hypertension (vasopressors)
3. Hemodilution (HCT 30%)
4. Calcium channel blockers (Nimodipine or Nicardipine) |
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Term
| What is a big concern for us during induction of someone with an aneurysm? |
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Definition
| Rupture or rebleeding of the aneurysm. Rupture = mortality. |
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Term
What is transmural pressure?
What does transmural pressure have to do with aneurysms? |
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Definition
| The pressure on the inside minus the pressure on the outside. If the pressure on the inside is too much, the wall tears. If the pressure on the outside is too much, the vessel can tear or collapse. So during induction and maintenance, we need to avoid increasing the transmural pressure and maintaining CPP |
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Term
| What are some specific things we might do that would increase wall stress in an aneurysm and cause potential rupture? |
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Definition
| Light anesthesia leading to sudden changes in MAP, or hyperventilation, leading to a sudden decrease in ICP |
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Term
When do you want to replace the NPO deficit during an aneurysm clipping?
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Definition
| Once the dura is open, but prior to the aneurysm clipping. Replacing it sooner, might result in brain swelling, increasing the ICP. |
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Term
What do you want available prior to clipping?
Temporary clips are placed proximally and distal to the aneurysm. What hemodynamic parameters are we shooting for during a temporary clip?
How does this differ is temporary clips are not being used? |
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Definition
Blood.
MAP should be kept normal-high to maintain collateral circulation through the circle of willis. However, is temporary clips are not used, deliberate hypotension should be used, targeting a MAP of 40-50. This can be done with nipride, esmolol, isoflurane--short acting drugs! |
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Term
Oops--the aneurysm ruptured.
What do we need to do? |
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Definition
1. Institute hypotension (the pt will do this as they bleed out)
2. Aggressive fluid and blood therapy
3. Cerebral protective agents (pentothal)
4. Carotid compression up to 3 minutes |
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Term
| What is an AV malformation? |
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Definition
| A congenital lesion forming high-flow low resistance shunts. No capillary bed exists. The high arterial pressure dilates the draining veins. The high flow through the AVM causes a steal phenomena. Pts frequently preset post bleed. |
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Term
| What happens to vessels distal to the AVM? What happens after the AVM is repaired? |
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Definition
| They compensate for decreased flow by shifting the autoregulation curve to the left. Following resection, flow is restored. The high pressure flow through tissue not used to the pressure can produce edema distal to the AVM. Treatment may be embolization or surgical clipping. |
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Term
True or false?
In regards to tumors:
1. Symptoms depend on location, size, and type of tumor.
2. We have no treatment to treat edema around the tumor.
3. Radiation my be used to reduce the size of the tumor.
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Definition
1. True
2. False. Steroids may be used.
3. True. Be cautious of friable tissue |
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Term
| Tumor location is often categorized into 2 general areas. What are they? |
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Definition
| Supratentorial and Infratentorial. |
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Term
| What's the biggest implication associated with supratentorial lesions? |
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Definition
| Difficulty with managing ICP (related to area of CSF production/absorption). |
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Term
| The infratentorial space is small and confined in the posterior fossa. What is contained in this area? What are the implications of this? |
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Definition
| Contains the medulla, pons, cerebellum, lower cranial nerves, motor and sensory pathways. Infratentorial lesions can create problems with mass effect or brainstem structures and hydrocephalus. This can lead to serious hemodynamic changes, arrhythmias, elevated ICP and reduced CPP. |
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