6901 Neuro Part II Flashcards
1
Q
Low doses of volatile agents do what to CBF?
A
it’s either unchanged or increased
2
Q
Low doses of volatile agents do what to CBF?
A
it’s either unchanged or increased
3
Q
What happens to CBF in higher doses of volatile agent?
A
increases bc of the vasodilator effect
4
Q
Autoregulation is impaired with what MAC?
A
> 1
5
Q
Least and worst problematic inhalational agent?
A
sevo; halothane
6
Q
Vasodilator influence of volatile agents is opposed by?
A
decreased CMRO2
7
Q
Coupling includes what 2 values?
A
CBV and CMRO2
8
Q
Coupling occurs at what MAC value?
A
9
Q
What do volatile agents do to the coupling effect?
A
alter the coupling effect by redistributing the blood flow
10
Q
Uncoupling is when?
A
CBF increases and CMR does not
11
Q
What is circulatory steal?
A
increase in blood flow to normal areas but in ischemic areas vessels are maximally dilated and blood is redistributed away from ischemic area
12
Q
Only what type of brain tissue can constrict?
A
normal
13
Q
What happens to CBF in higher doses of volatile agent?
A
increases bc of the vasodilator effect
14
Q
Autoregulation is impaired with what MAC?
A
> 1
15
Q
Least and worst problematic inhalational agent?
A
sevo; halothane
16
Q
Vasodilator influence of volatile agents is opposed by?
A
decreased CMRO2
17
Q
Coupling includes what 2 values?
A
CBV and CMRO2
18
Q
Coupling occurs at what MAC value?
A
less than 1
19
Q
What do volatile agents do to the coupling effect?
A
alter the coupling effect by redistributing the blood flow
20
Q
Uncoupling is when?
A
CBF increases and CMR does not
21
Q
What is circulatory steal?
A
increase in blood flow to normal areas but in ischemic areas vessels are maximally dilated and blood is redistributed away from ischemic area
22
Q
Only what type of brain tissue can constrict?
A
normal
23
Q
What do volatile agents do to the coupling effect?
A
luxury perfusion which is when increased CBF causes decreased CMRO2
24
Q
What type of MACs cause luxury perfusion/uncoupling?
A
higher
25
What is Robin Hood phenomenon?
vasoconstriction in normal vessels in the brain (decrease flow to normal area and increase flow to ischemic area)
26
Barbs cause what?
vasoconstriction
27
Effects of CBF last how long with all volatile agents?
2-5 hours
28
Which volatile agent causes the least vasodilation?
Iso
29
Which volatile agent causes biggest reduction in CMRO2?
Iso
30
Does N20 interfere with MEPs?
yes
31
What is the consensus about use of N20 in intracranial surgery?
controversial
32
N20 has been shown to increase what 3 things?
ICP, CBF, CMRO2
33
What's significant about use of N20 with hypocapnia and IV anesthetics?
no change in CBF
34
Does Iso or Sevo increase the CBV more?
Iso
35
What does propofol do to CBF and CMRO2?
dose dependent decrease
36
Can you use propofol for MEP monitoring?
yes
37
What relaxes the brain better than volatile anesthetics?
propofol
38
What does etomidate do to CBF, CMRO2, and ICP?
decrease
39
The only agent that dilates cerebral vasculature and increases CBF by 60-80%?
ketamine
40
What type of effect do opioids have on CBF, CMRO2, and ICP?
minimal
41
What do benzos do to CBF, CMRO2?
decrease them to a lesser extent than barbs
42
What type of drug decreases CMRO2 the most?
barbs
43
What type of drugs decrease CBF the most?
propofol
44
Drug that is useful for awake craniotomy and carotid endarectomy?
dexmetomidine
45
Why is dexmetomidine a good drug for smokers?
their airways are really reactive and this allows for a smoother emergence
46
What does precedex do to CBF and CMRO2?
decreases CBF w/out decrease in CMRO2
47
Downfall to precedex?
may limit adequate cerebral oxygenation
48
Should you avoid suxxs when rapid paralysis is desired?
no
49
What is suxxs effect on CBF, CMRO2, ICP? What can you do to blunt that response?
increases prob d/t the fasciculations; give nonfasciculating dose
50
NMDAs effect on CBF, CMRO2, ICP?
little
51
Do you need to avoid NMDAs for cranial nerve monitoring?
yes
52
What about NMDAs may cause increased CBF?
histamine release that leads to dilation
53
What may NMDAs interact with?
seizure meds like phenytoin
54
If pt is on a lot of meds with hepatic enzyme induction what does that mean for suxxs and NMDAs?
rapidly metabolized and don't last long; may need larger dose
55
These drugs are preferred for control of HTN after intracranial procedures?
Esmolol, Labetolol
56
What effect do Esmolol and Labetolol have on CBF and CMRO2?
none
57
Caution with use of these antiHTN drugs that impair autoregulation and dilate cerebral vessels and cause increased CBF and ICP?
nipride, nitro, hydralazine
58
Drug used to prevent vasospasm after subarachnoid bleed?
nimodipine
59
Adenosine is used for aneurysm clip surgeries why?
a lot easier to place clip if heart brady or stopped
60
Drug used during Na thiopental admin to offset hypotension?
phenylephrine
61
Most widely used drugs for decreasing CMR, with objective of causing coupled reduction in CBF and CBV?
barbs
62
What's the end point for maximal brain protection?
burst suppression
63
Another drug that may cause coupled reduction in CBF and CBV?
propofol
64
How do glucocorticoids work for brain surgery?
penetrate the BBB and decrease edema associated with lesions
65
Most commonly used glucocorticoid regimen during intracranial surgery?
dexamethasone 4mg q6h
66
How long does it take to see effects from glucocorticoids in decreasing ICP?
several hours; so a lot are started 48 hours before surgery
67
A drug that is given prophylactically to decrease cortical irritation?
dilantin
68
These type of diuretics produce general diuresis and decrease the rate of CSF production and decrease cerebral edema?
loop diuretics
69
These type of diuretics decrease the water content of the brain?
osmotic
70
Do osmotic diuretics decrease ICF or ECF water?
both
71
Why do you give mannitol slowly?
may produce rapid vasodilation (hyperosmolarity), increased CBF, a transient rise in ICP, and increase in CBV
72
How quickly should you give mannitol and what should you monitor during it?
15 min; ICP
73
Dose of mannitol?
0.25-1g/kg
74
What do you have to do to prevent edema in prolonged surgeries if you have given mannitol during intracranial surgery?
check serum Na levels on regular basis
75
3 times fent, lido, prop should be given during intracranial surgery to blunt SNS response?
intubation, suctioning, skull pin application
76
Great risk of ICP spikes and brain herniation if midline shift >?
5cm
77
S/s increased ICP?
N/V, HTN, bradycardia, personality change, altered LOC, papilloedema, seizures, neuro deficits, resp pattern
78
How high should HOB be elevated to help with venous drainage?
15-30
79
How soon should intracranial surgery be delayed after balloon angioplasty, BMS, and DES?
> 2 weeks angioplasty, 4-6 BMS, 12 mos DES
80
Why do you use benzos and opioids with caution as premedication in brain surgery?
respiratory depression and increased ICP
81
In patients with midline shift and abnormal ventricular size what should you do with premedication?
omit
82
What 3 things should you avoid in neurosurgical patients?
hypotension, HTN, prolonged apnea
83
How should you treat hypotension in neurosurgical pts?
gentle volume and alpha adrenergic agonist
84
Which surgery do you need to be particularly mindful in preventing HTN with DL?
aneurysmal subarachnoid hemorrhage bc it can prevent recurrent hemorrhage from the aneurysm
85
Why should you prevent apnea in neurosurgical pt?
it causes increase in PaCO2 and corresponding cerebral vasodilation and decreases CPP
86
How can you blunt the effects of induction in neurosurgical pt?
fentanyl and lido 1.5 mg/kg
87
What does a flexed head impede?
jugular venous drainage and so it increases ICP
88
Why should you make sure all circuit connections are tight in neurosurgical pt?
bed is rotated 90-180 degrees
89
Cervical collar placement makes for a difficult what and therefore?
intubation; very sensitive to hypotension and HTN
90
2 contraindictions for suxxs use?
weakness or paralysis
91
2 conditions in which suxxs can only be used for the 48 hours following the injury? And why is that?
acute stroke or spinal cord injury; up regulation of the K receptors leading to hyperkalemia
92
Most IV agents (3) are indirect cerebral vasoconstrictors and decrease CBF, CMR leading to preserved autoregulation and CO2 activity?
propofol, thiopental, etomidate
93
Does dexmetomidine interfere with electrophysiological mapping?
no
94
What MAC of volatile agent should be used with SSEP monitoring and brain relaxation?
95
The 3 primary considerations in neurosurgery?
type of neuromonitoring planned, optimal brain relaxation, balance between adequate analgesia and ability to assess neuro function at the end of the surgical procedure
96
3 things to do to maintain brain relaxation?
o2/air infusion
97
4 ways to decrease ICP for optimal brain relaxation?
mannitol, hypertonic saline, TIVA, hypocapnia
98
One way to offset cerebral vasodilation from inhalation agents?
hypocapnia
99
MEP monitoring gets optimal signal with what type of anesthesia?
TIVA
100
A benefit of propofol infusion is that it provides better relaxation by further decreasing?
CBV
101
How does muscle relaxation facilitate venous drainage?
relaxes chest wall which decreases intrathoracic pressure and facilitates venous drainage
102
Some considerations with hyperventilation in neurosurgery?
cerebral vasoconstriction maintains decreased CBF and CBV, has a potential for causing or exacerbating cerebral ischemia, avoid in all pts with TBI, maintain PaCO2 between 30 and 35
103
What's the exception for avoiding hyperventilation in all TBI pts?
if there is an acute increase in ICP hyperventilation can be done
104
A PaCO2 less than what should be discussed with the surgeon?
30
105
The goal for CVP in intracranial surgery?
euvolemia/ normal CVP
106
Fluid management in intracranial surgeries: pt should be kept (3)?
isovolemic, isotonic, and isooncotic
107
Fluid rate for intracranial surgery?
0.5-1 mL/kg/h
108
Should pre and intraop fluid and blood loss be replaced in intracranial pt?
yes
109
Is BBB subject to water movement?
yes
110
How does hypertonic saline reduce ICP?
osmotic effect and ability to remain outside of effective BBB
111
2 side effects of hypertonic saline?
electrolyte abnormalities, cardiac failure
112
What type of fluids should you avoid in intracranial pts?
dextrose containing
113
Why is it important to maintain normoglycemia in pts undergoing brain surgery?
high glucose levels may exacerbate neuro injury during ischemia
114
Target blood sugar in brain surgery?
140-180
115
When should you check glucose levels if pt having brain surgery?
definitely preop and check them frequently (q30 min) after
116
Intraop hyperglycemia is common in those undergoing?
emergent/urgent craniotomy following TBI
117
Increased variability in blood glucose can lead to?
increased osmotic shifts
118
How does hypoglycemia effect the brain?
it lowers brain tissue glucose concentration and the precipitation of brain energy crisis
119
Once the dura has been closed where do you maintain the BP?
at baseline
120
Signs of needing to delay extubation d/t upper airway edema?
facial edema and absence of cuff leak
121
3 considerations for prior to closure of dura?
1. BP parameters should be set 2. PaCO2 should be allowed to return to normal; BP raised 120% above baseline 3. ability of brain to withstand such challenges can be directly assessed by the surgeon
122
Why may normal autoregulation not exist after brain surgery?
BBB leakage= hemorrhage and edema
123
Late emergence may mask a problem such as?
hematoma or hydrocephalus
124
There is a relationship between HTN and what formation during emergence?
hematoma
125
3 goals of emergence after brain surgery?
avoid coughing or straining (with lido), sudden emergence may lead to uncontrolled BP, titrate short acting HTNives such as esmolol and labetolol
126
Intraop monitoring for most intracranial procedures includes?
7 ASA monitors, 2 IVs, a line 0ed at level of external auditory meatus, foley, nerve stimulator, neurologic monitors (EEG), maybe central line
127
7 things which influence ICP?
MAP/autoregulation, PaCO2, PaO2, viscosity, CMR (arousal, pain, seizures, temp), anesthetics, vasoactive agents
128
Probably most common reason for neuro surgery?
surgery for tumors
129
Common presentation for supratentorial surgery?
seizures, HA, endocrine abnormalities, aphasia, cognitive decline
130
Common presentation for infratentorial surgery?
altered consciousness, nystagmus, abnormal ?
131
Tentorium divides?
cerebral hemispheres from hind brain/cerebellum
132
Tumors leading to intracranial HTN are at risk for?
cerebral ischemia and herniation
133
3 devastating complications from brain tumor surgery?
brainstem injury-quadraplegia, VAE, pneumocephalus
134
5 considerations for brain tumor surgery?
may be in unusual position, adequate relaxation of the brain optimizes surgical conditions, CV effects, avoid complications from surgery, assess preop LOC and CT
135
Neck flexion can lead to what with the ETT?
kinking and right mainstem intubation
136
4 ways to promote adequate brain relaxation?
sub MAC or TIVA, mild to moderate hyperventilation, minimizing tumor edema (dexamethasone, mannitol, HTS), preventing fullness from venous congestion (minimize excessive rotation of neck)
137
Why do you have to pay meticulous attention to the EEG and a line in brain surgery?
brainstem is involved in systemic HDs
138
What part of brain contains major motor and sensory pathways, CV and resp centers, RAS, and cranial nerves?
posterior fossa
139
What part of the brain is involved in systemic hemodynamics and can cause rapid alterations in BP and HR?
brainstem
140
What do you do if your patient starts having rapid changes in BP and HR during brain surgery?
let the surgeon know
141
What position increases the likelihood of pneumocephalus? And why?
sitting position; air can readily enter subarachnoid space as CSF is lost
142
When does tension pneumocephalus occur?
when brain expands so much and compresses the brain
143
3 things pneumocephalus can cause?
delayed emergence, CV collapse, neuro deficits
144
VAE usually occurs when surgical site is how much above the heart?
20 cm
145
When do you particularly have to watch for VAE?
turning of brain flap and bone work
146
What increases risk of VAE?
when open vessels cannot collapse
147
Air is entrained thru what in VAE?
venous sinuses
148
Massive air embolism produces?
major HD changes
149
Incidence of VAE during craniotomy? And during cervical laminectomies?
40-45%; 10-15%
150
What happens in venous air embolism?
airlock w/in the right ventricle leads to RHF which leads to decreased LV filling pressures which leads to decreased CO/BP and dysrhythmias. vascular obstruction increases dead space, nitrogen increases before ETCO2 decreases and SaO2 decreases
151
What is a paradoxic air embolism?
air enters thru venous circulation and travels thru patent foramen ovale to the arterial side. it may present as CVA or coronary event
152
Where do you place the precordial doppler to listen for VAE? And how much air can it detect?
between the 3rd and 6th ICS on the right sternal border; 0.25 mL air
153
The greater the air embolus, the greater the drop in?
ETCO2
154
Most sensitive monitor for VAE?
TEE
155
End tidal gas monitoring in VAE shows?
decrease in ETCO2 and presence of end tidal nitrogen
156
Where do you want the tip of the right atrial catheter to aspirate VAE?
junction between the SVC and right atrium
157
Sensitivity for detection of VAE?
TEE > doppler > PAP and ETCO2 > CVC > BP > EKG
158
Treatment of VAE?
tell surgeon, will flood field, 100 % FiO2 and turn of N2O, aspirate RA catheter, support BP with ephedrine and fluids, compress jugular veins to minimize air entrapment, can add PEEP if BP will tolerate, left lateral position or operative site lower than right atrium, CV support as needed, supine
159
S/s pituitary tumor?
neuro, visual, and hormonal changes
160
What's the major visual change that happens when pt has pituitary tumor?
2 nasal sides of the field get cut out
161
7 symptoms of pituitary tumor?
amenorrhea, galactorrhea, Cushings (increased ACTH), acromegaly (increased GH), hyperthyroidism, panhypopituitarism (hormone replacement requiring cortisol, levothyroxine, possibly DDAVP), DI
162
Intracranial approach for pituitary surgery is used for?
tumors > 10 cm
163
Some benefits of the transphenoidal approach to pituitary surgery?
reduced morbidity and mortality d/t decreased blood loss and less manipulation of brain tissue, panhypopituitarism and DI reduced
164
Monitoring for pituitary surgery?
glucose and lytes
165
Common complication from pituitary surgery?
DI
166
Is DI temporary or permanent?
can be both
167
DI is loss of what hormone production?
ADH
168
Some descriptions of DI?
may occur intra or post op, diuresis as evidenced by urine osmo of
169
Treatment of DI?
DDAVP 0.5-1 microgram IV or SQ
170
Most patients with an aneurysm have a normal ICP unless?
it has ruptured
171
S/s of a cerebral aneurysm?
severe HA, focal neurological deficits, lethargy, coma
172
Peak age for rupture of a cerebral aneursym?
55-60 years
173
Leading cause of subarachnoid hemorrhage?
rupture of saccular aneurysm
174
Type of aneurysm that is usually d/t an infection?
mycotic
175
Type of aneurysm usually caused by cervical neck trauma?
traumatic aneurysm
176
Type of aneurysm where plaque starts crumbling and force of heart pumping starts dissecting vascular wall away from plaque
atherosclerotic aneurysm
177
What % of ppl with SAH die or have neurologic disabilities?
50%
178
Type of aneurysm that looks like a pouch?
saccular
179
What's the classification scale for SAH?
Hunt and Hess Classification
180
Hunt and Hess classification where there is drowsiness, confusion, or mild focal deficits?
3
181
Hunt and Hess classification where pt is in deep coma, decerebrate rigidity, and moribound appearance?
5
182
How are aneurysms repaired?
surgical or endovascular intervention
183
Some complications pts with SAH are at risk for?
cardiac dysfunction, neurogenic or cardiogenic pulmonary edema, hydrocephalus, hemorrhage
184
Some anesthetic considerations for aneurysm repair?
control HDs (prevent SNS during DL and placement of Mayfield collar w narc and lido), TIVA or sub MAC VA, mild to mod hyperventilation, mannitol (0.5 to 1 g/kg), lumbar drain or external ventricular to drain CSF,
185
What do you have to keep in mind with brain relaxation and SAH?
brain relaxation may be difficult to achieve
186
Complications of cerebral aneurysm repair?
rebleeding,
187
How much of a chance is there of rebleeding the first few days following SAH?
50%
188
Is rebleeding of a previously ruptured SAH life threatening?
yes
189
Where is a cerebral aneurysm clip placed?
right at neck of aneurysm
190
What cardiac and pulmonary issues are common during SAH?
ST changes, dysrhythmias, elevated troponin, cardiogenic shock
191
When should surgical clipping of ruptured aneurysm be delayed?
hemodynamically unstable pt
192
When repairing a cerebral aneurysm, when is the risk of recurrent hemorrhage removed?
once secured with an aneurysm clip
193
Reactive narrowing of cerebral arteries following SAH repair is called?
vasospasm
194
What causes vasospasm after cerebral aneurysm repair?
breakdown products of Hg from the blood that has accumulated around the vessels of the circle of willis
195
Leading cause of morbidity and mortality after SAH?
vasospasm
196
What 3 negative effects does vasospasm have?
impairs circulation and leads to ischemia and may lead to infarction
197
What's the ratio of patients with SAH who develop vasospasm?
1/4
198
In 60% of pts vasospasm can be detected with?
angiography (and only half develop symptoms)
199
Vasospasm peaks how many days after surgery?
4-9 days
200
Vasospasm treatment depends on?
maintaining CPP
201
Triple H treatment for vasospasm is?
HTN, hypervol, hemodilution
202
Most commonly employed pressors for vasospasm?
phenylephrine and dopamine
203
2 meds which decrease the morbidity of ischemia occurring after SAH?
nimodipine (po) and nicardipine
204
Can angioplasty treat vasospasm?
yes
205
Why does vasospasm depend on CPP?
ischemic areas have impaired autoregulation and CBF depends on CPP
206
When treating vasospasm with HTN what parameters do you want to follow?
SBP 160-200 and MAP 20-30 mm above baseline
207
How does an endovascular treatment of an aneurysm work?
intra arterial catheter deploys coils in to the aneurysm that cause it to thrombose
208
Complications after endovascular repair of aneurysm?
hemorrhage, stroke, vessel dissection
209
4 anesthetic considerations during endovascular repair of aneurysm?
general anesthesia; patient movement is devastating (muscle relaxation), hyperventilation should be avoided because it decreases CBF and makes access more challenging, heparin/protamine
210
A congenital abnormal vascular connection between the arterial and venous circulation is?
AVM
211
2 bad characteristics of AVM?
bypasses the walls of the capillaries and the vessel walls are thin and can easily rupture
212
Gold standard for cerebral AVM diagnosis?
cerebral angiography
213
3 sx of AVM?
bleeding, seizures, focal neuro deficits
214
2 types of surgeries to cure AVM?
open surgery or radiosurgery
215
Why is autoregulation of blood flow missing in AVM repair?
vasogenic edema and hemorrhage
216
Anesthetic problems for AVM?
similar to those of aneurysm, the operation is more complicated and there is more blood loss
217
What do you have to aggressively control in AVM pts during surgery?
HTN
218
Immediate post op neuro exam after what type of surgery?
AVM
219
2 types of surgery where want pt awake to assess neuro status?
awake crani and epilepsy surgery
220
Contraindications to awake brain surgery?
anxiety, claustrophobia, pysch disorders, difficult airway, OSA, orthopnea, high BMI
221
Intraop considerations for awake crani?
keep direct visual contact and calm quiet environment, comfortable room temp, talk to pt, use prop and dex 0.3-0.6 ug/kg/min
222
Preferred method for epilepsy surgery and tumor resection?
asleep awake asleep
223
What type of anesthesia is used for AAA brain surgery?
general with local infiltration
224
When does pt emerge for AAA surgery?
middle of surgery
225
Why does neurosurgeon apply electrical stimulation mapping in AAA surgery?
allows for maximal tumor resection while minimizing neuro deficits
226
What meds should you avoid during AAA and why?
benzos; interferes with electrocorticography
227
Airways to use for AAA?
LMA, ETT, none
228
Goal with head trauma?
secure ETT quickly without moving neck
229
How is axial cervical stabilization done?
one anesthetist puts traction on angle of mandible and the other inserts
230
What may help to prevent displacement of cervical fractures?
bimanual application
231
5 clinical criteria to clear spine in conscious trauma pts?
no posterior midline cervical spine tenderness, alert, not intoxicated, no painful distracting injuries, no focal deficits
232
Components of GCS?
eye opening, verbal, best motor response
233
3 criteria r/t GCS that require intubation?
hypoventilation, absence of gag, GCS
234
When cerebral autoregulation is impaired it is dependent on?
CPP
235
Some considerations for head trauma surgery pts?
avoid HTN, hypotension; cerebral autoregulation may be impaired after TBI, fluid (isotonic fluid, blood, colloids) use is controversial, albumin should not be used unless hypoalbuminemic
236
Goal is to maintain CPP in what for head trauma pt?
50-70
237
Why do you have to be careful about rapid restoration of intravascular volume in head trauma pts?
cerebral edema can result
238
Does moderate hypothermia improve outcomes in head injury pt?
no
239
Goals for PaO2, ETCO2, and O2 sat in head injury pt?
PaO2> 60, ETCO2 30-35, O2 sat >90%
240
Fluids to use for head trauma surgery pt?
mannitol, HTS
241
When can you use barbs in head trauma pts?
when HD stable and adequately resuscitated; don't use if MAP and CPP can't be maintained
242
TIA's happen when carotid is stenosed > __ %?
60%
243
Types of anesthesia for carotid surgery?
general, regional, angioplasty, stenting, superficial or deep cervical plexus block
244
What should the goal be with BP for carotid surgery and what makes it difficult to control?
keep baseline; infuse lido before start so it makes it difficult to control
245
In carotid surgery, before clamping the ICA a perfusion pressure (stump) is measured and if it's less than ___=___ then shunt may be used to prevent ischemia or rely on collateral flow?
20-40
246
When are heparin and protamine given during carotid surgery?
heparin: just before clamping; protamine: prior to skin closure
247
Intraop considerations for carotid surgery?
control BP, BP >180 may be associated with CVA, cerebral oximetry may be used, EEG, SSEPs may be used, maintain SBP and MAP 20% over baseline especially if shunt is used (phenyl drip), prevent coughing and large swings in BP, treat HTN to avoid cerebral edema, foley, central line, rapid emergence
248
Normal cerebral oximetry value?
60-80
249
Caution w foley and cl in carotid surgery?
can cause HTN especially in men
250
Potential complications of CEA?
CVA, MI, nerve injuries, wound hematomas, infection
251
Most common nerve injuries in CEA?
hypoglossal, SL, RLN
252
Assessment for wound hematoma in CEA? And what is wound hematoma usually precipitated by?
tracheal deviation; BP goes up
253
Carotid artery stenting is done in what type of patients?
those who are poor candidates for surgery
254
What type of anesthesia is carotid stenting performed under?
sedation and converted to general if risk of comorbidities
255
What do you have to be prepared for during carotid stent placement?
HD changes- brady, asystole during balloon angioplasty of internal carotid artery bc it sits next to vagal
256
What do you not want to use to pretreat for prevention of brady/asystole in carotid pts and why?
atropine bc tachycardia not desirable in these pts
257
What should be immediately available intraop for those pts with vascular lesions?
blood
258
Do craniotomy pts have severe pain?
no
259
In general, what 2 gasses have way more effect on motor and sensory evoked potentials than IV agents?
nitrous and volatile agents
260
EEG is used to assess what 3 things?
cerebral perfusion, metabolism, and anesthetic depthg
261
Cerebral ischemia produces similar level of changes on the EEG as what type of anesthesia?
deep anesthesia
262
EEG is a summation of excitatory and inhibitory responses produced where?
cerebral cortex
263
Can an EEG detect cerebral ischemia?
yes
264
Des and Sevo produce burst suppression at what doses?
Des >1.2; Sevo > 1.5 MAC
265
Inhalational agents produce EEG activation at what MAC?
subanesthetic
266
Small doses of barbs cause what EEG changes and regular doses cause what?
small: activation; regular: depression
267
Benzos in small doses cause what EEG changes and opioids cause what changes?
benzos: activation; opioids: depression
268
etomidate in small doses causes what EEG changes? What ab propofol?
small doses of etomidate: activation; propofol: depression
269
Etomidate in regular doses causes what EEG changes?
depression
270
N2O causes what type of EEG changes?
activation
271
What does ketamine do to EEG changes?
activation
272
What do hypocapnia, mild hypercapnia, and marked hypercapnia do to EEG changes?
hypocapnia: depression; mild hypercapnia: activation; marked hypercapnia: depression
273
What do sensory stimulation and hypothermia do to EEG?
sensory stimulation: activation; hypothermia: depression
274
What do early, late hypoxia, and ischemia do to EEG?
early hypoxia: activation; late hypoxia: depression; ischemia: depression
275
What 3 drugs produce a similar EEG pattern?
barbs, propofol, etomidate
276
Only agents capable of producing burst suppression and electrical silence at high doses?
IV agents
277
SSEPs test the integrity of?
dorsal spinal columns, ascending tracts, sensory cortex, supplied by posterior spinal artery
278
3 surgeries where SSEPs are useful?
spinal surgery, CEA, aortic surgery
279
This has the greatest effect causing dose dependent decrease in amplitude and increase in latency?
volatile agents
280
An increase in latency and decrease in amplitude can mean?
ischemia
281
4 physiologic factors which influence SSEPs?
temp, PaO2, PaCO2, SBP
282
Do muscle relaxants effect SSEPs? Do all anesthetics?
no; yes
283
Sensory tracts in dorsal spinal columns go which way and are found where?
afferent or towards and found in posterior root of spinal column
284
Motor tracts in dorsal spinal columns go which way and are found where?
efferent, away and in anterior root of spinal column
285
Brainstem auditory evoked response tests what?
8th cranial nerve and auditory pathways above the pons
286
Visual evoked potentials are used to measure what?
optic nerve and occipital cortex during resections of large pituitary tumors
287
Fentanyl in large doses does what to BAER?
does not effect
288
BAER are used for what surgeries?
acoustic tumor surgery and pts at risk of brainstem
289
Do IV or inhalational agents effect BAER readings more?
inhalational
290
MEPs assess ftn of?
motor cortex and descending tracts supplied by anterior spinal artery
291
SSEPs travel where?
along posterior tracts of spinal cord
292
What surgeries may use MEPs?
aortic surgery to assess spinal cord perfusion
293
These 3 things suppress MEP response? So what is recommended for use with MEPs?
volatiles, N20, NMDAs; TIVA
294
This is the recording of electrical activity of muscle that is irritated or injured?
EMG
295
Purpose of EMG?
identify nerves and test their integrity
296
Nerve that is most often monitored with EMG?
facial; VII
297
What type of anesthesia may mimic neuronal imitation with EMG?
light anesthesia
298
Where are electrodes placed for EMG monitoring?
subdermally over muscle
299
Standard of care for acoustic tumor surgery or when increased risks of facial nerve functioning?
EMG
300
Can you use NMDA with EMG monitoring?
yes, but should be maintained at light level
301
EEG is often used for what type of surgery?
carotid endarectomy
302
This type of neuro monitoring is used to detect inadequate spinal cord flow?
SSEP
303
Nerves EMG monitors?
VII, III, IV, V, XI
