Nervous System Flashcards
(45 cards)
1
Q
Review of MS signs and symptoms?
A
- Paralysis (characteristics of skeletal muscles are similar to disuse myopathy– extrajunctional receptor upregulation)
- sometimes can be more sensitivie to NDMR or more resistant
- sensory distrubances- positioning, note pre-existing issues
- autonomic disturbances- wide swings in BP
- lack of coordination
- visual impairment- document pre-existing deficits!
- seizures
- emotional disturbances
2
Q
What are some implications for general anesthetic plan for patient with MS?
A
- Impact of sx and anesthesia on the disease process is controversial
- minimize impact of surgical stress consider the B/R/A to elective procedures
- avoid increase in body temp (even 1 degree) promotes exacerbation
- avoid infection and emotional stress
- exacerbation and remission periods are sporadic and difficult to determine if relationship exists w/ srugery/anesthesia and exacerbation
3
Q
What are considerations for induction of a patient with MS?
A
-
Consider supplementation with corticosteroids
- if on chronic supplementaiton, cortisol HPA axis can be suppressed (downregulated) and not able to respond to increase stress response needed.
- need 20 mg/day under normal circumstances. up to 100mg/day when under extreme stress
- no IV or inahled anesthetic is superior in the management of MS patient
-
Consider potential for ANS dysfunction- be prepared for a labile pt
- increased hypotension with IV and volatile agents, position changes, PP vent, etc
- Might want fluid bolus, ask about orthostatic hypotension, may not compensate with vasodilation etc
-
Muscle relaxants
- avoid succinylcholine (risk of hyperkalemia in these patients)
- prolonged responses may occur with NDMR if patient has decreased muscle mass
- resistance to NDMR also possible (proliferation of extra-junctional cholinergic receptors)
4
Q
Considerations for maintenance and emergence of patient with MS?
A
- Monitor for ANS dysfunction and effects of cardiotoxic therapy= lower threshold for arterial line
- consider baseline muscle weakness during emergence, extubate wide awake, with full NMB reversal confirmation
- post-operative neuro evaluation helpful to detect exacerbation compare with preop findings
5
Q
Regional anesthesia implications for patient with MS?
A
- The histopathology of local anesthetic toxicity is similar to the demyelination of peripheral nervs that occurs with MS
- concern with local reaching axon at much higher concentration compared to normal
- Regional best avoided if no strong reason to use (epidurals have been considered acceptable in OB and tx of pain syndromes)
- need big talk about R/B
- spinal anesthetics have been associated with postop exacerbations
- epidural anesthetics and peripheral nerve blocks- no reports of exacerbations
- may need more theoretical outcome
6
Q
Review of GBS?
A
- peripheral demyelination d/t infection
- Bilateral facial paralysis- bulbar involvement
- increase risk aspiration
- difficulty swallowing- pharyngeal muscle weakness
- impaired ventilation- intercostal muscle paralysis
- LMA mostly contraindicated- probably won’t keep up with MV
- flaccid/decreased deep tendon reflexes- lower motor nerve involvement
- extremity paresthesias
- pain- HA, backache, muscle tenderness
7
Q
autonomic dysfunction in GBS s/s?
A
Autonomic nervous system dysfunction
- Labile BP
- diaphoresis
- peripheral vasoconstriction
- tachycardia at rest
- EKG- conduction abnormal
- severe orthostatic hypotension
8
Q
Considerations for general anesthesia in GBS?
A
-
60% demonstrate ANS dysfunction= pt does not compensate for physiological stressors normally
- hypotension with PP (positive pressure) vent, blood loss or position change
- HTN with DVL and pain
- HTN with indirect acting vasopressors and alpha sympathomimetics= consider fluids before ephedrine
- use phenylephrine for hypotension
- invasive arterial line mandatory
- maintain preload with fluids
- altered temp regulation
- avoid succinylcholine- even after clinical recovery
- Use NDMR with minimal CV effects (vec) and monitor crefully for increased sensitivity or resistance
- secondary to muscle weakness post op, positive pressure vnetilation usually necessary
-
if extubaiton planned- vigilant moniotring necessary- high risk for Resp failure!
*
9
Q
What are considerations for regional anesthesia in GBS?
A
- Epidural opioids can be beneficial for sensory related pain and discomfort
- regional techniques can be used with caution- patients are sensitivie to local anesthetics (presence of the sodium channel blocking factor?)
- high incidence of ANS dysfunction- epidural with slower onset preferred to rapid onset of subarachnoid (spinal) anesthesia
- huge SNS decrease with spinal, onset with epidural is easier to control
10
Q
Review of parkinson’s disease treatment?
A
- Increase the concentration of dopamine in basal ganglia or the receptor response to dopamine
- Levodopa (DA precursor) and decarboxylase inhibitor (prevents peripheral conversion of DA- more to CNS)
- Amantadine
- MAOs (deprenyl, selegiline)
11
Q
What are some treatment side effects for parkinson’s disease?
A
- MOtor (dyskinesias)
- psychiatric (mania, agitations, hallucinations, paranoia)
- CV (increased contractility and heart rate, orthostatic hypotension)
- especially with levodopa on board
- GI (N,V stimulation of chemoreceptor trigger zone by DA)
12
Q
What are some anesthetic considerations for patient with parkinsons on levodopa?
A
- Consider interactions and side effects of levodopa when planning anesthetic
- avoid dopamine antagonists (ie metoclopramide)
- e1/2 T of levadopa short. >6 hours will see withdrawal effects such as skeletal muscle rigidity interfering with ventilation
- 20 minutes before induciton give dose, repeat as needed intraop (OG tube) and post op
- If oral dose cannot be givne, apomorphine SQ is a dopamine agonist that can be given
13
Q
General anesthesia consideraitons for patient with parkinsons?
A
- Aspiration risk- consider RSI (excessive salivation, dysphagia, esophageal dysfunction)
-
Avoid dopamine antagonists - unles L-dopa CV SE at basal ganglia
- butyrophenones (droperidol)
- phenothiazines (ie compazine)
- metoclopramide
- ANS dysfunction- expect BP to be labile and potential for dysrhythmias
- Alfentanil and fentanyl reported to cause acute dystonic reaction
- (decrease in central dopaminergic transmission by the opioid)
- Ketamine can be used but consider increased SNS stim issue
- expect patients to be volume depleted- aggressive fluid plan
- all types of MR acceptable
- Isoflurane, sevo, des acceptable- may experience exaggerated BP decreases
- Extubate wide awake after fullr eversal criteria met
- educate patient and caregiver that patient may experience delayed onset mental confusion post op
- can be 24 hours off, warn caregiver
14
Q
What are anesthetic considerations for deep brain stimulation insertion?
A
- Surgeon will use microelectrode recordings of speicfic nuclei- usually “Awake” pt
- TIVA with prop for scan, then to OR, wake pt up to do microelectrode part
- levadopa may be held to enahnce
- avoid drugs that enhance GABA
- opioids, dexmedetomidine best
- avoid excessive sedation
- neuro assesmsent
- airway mgt
- Sitting position
- Avoiding- HTN, sz, and intracrnaial hemorrhage
15
Q
What are some respiratory considerations for SCI?
A
- C4 and above- usually require ventilatory assistance diaphragm inovlved
- C5 and below- accessory muscle loss- decreased expiratory reserve volume
- keep in mind that even though injury may be at specific level, edema in immediate injury may make injury appear higher and cause respiratory issues
-
Catecholamine surge (part of disease process- bodies are smart and realize SCI is bad, so you get massive release of catecholamines)
- tachycardia/HTN
- pulmonary edema- particularly if poor EF. Translocate blood very fast into central circulation
- PVC and ST-T wave ECG changes- will also happen in SAH. usually self limited
- Quadriplegic patients breathe best in SUPINE position
- Tracheal suctioning- high spinal transection= unopposed vagal stimuli, may cause bradycardia and cardiac arrest especially during hypoxemia
16
Q
Anesthesia considerations around intubation with acute SCI?
A
- Require mechnical ventilation of lungs (abdominal/intercostal paralysis + GA= cannot maintain spontaneous ventilation)
- DVL with in-line stabilization/emergency situations with usntable/uncertain c-spine stability (unconscious, combative, or hypoxemic patients)
- one patient stabilizing head, 2nd laryngoscopy, 3rd cricoid
- An awake, alert and cooperative pt- awake fiberoptic intubation, blind nasal intubaiton, transillumination with a lighted stylet, the use of an intubating LMA or bullard laryngoscope (if blood or deformity does not contraindicate)
17
Q
Implications for general anesthesia with acute SCI?
A
- Expect hemodynamic instability (spinal shock)
- blood loss is not large UNLESS… harvesting the iliac crest bone graft or vertebral body corpectomy
- thoracic and lumbar regions > blood loss than cervical
- invasive arterial pressure moniotring required
- elderly pt/significant hemodynamic lability preop may require a PA catheter
- aggressive fluids, blood repalcement and continue preop vasopressors to combat extensive peripheral vasodilation (important- impairment of autoregulation in the region of the injury)
- Poikilothermic (same as room temp) below level of spinal cord transection- BAIR hugger, room temp, humidifier, etc
- N2O (if closed air spaces ruled out), Inhaled agents, IV agents all acceptable
- NDMR- all acceptable (pancuronium SNS stim may be desirable)
- succinylcholine- OK if in 1st few hrs after injury- then avoid
18
Q
What are general anesthesia considerations for chronic SCI?
A
- Renal failure/insuffieicncy common
- High DVT risk
- position carefully (increased risk for fracture/skin breakdown)
- chronic pain common
- spasticity in skeletal muscle- often treated with baclofen
- note natural ROM, maintain positioning, don’t try to straighten arm when paralyzed, etc.
- surgery may bring on pt’s 1st incidence of autonomic dysreflexia
- most common above T6. Can be as low as T10
- VA, epidural or intrathecal anesthesia effective in prevention
- BP drop not as dramatic with epidural, however, may not be even distribution of meds with epidural. can get one half body more anesthetized
- have vasodilator available (NTP 1-2 mcg/kg IV) for acute BP increases, gtt for persistent HTN
- Succinylcholine contraindicated >24 hours after injury (peak hyperkalemia 3-6 months post injury)
- NDMR acceptable for DVL and prevention of surgical stimulation related muscle spasms
- patients should be monitored post op for the development of autonomic dysreflexia
- can develop after anesthetic wears off
19
Q
Seizure anesthetic consierations?
A
- Consider additvie effect of anticonvulsants and sedative/anesthetic drugs
- consider coag, end organ and enzyme induciton issues with anticonvulsant therapy
- anticonvulsant medications should be continued AM of sx, intra op and postop
20
Q
Which agents should be avoided intraop with hx seizure?
A
- Methohexital
- ketamine
- etomidate- concern for seizure
- meperidine- normeperidine that can cause sz
- +/- atracurium and cisatracurium (laudanosine)- in theory with laudanosine
- enflurane- just horrible for neuro
- alfentanil- concern for sz
on the other hand, if sx trying to find where sz focus is, may actually encourage use
21
Q
What are intraoperative signs of seizure? Treatment?
A
- BP and HR changes +/- clonic movement dpeending on NMB
Treatment:
- IV TPL. propofol, bnzodiazepine <– treatments
- direct application of cold saline to brain surface
- ABG and temp monitoring
22
Q
What are indicators for increased ICP without ventric?
A
- LOC
- lethargy
- N/V
- cushing triad
- scans, etc
23
Q
What are 5 determinants of CBF?
A
-
PaCO2 (keep 25-30)
- direct increase.
- can use to advantage, ie hyperventilating when intubating until able to visualize brain
- hypercarbia is detrimental with increased ICP
-
PaO2
- pretty steady until Pao2 <50, then CBF increase significantly
-
Arterial pressure, autoregulation
- 50/70-150/170 (depending on book)
- keep in autoregulation range
- keep CPP >60/70
-
Venous pressure
- If venous pressure increases, will obstruct cerebral outflow
- also can contribute to brain volume if backed up
-
anesthetic drugs and techniques
- mismatch with VA “luxury flow” (CBF increases, CRMO down)
- don’t go above 1 MAC typically
-
ketamine controversial and may cause ICP to go up
- can also argue ketamine would be better at maintaining CPP
- IV agents ideal (decrease CBF and CRMO)
24
Q
What can happend to CBF with lack of autoregulation?
A
CBF can be signifantly decreased due to lack of autoregulation
- loss of autoregulation is common with many various cerebral pathology (hemorrhage, brain tumor)
- If CPP 70 and ICP 25- need MAP of 100
- If autoregulation intact, may be fine and maintaining good CBF
- However, if autoregulation not intact, may not be sufucient BP to support CBF
- CBF @ <25 mL/100g/min- may have isoelectric EEG
from patho:
- Normal CBF= 50 mL/100g brain tissue/min
25
Concern with anesthetic drugs with increased ICP?
* **All volatile agents 0.6-1.0 MAC "uncouple" CMOR2 and CBF (*luxury perfusion)***
* Vasodilation in face of decreased metabolic need
* greater the concentration, the more extreme the uncoupling
* use IV agents (propofol) and hypocapnia to help compensate
* N2O less interference w/ autoreg. compared with sevo/des/iso/etc
* tension pneumocephalus possible
* **IV anesthetics are vasoconstrictors and will decrease CBF and ICP in general**
* KETAMINE IS THE EXCEPTION- don't use in face of increased ICP
* Thiopental- *vasoconstricts healthy tissue, vasodilates injured area "takes from rich and gives to poor"*
* Prop and barbs best
* Midazolam, opioids, etomidate OK- *avoid respiratory depression*
26
What are clinical anesthetic managmeent principles for elevated ICP?
* Reduce ICP
* posture, hyperventilation, CSF drainage, hyperosmotics, diuresis, corticosteroids (*only in brain tumor, reduce ring of edema)*, barbiturates
* Reduce CMRO2
* premedication- *don't want pt bucking at any point*
* smooth induction, maintenance, emergency
* VAE detection
* *the higher degree of head elevation (any \> 15degree above heart), can entrain air*
27
What are some important considerations preop for a patient with intracranial tumor?
* Where is pt on ICP curve?
* HA
* N/v
* neuro changes
* seizures
* increased BP and decreased HR
* CT/MRI- midline shift?
* If tumor near hypothalamus (SNS stim, alteration in LOC, temp, and fluid reg)
* Be careful with sedative pre-meds
* *can increase CO2 and lead to increased ICP*
* Cerebral edema- corticosteroids
28
Monitors/IV considerations for intracranial tumors?
* 2 large bore IVs
* PRBC's available (visualize personally)
* Use NS/normosol
* Standard minotrs
* EKG especialyl valuable in infratentorial tumor resection--\> *can be doing sx in critical CV/resp centers, first sign usually ectopy*
* Art line, temp and PNS mandatory
* pressure transducer at level of external auditory meatus (circle of willis)
* *if pushing for mild hypothermia need muscle relaxant*
* +/- CVP/PA (consider pt position/bleeding risk/baseline status)
29
Induction considerations for intracranial tumors\>
* Induction- blunt hemodynamic changes with DVL
* Optimize ICP preinduction with osmotherapy (*discuss with neurosx)*
* Preoxygenate FULLY
* TPL (3-5 mg/kg) or propofol (1.25-2.5 mg/kg)
* *have prop bolus ready for when they put pins in place*
* Opioid (fentanyl 3-5 mcg/kg)
* *painful part until dura resected, then not so painful*
* NDMR muscle relaxant- use PNS
* Lidocaine 1.5 mg/kg
* *can use LTA to help with patient tolerating tube upon wake up*
* Consider an additional 2-3 mg/kg of TPL after twitch response disappears and before intubation
* esmolol infusions are also recommended for HR and BP control
30
Maintenance considerations for intracranial tumors?
* Paco2 30-35 (etco2 25-30)
* +/- VA (0.6-1 MAC) and N2O consider baseline intracranial compliance
* avoid patient movement
* if low compliance, consider TIVA and low dose isoflurane for amnesia
31
Emergence considerations for intracranial tumors?
* Bucking can cause HTN and ICP elevation= cerebral edema and hemorrhage
* no reversal until head dressing applied
* IV lidocaine 1.5 mg/kg
* antihypertensives
* extubated when fully reversed and responsive
* Leave ETT in place until following commands
* HOB 30 degress
* warm patient to comfortable temp
32
Venous air embolism rate of occurrence? Sources?
* Rate of occurrence depends on procedure, patient position and method of detection used
* Surgeries of concern: posterior fossa, upper c-spine procedures and supratentorial procedures (ex parasagittal or meningiomas near sagittal sinus, craniosynostosis proceudre)
* VAE sources are emissary and cervical epidural veins and the major cerebral venous sinuses (transverse, sigmoid and posterior half of sagittal sinus) all may be non-collapsible because of dural attachements
33
What is rate of sensitiivty from most--\> least detection of VAE?
What is gold standard for VAE detection?
* Transesophageal echo
* Concern for perforation of esophagus
* not 100% benign
* best to detect and will see before any physiologic change
* doppler
* standard of care. placed at 2nd-4th intercostal space
* hear when air is entrained
* PAP/ etco2
* **combo of doppler and ETCO2 is gold standard**
* **_drop in ETCO2 noted_**
* CO/CVP
* BP, ECG, Stetho
* these are late signs, and close to CV collapse
34
Management of acute VAE?
* Prevent further air injury
* notify surgeon (floor or pack surgical field)
* jugular compression
* lower the head
* treat the intravascular air
* aspirate via R heart cath
* discontinue N2O
* Fio2 1
* Turn lateral with right side up (if possible)
* pressors/inotropes/CPR
35
Anesthesia consideration for head trauma?
* **Blood pressure**
* maintain **CPP 50-70 mmHg**
* **hyperventilation**
* routine use discouraged OK acute ICP mgt, herniation prevention, minimizing retractor pressure, improve surgical access
* **Fluids**- maintain intravascular volume
* prevent reduced serum osmolarity colloid oncotic pressure
* 0.9% saline, normosl/plasmalyte, 5% albumin, blood products bettern than LR (hypoosmolar)
* avoid glucose containing IVF in all neuro cases
* BG concentration \<180
36
Monitors for head trauma?
* EKG, NIBP, Sao2, ETCO2, PNS, temp
* don'ts delay an emergency crani for line placement!
* arterial line indicated- pre induction best!
* +/- right heart catheter (hemodynamics/VAE risk)
37
Induction consideration for head trauma?
* Lidocaine 1-1.5 mg/kg IV
* IV anesthetics (excpet ketamine)
* consider hemodynamic stability needs
* opioids good choice (consider post op disposition)
* NDMR (avoid histamine (*decrease histamine related vasodilation)*, avoid succ if non-emergent)
38
Maintenance consideraiton for head trauma?
* N2O ok as long as pneumocephalus ruled out
* +/- VA until cranium open, based on ICP
* Important to prevent movement
39
Emergence considerations ofr head trauma?
* Transport intubated, sedated patient ot ICU (Swelling max 12-72 hours post injury)
* avoid HTN, coughing
* labetalol, esmolol, and TPL helpful
40
Preop consideration for pt with hx of CVA?
* Determine: how long, what are deficits?
* increased risk adverse otucomes in first 9 months
* meds (BP, antithrombotic, anticoag, antiPLT)
* *with anticoag, may want to have pt continue taking ASA if low bleeding risk*
* No anesthetic technique definitively contraindicated except neuraxial in para/hemiplegia or active anticoag use
* Consider target BP throughout
* **DO NOT monitor NMB on affected extremitiy!!!**
* **will get 4/4 twitches all the time!**
41
Intracranial aneurysm/SAH and anesthetic mgt?
* Manage: risk of aneurysm rupture, cerebral ischemia, and faciliate sx exposure
* **acute HTN= risk of rerupture= often FATAL**
* ***DON'T disrupt the clot!***
* Brain relaxation will faciliate surgical access
* *mannitol*
* *3% saline*
* *hyperventilation through induction phase!*
* **high-normal MAP** to prevent critical **reduction** of **CBF** to ischemic penumbra around SAH
* *not too high that promotes rupture*
* *rather have hypotension during induction*
* **Tight control of MAP** as surgeon **clips** the aneurysm and/or **controls bleeding** from a ruptured aneurysm
* *might ask you to lower BP during bleeds then raise it back up*
* major intraoperative complication= **hemorrhage**-- never foget that re-bleeding kills!
42
Monitoring for Intracranial aneurysm/SAH?
* Arterial line
* +/- CVP (large dose mannitol/guide volume replacemnet- especially with vasospasm/resus with bleeding)
* +/- EEG or SSEP/MEP
* *main consideration is to maintain level of anesthesia, and keep stable anesthetic plan. If you do give bolus, everybody in room needs to know*
* *NMB only on induction*
43
Induction consideration with intracranial aneurysm/SAH?
* Prevent hypertension and hypotension and ICP control
* lidocaine+ esmolol/labetalol+ opioids + high dose TPL or propofol
44
Considerations of maintenance of intracranial aneurysm/SAH
* +/- VA nad N2O depending on ICP- contorl of MAP is priority
* if high ICP - prop gtt (100-300 mcg/kg/hr after bolus) + fentanyl (1-4 cmg/kg/hr)+ 0.5 MAC iso and o2
* \<10 mcg/kg fentanyl if extubation planned
* Regional controlled **hypotension** (**vascular clamp** on the parent artery supplying the aneurysm **\<10 min**)
* **NEED TO DOCUMENT TIME!!**
* **Ensure deep anesthesia** with propofol boluses during application of head pins, scalp incision, turning the bone flap and opening dura-- prevent HTN resposne!
45
Fluid /emergenc/post op consideration intracrnail aneurysm/SAH
Fluid
* Prior to clipping limit to maintenance and deficit
* PRBC should be immediatlely available
* after clipping CVP can be increaed 10-12 mmHg
Emergence
* avoid coughing, straining, hypercarbia, and HTN
* Grade 1-2 with no intraop complication may be exxtubated in OR
* grades 3-5 or intraop complications should remain intubated on mech ventilation
Post op
* contorl HTN to avoid cerebral edema and hematoma (contorl pain, avoid increased paco2, antiHTN drugs
* also vasospasm remains a threat
* high normal intravascular volue, avoid hypotension
