Nervous System Flashcards
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
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
33
Q
What is rate of sensitiivty from most–> least detection of VAE?
What is gold standard for VAE detection?
A
- 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
-
combo of doppler and ETCO2 is gold standard
- CO/CVP
- BP, ECG, Stetho
- these are late signs, and close to CV collapse
