Chapter 18 - spine sx Flashcards

1
Q

What factors are you looking for in deciding if patient will be difficult intubation and difficult ventilatoin? What is your goal with intubation in a patient with cervical stenosis?

A

Goal: minimize neck movement with mask ventilation and laryngoscopy + intubation

Factors for difficult ventilation:

  • MP3 or 4, OSA, snoring, edentulous, neck circum > 40 cm, short + stocky neck, large beard, large tongue, prior history

Factors for difficult intubation:

  • MP3 or 4, OSA, neck circum >4 cm, poor cervical ROM, unable to assume sniff position, large tongue, TM < 6cm, poor upper lip bite, poor submandib compliance (head/neck radiation), interincisor distance < 3 cm, prior history
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2
Q

does severe cervical stenosis necessitate awake FOB? what is your goal with intubation?

A

Goal: minimize neck movement with mask ventilation and laryngoscopy + intubation

Awake vs Asleep:

  • indicators of difficult vent
  • indicators of difficult intub
  • cooperative vs uncooperative
  • full stomach
  • large amount of secretions or blood or debri (trauma patient; will obscure FOB view)

Asleep

  • consider if patient not full stomach + does not have predictors of difficult ventilation
  • use glidescope to minimize neck movement (or glidescope assisted FOB)
  • manual in-line stabilization (if not in C-Collar)
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3
Q

how is chronic pain managed during spine surgery (how would you manage patient in pre-op period and intra-op period)?

A

Preop

  • if patient on chronic pain meds, tell patient to take their usual pain meds
  • Patients who fail to take their chronic pain meds:
    • calculate daily oral morphine equivalent, and provide some opiod morning of surgery
  • multi-modal analgesia: gabapentin, celebrex (if allowed by sx), long acting opioid

Intra-op

  • methadone or ketamine -> shown to reduce pain 48hrs post-op
    • methadone - 0.2 mg/kg IV
    • ketamine - 0.5mg/kg IV + infusion 10 mcg/kg/min intraop (stop at closure)
  • use
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4
Q

Describe SSEPs and MEPs

A

SSEPs

  • integrity of dorsal columns of spinal cord
  • stimulation delivered on a peripheral nerve, sensed at cerbral cortex

MEPs

  • integrity of anterior spinal cord (motor tracts)
  • stimuli delivered at cerebral cortex, sensed at peripheral motor nerve
  • cannot use NMBD
  • very sensitive to anesthesia
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5
Q

what could loss of neuromonitoring signal represent (loss of signal at surgical site, loss of signal at non-surgical site, global loss of signal)?

A

neuromonitor signal loss: dec amplitude, inc latency

Surgical site signal loss:

  • ischemia from trauma
  • compression
  • transection

non-surgical site signal loss:

  • check position of affected limb (nerve compression, arterial compression) 2/2 positioning of patient

global loss of signal:

  • anesthetic overdose
    • high volatile anes conc, bolus of IV agent, muscle relaxant
  • hypotension
  • severe anemia (decrease O2 tissue perfusion)
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6
Q

what does propofol, volatile anes, etomidate, and ketamine do to waveform amplitude and latecy of neuromonitoring?

A

Propofol + volatiles anes

  • increase latency, dec amplitutde

Etomidate + ketamine

  • no change in latency, inc amplitutde
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7
Q

What will your anesthesia plan be for patients undergoing neurophysiologic monitoring (SSEPs, MEPs, or both)?

A

goal - constant depth of anesthesia

  • serve as baseline neuromonitoring signal

MEPs more sensitive to anesthesia

Maintenance

  • amnesia, unconsciousness, autonomic control -
    • low dose volatile anes (MAC < 0.7 - 0.5)
    • or low-mod dose propofol infusion
  • analgesia + reduce anesthetic conc
    • opioid infusion (remi) -> does not affect monitoring
  • muscle relaxation
    • SSEP -> provide
    • MEPs - > do not give
      • during intubation, use sux or antagnoize Roc before baseline signal obtained
  • IV boluses during sx
    • avoid; let OR team know if you have to give
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8
Q

what are considerations for prone positioning in a patient undergoing spine surgery?

A

1) Neutral position of cervical spine
* maintain neck in neutral position with foam headrest or cervical traction devices
2) eye and ear pressure

  • avoid turning face to one side
    • assoc with blindness and stroke
  • frequent checks of eye and ear position q30-60 min

3) Arm positioning (minimize brachial plexus injury)

  • c-spine surgery -> arms secured at sides
  • lumbar surgery -> superman; arms positioned at 90degres in all planes, arm boards, avoid excessive abduction

4) abdomen and breast protection

  • bolsters from tip of shoulders to iliac crest
  • decrease pressure of breast and abdomen (hang freely)
    • allows for venous return and diaphragmatic excrusion during ventilation
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9
Q

patient is undergoing spine surgery, and the surgeon asks you for induced hypotension to minimize blood loss. would you do this? are there other ways to minimze blood loss?

A
  • brain and spinal cord autoregulate b/w 50 - 150 mmHg
  • pathology may disrupt autoregulation -> blood flow becomes pressure dependent

Induced Hypotension

  • cardiac ischemic injury
  • ischemic optic neuropathy (esp in prone position)
  • end organ hypo-perfusion
  • cause reigonal ischemia to surgical site (esp since autoregulation may be disrupted)

minimize blood loss

  • consier antifibrinolytics
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10
Q

What is context sensitive half-time? How would you use your knowledge of propofol pharmacology to ensure a rapid but safe emergence?

A

context sens half time

  • time it takes to decrease plasma concentration of a drug by 50% after a steady-state infusion has been turned off
  • Propofol - turn off approx 40 minutes before surgical finish (if this was a long procedure)
    • keep in mind, propofol does not cause muscle relaxation -> self extubate in prone position
    • Can use EEG to give some insignt into tapering anesthesia.
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